AndEngine之DEMO学习（十五）MultiTouchExample

      接下来的一个例子MultiTouchExample，多个实体拖拽的实现。这个例子中采用了通常意义上的拖拽三个阶段的定义：物体被拽起、物体被拖动、物体被放下。另一方面在多实体响应事件中，当一个实体被拖起，那其他实体应该不会再响应ActionDown（否则会有很多实体被拖起），这样这屏幕点击事件中有一个setTouchAreaBindingOnActionDownEnabled的设置，完成这个需要。

package org.andengine.examples;import java.util.HashMap;import org.andengine.engine.camera.Camera;import org.andengine.engine.options.EngineOptions;import org.andengine.engine.options.ScreenOrientation;import org.andengine.engine.options.resolutionpolicy.RatioResolutionPolicy;import org.andengine.entity.scene.Scene;import org.andengine.entity.scene.background.Background;import org.andengine.entity.sprite.Sprite;import org.andengine.entity.util.FPSLogger;import org.andengine.examples.adt.card.Card;import org.andengine.input.touch.TouchEvent;import org.andengine.input.touch.controller.MultiTouch;import org.andengine.opengl.texture.TextureOptions;import org.andengine.opengl.texture.atlas.bitmap.BitmapTextureAtlas;import org.andengine.opengl.texture.atlas.bitmap.BitmapTextureAtlasTextureRegionFactory;import org.andengine.opengl.texture.region.ITextureRegion;import org.andengine.opengl.texture.region.TextureRegionFactory;import org.andengine.ui.activity.SimpleBaseGameActivity;import android.widget.Toast;public class MultiTouchExample extends SimpleBaseGameActivity {private static final int CAMERA_WIDTH = 720;private static final int CAMERA_HEIGHT = 480;private Camera mCamera;private BitmapTextureAtlas mCardDeckTexture;private Scene mScene;private HashMap<Card, ITextureRegion> mCardTotextureRegionMap;@Overridepublic EngineOptions onCreateEngineOptions() {this.mCamera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);final EngineOptions engineOptions = new EngineOptions(true, ScreenOrientation.LANDSCAPE_FIXED, new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), this.mCamera);engineOptions.getTouchOptions().setNeedsMultiTouch(true);if(MultiTouch.isSupported(this)) {if(MultiTouch.isSupportedDistinct(this)) {Toast.makeText(this, "MultiTouch detected --> Both controls will work properly!", Toast.LENGTH_SHORT).show();} else {Toast.makeText(this, "MultiTouch detected, but your device has problems distinguishing between fingers.\n\nControls are placed at different vertical locations.", Toast.LENGTH_LONG).show();}} else {Toast.makeText(this, "Sorry your device does NOT support MultiTouch!\n\n(Falling back to SingleTouch.)\n\nControls are placed at different vertical locations.", Toast.LENGTH_LONG).show();}return engineOptions;}@Overridepublic void onCreateResources() {BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");this.mCardDeckTexture = new BitmapTextureAtlas(this.getTextureManager(), 1024, 512, TextureOptions.BILINEAR);BitmapTextureAtlasTextureRegionFactory.createFromAsset(this.mCardDeckTexture, this, "carddeck_tiled.png", 0, 0);this.mCardDeckTexture.load();this.mCardTotextureRegionMap = new HashMap<Card, ITextureRegion>();//同一个纹理的不同纹理范围，有些像瓦片纹理范围/* Extract the TextureRegion of each card in the whole deck. */for(final Card card : Card.values()) {final ITextureRegion cardTextureRegion = TextureRegionFactory.extractFromTexture(this.mCardDeckTexture, card.getTexturePositionX(), card.getTexturePositionY(), Card.CARD_WIDTH, Card.CARD_HEIGHT);this.mCardTotextureRegionMap.put(card, cardTextureRegion);}}@Overridepublic Scene onCreateScene() {this.mEngine.registerUpdateHandler(new FPSLogger());this.mScene = new Scene();this.mScene.setOnAreaTouchTraversalFrontToBack();this.addCard(Card.CLUB_ACE, 200, 100);this.addCard(Card.HEART_ACE, 200, 260);this.addCard(Card.DIAMOND_ACE, 440, 100);this.addCard(Card.SPADE_ACE, 440, 260);this.mScene.setBackground(new Background(0.09804f, 0.6274f, 0.8784f));//让TouchArea事件绑定给完成了ActionDown的实体，其他实体无法接收到事件。this.mScene.setTouchAreaBindingOnActionDownEnabled(true);return this.mScene;}private void addCard(final Card pCard, final int pX, final int pY) {final Sprite sprite = new Sprite(pX, pY, this.mCardTotextureRegionMap.get(pCard), this.getVertexBufferObjectManager()) {//标记，表示你已经进入拖拽状态。boolean mGrabbed = false;@Overridepublic boolean onAreaTouched(final TouchEvent pSceneTouchEvent, final float pTouchAreaLocalX, final float pTouchAreaLocalY) {switch(pSceneTouchEvent.getAction()) {//物体被拽起case TouchEvent.ACTION_DOWN:this.setScale(1.25f);this.mGrabbed = true;break;//物体被拖动case TouchEvent.ACTION_MOVE:if(this.mGrabbed) {this.setPosition(pSceneTouchEvent.getX() - Card.CARD_WIDTH / 2, pSceneTouchEvent.getY() - Card.CARD_HEIGHT / 2);}break;//物体被放下case TouchEvent.ACTION_UP:if(this.mGrabbed) {this.mGrabbed = false;this.setScale(1.0f);}break;}return true;}};this.mScene.attachChild(sprite);this.mScene.registerTouchArea(sprite);}}