AndEngine之DEMO學習（十四）TouchDragExample

     一路坑坑窪窪的過來，總算到了Touch部分DEMO，這些例子都是通過Android的單點觸控和多點觸控實現的，包括縮放、拖拽、滾動等各類實現。感覺這部分是相對輕鬆的一塊，主要目的是瞭解他的程序結構。先來第一個例子，拖拽的示例。

     這個例子中只是讓精靈的座標設置觸控的座標，完成精靈隨手指觸控移動的效果，但是還是會有一定的延時感。下面上代碼：

package org.andengine.examples;

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.input.touch.TouchEvent;
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.ui.activity.SimpleBaseGameActivity;

import android.widget.Toast;

public class TouchDragExample extends SimpleBaseGameActivity {

	private static final int CAMERA_WIDTH = 720;
	private static final int CAMERA_HEIGHT = 480;

	private BitmapTextureAtlas mBitmapTextureAtlas;
	private ITextureRegion mFaceTextureRegion;

	@Override
	public EngineOptions onCreateEngineOptions() {
		Toast.makeText(this, "Touch & Drag the face!", Toast.LENGTH_LONG).show();

		final Camera camera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);

		return new EngineOptions(true, ScreenOrientation.LANDSCAPE_FIXED, new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), camera);
	}

	@Override
	public void onCreateResources() {
		BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");

		this.mBitmapTextureAtlas = new BitmapTextureAtlas(this.getTextureManager(), 32, 32, TextureOptions.BILINEAR);
		this.mFaceTextureRegion = BitmapTextureAtlasTextureRegionFactory.createFromAsset(this.mBitmapTextureAtlas, this, "face_box.png", 0, 0);
		this.mBitmapTextureAtlas.load();
	}

	@Override
	public Scene onCreateScene() {
		this.mEngine.registerUpdateHandler(new FPSLogger());

		final Scene scene = new Scene();
		scene.setBackground(new Background(0.09804f, 0.6274f, 0.8784f));

		final float centerX = (CAMERA_WIDTH - this.mFaceTextureRegion.getWidth()) / 2;
		final float centerY = (CAMERA_HEIGHT - this.mFaceTextureRegion.getHeight()) / 2;
		final Sprite face = new Sprite(centerX, centerY, this.mFaceTextureRegion, this.getVertexBufferObjectManager()) {
			//touch事件中，當Sprite的區域被觸點是響應
			@Override
			public boolean onAreaTouched(final TouchEvent pSceneTouchEvent, final float pTouchAreaLocalX, final float pTouchAreaLocalY) {
				//設置位置隨SceneTouchEvent的座標改變。
				this.setPosition(pSceneTouchEvent.getX() - this.getWidth() / 2, pSceneTouchEvent.getY() - this.getHeight() / 2);
				return true;
			}
		};
		//放大4倍
		face.setScale(4);
		scene.attachChild(face);
		scene.registerTouchArea(face);
		scene.setTouchAreaBindingOnActionDownEnabled(true);

		return scene;
	}
}