Reimplement drag button

app/build.gradle

@@ -71,7 +71,6 @@ dependencies {
         exclude group: 'org.json'
     }
     compile ':measure:'
-    compile ':drag-button:1.1@aar'
     compile ':square-otto:1.3.9-SNAPSHOT'
     apt ':square-otto-compiler:1.3.9-SNAPSHOT'
     apt 'com.squareup:javapoet:1.5.1'

app/src/main/java/org/solovyev/android/calculator/CppNumeralBase.java

@@ -1,107 +0,0 @@
-/*
- * Copyright 2013 serso aka se.solovyev
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- * Contact details
- *
- * Email: se.solovyev@gmail.com
- * Site:  http://se.solovyev.org
- */
-
-package org.solovyev.android.calculator;
-
-import org.solovyev.android.calculator.keyboard.KeyboardUi;
-import org.solovyev.android.views.dragbutton.DirectionDragButton;
-import org.solovyev.android.views.dragbutton.DragDirection;
-
-import jscl.NumeralBase;
-
-import javax.annotation.Nonnull;
-
-public enum CppNumeralBase {
-
-    bin(NumeralBase.bin) {
-        @Override
-        public void toggleButtons(boolean show, @Nonnull KeyboardUi ui) {
-            toggleButton(show, ui.button0);
-            toggleButton(show, ui.button1);
-        }
-    },
-
-    oct(NumeralBase.oct) {
-        @Override
-        public void toggleButtons(boolean show, @Nonnull KeyboardUi ui) {
-            bin.toggleButtons(show, ui);
-            toggleButton(show, ui.button2);
-            toggleButton(show, ui.button3);
-            toggleButton(show, ui.button4);
-            toggleButton(show, ui.button5);
-            toggleButton(show, ui.button6);
-            toggleButton(show, ui.button7);
-        }
-    },
-
-    dec(NumeralBase.dec) {
-        @Override
-        public void toggleButtons(boolean show, @Nonnull KeyboardUi ui) {
-            oct.toggleButtons(show, ui);
-            toggleButton(show, ui.button8);
-            toggleButton(show, ui.button9);
-        }
-    },
-
-    hex(NumeralBase.hex) {
-        @Override
-        public void toggleButtons(boolean show, @Nonnull KeyboardUi ui) {
-            dec.toggleButtons(show, ui);
-            toggleLeftButton(show, ui.button1);
-            toggleLeftButton(show, ui.button2);
-            toggleLeftButton(show, ui.button3);
-            toggleLeftButton(show, ui.button4);
-            toggleLeftButton(show, ui.button5);
-            toggleLeftButton(show, ui.button6);
-        }
-
-        protected final void toggleLeftButton(boolean show, @Nonnull DirectionDragButton button) {
-            button.showDirectionText(show, DragDirection.left);
-            button.invalidate();
-        }
-    };
-
-    @Nonnull
-    public final NumeralBase numeralBase;
-
-    CppNumeralBase(@Nonnull NumeralBase numeralBase) {
-        this.numeralBase = numeralBase;
-    }
-
-    @Nonnull
-    public static CppNumeralBase valueOf(@Nonnull NumeralBase nb) {
-        for (CppNumeralBase cppNumeralBase : values()) {
-            if (cppNumeralBase.numeralBase == nb) {
-                return cppNumeralBase;
-            }
-        }
-
-        throw new IllegalArgumentException(nb + " is not supported numeral base!");
-    }
-
-    public abstract void toggleButtons(boolean show, @Nonnull KeyboardUi ui);
-
-    protected final void toggleButton(boolean show, @Nonnull DirectionDragButton button) {
-        button.setShowText(show);
-        button.invalidate();
-    }
-}

app/src/main/java/org/solovyev/android/calculator/FloatingCalculatorKeyboard.java

@@ -1,10 +1,8 @@
 package org.solovyev.android.calculator;
 
-import android.graphics.PointF;
 import android.support.annotation.IdRes;
 import android.support.annotation.NonNull;
 import android.text.TextUtils;
-import android.view.MotionEvent;
 import android.view.View;
 import android.widget.Button;
 import android.widget.LinearLayout;
@@ -12,15 +10,15 @@ import org.solovyev.android.calculator.keyboard.BaseFloatingKeyboard;
 import org.solovyev.android.calculator.keyboard.FloatingKeyboard;
 import org.solovyev.android.calculator.view.EditTextLongClickEraser;
 import org.solovyev.android.views.dragbutton.DirectionDragButton;
-import org.solovyev.android.views.dragbutton.DragButton;
+import org.solovyev.android.views.dragbutton.DirectionDragListener;
 import org.solovyev.android.views.dragbutton.DragDirection;
-import org.solovyev.android.views.dragbutton.SimpleDragListener;
+import org.solovyev.android.views.dragbutton.DragEvent;
 
 import java.util.List;
 
 import static android.view.HapticFeedbackConstants.*;
-import static org.solovyev.android.views.dragbutton.DirectionDragButton.Direction.down;
+import static org.solovyev.android.views.dragbutton.DragDirection.down;
-import static org.solovyev.android.views.dragbutton.DirectionDragButton.Direction.up;
+import static org.solovyev.android.views.dragbutton.DragDirection.up;
 
 
 public class FloatingCalculatorKeyboard extends BaseFloatingKeyboard {
@@ -29,12 +27,17 @@ public class FloatingCalculatorKeyboard extends BaseFloatingKeyboard {
     @NonNull
     private final List<String> parameterNames;
     @NonNull
-    private final SimpleDragListener dragListener;
+    private final DirectionDragListener dragListener;
 
     public FloatingCalculatorKeyboard(@NonNull User user, @NonNull List<String> parameterNames) {
         super(user);
         this.parameterNames = parameterNames;
-        this.dragListener = new SimpleDragListener(buttonHandler, user.getContext());
+        this.dragListener = new DirectionDragListener(user.getContext()) {
+            @Override
+            protected boolean onDrag(@NonNull View view, @NonNull DragEvent event, @NonNull DragDirection direction) {
+                return buttonHandler.onDrag(view, direction);
+            }
+        };
     }
 
     public void makeView(boolean landscape) {
@@ -73,29 +76,29 @@ public class FloatingCalculatorKeyboard extends BaseFloatingKeyboard {
         addButton(row, 0, parametersCount > 0 ? parameterNames.get(0) : "x");
         addButton(row, 0, "7");
         addButton(row, 0, "8");
-        addButton(row, 0, "9").setText("π", up).setText("e", down);
+        addButton(row, 0, "9").setText(up, "π").setText(down, "e");
-        addOperationButton(row, R.id.cpp_kb_button_multiply, "×").setText("^n", up).setText("^2", down);
+        addOperationButton(row, R.id.cpp_kb_button_multiply, "×").setText(up, "^n").setText(down, "^2");
         addOperationButton(row, R.id.cpp_kb_button_plus, "+");
         addButton(row, R.id.cpp_kb_button_clear, "C");
 
         row = makeRow();
-        addButton(row, R.id.cpp_kb_button_brackets, "( )").setText("(", up).setText(")", down);
+        addButton(row, R.id.cpp_kb_button_brackets, "( )").setText(up, "(").setText(down, ")");
         addButton(row, 0, parametersCount > 1 ? parameterNames.get(1) : "y");
         addButton(row, 0, "4");
         addButton(row, 0, "5");
         addButton(row, 0, "6");
-        addOperationButton(row, R.id.cpp_kb_button_divide, "/").setText("%", up).setText("sqrt", down);
+        addOperationButton(row, R.id.cpp_kb_button_divide, "/").setText(up, "%").setText(down, "sqrt");
         addOperationButton(row, R.id.cpp_kb_button_minus, "−");
         final View backspace = addImageButton(row, R.id.cpp_kb_button_backspace, R.drawable.ic_backspace_grey300_24dp);
         EditTextLongClickEraser.attachTo(backspace, user.getEditor(), user.isVibrateOnKeypress());
 
         row = makeRow();
         addButton(row, R.id.cpp_kb_button_functions_constants, "f/π");
-        addButton(row, 0, ".").setText(",", up);
+        addButton(row, 0, ".").setText(up, ",");
         addButton(row, 0, "1");
         addButton(row, 0, "2");
         addButton(row, 0, "3");
-        addButton(row, 0, "0").setText("00", up).setText("000", down);
+        addButton(row, 0, "0").setText(up, "00").setText(down, "000");
         addImageButton(row, R.id.cpp_kb_button_space, R.drawable.ic_space_bar_grey300_24dp);
         addImageButton(row, R.id.cpp_kb_button_close, R.drawable.ic_done_grey300_24dp);
     }
@@ -104,15 +107,15 @@ public class FloatingCalculatorKeyboard extends BaseFloatingKeyboard {
         LinearLayout row = makeRow();
         addButton(row, 0, "7");
         addButton(row, 0, "8");
-        addButton(row, 0, "9").setText("π", up).setText("e", down);
+        addButton(row, 0, "9").setText(up, "π").setText(down, "e");
-        addOperationButton(row, R.id.cpp_kb_button_multiply, "×").setText("^n", up).setText("^2", down);
+        addOperationButton(row, R.id.cpp_kb_button_multiply, "×").setText(up, "^n").setText(down, "^2");
         addButton(row, R.id.cpp_kb_button_clear, "C");
 
         row = makeRow();
         addButton(row, 0, "4");
         addButton(row, 0, "5");
         addButton(row, 0, "6");
-        addOperationButton(row, R.id.cpp_kb_button_divide, "/").setText("%", up).setText("sqrt", down);
+        addOperationButton(row, R.id.cpp_kb_button_divide, "/").setText(up, "%").setText(down, "sqrt");
         final View backspace = addImageButton(row, R.id.cpp_kb_button_backspace, R.drawable.ic_backspace_grey300_24dp);
         EditTextLongClickEraser.attachTo(backspace, user.getEditor(), user.isVibrateOnKeypress());
 
@@ -124,9 +127,9 @@ public class FloatingCalculatorKeyboard extends BaseFloatingKeyboard {
         addImageButton(row, R.id.cpp_kb_button_space, R.drawable.ic_space_bar_grey300_24dp);
 
         row = makeRow();
-        addButton(row, R.id.cpp_kb_button_brackets, "( )").setText("(", up).setText(")", down);
+        addButton(row, R.id.cpp_kb_button_brackets, "( )").setText(up, "(").setText(down, ")");
-        addButton(row, 0, "0").setText("00", up).setText("000", down);
+        addButton(row, 0, "0").setText(up, "00").setText(down, "000");
-        addButton(row, 0, ".").setText(",", up);
+        addButton(row, 0, ".").setText(up, ",");
         addOperationButton(row, R.id.cpp_kb_button_minus, "−");
         addImageButton(row, R.id.cpp_kb_button_keyboard, R.drawable.ic_keyboard_grey300_24dp);
 
@@ -163,7 +166,7 @@ public class FloatingCalculatorKeyboard extends BaseFloatingKeyboard {
 
     }
 
-    private class ButtonHandler implements View.OnClickListener, SimpleDragListener.DragProcessor {
+    private class ButtonHandler implements View.OnClickListener {
 
         @NonNull
         private final User user = getUser();
@@ -222,16 +225,8 @@ public class FloatingCalculatorKeyboard extends BaseFloatingKeyboard {
             user.insertText(((Button) v).getText(), 0);
         }
 
-        @Override
+        private boolean onDrag(@NonNull View button, @NonNull DragDirection direction) {
-        public boolean processDragEvent(@NonNull DragDirection direction, @NonNull DragButton button, @NonNull PointF startPoint, @NonNull MotionEvent e) {
+            final String text = ((DirectionDragButton) button).getTextValue(direction);
-            switch (button.getId()) {
-                default:
-                    return onDefaultDrag(button, direction);
-            }
-        }
-
-        private boolean onDefaultDrag(@NonNull DragButton button, @NonNull DragDirection direction) {
-            final String text = ((DirectionDragButton) button).getText(direction);
             if (TextUtils.isEmpty(text)) {
                 return false;
             }

app/src/main/java/org/solovyev/android/calculator/keyboard/BaseFloatingKeyboard.java

@@ -104,7 +104,6 @@ public abstract class BaseFloatingKeyboard implements FloatingKeyboard {
         final DirectionDragButton button = addButton(row, id, text);
         button.setBackgroundResource(R.drawable.material_button_light_primary);
         button.setTextColor(Color.WHITE);
-        button.setDirectionTextColor(Color.WHITE);
         return button;
     }
 

app/src/main/java/org/solovyev/android/calculator/keyboard/BaseKeyboardUi.java

@@ -12,26 +12,38 @@ import android.util.TypedValue;
 import android.view.View;
 import android.widget.ImageView;
 import android.widget.TextView;
-import org.solovyev.android.calculator.*;
+
+import org.solovyev.android.calculator.ActivityLauncher;
+import org.solovyev.android.calculator.App;
+import org.solovyev.android.calculator.BaseActivity;
+import org.solovyev.android.calculator.Calculator;
+import org.solovyev.android.calculator.Editor;
+import org.solovyev.android.calculator.Keyboard;
+import org.solovyev.android.calculator.Preferences;
+import org.solovyev.android.calculator.PreferredPreferences;
 import org.solovyev.android.calculator.buttons.CppSpecialButton;
 import org.solovyev.android.views.Adjuster;
 import org.solovyev.android.views.dragbutton.DirectionDragButton;
+import org.solovyev.android.views.dragbutton.DirectionDragListener;
 import org.solovyev.android.views.dragbutton.DragButton;
 import org.solovyev.android.views.dragbutton.DragDirection;
-import org.solovyev.android.views.dragbutton.SimpleDragListener;
+import org.solovyev.android.views.dragbutton.DragEvent;
 
-import javax.annotation.Nonnull;
-import javax.inject.Inject;
 import java.util.ArrayList;
 import java.util.List;
 
+import javax.annotation.Nonnull;
+import javax.inject.Inject;
+
 import static android.content.res.Configuration.ORIENTATION_PORTRAIT;
-import static android.view.HapticFeedbackConstants.*;
+import static android.view.HapticFeedbackConstants.FLAG_IGNORE_GLOBAL_SETTING;
+import static android.view.HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING;
+import static android.view.HapticFeedbackConstants.KEYBOARD_TAP;
 import static org.solovyev.android.calculator.App.cast;
 import static org.solovyev.android.calculator.Preferences.Gui.Layout.simple;
 import static org.solovyev.android.calculator.Preferences.Gui.Layout.simple_mobile;
 
-public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPreferenceChangeListener, SimpleDragListener.DragProcessor, View.OnClickListener {
+public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPreferenceChangeListener, View.OnClickListener {
 
     public static float getTextScale(@NonNull Context context) {
         return App.isTablet(context) ? 0.4f : 0.5f;
@@ -43,7 +55,7 @@ public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPrefer
     @NonNull
     private final List<DragButton> dragButtons = new ArrayList<>();
     @NonNull
-    protected final SimpleDragListener listener;
+    protected final DirectionDragListener listener;
     @Inject
     SharedPreferences preferences;
     @Inject
@@ -64,7 +76,12 @@ public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPrefer
     private final float textScale;
 
     public BaseKeyboardUi(@NonNull Application application) {
-        listener = new SimpleDragListener(this, application);
+        listener = new DirectionDragListener(application) {
+            @Override
+            protected boolean onDrag(@NonNull View view, @NonNull DragEvent event, @NonNull DragDirection direction) {
+                return BaseKeyboardUi.this.onDrag(view, direction);
+            }
+        };
         textScale = getTextScale(application);
     }
 
@@ -76,6 +93,8 @@ public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPrefer
         }
     }
 
+    protected abstract boolean onDrag(@NonNull View view, @NonNull DragDirection direction);
+
     public void onCreateView(@Nonnull Activity activity, @Nonnull View view) {
         cast(activity.getApplication()).getComponent().inject(this);
         preferences.registerOnSharedPreferenceChangeListener(this);
@@ -132,7 +151,7 @@ public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPrefer
         if (button == null) {
             return;
         }
-        button.showDirectionText(false, direction);
+        button.setShowDirectionText(direction, false);
     }
 
     public void onDestroyView() {

app/src/main/java/org/solovyev/android/calculator/keyboard/KeyboardUi.java

@@ -3,20 +3,15 @@ package org.solovyev.android.calculator.keyboard;
 import android.app.Activity;
 import android.app.Application;
 import android.content.SharedPreferences;
-import android.graphics.PointF;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.text.TextUtils;
 import android.util.Log;
-import android.view.MotionEvent;
 import android.view.View;
 import android.widget.Button;
 import android.widget.ImageButton;
-import butterknife.Bind;
+
-import butterknife.ButterKnife;
-import jscl.AngleUnit;
-import jscl.NumeralBase;
 import org.solovyev.android.calculator.ActivityLauncher;
-import org.solovyev.android.calculator.CppNumeralBase;
 import org.solovyev.android.calculator.Engine;
 import org.solovyev.android.calculator.R;
 import org.solovyev.android.calculator.buttons.CppSpecialButton;
@@ -29,8 +24,17 @@ import org.solovyev.android.views.dragbutton.DragDirection;
 import javax.annotation.Nonnull;
 import javax.inject.Inject;
 
-import static org.solovyev.android.calculator.Engine.Preferences.*;
+import butterknife.Bind;
-import static org.solovyev.android.views.dragbutton.DragDirection.*;
+import butterknife.ButterKnife;
+import jscl.AngleUnit;
+import jscl.NumeralBase;
+
+import static org.solovyev.android.calculator.Engine.Preferences.angleUnit;
+import static org.solovyev.android.calculator.Engine.Preferences.multiplicationSign;
+import static org.solovyev.android.calculator.Engine.Preferences.numeralBase;
+import static org.solovyev.android.views.dragbutton.DragDirection.down;
+import static org.solovyev.android.views.dragbutton.DragDirection.left;
+import static org.solovyev.android.views.dragbutton.DragDirection.up;
 
 public class KeyboardUi extends BaseKeyboardUi {
 
@@ -97,17 +101,13 @@ public class KeyboardUi extends BaseKeyboardUi {
     }
 
     public void toggleNumericDigits() {
-        toggleNumericDigits(numeralBase.getPreference(preferences));
+        final boolean hex = numeralBase.getPreference(preferences) == NumeralBase.hex;
-    }
+        button1.setShowDirectionText(left, hex);
-
+        button2.setShowDirectionText(left, hex);
-    public void toggleNumericDigits(@Nonnull NumeralBase currentNumeralBase) {
+        button3.setShowDirectionText(left, hex);
-        for (NumeralBase numeralBase : NumeralBase.values()) {
+        button4.setShowDirectionText(left, hex);
-            if (currentNumeralBase != numeralBase) {
+        button5.setShowDirectionText(left, hex);
-                CppNumeralBase.valueOf(numeralBase).toggleButtons(false, this);
+        button6.setShowDirectionText(left, hex);
-            }
-        }
-
-        CppNumeralBase.valueOf(currentNumeralBase).toggleButtons(true, this);
     }
 
     public void onCreateView(@Nonnull Activity activity, @Nonnull View view) {
@@ -227,8 +227,8 @@ public class KeyboardUi extends BaseKeyboardUi {
     }
 
     @Override
-    public boolean processDragEvent(@Nonnull DragDirection direction, @Nonnull DragButton button, @Nonnull PointF point, @Nonnull MotionEvent event) {
+    protected boolean onDrag(@NonNull View view, @NonNull DragDirection direction) {
-        switch (button.getId()) {
+        switch (view.getId()) {
             case R.id.cpp_button_vars:
                 launcher.showConstantEditor();
                 return true;
@@ -254,15 +254,15 @@ public class KeyboardUi extends BaseKeyboardUi {
                 }
                 return false;
             case R.id.cpp_button_6:
-                return processAngleUnitsButton(direction, (DirectionDragButton) button);
+                return processAngleUnitsButton(direction, (DirectionDragButton) view);
             case R.id.cpp_button_round_brackets:
                 if (direction == left) {
                     keyboard.roundBracketsButtonPressed();
                     return true;
                 }
-                return processDefault(direction, button);
+                return processDefault(direction, (DragButton) view);
             default:
-                return processDefault(direction, button);
+                return processDefault(direction, (DragButton) view);
         }
     }
 
@@ -270,7 +270,7 @@ public class KeyboardUi extends BaseKeyboardUi {
         if (direction == DragDirection.left) {
             return processDefault(direction, button);
         }
-        final String text = button.getText(direction);
+        final String text = button.getTextValue(direction);
         if (TextUtils.isEmpty(text)) {
             return processDefault(direction, button);
         }
@@ -288,7 +288,7 @@ public class KeyboardUi extends BaseKeyboardUi {
     }
 
     private boolean processDefault(@Nonnull DragDirection direction, @Nonnull DragButton button) {
-        final String text = ((DirectionDragButton) button).getText(direction);
+        final String text = ((DirectionDragButton) button).getTextValue(direction);
         return keyboard.buttonPressed(text);
     }
 }

app/src/main/java/org/solovyev/android/calculator/keyboard/PartialKeyboardUi.java

@@ -4,12 +4,10 @@ import android.app.Activity;
 import android.app.Application;
 import android.content.SharedPreferences;
 import android.content.res.Configuration;
-import android.graphics.PointF;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.text.TextUtils;
 import android.util.Log;
-import android.view.MotionEvent;
 import android.view.View;
 import android.widget.Button;
 import android.widget.ImageButton;
@@ -21,7 +19,6 @@ import org.solovyev.android.calculator.buttons.CppSpecialButton;
 import org.solovyev.android.calculator.view.EditorLongClickEraser;
 import org.solovyev.android.calculator.view.NumeralBasesButton;
 import org.solovyev.android.views.dragbutton.DirectionDragButton;
-import org.solovyev.android.views.dragbutton.DragButton;
 import org.solovyev.android.views.dragbutton.DragDirection;
 
 import javax.annotation.Nonnull;
@@ -115,8 +112,8 @@ public class PartialKeyboardUi extends BaseKeyboardUi {
     }
 
     @Override
-    public boolean processDragEvent(@Nonnull DragDirection direction, @Nonnull DragButton button, @Nonnull PointF point, @Nonnull MotionEvent event) {
+    protected boolean onDrag(@NonNull View view, @NonNull DragDirection direction) {
-        switch (button.getId()) {
+        switch (view.getId()) {
             case R.id.cpp_button_right:
                 editor.setCursorOnEnd();
                 return true;
@@ -134,7 +131,7 @@ public class PartialKeyboardUi extends BaseKeyboardUi {
 
                 return false;
             case R.id.cpp_button_clear:
-                return processNumeralBaseButton(direction, (DirectionDragButton) button);
+                return processNumeralBaseButton(direction, (DirectionDragButton) view);
         }
         return false;
     }
@@ -159,7 +156,7 @@ public class PartialKeyboardUi extends BaseKeyboardUi {
     }
 
     private boolean processNumeralBaseButton(@Nonnull DragDirection direction, @Nonnull DirectionDragButton button) {
-        final String text = button.getText(direction);
+        final String text = button.getTextValue(direction);
         if (TextUtils.isEmpty(text)) {
             return false;
         }

app/src/main/java/org/solovyev/android/calculator/view/AngleUnitsButton.java

@@ -23,16 +23,18 @@
 package org.solovyev.android.calculator.view;
 
 import android.content.Context;
-import android.graphics.Paint;
 import android.support.v4.content.ContextCompat;
-import android.text.TextPaint;
 import android.util.AttributeSet;
-import jscl.AngleUnit;
+
 import org.solovyev.android.calculator.R;
 import org.solovyev.android.views.dragbutton.DirectionDragButton;
+import org.solovyev.android.views.dragbutton.DirectionTextView;
+import org.solovyev.android.views.dragbutton.DragDirection;
 
 import javax.annotation.Nonnull;
 
+import jscl.AngleUnit;
+
 public class AngleUnitsButton extends DirectionDragButton {
 
     @Nonnull
@@ -40,37 +42,29 @@ public class AngleUnitsButton extends DirectionDragButton {
 
     public AngleUnitsButton(Context context, @Nonnull AttributeSet attrs) {
         super(context, attrs);
-    }
+        updateDirectionColors();
-
-    @Override
-    protected void initDirectionTextPaint(@Nonnull Paint basePaint, @Nonnull DirectionTextData textData) {
-        super.initDirectionTextPaint(basePaint, textData);
-
-        final String text = textData.getText();
-        final TextPaint paint = textData.getPaint();
-
-        final int color = getDirectionTextColor(text);
-        paint.setColor(color);
-        if (!isCurrentAngleUnits(text)) {
-            paint.setAlpha(directionTextAlpha);
-        }
-    }
-
-    int getDirectionTextColor(@Nonnull String directionText) {
-        if (isCurrentAngleUnits(directionText)) {
-            return ContextCompat.getColor(getContext(), R.color.cpp_selected_angle_unit_text);
-        }
-        return ContextCompat.getColor(getContext(), R.color.cpp_text);
     }
 
     boolean isCurrentAngleUnits(@Nonnull String directionText) {
-        return this.angleUnit.name().equals(directionText);
+        return angleUnit.name().equals(directionText);
     }
 
     public void setAngleUnit(@Nonnull AngleUnit angleUnit) {
-        if (this.angleUnit != angleUnit) {
+        if (this.angleUnit == angleUnit) {
+            return;
+        }
         this.angleUnit = angleUnit;
-            invalidate();
+        updateDirectionColors();
+    }
+
+    private void updateDirectionColors() {
+        for (DragDirection direction : DragDirection.values()) {
+            final DirectionTextView.Text text = getText(direction);
+            if (isCurrentAngleUnits(text.getValue())) {
+                text.setColor(ContextCompat.getColor(getContext(), R.color.cpp_selected_angle_unit_text), 1f);
+            } else {
+                text.setColor(ContextCompat.getColor(getContext(), R.color.cpp_text), DirectionTextView.DEF_ALPHA);
+            }
         }
     }
 }

app/src/main/java/org/solovyev/android/calculator/view/NumeralBasesButton.java

@@ -23,16 +23,18 @@
 package org.solovyev.android.calculator.view;
 
 import android.content.Context;
-import android.graphics.Paint;
 import android.support.v4.content.ContextCompat;
-import android.text.TextPaint;
 import android.util.AttributeSet;
-import jscl.NumeralBase;
+
 import org.solovyev.android.calculator.R;
 import org.solovyev.android.views.dragbutton.DirectionDragButton;
+import org.solovyev.android.views.dragbutton.DirectionTextView;
+import org.solovyev.android.views.dragbutton.DragDirection;
 
 import javax.annotation.Nonnull;
 
+import jscl.NumeralBase;
+
 public class NumeralBasesButton extends DirectionDragButton {
 
     @Nonnull
@@ -40,31 +42,11 @@ public class NumeralBasesButton extends DirectionDragButton {
 
     public NumeralBasesButton(Context context, @Nonnull AttributeSet attrs) {
         super(context, attrs);
-    }
+        updateDirectionColors();
-
-    @Override
-    protected void initDirectionTextPaint(@Nonnull Paint basePaint, @Nonnull DirectionTextData textData) {
-        super.initDirectionTextPaint(basePaint, textData);
-
-        final String text = textData.getText();
-        final TextPaint paint = textData.getPaint();
-
-        final int color = getDirectionTextColor(text);
-        paint.setColor(color);
-        if (!isCurrentNumberBase(text)) {
-            paint.setAlpha(directionTextAlpha);
-        }
-    }
-
-    int getDirectionTextColor(@Nonnull String directionText) {
-        if (isCurrentNumberBase(directionText)) {
-            return ContextCompat.getColor(getContext(), R.color.cpp_selected_angle_unit_text);
-        }
-        return ContextCompat.getColor(getContext(), R.color.cpp_text);
     }
 
     boolean isCurrentNumberBase(@Nonnull String directionText) {
-        return this.numeralBase.name().equals(directionText);
+        return numeralBase.name().equals(directionText);
     }
 
     public void setNumeralBase(@Nonnull NumeralBase numeralBase) {
@@ -72,6 +54,17 @@ public class NumeralBasesButton extends DirectionDragButton {
             return;
         }
         this.numeralBase = numeralBase;
-        invalidate();
+        updateDirectionColors();
+    }
+
+    private void updateDirectionColors() {
+        for (DragDirection direction : DragDirection.values()) {
+            final DirectionTextView.Text text = getText(direction);
+            if (isCurrentNumberBase(text.getValue())) {
+                text.setColor(ContextCompat.getColor(getContext(), R.color.cpp_selected_angle_unit_text), 1f);
+            } else {
+                text.setColor(ContextCompat.getColor(getContext(), R.color.cpp_text), DirectionTextView.DEF_ALPHA);
+            }
+        }
     }
 }

app/src/main/java/org/solovyev/android/calculator/wizard/ChooseModeWizardStep.java

@@ -35,7 +35,7 @@ import javax.annotation.Nonnull;
 
 import static org.solovyev.android.calculator.wizard.CalculatorMode.engineer;
 import static org.solovyev.android.calculator.wizard.CalculatorMode.simple;
-import static org.solovyev.android.views.dragbutton.DirectionDragButton.Direction.*;
+import static org.solovyev.android.views.dragbutton.DragDirection.*;
 
 public class ChooseModeWizardStep extends WizardFragment implements AdapterView.OnItemSelectedListener {
 
@@ -66,13 +66,13 @@ public class ChooseModeWizardStep extends WizardFragment implements AdapterView.
         boolean simple = mode == CalculatorMode.simple;
         description.setText(simple ? R.string.cpp_wizard_mode_simple_description : R.string.cpp_wizard_mode_engineer_description);
         if (simple) {
-            button.setText("", up);
+            button.setText(up, "");
-            button.setText("", down);
+            button.setText(down, "");
-            button.setText("", left);
+            button.setText(left, "");
         } else {
-            button.setText("sin", up);
+            button.setText(up, "sin");
-            button.setText("ln", down);
+            button.setText(down, "ln");
-            button.setText("i", left);
+            button.setText(left, "i");
         }
     }
 

app/src/main/java/org/solovyev/android/calculator/wizard/DragButtonWizardStep.java

@@ -22,12 +22,9 @@
 
 package org.solovyev.android.calculator.wizard;
 
-import static org.solovyev.android.calculator.App.cast;
-
-import android.graphics.PointF;
 import android.graphics.Typeface;
 import android.os.Bundle;
-import android.view.MotionEvent;
+import android.support.annotation.NonNull;
 import android.view.View;
 import android.widget.TextView;
 
@@ -36,16 +33,17 @@ import org.solovyev.android.calculator.R;
 import org.solovyev.android.calculator.keyboard.BaseKeyboardUi;
 import org.solovyev.android.views.Adjuster;
 import org.solovyev.android.views.dragbutton.DirectionDragButton;
-import org.solovyev.android.views.dragbutton.DragButton;
+import org.solovyev.android.views.dragbutton.DirectionDragListener;
 import org.solovyev.android.views.dragbutton.DragDirection;
-import org.solovyev.android.views.dragbutton.SimpleDragListener;
+import org.solovyev.android.views.dragbutton.DragEvent;
 
 import java.util.Arrays;
 
-import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static org.solovyev.android.calculator.App.cast;
+
 public class DragButtonWizardStep extends WizardFragment {
 
     private static final String ACTION = "action";
@@ -75,8 +73,16 @@ public class DragButtonWizardStep extends WizardFragment {
 
         final DirectionDragButton dragButton =(DirectionDragButton) root.findViewById(R.id.wizard_dragbutton);
         dragButton.setOnClickListener(this);
-        dragButton.setOnDragListener(
+        dragButton.setOnDragListener(new DirectionDragListener(getActivity()) {
-                new SimpleDragListener(new DragButtonProcessor(), getActivity()));
+            @Override
+            protected boolean onDrag(@NonNull View view, @NonNull DragEvent event, @NonNull DragDirection direction) {
+                if (action.dragDirection == direction) {
+                    setNextAction();
+                    return true;
+                }
+                return false;
+            }
+        });
         BaseActivity.setFont(dragButton, typeface);
         Adjuster.adjustText(dragButton, BaseKeyboardUi.getTextScale(getActivity()));
         actionTextView = (TextView) root.findViewById(R.id.wizard_dragbutton_action_textview);
@@ -143,18 +149,4 @@ public class DragButtonWizardStep extends WizardFragment {
         }
         super.onClick(v);
     }
-
-    private class DragButtonProcessor implements SimpleDragListener.DragProcessor {
-        @Override
-        public boolean processDragEvent(@Nonnull DragDirection dragDirection,
-                                        @Nonnull DragButton dragButton,
-                                        @Nonnull PointF startPoint,
-                                        @Nonnull MotionEvent motionEvent) {
-            if (action.dragDirection == dragDirection) {
-                setNextAction();
-                return true;
-            }
-            return false;
-        }
-    }
 }

app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragButton.java

@@ -0,0 +1,86 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.support.annotation.ColorInt;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.text.TextPaint;
+import android.util.AttributeSet;
+
+import javax.annotation.Nonnull;
+
+public class DirectionDragButton extends DragButton {
+    private final DirectionTextView textView = new DirectionTextView();
+    @NonNull
+    private final TextPaint baseTextPaint = new TextPaint();
+
+    public DirectionDragButton(Context context) {
+        super(context);
+        init(null);
+    }
+
+    public DirectionDragButton(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        init(attrs);
+    }
+
+    public DirectionDragButton(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        init(attrs);
+    }
+
+    public DirectionDragButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+        init(attrs);
+    }
+
+    private void init(@Nullable AttributeSet attrs) {
+        textView.init(this, attrs);
+        baseTextPaint.set(getPaint());
+    }
+
+    @Override
+    public boolean onPreDraw() {
+        final TextPaint paint = getPaint();
+        if (baseTextPaint.getTextSize() != paint.getTextSize() ||
+                baseTextPaint.getColor() != paint.getColor() ||
+                baseTextPaint.getAlpha() != paint.getAlpha()) {
+            baseTextPaint.set(paint);
+            textView.setBaseTextPaint(paint);
+        }
+        return super.onPreDraw();
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+        textView.draw(canvas);
+    }
+
+    @NonNull
+    public String getTextValue(@NonNull DragDirection direction) {
+        return getText(direction).getValue();
+    }
+
+    @NonNull
+    public DirectionDragButton setText(@NonNull DragDirection direction, @NonNull String value) {
+        getText(direction).setValue(value);
+        return this;
+    }
+
+    @Nonnull
+    protected DirectionTextView.Text getText(@NonNull DragDirection direction) {
+        return textView.getText(direction);
+    }
+
+    public void setShowDirectionText(@NonNull DragDirection direction, boolean show) {
+        getText(direction).setVisible(show);
+    }
+
+    public void setDirectionTextColor(@ColorInt int color) {
+        for (DragDirection direction : DragDirection.values()) {
+            getText(direction).setColor(color);
+        }
+    }
+}

app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragListener.java

@@ -0,0 +1,67 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.content.Context;
+import android.graphics.PointF;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.view.View;
+
+import org.solovyev.android.calculator.R;
+
+import static java.lang.Math.toDegrees;
+import static org.solovyev.android.views.dragbutton.Drag.distance;
+import static org.solovyev.android.views.dragbutton.Drag.getAngle;
+import static org.solovyev.android.views.dragbutton.Drag.sum;
+
+
+public abstract class DirectionDragListener implements DragListener {
+
+    @NonNull
+    private static final PointF axis = new PointF(0, 1);
+
+    private final float minDistancePxs;
+    private final boolean[] right = new boolean[1];
+
+    public DirectionDragListener(@NonNull Context context) {
+        this.minDistancePxs = context.getResources().getDimensionPixelSize(R.dimen.drag_min_distance);
+    }
+
+    @Override
+    public boolean onDrag(@NonNull View view, @NonNull DragEvent e) {
+        final long duration = e.motionEvent.getEventTime() - e.motionEvent.getDownTime();
+        if (duration < 40 || duration > 2500) {
+            return false;
+        }
+
+        final float distance = distance(e.start, e.end);
+        if (distance < minDistancePxs) {
+            return false;
+        }
+
+        final double angle = toDegrees(getAngle(e.start, sum(e.start, axis), e.end, right));
+        final DragDirection direction = getDirection((float) angle, right[0]);
+        if (direction == null) {
+            return false;
+        }
+
+        return onDrag(view, e, direction);
+    }
+
+    protected abstract boolean onDrag(@NonNull View view, @NonNull DragEvent event, @NonNull DragDirection direction);
+
+    @Nullable
+    private static DragDirection getDirection(float angle, boolean right) {
+        for (DragDirection direction : DragDirection.values()) {
+            if (direction == DragDirection.left && right) {
+                continue;
+            }
+            if (direction == DragDirection.right && !right) {
+                continue;
+            }
+            if (direction.angleFrom <= angle && angle <= direction.angleTo) {
+                return direction;
+            }
+        }
+        return null;
+    }
+}

app/src/main/java/org/solovyev/android/views/dragbutton/DirectionTextView.java

@@ -0,0 +1,217 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.graphics.Canvas;
+import android.graphics.PointF;
+import android.graphics.Rect;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.text.TextPaint;
+import android.text.TextUtils;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.TextView;
+
+import com.google.common.base.Strings;
+
+import org.solovyev.android.Check;
+import org.solovyev.android.calculator.R;
+
+import java.util.EnumMap;
+import java.util.Map;
+
+public class DirectionTextView {
+
+    public static final float DEF_ALPHA = 0.55f;
+    public static final float DEF_SCALE = 0.4f;
+
+    @NonNull
+    private final Map<DragDirection, Text> texts = new EnumMap<>(DragDirection.class);
+
+    public DirectionTextView() {
+    }
+
+    public void init(@NonNull TextView view, @Nullable AttributeSet attrs) {
+        init(view, attrs, view.getPaint());
+    }
+
+    public void setBaseTextPaint(@NonNull TextPaint baseTextPaint) {
+        for (Text text : texts.values()) {
+            text.initPaint(baseTextPaint);
+        }
+    }
+
+    public void init(@NonNull View view, @Nullable AttributeSet attrs, @NonNull TextPaint baseTextPaint) {
+        Check.isTrue(texts.isEmpty());
+        final Context context = view.getContext();
+        final int defColor = baseTextPaint.getColor();
+        final int defPadding = context.getResources().getDimensionPixelSize(R.dimen.cpp_direction_text_default_padding);
+        final float minTextSize = context.getResources().getDimensionPixelSize(R.dimen.cpp_direction_text_min_size);
+
+
+        if (attrs == null) {
+            for (DragDirection direction : DragDirection.values()) {
+                final Text text = new Text(direction, view, minTextSize);
+                text.init(baseTextPaint, null, DEF_SCALE, defColor, DEF_ALPHA, defPadding);
+                texts.put(direction, text);
+            }
+            return;
+        }
+        final TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.DirectionText);
+        final float scale = array.getFloat(R.styleable.DirectionText_directionTextScale, DEF_SCALE);
+        final float alpha = array.getFloat(R.styleable.DirectionText_directionTextAlpha, DEF_ALPHA);
+        final int color = array.getColor(R.styleable.DirectionText_directionTextColor, defColor);
+        final int padding = array.getDimensionPixelSize(R.styleable.DirectionText_directionTextPadding, defPadding);
+        for (DragDirection direction : DragDirection.values()) {
+            final Text text = new Text(direction, view, minTextSize);
+            text.init(baseTextPaint, array, scale, color, alpha, padding);
+            texts.put(direction, text);
+        }
+        array.recycle();
+    }
+
+    public void draw(@NonNull Canvas canvas) {
+        for (Text text : texts.values()) {
+            text.draw(canvas);
+        }
+    }
+
+    @NonNull
+    public Text getText(@NonNull DragDirection direction) {
+        return texts.get(direction);
+    }
+
+    public static class Text {
+        public final Rect bounds = new Rect();
+        @NonNull
+        private final TextPaint paint = new TextPaint();
+        @NonNull
+        private final DragDirection direction;
+        @NonNull
+        private final View view;
+        private final float minTextSize;
+        @NonNull
+        private final PointF position = new PointF(-1, -1);
+        @NonNull
+        private String value = "";
+        private float scale;
+        private int color;
+        private float alpha;
+        private boolean visible = true;
+        private int padding;
+
+        public Text(@NonNull DragDirection direction, @NonNull View view, float minTextSize) {
+            this.direction = direction;
+            this.view = view;
+            this.minTextSize = minTextSize;
+        }
+
+        public void init(@NonNull TextPaint base, @Nullable TypedArray array, float defScale, int defColor, float defAlpha, int defPadding) {
+            if (array != null) {
+                if (array.hasValue(direction.textAttr)) {
+                    value = Strings.nullToEmpty(array.getString(direction.textAttr));
+                }
+                scale = array.getFloat(direction.scaleAttr, defScale);
+            } else {
+                value = "";
+                scale = defScale;
+            }
+            alpha = defAlpha;
+            color = defColor;
+            padding = defPadding;
+            initPaint(base);
+        }
+
+        public void initPaint(@NonNull TextPaint base) {
+            paint.set(base);
+            paint.setColor(color);
+            paint.setAlpha(intAlpha());
+            paint.setTextSize(Math.max(base.getTextSize() * scale, minTextSize));
+            invalidate(true);
+        }
+
+        private int intAlpha() {
+            return (int) (255 * alpha);
+        }
+
+        public void setVisible(boolean visible) {
+            if (this.visible == visible) {
+                return;
+            }
+            this.visible = visible;
+            invalidate(false);
+        }
+
+        public void setColor(int color) {
+            setColor(color, this.alpha);
+        }
+
+        public void setColor(int color, float alpha) {
+            if (this.color == color && this.alpha == alpha) {
+                return;
+            }
+            this.color = color;
+            this.alpha = alpha;
+            paint.setColor(color);
+            paint.setAlpha(intAlpha());
+            invalidate(false);
+        }
+
+        private void invalidate(boolean remeasure) {
+            Check.isNotNull(view);
+            view.invalidate();
+            if (remeasure) {
+                position.set(-1, -1);
+            }
+        }
+
+        public void draw(@NonNull Canvas canvas) {
+            if (!visible || TextUtils.isEmpty(value)) {
+                return;
+            }
+            if (position.x < 0 || position.y < 0) {
+                calculatePosition();
+            }
+            canvas.drawText(value, position.x, position.y, paint);
+        }
+
+        private void calculatePosition() {
+            paint.getTextBounds(value, 0, value.length(), bounds);
+            switch (direction) {
+                case up:
+                case down:
+                    position.x = view.getWidth() - view.getPaddingLeft() - padding - bounds.width();
+                    if (direction == DragDirection.up) {
+                        position.y = view.getPaddingTop() + padding + bounds.height();
+                    } else {
+                        position.y = view.getHeight() - view.getPaddingBottom() - padding;
+                    }
+                    break;
+                case left:
+                case right:
+                    if (direction == DragDirection.left) {
+                        position.x = view.getPaddingLeft() + padding;
+                    } else {
+                        position.x = view.getWidth() - view.getPaddingLeft() - padding - bounds.width();
+                    }
+                    final int availableHeight = view.getHeight() - view.getPaddingTop() - view.getPaddingBottom();
+                    position.y = view.getPaddingTop() + padding + availableHeight / 2 + bounds.height() / 2;
+                    break;
+            }
+        }
+
+        @NonNull
+        public String getValue() {
+            return value;
+        }
+
+        public void setValue(@NonNull String value) {
+            if (TextUtils.equals(this.value, value)) {
+                return;
+            }
+            this.value = value;
+            invalidate(true);
+        }
+    }
+}

app/src/main/java/org/solovyev/android/views/dragbutton/Drag.java

@@ -0,0 +1,56 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.graphics.PointF;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+final class Drag {
+
+    private Drag() {
+    }
+
+    public static float distance(@NonNull PointF start,
+                                 @NonNull PointF end) {
+        return norm(end.x - start.x, end.y - start.y);
+    }
+
+    @NonNull
+    public static PointF subtract(@NonNull PointF p1, @NonNull PointF p2) {
+        return new PointF(p1.x - p2.x, p1.y - p2.y);
+    }
+
+    @NonNull
+    public static PointF sum(@NonNull PointF p1, @NonNull PointF p2) {
+        return new PointF(p1.x + p2.x, p1.y + p2.y);
+    }
+
+    public static float norm(@NonNull PointF point) {
+        return norm(point.x, point.y);
+    }
+
+    private static float norm(float x, float y) {
+        //noinspection SuspiciousNameCombination
+        return (float) Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
+    }
+
+    public static float getAngle(@NonNull PointF start,
+                                 @NonNull PointF axisEnd,
+                                 @NonNull PointF end,
+                                 @Nullable boolean[] right) {
+        final PointF axisVector = subtract(axisEnd, start);
+        final PointF vector = subtract(end, start);
+
+        double a_2 = Math.pow(distance(vector, axisVector), 2);
+        double b = norm(vector);
+        double b_2 = Math.pow(b, 2);
+        double c = norm(axisVector);
+        double c_2 = Math.pow(c, 2);
+
+        if (right != null) {
+            right[0] = axisVector.x * vector.y - axisVector.y * vector.x < 0;
+        }
+
+        return (float) Math.acos((-a_2 + b_2 + c_2) / (2 * b * c));
+    }
+
+}

app/src/main/java/org/solovyev/android/views/dragbutton/DragButton.java

@@ -0,0 +1,51 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.os.Build;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.widget.Button;
+
+public class DragButton extends Button {
+    @NonNull
+    private final DragGestureDetector dragDetector = new DragGestureDetector(this);
+
+    public DragButton(Context context) {
+        super(context);
+    }
+
+    public DragButton(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public DragButton(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+    public DragButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        if (dragDetector.onTouchEvent(event)) {
+            final MotionEvent cancelEvent = DragGestureDetector.makeCancelEvent(event);
+            super.onTouchEvent(cancelEvent);
+            cancelEvent.recycle();
+            return true;
+        }
+        return super.onTouchEvent(event);
+    }
+
+    public void setOnDragListener(@Nullable DragListener listener) {
+        dragDetector.setListener(listener);
+    }
+
+    public void setVibrateOnDrag(boolean vibrateOnDrag) {
+        dragDetector.setVibrateOnDrag(vibrateOnDrag);
+    }
+}

app/src/main/java/org/solovyev/android/views/dragbutton/DragDirection.java

@@ -0,0 +1,27 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.support.annotation.StyleableRes;
+
+import org.solovyev.android.calculator.R;
+
+public enum DragDirection {
+
+    up(180f - 45f, 180f - 0f, R.styleable.DirectionText_directionTextUp, R.styleable.DirectionText_directionTextScaleUp),
+    down(0f, 45f, R.styleable.DirectionText_directionTextDown, R.styleable.DirectionText_directionTextScaleDown),
+    left(90f - 45f, 90f + 45f, R.styleable.DirectionText_directionTextLeft, R.styleable.DirectionText_directionTextScaleLeft),
+    right(90f - 45f, 90f + 45f, R.styleable.DirectionText_directionTextRight, R.styleable.DirectionText_directionTextScaleRight);
+
+    final float angleFrom;
+    final float angleTo;
+    @StyleableRes
+    final int textAttr;
+    @StyleableRes
+    final int scaleAttr;
+
+    DragDirection(float angleFrom, float angleTo, int textAttr, int scaleAttr) {
+        this.angleFrom = angleFrom;
+        this.angleTo = angleTo;
+        this.textAttr = textAttr;
+        this.scaleAttr = scaleAttr;
+    }
+}

app/src/main/java/org/solovyev/android/views/dragbutton/DragEvent.java

@@ -0,0 +1,23 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.graphics.PointF;
+import android.support.annotation.NonNull;
+import android.view.MotionEvent;
+
+public class DragEvent {
+
+    @NonNull
+    public final PointF start;
+
+    @NonNull
+    public final PointF end;
+
+    @NonNull
+    public final MotionEvent motionEvent;
+
+    public DragEvent(@NonNull PointF start, @NonNull MotionEvent motionEvent) {
+        this.start = start;
+        this.end = new PointF(motionEvent.getX(), motionEvent.getY());
+        this.motionEvent = motionEvent;
+    }
+}

app/src/main/java/org/solovyev/android/views/dragbutton/DragGestureDetector.java

@@ -0,0 +1,77 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.graphics.PointF;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.view.MotionEvent;
+import android.view.View;
+
+import org.solovyev.android.Check;
+
+import static android.view.HapticFeedbackConstants.FLAG_IGNORE_GLOBAL_SETTING;
+import static android.view.HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING;
+import static android.view.HapticFeedbackConstants.KEYBOARD_TAP;
+
+public class DragGestureDetector {
+
+    @NonNull
+    private final View view;
+    @Nullable
+    private DragListener listener;
+    @Nullable
+    private PointF start;
+    private boolean vibrateOnDrag = true;
+
+    public DragGestureDetector(@NonNull View view) {
+        this.view = view;
+    }
+
+    @NonNull
+    static MotionEvent makeCancelEvent(@NonNull MotionEvent original) {
+        final MotionEvent event = MotionEvent.obtain(original);
+        event.setAction(MotionEvent.ACTION_CANCEL);
+        return event;
+    }
+
+    public boolean onTouchEvent(@NonNull MotionEvent event) {
+        switch (event.getAction()) {
+            case MotionEvent.ACTION_DOWN:
+                startTracking(event);
+                return false;
+            case MotionEvent.ACTION_CANCEL:
+            case MotionEvent.ACTION_UP:
+                return stopTracking(event);
+        }
+
+        return false;
+    }
+
+    private boolean stopTracking(@NonNull MotionEvent event) {
+        if (start == null || listener == null) {
+            start = null;
+            return false;
+        }
+        if (!listener.onDrag(view, new DragEvent(start, event))) {
+            start = null;
+            return false;
+        }
+        start = null;
+        if (vibrateOnDrag) {
+            view.performHapticFeedback(KEYBOARD_TAP, FLAG_IGNORE_GLOBAL_SETTING | FLAG_IGNORE_VIEW_SETTING);
+        }
+        return true;
+    }
+
+    public void setVibrateOnDrag(boolean vibrateOnDrag) {
+        this.vibrateOnDrag = vibrateOnDrag;
+    }
+
+    private void startTracking(@NonNull MotionEvent event) {
+        Check.isNull(start);
+        start = new PointF(event.getX(), event.getY());
+    }
+
+    public void setListener(@Nullable DragListener listener) {
+        this.listener = listener;
+    }
+}

app/src/main/java/org/solovyev/android/views/dragbutton/DragListener.java

@@ -0,0 +1,11 @@
+package org.solovyev.android.views.dragbutton;
+
+import android.support.annotation.NonNull;
+import android.view.View;
+
+import java.util.EventListener;
+
+
+public interface DragListener extends EventListener {
+    boolean onDrag(@NonNull View view, @NonNull DragEvent event);
+}

app/src/main/res/layout/cpp_app_button_0.xml

@@ -29,6 +29,6 @@
     a:id="@id/cpp_button_0"
     style="?attr/cpp_button_style_digit"
     a:text="0"
-    c:textDown="000"
+    c:directionTextDown="000"
-    c:textUp="00"
+    c:directionTextUp="00"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_1.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_1"
     style="?attr/cpp_button_style_digit"
     a:text="1"
-    c:textDown="asin"
+    c:directionTextDown="asin"
-    c:textLeft="A"
+    c:directionTextLeft="A"
-    c:textUp="sin"
+    c:directionTextUp="sin"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_2.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_2"
     style="?attr/cpp_button_style_digit"
     a:text="2"
-    c:textDown="acos"
+    c:directionTextDown="acos"
-    c:textLeft="B"
+    c:directionTextLeft="B"
-    c:textUp="cos"
+    c:directionTextUp="cos"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_3.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_3"
     style="?attr/cpp_button_style_digit"
     a:text="3"
-    c:textDown="atan"
+    c:directionTextDown="atan"
-    c:textLeft="C"
+    c:directionTextLeft="C"
-    c:textUp="tan"
+    c:directionTextUp="tan"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_4.xml

@@ -28,7 +28,7 @@
     a:id="@id/cpp_button_4"
     style="?attr/cpp_button_style_digit"
     a:text="4"
-    c:textDown="y"
+    c:directionTextDown="y"
-    c:textLeft="D"
+    c:directionTextLeft="D"
-    c:textUp="x"
+    c:directionTextUp="x"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_5.xml

@@ -28,7 +28,7 @@
     a:id="@id/cpp_button_5"
     style="?attr/cpp_button_style_digit"
     a:text="5"
-    c:textDown="j"
+    c:directionTextDown="j"
-    c:textLeft="E"
+    c:directionTextLeft="E"
-    c:textUp="t"
+    c:directionTextUp="t"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_6.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_6"
     style="?attr/cpp_button_style_digit"
     a:text="6"
-    c:textDown="rad"
+    c:directionTextDown="rad"
-    c:textLeft="F"
+    c:directionTextLeft="F"
-    c:textUp="deg"
+    c:directionTextUp="deg"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_7.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_7"
     style="?attr/cpp_button_style_digit"
     a:text="7"
-    c:textDown="!"
+    c:directionTextDown="!"
-    c:textLeft="0b:"
+    c:directionTextLeft="0b:"
-    c:textUp="i"
+    c:directionTextUp="i"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_8.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_8"
     style="?attr/cpp_button_style_digit"
     a:text="8"
-    c:textDown="lg"
+    c:directionTextDown="lg"
-    c:textLeft="0d:"
+    c:directionTextLeft="0d:"
-    c:textUp="ln"
+    c:directionTextUp="ln"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_9.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_9"
     style="?attr/cpp_button_style_digit"
     a:text="9"
-    c:textDown="e"
+    c:directionTextDown="e"
-    c:textLeft="0x:"
+    c:directionTextLeft="0x:"
-    c:textUp="π"
+    c:directionTextUp="π"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_clear.xml

@@ -29,6 +29,6 @@
     style="?attr/cpp_button_style_control_image"
     a:text="@string/c_clear"
     a:textStyle="bold"
-    c:textDown="bin"
+    c:directionTextDown="bin"
-    c:textLeft="hex"
+    c:directionTextLeft="hex"
-    c:textUp="dec" />
+    c:directionTextUp="dec" />

app/src/main/res/layout/cpp_app_button_division.xml

@@ -29,6 +29,6 @@
     a:id="@id/cpp_button_division"
     style="?attr/cpp_button_style_operation"
     a:text="/"
-    c:textDown="√"
+    c:directionTextDown="√"
-    c:textUp="%"
+    c:directionTextUp="%"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_dot.xml

@@ -29,5 +29,5 @@
     a:id="@id/cpp_button_period"
     style="?attr/cpp_button_style_digit"
     a:text="."
-    c:textUp=","
+    c:directionTextUp=","
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_equals.xml

@@ -28,6 +28,6 @@
     a:id="@id/cpp_button_equals"
     style="?attr/cpp_button_style_control"
     a:text="="
-    c:textDown="@string/cpp_plot_button_text"
+    c:directionTextDown="@string/cpp_plot_button_text"
-    c:textUp="≡"
+    c:directionTextUp="≡"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_equals_no_bg.xml

@@ -31,6 +31,6 @@
     a:text="="
     a:textColor="?android:attr/textColorPrimary"
     c:directionTextColor="?android:attr/textColorPrimary"
-    c:textDown="@string/cpp_plot_button_text"
+    c:directionTextDown="@string/cpp_plot_button_text"
-    c:textUp="≡"
+    c:directionTextUp="≡"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_functions.xml

@@ -30,5 +30,5 @@
     style="?attr/cpp_button_style_control"
     a:text="@string/cpp_kb_functions"
     a:textStyle="italic"
-    c:textUp="+ƒ"
+    c:directionTextUp="+ƒ"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_history.xml

@@ -28,5 +28,5 @@
     style="?attr/cpp_button_style_control"
     a:text="@string/c_history_button"
     a:textStyle="bold"
-    c:textDown="@string/cpp_kb_redo"
+    c:directionTextDown="@string/cpp_kb_redo"
-    c:textUp="@string/cpp_kb_undo" />
+    c:directionTextUp="@string/cpp_kb_undo" />

app/src/main/res/layout/cpp_app_button_left.xml

@@ -29,5 +29,5 @@
     a:id="@id/cpp_button_left"
     style="?attr/cpp_button_style_control"
     a:text="◁"
-    c:textUp="◁◁"
+    c:directionTextUp="◁◁"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_minus.xml

@@ -28,5 +28,5 @@
     a:id="@id/cpp_button_subtraction"
     style="?attr/cpp_button_style_operation"
     a:text="−"
-    c:textDown="@string/cpp_kb_operators"
+    c:directionTextDown="@string/cpp_kb_operators"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_multiplication.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_multiplication"
     style="?attr/cpp_button_style_operation"
     a:text="×"
-    c:textDown="^2"
+    c:directionTextDown="^2"
-    c:textLeft="Π"
+    c:directionTextLeft="Π"
-    c:textUp="^"
+    c:directionTextUp="^"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_plus.xml

@@ -28,6 +28,6 @@
     a:id="@id/cpp_button_plus"
     style="?attr/cpp_button_style_operation"
     a:text="+"
-    c:textDown="E"
+    c:directionTextDown="E"
-    c:textUp="°"
+    c:directionTextUp="°"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_right.xml

@@ -29,5 +29,5 @@
     a:id="@id/cpp_button_right"
     style="?attr/cpp_button_style_control"
     a:text="▷"
-    c:textUp="▷▷"
+    c:directionTextUp="▷▷"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_round_brackets.xml

@@ -29,7 +29,7 @@
     a:id="@id/cpp_button_round_brackets"
     style="?attr/cpp_button_style_digit"
     a:text="( )"
-    c:textDown=")"
+    c:directionTextDown=")"
-    c:textLeft="(…)"
+    c:directionTextLeft="(…)"
-    c:textUp="("
+    c:directionTextUp="("
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_app_button_vars.xml

@@ -30,5 +30,5 @@
     style="?attr/cpp_button_style_control"
     a:text="@string/cpp_kb_variables"
     a:textStyle="italic"
-    c:textUp="+π"
+    c:directionTextUp="+π"
     tools:ignore="HardcodedText" />

app/src/main/res/layout/cpp_wizard_step_drag_button.xml

@@ -53,7 +53,7 @@
         a:minHeight="100dp"
         a:minWidth="100dp"
         a:text="9"
-        c:textDown="^2"
+        c:directionTextDown="^2"
-        c:textUp="%" />
+        c:directionTextUp="%" />
 
 </LinearLayout>

app/src/main/res/values-land/text_non_translatable.xml

@@ -1,4 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <string name="cpp_direction_text_size" translatable="false">0.4;0.4;0.4;0.4</string>
-</resources>

app/src/main/res/values-small/dimens.xml

@@ -21,8 +21,8 @@
   -->
 
 <resources>
-    <dimen name="cpp_fragment_text_size">15sp</dimen>
     <dimen name="cpp_min_editor_text_size">18sp</dimen>
     <dimen name="cpp_display_text_size">20sp</dimen>
     <dimen name="cpp_clickable_area_size">40dp</dimen>
+    <dimen name="cpp_keyboard_button_direction_text_padding">1dp</dimen>
 </resources>

app/src/main/res/values/dimens.xml

@@ -8,8 +8,12 @@
     <dimen name="min_expanded_height_lock_screen">300dp</dimen>
     <dimen name="cpp_text_size">20sp</dimen>
     <dimen name="cpp_button_padding">1px</dimen>
+    <dimen name="cpp_direction_text_default_padding">2dp</dimen>
+    <dimen name="cpp_direction_text_min_size">9dp</dimen>
+    <item name="cpp_direction_text_scale" format="float" type="dimen">0.3</item>
     <dimen name="cpp_button_corner">1dp</dimen>
 
+    <dimen name="cpp_keyboard_button_direction_text_padding">4dp</dimen>
     <dimen name="cpp_keyboard_button_text_size">30dp</dimen>
     <dimen name="cpp_keyboard_simple_image_button_padding">12dp</dimen>
 

app/src/main/res/values/drag_attrs.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <declare-styleable name="DirectionText">
+        <attr name="directionTextColor" format="color"/>
+        <attr name="directionTextAlpha" format="float"/>
+        <attr name="directionTextUp" format="string"/>
+        <attr name="directionTextDown" format="string"/>
+        <attr name="directionTextRight" format="string"/>
+        <attr name="directionTextLeft" format="string"/>
+        <attr name="directionTextScale" format="float"/>
+        <attr name="directionTextPadding" format="dimension"/>
+        <attr name="directionTextScaleUp" format="float"/>
+        <attr name="directionTextScaleDown" format="float"/>
+        <attr name="directionTextScaleRight" format="float"/>
+        <attr name="directionTextScaleLeft" format="float"/>
+    </declare-styleable>
+</resources>

app/src/main/res/values/drag_dimens.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <dimen name="drag_min_distance">25dp</dimen>
+</resources>

app/src/main/res/values/styles.xml

@@ -39,7 +39,8 @@
         <item name="android:textColor">@color/cpp_button_text</item>
         <item name="android:scaleType">centerInside</item>
         <item name="directionTextColor">@color/cpp_button_text</item>
-        <item name="directionTextScale">@string/cpp_direction_text_size</item>
+        <item name="directionTextScale">@dimen/cpp_direction_text_scale</item>
+        <item name="directionTextPadding">@dimen/cpp_keyboard_button_direction_text_padding</item>
     </style>
 
     <style name="CppText.Editor.Onscreen.Light" parent="CppText.Editor.Onscreen">

app/src/main/res/values/text_non_translatable.xml

@@ -5,7 +5,6 @@
     <string name="cpp_kb_operators" translatable="false">∂</string>
     <string name="cpp_kb_undo" translatable="false">↶</string>
     <string name="cpp_kb_redo" translatable="false">↷</string>
-    <string name="cpp_direction_text_size" translatable="false">0.3;0.3;0.3;0.3</string>
     <string name="cpp_plot_add_function" translatable="false">+</string>
     <string name="cpp_plot_zoom_in" translatable="false">+</string>
     <string name="cpp_plot_zoom_reset" translatable="false">0</string>

app/src/test/java/org/solovyev/android/calculator/view/AngleUnitsButtonTest.java

@@ -1,8 +1,8 @@
 package org.solovyev.android.calculator.view;
 
 import android.app.Activity;
-
 import android.os.Build;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -20,10 +20,7 @@ import java.util.ArrayList;
 import static jscl.AngleUnit.deg;
 import static jscl.AngleUnit.grad;
 import static jscl.AngleUnit.rad;
-import static jscl.AngleUnit.turns;
-import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotSame;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -41,17 +38,6 @@ public class AngleUnitsButtonTest {
         button = new AngleUnitsButton(context, activity.createAttributeSet(new ArrayList<Attribute>(), AngleUnitsButton.class));
     }
 
-    @Test
-    public void testShouldReturnDifferentColorsForDifferentAngleUnits() throws Exception {
-        button.setAngleUnit(deg);
-
-        assertEquals(button.getDirectionTextColor(deg.name()), button.getDirectionTextColor(deg.name()));
-        assertEquals(button.getDirectionTextColor(grad.name()), button.getDirectionTextColor(rad.name()));
-        assertNotSame(button.getDirectionTextColor(deg.name()), button.getDirectionTextColor(rad.name()));
-        assertNotSame(button.getDirectionTextColor(deg.name()), button.getDirectionTextColor(grad.name()));
-        assertNotSame(button.getDirectionTextColor(deg.name()), button.getDirectionTextColor(turns.name()));
-    }
-
     @Test
     public void testIsCurrentAngleUnits() throws Exception {
         button.setAngleUnit(rad);

app/src/test/java/org/solovyev/android/calculator/view/NumeralBasesButtonTest.java

@@ -1,8 +1,8 @@
 package org.solovyev.android.calculator.view;
 
 import android.app.Activity;
-
 import android.os.Build;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -20,10 +20,7 @@ import java.util.ArrayList;
 import static jscl.NumeralBase.bin;
 import static jscl.NumeralBase.dec;
 import static jscl.NumeralBase.hex;
-import static jscl.NumeralBase.oct;
-import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotSame;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -41,17 +38,6 @@ public class NumeralBasesButtonTest {
         button = new NumeralBasesButton(context, activity.createAttributeSet(new ArrayList<Attribute>(), NumeralBasesButton.class));
     }
 
-    @Test
-    public void testShouldReturnDifferentColorsForDifferentNumeralBase() throws Exception {
-        button.setNumeralBase(dec);
-
-        assertEquals(button.getDirectionTextColor(dec.name()), button.getDirectionTextColor(dec.name()));
-        assertEquals(button.getDirectionTextColor(hex.name()), button.getDirectionTextColor(bin.name()));
-        assertNotSame(button.getDirectionTextColor(dec.name()), button.getDirectionTextColor(bin.name()));
-        assertNotSame(button.getDirectionTextColor(dec.name()), button.getDirectionTextColor(hex.name()));
-        assertNotSame(button.getDirectionTextColor(dec.name()), button.getDirectionTextColor(oct.name()));
-    }
-
     @Test
     public void testIsCurrentNumeralBase() throws Exception {
         button.setNumeralBase(dec);