From 70ff5a109e1eddf7373a5b8bc8328fddcb044a12 Mon Sep 17 00:00:00 2001
From: serso <se.solovyev@gmail.com>
Date: Sat, 16 Jul 2011 23:25:12 +0400
Subject: [PATCH] drag button calibration

---
 AndroidManifest.xml                           |  23 +--
 gen/org/solovyev/android/calculator/R.java    |  82 ++++++----
 res/layout/drag_button_calibration.xml        |  27 ++++
 res/menu/main_menu.xml                        |   9 ++
 res/values-ru/strings.xml                     |   2 +-
 res/values/strings.xml                        |  11 +-
 res/xml/preferences.xml                       |  20 +++
 ...alculator.java => CalculatorActivity.java} | 144 ++++++++++++------
 .../CalculatorPreferencesActivity.java        |  44 ++++++
 .../DragButtonCalibrationActivity.java        | 140 +++++++++++++++++
 src/org/solovyev/android/view/DragButton.java |  20 ++-
 .../solovyev/android/view/DragDirection.java  |   4 +-
 src/org/solovyev/android/view/DragEvent.java  |  15 +-
 .../android/view/SimpleOnDragListener.java    | 124 +++++++--------
 src/org/solovyev/util/math/MathUtils.java     |  28 +++-
 15 files changed, 532 insertions(+), 161 deletions(-)
 create mode 100644 res/layout/drag_button_calibration.xml
 create mode 100644 res/menu/main_menu.xml
 create mode 100644 res/xml/preferences.xml
 rename src/org/solovyev/android/calculator/{Calculator.java => CalculatorActivity.java} (63%)
 create mode 100644 src/org/solovyev/android/calculator/CalculatorPreferencesActivity.java
 create mode 100644 src/org/solovyev/android/calculator/DragButtonCalibrationActivity.java

diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index c6e6e261..0fa5d311 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -4,15 +4,20 @@
 	  package="org.solovyev.android.calculator"
       versionCode="1"
       versionName="1.0">
-    <a:uses-sdk a:minSdkVersion="8"/>
 
-    <a:application a:icon="@drawable/icon" a:label="@string/app_name_caption">
-        <a:activity a:name=".Calculator" a:label="@string/app_name_caption">
-            <a:intent-filter>
-                <a:action a:name="android.intent.action.MAIN" />
-                <a:category a:name="android.intent.category.LAUNCHER" />
-            </a:intent-filter>
-        </a:activity>
+	<uses-sdk a:minSdkVersion="8"/>
 
-    </a:application>
+    <application a:icon="@drawable/icon" a:label="@string/c_app_name">
+
+		<activity a:name=".CalculatorActivity" a:label="@string/c_app_name">
+            <intent-filter>
+                <action a:name="android.intent.action.MAIN" />
+                <category a:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+		<activity a:name=".CalculatorPreferencesActivity" a:label="@string/c_app_settings"/>
+		<activity a:name=".DragButtonCalibrationActivity" a:label="@string/c_prefs_drag_button_calibration"/>
+
+    </application>
 </manifest>
\ No newline at end of file
diff --git a/gen/org/solovyev/android/calculator/R.java b/gen/org/solovyev/android/calculator/R.java
index 10453268..33366b49 100644
--- a/gen/org/solovyev/android/calculator/R.java
+++ b/gen/org/solovyev/android/calculator/R.java
@@ -30,43 +30,63 @@ containing a value of this type.
         public static final int icon=0x7f020000;
     }
     public static final class id {
-        public static final int curlyBracketsButton=0x7f060013;
-        public static final int editText=0x7f060000;
-        public static final int eigthDigitButton=0x7f06000f;
-        public static final int equalsButton=0x7f060011;
-        public static final int fiveDigitButton=0x7f060009;
-        public static final int fourDigitButton=0x7f060008;
-        public static final int historyButton=0x7f060018;
-        public static final int minusButton=0x7f06000c;
-        public static final int muliplicationButton=0x7f060005;
-        public static final int nineDigitButton=0x7f060010;
-        public static final int numericButton=0x7f060016;
-        public static final int oneDigitButton=0x7f060002;
-        public static final int piButton=0x7f060019;
-        public static final int plusButton=0x7f060006;
-        public static final int pointDigitButton=0x7f060015;
-        public static final int resultEditText=0x7f060001;
-        public static final int roundBracketsButton=0x7f060007;
-        public static final int sevenDigitButton=0x7f06000e;
-        public static final int simplifyButton=0x7f060017;
-        public static final int sixDigitButton=0x7f06000a;
-        public static final int sqrtButton=0x7f060012;
-        public static final int squareBracketsButton=0x7f06000d;
-        public static final int subtractionButton=0x7f06000b;
-        public static final int threeDigitButton=0x7f060004;
-        public static final int twoDigitButton=0x7f060003;
-        public static final int zeroDigitButton=0x7f060014;
+        public static final int calibrationButton=0x7f080000;
+        public static final int calibrationStart=0x7f080001;
+        public static final int curlyBracketsButton=0x7f080015;
+        public static final int editText=0x7f080002;
+        public static final int eigthDigitButton=0x7f080011;
+        public static final int equalsButton=0x7f080013;
+        public static final int fiveDigitButton=0x7f08000b;
+        public static final int fourDigitButton=0x7f08000a;
+        public static final int historyButton=0x7f08001a;
+        public static final int menu_item_help=0x7f08001d;
+        public static final int menu_item_settings=0x7f08001c;
+        public static final int minusButton=0x7f08000e;
+        public static final int muliplicationButton=0x7f080007;
+        public static final int nineDigitButton=0x7f080012;
+        public static final int numericButton=0x7f080018;
+        public static final int oneDigitButton=0x7f080004;
+        public static final int piButton=0x7f08001b;
+        public static final int plusButton=0x7f080008;
+        public static final int pointDigitButton=0x7f080017;
+        public static final int resultEditText=0x7f080003;
+        public static final int roundBracketsButton=0x7f080009;
+        public static final int sevenDigitButton=0x7f080010;
+        public static final int simplifyButton=0x7f080019;
+        public static final int sixDigitButton=0x7f08000c;
+        public static final int sqrtButton=0x7f080014;
+        public static final int squareBracketsButton=0x7f08000f;
+        public static final int subtractionButton=0x7f08000d;
+        public static final int threeDigitButton=0x7f080006;
+        public static final int twoDigitButton=0x7f080005;
+        public static final int zeroDigitButton=0x7f080016;
     }
     public static final class layout {
-        public static final int main=0x7f030000;
+        public static final int drag_button_calibration=0x7f030000;
+        public static final int main=0x7f030001;
+    }
+    public static final class menu {
+        public static final int main_menu=0x7f070000;
     }
     public static final class string {
-        public static final int app_name_caption=0x7f040000;
-        public static final int syntax_error=0x7f040001;
+        public static final int c_app_name=0x7f050000;
+        public static final int c_app_settings=0x7f050001;
+        public static final int c_down=0x7f050008;
+        public static final int c_help=0x7f050004;
+        public static final int c_prefs_drag_button_calibration=0x7f050006;
+        public static final int c_prefs_drag_button_calibration_summary=0x7f050007;
+        public static final int c_prefs_main_category=0x7f050005;
+        public static final int c_restart=0x7f05000a;
+        public static final int c_settings=0x7f050003;
+        public static final int c_up=0x7f050009;
+        public static final int syntax_error=0x7f050002;
     }
     public static final class style {
-        public static final int digitButtonStyle=0x7f050001;
-        public static final int editTextInputStyle=0x7f050000;
+        public static final int digitButtonStyle=0x7f060001;
+        public static final int editTextInputStyle=0x7f060000;
+    }
+    public static final class xml {
+        public static final int preferences=0x7f040000;
     }
     public static final class styleable {
         /** Attributes that can be used with a DragButton.
diff --git a/res/layout/drag_button_calibration.xml b/res/layout/drag_button_calibration.xml
new file mode 100644
index 00000000..c77f4f2e
--- /dev/null
+++ b/res/layout/drag_button_calibration.xml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<LinearLayout xmlns:a="http://schemas.android.com/apk/res/android"
+			  xmlns:calc="http://schemas.android.com/apk/res/org.solovyev.android.calculator"
+
+			  a:orientation="vertical"
+			  a:padding="6dp"
+			  a:layout_width="fill_parent"
+			  a:layout_height="fill_parent">
+
+
+	<org.solovyev.android.view.DragButton a:id="@+id/calibrationButton"
+										  a:text=""
+										  calc:textUp="@string/c_up"
+										  calc:textDown="@string/c_down"
+										  style="@style/digitButtonStyle"
+										  a:layout_width="50dp"
+										  a:layout_height="50dp"
+										  a:gravity="center_vertical"			/>
+
+	<Button a:id="@+id/calibrationStart"
+			a:text="@string/c_restart"
+			a:layout_width="wrap_content"
+			a:layout_height="wrap_content"
+			a:onClick="restartClickHandler"
+			a:gravity="bottom"/>
+</LinearLayout>
diff --git a/res/menu/main_menu.xml b/res/menu/main_menu.xml
new file mode 100644
index 00000000..53b9290d
--- /dev/null
+++ b/res/menu/main_menu.xml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<menu xmlns:a="http://schemas.android.com/apk/res/android">
+	<item a:id="@+id/menu_item_settings"
+		  a:title="@string/c_settings"/>
+
+	<item a:id="@+id/menu_item_help"
+		  a:title="@string/c_help"/>
+</menu>
\ No newline at end of file
diff --git a/res/values-ru/strings.xml b/res/values-ru/strings.xml
index 0d00b21b..33d8c13c 100644
--- a/res/values-ru/strings.xml
+++ b/res/values-ru/strings.xml
@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
-    <string name="app_name_caption">Калькулятор</string>
+    <string name="c_app_name">Калькулятор</string>
 </resources>
diff --git a/res/values/strings.xml b/res/values/strings.xml
index fc8fb691..e6dd71f6 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -1,5 +1,14 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
-    <string name="app_name_caption">Calculator</string>
+    <string name="c_app_name">Calculator</string>
+    <string name="c_app_settings">Calculator</string>
     <string name="syntax_error">Syntax error</string>
+	<string name="c_settings">Settings</string>
+	<string name="c_help">Help</string>
+	<string name="c_prefs_main_category">Main settings</string>
+	<string name="c_prefs_drag_button_calibration">Drag button calibration</string>
+	<string name="c_prefs_drag_button_calibration_summary">Allows to calibrate drag button behaviour</string>
+	<string name="c_down">Down</string>
+	<string name="c_up">Up</string>
+	<string name="c_restart">Restart</string>
 </resources>
diff --git a/res/xml/preferences.xml b/res/xml/preferences.xml
new file mode 100644
index 00000000..0ee7d313
--- /dev/null
+++ b/res/xml/preferences.xml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<PreferenceScreen xmlns:a="http://schemas.android.com/apk/res/android">
+	<PreferenceCategory a:title="@string/c_prefs_main_category">
+
+
+		<Preference
+				a:title="@string/c_prefs_drag_button_calibration"
+				a:summary="@string/c_prefs_drag_button_calibration_summary"
+				a:key="dragButtonCalibration"/>
+
+		<CheckBoxPreference
+				a:title="Checkbox Preference"
+				a:defaultValue="false"
+				a:summary="This preference can be true or false"
+				a:key="checkboxPref"/>
+
+	</PreferenceCategory>
+
+</PreferenceScreen>
\ No newline at end of file
diff --git a/src/org/solovyev/android/calculator/Calculator.java b/src/org/solovyev/android/calculator/CalculatorActivity.java
similarity index 63%
rename from src/org/solovyev/android/calculator/Calculator.java
rename to src/org/solovyev/android/calculator/CalculatorActivity.java
index f2d4c58f..9f2e16f6 100644
--- a/src/org/solovyev/android/calculator/Calculator.java
+++ b/src/org/solovyev/android/calculator/CalculatorActivity.java
@@ -3,13 +3,11 @@ package org.solovyev.android.calculator;
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
 
+import android.content.Intent;
+import android.view.*;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.solovyev.android.calculator.R;
-import org.solovyev.android.view.DragButton;
-import org.solovyev.android.view.DragEvent;
-import org.solovyev.android.view.OnDragListener;
-import org.solovyev.android.view.SimpleOnDragListener;
+import org.solovyev.android.view.*;
 import org.solovyev.util.StringUtils;
 import org.solovyev.util.math.MathEntityType;
 
@@ -19,14 +17,14 @@ import bsh.Interpreter;
 import android.app.Activity;
 import android.os.Bundle;
 import android.util.Log;
-import android.view.View;
 import android.widget.EditText;
+import org.solovyev.util.math.Point2d;
 
-public class Calculator extends Activity {
+public class CalculatorActivity extends Activity {
 
 	@NotNull
 	private EditText editText;
-	
+
 	@NotNull
 	private EditText resultEditText;
 
@@ -35,18 +33,36 @@ public class Calculator extends Activity {
 
 	@NotNull
 	private HistoryHelper<EditorHistoryState> historyHelper;
-	
-	/** Called when the activity is first created. */
+
+	/**
+	 * Called when the activity is first created.
+	 */
 	@Override
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 		setContentView(R.layout.main);
 
 		this.editText = (EditText) findViewById(R.id.editText);
-		
+
 		this.resultEditText = (EditText) findViewById(R.id.resultEditText);
 
-		final SimpleOnDragListener onDragListener = new SimpleOnDragListener();
+		final SimpleOnDragListener onDragListener = new SimpleOnDragListener(new SimpleOnDragListener.DragProcessor() {
+			@Override
+			public boolean processDragEvent(@NotNull DragDirection dragDirection, @NotNull DragButton dragButton, @NotNull Point2d startPoint2d, @NotNull MotionEvent motionEvent) {
+				boolean result = isDirectionSupported(dragButton, dragDirection);
+
+				if (result) {
+					processButtonAction(dragButton, getActionText(dragButton, dragDirection));
+				}
+
+				return result;
+			}
+
+			public boolean isDirectionSupported(@NotNull DragButton dragButton, @NotNull DragDirection direction) {
+				return !StringUtils.isEmpty(getActionText(dragButton, direction));
+			}
+
+		});
 
 		// todo serso: check if there is more convenient method for doing this
 		final R.id ids = new R.id();
@@ -59,31 +75,31 @@ public class Calculator extends Activity {
 						((DragButton) view).setOnDragListener(onDragListener);
 					}
 				} catch (IllegalArgumentException e) {
-					Log.e(Calculator.class.getName(), e.getMessage());
+					Log.e(CalculatorActivity.class.getName(), e.getMessage());
 				} catch (IllegalAccessException e) {
-					Log.e(Calculator.class.getName(), e.getMessage());
+					Log.e(CalculatorActivity.class.getName(), e.getMessage());
 				}
 			}
 		}
 
-		((DragButton) findViewById(R.id.historyButton)).setOnDragListener(new HistoryOnDragListener());
-		
+		((DragButton) findViewById(R.id.historyButton)).setOnDragListener(new SimpleOnDragListener(new HistoryDragProcessor()));
+
 		this.interpreter = new Interpreter();
 
 		try {
 			interpreter.eval(Preprocessor.wrap(JsclOperation.importCommands, "/jscl/editorengine/commands"));
 		} catch (EvalError e) {
-			Log.e(Calculator.class.getName(), e.getMessage());
+			Log.e(CalculatorActivity.class.getName(), e.getMessage());
 		}
-		
+
 		this.historyHelper = new SimpleHistoryHelper<EditorHistoryState>();
 		this.historyHelper.addState(getCurrentHistoryState());
 	}
-	
+
 	public void elementaryButtonClickHandler(@NotNull View v) {
 		eval(JsclOperation.elementary);
 	}
-	
+
 	public void numericButtonClickHandler(@NotNull View v) {
 		eval(JsclOperation.numeric);
 	}
@@ -97,25 +113,30 @@ public class Calculator extends Activity {
 			final String preprocessedString = Preprocessor.process(String.valueOf(editText.getText()));
 			resultEditText.setText(String.valueOf(interpreter.eval(Preprocessor.wrap(operation, preprocessedString))));
 		} catch (EvalError e) {
-			Log.e(Calculator.class.getName(), e.getMessage());
+			Log.e(CalculatorActivity.class.getName(), e.getMessage());
 			resultEditText.setText(R.string.syntax_error);
 		}
 	}
-	
+
 	public void digitButtonClickHandler(@NotNull View v) {
 		processButtonAction(v, ((DragButton) v).getTextMiddle());
 	}
-	
-	private final class HistoryOnDragListener implements OnDragListener {
-		@Override
-		public void onDrag(@NotNull DragButton dragButton, @NotNull DragEvent event) {
-			Log.d(String.valueOf(dragButton.getId()), "History on drag event start: " + event.getDirection());
 
-			String actionText = getActionText(dragButton, event);
+	private final class HistoryDragProcessor implements SimpleOnDragListener.DragProcessor {
+
+		@Override
+		public boolean processDragEvent(@NotNull DragDirection dragDirection, @NotNull DragButton dragButton, @NotNull Point2d startPoint2d, @NotNull MotionEvent motionEvent) {
+			boolean result = false;
+
+			Log.d(String.valueOf(dragButton.getId()), "History on drag event start: " + dragDirection);
+
+			String actionText = getActionText(dragButton, dragDirection);
 			if (!StringUtils.isEmpty(actionText)) {
 				try {
+					result = true;
+
 					final HistoryAction historyAction = HistoryAction.valueOf(actionText);
-					if ( historyHelper.isActionAvailable(historyAction) ){
+					if (historyHelper.isActionAvailable(historyAction)) {
 						final EditorHistoryState newState = historyHelper.doAction(historyAction, getCurrentHistoryState());
 						if (newState != null) {
 							setCurrentHistoryState(newState);
@@ -125,51 +146,53 @@ public class Calculator extends Activity {
 					Log.e(String.valueOf(dragButton.getId()), "Unsupported history action: " + actionText);
 				}
 			}
+
+			return result;
 		}
 	}
 
 	@Nullable
-	private static String getActionText(@NotNull DragButton dragButton, @NotNull DragEvent event) {
+	private static String getActionText(@NotNull DragButton dragButton, @NotNull DragDirection direction) {
 		final String result;
-		
-		switch(event.getDirection()) {
+
+		switch (direction) {
 			case up:
 				result = dragButton.getTextUp();
 				break;
-			
+
 			case down:
 				result = dragButton.getTextDown();
 				break;
-				
+
 			default:
 				result = null;
 				break;
 		}
-		
+
 		return result;
 	}
-	
-	public void setCurrentHistoryState(@Nullable EditorHistoryState editorHistoryState) {
+
+	public void setCurrentHistoryState(@NotNull EditorHistoryState editorHistoryState) {
 		this.editText.setText(editorHistoryState.getText());
 		this.editText.setSelection(editorHistoryState.getCursorPosition(), editorHistoryState.getCursorPosition());
 	}
-	
+
 	@NotNull
 	public EditorHistoryState getCurrentHistoryState() {
 		final EditorHistoryState result = new EditorHistoryState();
-		
+
 		result.setText(String.valueOf(this.editText.getText()));
 		result.setCursorPosition(this.editText.getSelectionStart());
-		
+
 		return result;
 	}
 
 	private void processButtonAction(@NotNull View v, @Nullable String text) {
-		//Toast.makeText(Calculator.this, text, Toast.LENGTH_SHORT).show();
+		//Toast.makeText(CalculatorActivity.this, text, Toast.LENGTH_SHORT).show();
 
 		if (!StringUtils.isEmpty(text)) {
 			final MathEntityType type = MathEntityType.getType(text);
-			
+
 			int cursorPositionOffset = 0;
 
 			if (type != null) {
@@ -187,10 +210,43 @@ public class Calculator extends Activity {
 				}
 
 			}
-			
+
 			this.editText.getText().insert(this.editText.getSelectionStart(), text);
 			this.editText.setSelection(this.editText.getSelectionStart() + cursorPositionOffset, this.editText.getSelectionEnd() + cursorPositionOffset);
-			this.historyHelper.addState(getCurrentHistoryState());			
+			this.historyHelper.addState(getCurrentHistoryState());
 		}
 	}
+
+	@Override
+	public boolean onCreateOptionsMenu(Menu menu) {
+		final MenuInflater menuInflater = getMenuInflater();
+		menuInflater.inflate(R.menu.main_menu, menu);
+		return true;
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(MenuItem item) {
+		boolean result;
+
+		switch (item.getItemId()) {
+			case R.id.menu_item_settings:
+				showSettings();
+				result = true;
+			case R.id.menu_item_help:
+				showHelp();
+				result = true;
+			default:
+				result = super.onOptionsItemSelected(item);
+		}
+
+		return result;
+	}
+
+	private void showSettings() {
+		startActivity(new Intent(this, CalculatorPreferencesActivity.class));
+	}
+
+	private void showHelp() {
+		Log.d(CalculatorActivity.class + "showHelp()", "Show help!");
+	}
 }
\ No newline at end of file
diff --git a/src/org/solovyev/android/calculator/CalculatorPreferencesActivity.java b/src/org/solovyev/android/calculator/CalculatorPreferencesActivity.java
new file mode 100644
index 00000000..6f81d673
--- /dev/null
+++ b/src/org/solovyev/android/calculator/CalculatorPreferencesActivity.java
@@ -0,0 +1,44 @@
+package org.solovyev.android.calculator;
+
+import android.app.Activity;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.os.Bundle;
+import android.preference.Preference;
+import android.preference.PreferenceActivity;
+import android.widget.Button;
+import android.widget.Toast;
+import org.apache.http.Header;
+
+import java.security.KeyStore;
+import java.util.List;
+import java.util.prefs.PreferencesFactory;
+
+/**
+ * User: serso
+ * Date: 7/16/11
+ * Time: 6:37 PM
+ */
+public class CalculatorPreferencesActivity extends PreferenceActivity {
+
+	@Override
+	protected void onCreate(Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+
+		addPreferencesFromResource(R.xml.preferences);
+
+		final Preference dragButtonCalibration = findPreference("dragButtonCalibration");
+		dragButtonCalibration.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
+
+			public boolean onPreferenceClick(Preference preference) {
+				startActivity(new Intent(CalculatorPreferencesActivity.this, DragButtonCalibrationActivity.class));
+				return true;
+			}
+		});
+	}
+
+	@Override
+	protected void onRestoreInstanceState(Bundle state) {
+		super.onRestoreInstanceState(state);
+	}
+}
diff --git a/src/org/solovyev/android/calculator/DragButtonCalibrationActivity.java b/src/org/solovyev/android/calculator/DragButtonCalibrationActivity.java
new file mode 100644
index 00000000..35cd2972
--- /dev/null
+++ b/src/org/solovyev/android/calculator/DragButtonCalibrationActivity.java
@@ -0,0 +1,140 @@
+package org.solovyev.android.calculator;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.preference.PreferenceActivity;
+import android.view.KeyEvent;
+import android.view.MotionEvent;
+import android.view.View;
+import android.widget.Toast;
+import org.jetbrains.annotations.NotNull;
+import org.solovyev.android.view.*;
+import org.solovyev.util.math.MathUtils;
+import org.solovyev.util.math.Point2d;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * User: serso
+ * Date: 7/16/11
+ * Time: 7:28 PM
+ */
+public class DragButtonCalibrationActivity extends Activity {
+
+
+	@NotNull
+	private DragDirection dragDirection = DragDirection.up;
+
+	private final List<DragData> dragHistory = new ArrayList<DragData>();
+
+	@Override
+	protected void onCreate(Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+
+		setContentView(R.layout.drag_button_calibration);
+
+		final DragButton calibrationButton = (DragButton) findViewById(R.id.calibrationButton);
+		calibrationButton.setOnDragListener(new CalibrationOnDragListener());
+
+		createDragDirection();
+	}
+
+	private void createDragDirection() {
+		dragDirection = Math.random() > 0.5 ? DragDirection.up : DragDirection.down;
+
+		Toast.makeText(this, dragDirection.name(), Toast.LENGTH_SHORT).show();
+	}
+
+	public void restartClickHandler(View v) {
+		createDragDirection();
+	}
+
+
+	private class CalibrationOnDragListener implements OnDragListener {
+
+		@Override
+		public boolean isSuppressOnClickEvent() {
+			return true;
+		}
+
+		@Override
+		public boolean onDrag(@NotNull DragButton dragButton, @NotNull DragEvent event) {
+			final Point2d startPoint = event.getStartPoint();
+			final MotionEvent motionEvent = event.getMotionEvent();
+
+			// init end point
+			final Point2d endPoint = new Point2d(motionEvent.getX(), motionEvent.getY());
+
+			float distance = MathUtils.getDistance(startPoint, endPoint);
+
+			double angle = Math.toDegrees(MathUtils.getAngle(startPoint, MathUtils.sum(startPoint, SimpleOnDragListener.axis), endPoint));
+
+			assert dragDirection == DragDirection.up || dragDirection == DragDirection.down;
+			if (dragDirection == DragDirection.up) {
+				angle = 180 - angle;
+			}
+
+			dragHistory.add(new DragData(distance, angle, dragDirection));
+
+			createDragDirection();
+
+			return true;
+		}
+	}
+
+	@Override
+	public boolean onKeyDown(int keyCode, KeyEvent event) {
+		if (keyCode == KeyEvent.KEYCODE_BACK) {
+			final List<Double> angleValues = new ArrayList<Double>();
+			final List<Double> distanceValues = new ArrayList<Double>();
+			for (DragData dragData : dragHistory) {
+				angleValues.add(dragData.getAngle());
+				distanceValues.add((double) dragData.getDistance());
+			}
+
+			double angleMean = MathUtils.countMean(angleValues);
+			double angleDeviation = MathUtils.countStandardDeviation(angleMean, angleValues);
+
+			double distanceMean = MathUtils.countMean(distanceValues);
+			double distanceDeviation = MathUtils.countStandardDeviation(distanceMean, distanceValues);
+
+			Toast.makeText(this, "Angle: m=" + angleMean + ", d=" + angleDeviation, Toast.LENGTH_SHORT).show();
+			Toast.makeText(this, "Distance: m=" + distanceMean + ", d=" + distanceDeviation, Toast.LENGTH_SHORT).show();
+
+		}
+
+
+		return super.onKeyDown(keyCode, event);
+	}
+
+
+	private class DragData {
+
+		private float distance;
+
+		private double angle;
+
+		@NotNull
+		private DragDirection direction;
+
+		private DragData(float distance, double angle, @NotNull DragDirection direction) {
+			this.distance = distance;
+			this.angle = angle;
+			this.direction = direction;
+		}
+
+		public float getDistance() {
+			return distance;
+		}
+
+		public double getAngle() {
+			return angle;
+		}
+
+		@NotNull
+		public DragDirection getDirection() {
+			return direction;
+		}
+	}
+}
diff --git a/src/org/solovyev/android/view/DragButton.java b/src/org/solovyev/android/view/DragButton.java
index f23ad371..991e3849 100644
--- a/src/org/solovyev/android/view/DragButton.java
+++ b/src/org/solovyev/android/view/DragButton.java
@@ -3,6 +3,7 @@ package org.solovyev.android.view;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.calculator.R;
+import org.solovyev.common.utils.StringsUtils;
 import org.solovyev.util.StringUtils;
 import org.solovyev.util.math.MathUtils;
 import org.solovyev.util.math.Point2d;
@@ -93,26 +94,29 @@ public class DragButton extends Button {
 		return onDragListener;
 	}
 
-	public void setTextUp(String textUp) {
+	public void setTextUp(@Nullable String textUp) {
 		this.textUp = textUp;
 	}
 
+	@Nullable
 	public String getTextUp() {
 		return textUp;
 	}
 
-	public void setTextDown(String textDown) {
+	public void setTextDown(@Nullable String textDown) {
 		this.textDown = textDown;
 	}
 
+	@Nullable
 	public String getTextDown() {
 		return textDown;
 	}
 
-	public void setTextMiddle(String textMiddle) {
+	public void setTextMiddle(@Nullable String textMiddle) {
 		this.textMiddle = textMiddle;
 	}
 
+	@Nullable
 	public String getTextMiddle() {
 		return textMiddle;
 	}
@@ -129,7 +133,11 @@ public class DragButton extends Button {
 		public boolean onTouch(@NotNull View v, @NotNull MotionEvent event) {
 			// processing on touch event
 
-			if (onDragListener != null) {
+			// in order to avoid possible NPEs
+			final Point2d localStartPoint = startPoint;
+			final OnDragListener localOnDragListener = onDragListener;
+
+			if (localOnDragListener != null) {
 				// only if onDrag() listener specified
 
 				Log.d(String.valueOf(getId()), "onTouch() for: " + getId() + " . Motion event: " + event);
@@ -150,8 +158,8 @@ public class DragButton extends Button {
 					case MotionEvent.ACTION_UP:
 						// stop tracking
 							
-						if (onDragListener.onDrag(DragButton.this, new DragEvent(startPoint, event))) {
-							if (onDragListener.isSuppressOnClickEvent()) {
+						if (localStartPoint != null && localOnDragListener.onDrag(DragButton.this, new DragEvent(localStartPoint, event))) {
+							if (localOnDragListener.isSuppressOnClickEvent()) {
 								// prevent on click action
 								setPressed(false);
 							}
diff --git a/src/org/solovyev/android/view/DragDirection.java b/src/org/solovyev/android/view/DragDirection.java
index 05cda57a..a45467b0 100644
--- a/src/org/solovyev/android/view/DragDirection.java
+++ b/src/org/solovyev/android/view/DragDirection.java
@@ -3,5 +3,7 @@ package org.solovyev.android.view;
 public enum DragDirection {
 
 	up, 
-	down;
+	down,
+	left,
+	right;
 }
diff --git a/src/org/solovyev/android/view/DragEvent.java b/src/org/solovyev/android/view/DragEvent.java
index c398bb39..4f49bd29 100644
--- a/src/org/solovyev/android/view/DragEvent.java
+++ b/src/org/solovyev/android/view/DragEvent.java
@@ -6,10 +6,10 @@ import org.solovyev.util.math.Point2d;
 import android.view.MotionEvent;
 
 public class DragEvent {
-	
+
 	@NotNull
 	private final Point2d startPoint;
-	
+
 	@NotNull
 	private final MotionEvent motionEvent;
 
@@ -18,16 +18,21 @@ public class DragEvent {
 		this.motionEvent = motionEvent;
 	}
 
+	/**
+	 * @return motion event started at start point
+	 */
 	@NotNull
 	public MotionEvent getMotionEvent() {
 		return motionEvent;
 	}
 
+	/**
+	 * @return start point of dragging
+	 */
 	@NotNull
 	public Point2d getStartPoint() {
 		return startPoint;
 	}
-	
-	
-	
+
+
 }
diff --git a/src/org/solovyev/android/view/SimpleOnDragListener.java b/src/org/solovyev/android/view/SimpleOnDragListener.java
index 92f1f501..4cf0264e 100644
--- a/src/org/solovyev/android/view/SimpleOnDragListener.java
+++ b/src/org/solovyev/android/view/SimpleOnDragListener.java
@@ -1,8 +1,6 @@
 package org.solovyev.android.view;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-import org.solovyev.util.StringUtils;
 import org.solovyev.util.math.MathUtils;
 import org.solovyev.util.math.Point2d;
 
@@ -12,8 +10,8 @@ import android.view.MotionEvent;
 public class SimpleOnDragListener implements OnDragListener {
 
 	@NotNull
-	private final Point2d axis = new Point2d(0, 1);
-	
+	public static final Point2d axis = new Point2d(0, 1);
+
 	private float minDragDist = 20f;
 
 	private float maxDragDist = 80f;
@@ -21,73 +19,79 @@ public class SimpleOnDragListener implements OnDragListener {
 	// max angle (in degrees!) between start and end point vector and axis
 	// vector to register drag event
 	private double maxAngle = 30;
+	
+	@NotNull
+	private DragProcessor dragProcessor;
+
+	public SimpleOnDragListener() {
+	}
+
+	public SimpleOnDragListener(@NotNull DragProcessor dragProcessor) {
+		this.dragProcessor = dragProcessor;
+	}
 
 	@Override
 	public boolean onDrag(@NotNull DragButton dragButton, @NotNull DragEvent event) {
+		boolean result = false;
+
 		logDragEvent(dragButton, event);
-		
-		processButtonAction(dragButton, getActionText(dragButton, event));
+
+		final Point2d startPoint = event.getStartPoint();
+		final MotionEvent motionEvent = event.getMotionEvent();
+
+		// init end point
+		final Point2d endPoint = new Point2d(motionEvent.getX(), motionEvent.getY());
+
+		float distance = MathUtils.getDistance(startPoint, endPoint);
+
+		if (minDragDist < distance && distance < maxDragDist) {
+			double angle = Math.toDegrees(MathUtils.getAngle(startPoint, MathUtils.sum(startPoint, axis), endPoint));
+
+			final DragDirection direction;
+			if (angle < maxAngle) {
+				direction = DragDirection.down;
+			} else if (180 - angle < maxAngle) {
+				direction = DragDirection.up;
+			} else {
+				direction = null;
+			}
+
+			if (direction != null) {
+				result = dragProcessor.processDragEvent(direction, dragButton, startPoint, motionEvent);
+			}
+		}
+
+		return result;
 	}
 
 	@Override
 	public boolean isSuppressOnClickEvent() {
 		return true;
 	}
-	
-	/**
-	 * Method creates drag event in case if all conditions are satisfied
-	 * 
-	 * @param event
-	 *            motion event
-	 * 
-	 * @return filled drag event object only if drag event is possible, null
-	 *         otherwise
-	 */
-	@Nullable
-	protected DragEvent getDragEvent(@NotNull MotionEvent event) {
-		DragEvent result = null;
 
-		if (startPoint != null) {
-			final Point2d endPoint = new Point2d(event.getX(), event.getY());
-			float distance = MathUtils.getDistance(startPoint, endPoint);
-
-			if (minDragDist < distance && distance < maxDragDist) {
-				double angle = Math.toDegrees(MathUtils.getAngle(startPoint, MathUtils.sum(startPoint, axis), endPoint));
-				
-				final DragDirection direction;
-				if (angle < maxAngle) {
-					direction = DragDirection.down;
-				} else if (180 - angle < maxAngle) {
-					direction = DragDirection.up;
-				} else {
-					direction = null;
-				}
-				
-				if (direction != null) {
-					if ( direction == DragDirection.up && StringUtils.isEmpty(textUp) ) {
-						// no action if text is empty
-					} else if  (direction == DragDirection.down && StringUtils.isEmpty(textDown)) {
-						// no action if text is empty
-					} else {
-						result = new DragEvent(direction);
-					}
-					
-				}
-			}
-		}
-
-		return result;
-	}
-	
 	private void logDragEvent(@NotNull DragButton dragButton, @NotNull DragEvent event) {
-			final Point2d startPoint = event.getStartPoint();
-			final MotionEvent motionEvent = event.getMotionEvent();
-			final Point2d endPoint = new Point2d(motionEvent.getX(), motionEvent.getY());
-			
-			Log.d(String.valueOf(dragButton.getId()), "Start point: " + startPoint + ", End point: " + endPoint);
-			Log.d(String.valueOf(dragButton.getId()), "Distance: " + MathUtils.getDistance(startPoint, endPoint));
-			Log.d(String.valueOf(dragButton.getId()), "Angle: " + Math.toDegrees(MathUtils.getAngle(startPoint, MathUtils.sum(startPoint, axis), endPoint)));
-			Log.d(String.valueOf(dragButton.getId()), "Axis: " + axis + " Vector: " + MathUtils.subtract(endPoint, startPoint));
-			Log.d(String.valueOf(dragButton.getId()), "Total time: " + (motionEvent.getEventTime() - motionEvent.getDownTime()) + " ms");
+		final Point2d startPoint = event.getStartPoint();
+		final MotionEvent motionEvent = event.getMotionEvent();
+		final Point2d endPoint = new Point2d(motionEvent.getX(), motionEvent.getY());
+
+		Log.d(String.valueOf(dragButton.getId()), "Start point: " + startPoint + ", End point: " + endPoint);
+		Log.d(String.valueOf(dragButton.getId()), "Distance: " + MathUtils.getDistance(startPoint, endPoint));
+		Log.d(String.valueOf(dragButton.getId()), "Angle: " + Math.toDegrees(MathUtils.getAngle(startPoint, MathUtils.sum(startPoint, axis), endPoint)));
+		Log.d(String.valueOf(dragButton.getId()), "Axis: " + axis + " Vector: " + MathUtils.subtract(endPoint, startPoint));
+		Log.d(String.valueOf(dragButton.getId()), "Total time: " + (motionEvent.getEventTime() - motionEvent.getDownTime()) + " ms");
+	}
+
+	@NotNull
+	public DragProcessor getDragProcessor() {
+		return dragProcessor;
+	}
+
+	public void setDragProcessor(@NotNull DragProcessor dragProcessor) {
+		this.dragProcessor = dragProcessor;
+	}
+
+	public interface DragProcessor {
+		
+		boolean processDragEvent(@NotNull DragDirection dragDirection, @NotNull DragButton dragButton, @NotNull Point2d startPoint2d, @NotNull MotionEvent motionEvent);
 	}
 }
\ No newline at end of file
diff --git a/src/org/solovyev/util/math/MathUtils.java b/src/org/solovyev/util/math/MathUtils.java
index 1a8ad4b5..6beda9b8 100644
--- a/src/org/solovyev/util/math/MathUtils.java
+++ b/src/org/solovyev/util/math/MathUtils.java
@@ -2,17 +2,19 @@ package org.solovyev.util.math;
 
 import org.jetbrains.annotations.NotNull;
 
+import java.util.List;
+
 public class MathUtils {
 
 	public static float getDistance(@NotNull Point2d startPoint,
-			@NotNull Point2d endPoint) {
+									@NotNull Point2d endPoint) {
 		return getNorm(subtract(endPoint, startPoint));
 	}
 
 	public static Point2d subtract(@NotNull Point2d p1, @NotNull Point2d p2) {
 		return new Point2d(p1.getX() - p2.getX(), p1.getY() - p2.getY());
 	}
-	
+
 	public static Point2d sum(@NotNull Point2d p1, @NotNull Point2d p2) {
 		return new Point2d(p1.getX() + p2.getX(), p1.getY() + p2.getY());
 	}
@@ -23,7 +25,7 @@ public class MathUtils {
 	}
 
 	public static float getAngle(@NotNull Point2d startPoint,
-			@NotNull Point2d axisEndPoint, @NotNull Point2d endPoint) {
+								 @NotNull Point2d axisEndPoint, @NotNull Point2d endPoint) {
 		final Point2d axisVector = subtract(axisEndPoint, startPoint);
 		final Point2d vector = subtract(endPoint, startPoint);
 
@@ -36,4 +38,24 @@ public class MathUtils {
 		return (float) Math.acos((-a_2 + b_2 + c_2) / (2 * b * c));
 	}
 
+	public static double countMean(@NotNull List<Double> objects) {
+
+		double sum = 0d;
+		for (Double object : objects) {
+			sum += object;
+		}
+
+		return objects.size() == 0 ? 0d : (sum / objects.size());
+	}
+
+	public static double countStandardDeviation(@NotNull Double mean, @NotNull List<Double> objects) {
+		double sum = 0d;
+
+		for (Double object : objects) {
+			sum += Math.pow(object - mean, 2);
+		}
+
+		return objects.size() == 0 ? 0d : Math.sqrt(sum / objects.size());
+	}
+
 }