Adding CrossCompatibility sample app.

Change-Id: I565584ea53212f61a9fbbb44e50da59f4ba06fff

build/sdk.atree

@@ -109,6 +109,7 @@ development/samples/CubeLiveWallpaper        samples/${PLATFORM_NAME}/CubeLiveWa
 development/samples/VoiceRecognitionService  samples/${PLATFORM_NAME}/VoiceRecognitionService
 development/samples/TicTacToeLib             samples/${PLATFORM_NAME}/TicTacToeLib
 development/samples/TicTacToeMain            samples/${PLATFORM_NAME}/TicTacToeMain
+development/samples/CrossCompatibility       samples/${PLATFORM_NAME}/CrossCompatibility
 
 # dx
 bin/dx platforms/${PLATFORM_NAME}/tools/dx

samples/CrossCompatibility/AndroidManifest.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+      package="com.example.android.touchexample"
+      android:versionCode="1"
+      android:versionName="1.0">
+    <application android:icon="@drawable/icon" android:label="@string/app_name">
+        <activity android:name=".TouchExampleActivity"
+                  android:label="@string/app_name">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+    </application>
+    <uses-sdk android:minSdkVersion="3" android:targetSdkVersion="8" />
+</manifest>

samples/CrossCompatibility/_index.html

@@ -0,0 +1,20 @@
+<p>This sample demonstrates how to design an application that is compatible across different Android versions. Applications
+should degrade gracefully on older platform versions, dropping features or providing
+when the platform support needed by features or functionality isn't available.</p>
+
+<p>In this case, the CrossCompatibility application shows how to use APIs that are not available in all Android versions and 
+still create a single <code>.apk</code> that runs on all Android versions.</p>
+
+<ul>
+<li>The main application's <a
+href="AndroidManifest.html">AndroidManifest.xml</a> file declares that it is backwards compatible with API level 3 devices with attribute <code>minSdkVersion</code> in the <code>uses-sdk</code> tag.
+ </li>
+<li>
+<a
+href="src/com/example/android/touchexample/VersionedGestureDetector.html">VersionedGestureDetector.java</a>
+is a version independent abstract class which factors out multitouch APIs that differ between platform versions. </li>
+
+</ul>
+
+<p> For more information on how to make your applications cross-compatible, please check out the original
+blogpost <a href="http://android-developers.blogspot.com/2010/07/how-to-have-your-cupcake-and-eat-it-too.html">here</a>.</p>

samples/CrossCompatibility/build.xml

@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project name="TouchExampleActivity" default="help">
+
+    <!-- The local.properties file is created and updated by the 'android' tool.
+         It contains the path to the SDK. It should *NOT* be checked in in Version
+         Control Systems. -->
+    <property file="local.properties" />
+
+    <!-- The build.properties file can be created by you and is never touched
+         by the 'android' tool. This is the place to change some of the default property values
+         used by the Ant rules.
+         Here are some properties you may want to change/update:
+
+         application.package
+             the name of your application package as defined in the manifest. Used by the
+             'uninstall' rule.
+         source.dir
+             the name of the source directory. Default is 'src'.
+         out.dir
+             the name of the output directory. Default is 'bin'.
+
+         Properties related to the SDK location or the project target should be updated
+          using the 'android' tool with the 'update' action.
+
+         This file is an integral part of the build system for your application and
+         should be checked in in Version Control Systems.
+
+         -->
+    <property file="build.properties" />
+
+    <!-- The default.properties file is created and updated by the 'android' tool, as well
+         as ADT.
+         This file is an integral part of the build system for your application and
+         should be checked in in Version Control Systems. -->
+    <property file="default.properties" />
+
+    <!-- Custom Android task to deal with the project target, and import the proper rules.
+         This requires ant 1.6.0 or above. -->
+    <path id="android.antlibs">
+        <pathelement path="${sdk.dir}/tools/lib/anttasks.jar" />
+        <pathelement path="${sdk.dir}/tools/lib/sdklib.jar" />
+        <pathelement path="${sdk.dir}/tools/lib/androidprefs.jar" />
+        <pathelement path="${sdk.dir}/tools/lib/apkbuilder.jar" />
+        <pathelement path="${sdk.dir}/tools/lib/jarutils.jar" />
+    </path>
+
+    <taskdef name="setup"
+        classname="com.android.ant.SetupTask"
+        classpathref="android.antlibs" />
+
+    <!-- Execute the Android Setup task that will setup some properties specific to the target,
+         and import the build rules files.
+
+         The rules file is imported from
+            <SDK>/platforms/<target_platform>/templates/android_rules.xml
+
+         To customize some build steps for your project:
+         - copy the content of the main node <project> from android_rules.xml
+         - paste it in this build.xml below the <setup /> task.
+         - disable the import by changing the setup task below to <setup import="false" />
+
+         This will ensure that the properties are setup correctly but that your customized
+         build steps are used.
+    -->
+    <setup />
+
+</project>

samples/CrossCompatibility/res/values/strings.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_name">TouchExample</string>
+</resources>

samples/CrossCompatibility/src/com/example/android/touchexample/TouchExampleActivity.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * 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.
+ */
+package com.example.android.touchexample;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.view.ViewGroup;
+
+public class TouchExampleActivity extends Activity {
+    /** Called when the activity is first created. */
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        TouchExampleView view = new TouchExampleView(this);
+        view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
+                ViewGroup.LayoutParams.MATCH_PARENT));
+
+        setContentView(view);
+    }
+}

samples/CrossCompatibility/src/com/example/android/touchexample/TouchExampleView.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * 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.
+ */
+package com.example.android.touchexample;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.drawable.Drawable;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+
+public class TouchExampleView extends View {
+    private Drawable mIcon;
+    private float mPosX;
+    private float mPosY;
+
+    private VersionedGestureDetector mDetector;
+    private float mScaleFactor = 1.f;
+
+    public TouchExampleView(Context context) {
+        this(context, null, 0);
+    }
+
+    public TouchExampleView(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public TouchExampleView(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+        mIcon = context.getResources().getDrawable(R.drawable.icon);
+        mIcon.setBounds(0, 0, mIcon.getIntrinsicWidth(), mIcon.getIntrinsicHeight());
+
+        mDetector = VersionedGestureDetector.newInstance(context, new GestureCallback());
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent ev) {
+        mDetector.onTouchEvent(ev);
+        return true;
+    }
+
+    @Override
+    public void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+
+        canvas.save();
+        canvas.translate(mPosX, mPosY);
+        canvas.scale(mScaleFactor, mScaleFactor);
+        mIcon.draw(canvas);
+        canvas.restore();
+    }
+
+    private class GestureCallback implements VersionedGestureDetector.OnGestureListener {
+        public void onDrag(float dx, float dy) {
+            mPosX += dx;
+            mPosY += dy;
+            invalidate();
+        }
+
+        public void onScale(float scaleFactor) {
+            mScaleFactor *= scaleFactor;
+
+            // Don't let the object get too small or too large.
+            mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
+
+            invalidate();
+        }
+    }
+}

samples/CrossCompatibility/src/com/example/android/touchexample/VersionedGestureDetector.java

@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * 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.
+ */
+package com.example.android.touchexample;
+
+import android.content.Context;
+import android.os.Build;
+import android.util.Log;
+import android.view.MotionEvent;
+import android.view.ScaleGestureDetector;
+
+public abstract class VersionedGestureDetector {
+    private static final String TAG = "VersionedGestureDetector";
+
+    OnGestureListener mListener;
+
+    public static VersionedGestureDetector newInstance(Context context,
+            OnGestureListener listener) {
+        final int sdkVersion = Integer.parseInt(Build.VERSION.SDK);
+        VersionedGestureDetector detector = null;
+        if (sdkVersion < Build.VERSION_CODES.ECLAIR) {
+            detector = new CupcakeDetector();
+        } else if (sdkVersion < Build.VERSION_CODES.FROYO) {
+            detector = new EclairDetector();
+        } else {
+            detector = new FroyoDetector(context);
+        }
+
+        Log.d(TAG, "Created new " + detector.getClass());
+        detector.mListener = listener;
+
+        return detector;
+    }
+
+    public abstract boolean onTouchEvent(MotionEvent ev);
+
+    public interface OnGestureListener {
+        public void onDrag(float dx, float dy);
+        public void onScale(float scaleFactor);
+    }
+
+    private static class CupcakeDetector extends VersionedGestureDetector {
+        float mLastTouchX;
+        float mLastTouchY;
+
+        float getActiveX(MotionEvent ev) {
+            return ev.getX();
+        }
+
+        float getActiveY(MotionEvent ev) {
+            return ev.getY();
+        }
+
+        boolean shouldDrag() {
+            return true;
+        }
+
+        @Override
+        public boolean onTouchEvent(MotionEvent ev) {
+            switch (ev.getAction()) {
+            case MotionEvent.ACTION_DOWN: {
+                mLastTouchX = getActiveX(ev);
+                mLastTouchY = getActiveY(ev);
+                break;
+            }
+            case MotionEvent.ACTION_MOVE: {
+                final float x = getActiveX(ev);
+                final float y = getActiveY(ev);
+
+                if (shouldDrag()) {
+                    mListener.onDrag(x - mLastTouchX, y - mLastTouchY);
+                }
+
+                mLastTouchX = x;
+                mLastTouchY = y;
+                break;
+            }
+            }
+            return true;
+        }
+    }
+
+    private static class EclairDetector extends CupcakeDetector {
+        private static final int INVALID_POINTER_ID = -1;
+        private int mActivePointerId = INVALID_POINTER_ID;
+        private int mActivePointerIndex = 0;
+
+        @Override
+        float getActiveX(MotionEvent ev) {
+            return ev.getX(mActivePointerIndex);
+        }
+
+        @Override
+        float getActiveY(MotionEvent ev) {
+            return ev.getY(mActivePointerIndex);
+        }
+
+        @Override
+        public boolean onTouchEvent(MotionEvent ev) {
+            final int action = ev.getAction();
+            switch (action & MotionEvent.ACTION_MASK) {
+            case MotionEvent.ACTION_DOWN:
+                mActivePointerId = ev.getPointerId(0);
+                break;
+            case MotionEvent.ACTION_CANCEL:
+            case MotionEvent.ACTION_UP:
+                mActivePointerId = INVALID_POINTER_ID;
+                break;
+            case MotionEvent.ACTION_POINTER_UP:
+                final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
+                        >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
+                final int pointerId = ev.getPointerId(pointerIndex);
+                if (pointerId == mActivePointerId) {
+                    // This was our active pointer going up. Choose a new
+                    // active pointer and adjust accordingly.
+                    final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
+                    mActivePointerId = ev.getPointerId(newPointerIndex);
+                    mLastTouchX = ev.getX(newPointerIndex);
+                    mLastTouchY = ev.getY(newPointerIndex);
+                }
+                break;
+            }
+
+            mActivePointerIndex = ev.findPointerIndex(mActivePointerId);
+            return super.onTouchEvent(ev);
+        }
+    }
+
+    private static class FroyoDetector extends EclairDetector {
+        private ScaleGestureDetector mDetector;
+
+        public FroyoDetector(Context context) {
+            mDetector = new ScaleGestureDetector(context,
+                    new ScaleGestureDetector.SimpleOnScaleGestureListener() {
+                @Override public boolean onScale(ScaleGestureDetector detector) {
+                    mListener.onScale(detector.getScaleFactor());
+                    return true;
+                }
+            });
+        }
+
+        @Override
+        boolean shouldDrag() {
+            return !mDetector.isInProgress();
+        }
+
+        @Override
+        public boolean onTouchEvent(MotionEvent ev) {
+            mDetector.onTouchEvent(ev);
+            return super.onTouchEvent(ev);
+        }
+    }
+}