有图有真相：

最近在做项目的时候用到了点击图片放大效果，于是就开始实现，本以为挺简单的，实现起来还是遇到不少的小问题啊：

第一：只实现点击图片放大，再次点击消失，这个好实现；

第二：只实现图片可以拖动，而且可以动态缩小放大，这个也好实现；

第三：第一 和第二同步实现就出现问题了：

具体的问题是：

（1）setOnClickListener 和 setOnTouchListener 同时设置的时候，若是setOnTouchListener的返回值为true,则不会再执行setOnClickListener ；若是返回为false,则会执行setOnClickListener 

（2）将setOnTouchListener的返回值设为false之后，运行项目，图片缩小放大之后会直接消失，也就是直接执行了setOnClickListener ，但是项目的要求是，图片移动了或者放大缩小了，依旧显示图片，只有点击的时候才会使图片消失，我于是就用一个变量进行控制手指点击屏幕之后的大小小于1的时候才算是点击了图片，从而让图片消失，具体不多说了，看图和代码：

public class ImageToFullScreenActivity extends Activity implements
		OnClickListener {
	private String mImageUrl;
	private ImageWorker mImageWorker;
	private int mImageWidth;
	private int mImageHeight;
	private ImageView mFullImageView;
	private LinearLayout mImageLayout;
	private ImageView mSaveImage;
	private Boolean isShutDownPic = true;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.image_to_full_screen);
		mImageUrl = getIntent().getStringExtra("imageUrl");
		init();
	}

	private void init() {
		mImageLayout = (LinearLayout) findViewById(R.id.image_layout);
		mFullImageView = (ImageView) findViewById(R.id.full_image);
		mSaveImage = (ImageView) findViewById(R.id.save_image);
		mSaveImage.setOnClickListener(this);

		mImageLayout.setOnClickListener(this);
		mFullImageView.setOnClickListener(this);
		mFullImageView.setOnTouchListener(new TouchListener());

		WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
		DisplayMetrics outMetrics = new DisplayMetrics();
		wm.getDefaultDisplay().getMetrics(outMetrics);
		mImageWidth = (int) (outMetrics.widthPixels * 1.0d);
		mImageHeight = mImageWidth;

		ImageCacheParams cacheParams = new ImageCacheParams();
		cacheParams.loadingResId = R.drawable.image_full_screen;
		cacheParams.memCacheSize = ImageCache.DEFAULT_MEM_CACHE_SIZE_BIG;
		cacheParams.reqWidth = mImageWidth;
		cacheParams.reqHeight = mImageHeight;
		mImageWorker = new ImageWorker(this,
				(HealthApplication) getApplication());
		mImageWorker.addParams(cacheParams);

		mImageWorker.loadBitmap(mImageUrl, mFullImageView);
		LayoutParams params = new LayoutParams(LayoutParams.FILL_PARENT,
				LayoutParams.FILL_PARENT);
		mFullImageView.setLayoutParams(params);
	}

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		switch (v.getId()) {
		case R.id.save_image:
			SaveImageToSysAlbum();
			break;
		case R.id.image_layout:
			if(isShutDownPic){
				ImageToFullScreenActivity.this.finish();
			}
			isShutDownPic = true;	
			break;
		case R.id.full_image:
			if(isShutDownPic){
				ImageToFullScreenActivity.this.finish();
			}
			isShutDownPic = true;									
			break;
		default:
			break;
		}
	}

	/**
	 * 將ImageView中的圖片保存到系统相册
	 */
	private void SaveImageToSysAlbum() {
		if (FileUtil.isSdCardExist()) {
			BitmapDrawable bmpDrawable = (BitmapDrawable) mFullImageView
					.getDrawable();
			Bitmap bmp = bmpDrawable.getBitmap();
			if (bmp != null) {
				try {
					/*
					 * ContentResolver cr = getContentResolver(); String url =
					 * MediaStore.Images.Media.insertImage(cr, bmp,
					 * String.valueOf(System.currentTimeMillis()), "");
					 */
					File tempFile = new File(Environment
							.getExternalStoragePublicDirectory(
									Environment.DIRECTORY_DCIM).getPath()
							+ "/"
							+ String.valueOf(System.currentTimeMillis())
							+ ".png");
					if (tempFile.exists()) {
						tempFile.delete();
					}
					try {
						tempFile.createNewFile();
					} catch (IOException e) {
						e.printStackTrace();
					}
					FileOutputStream fOut = null;
					try {
						fOut = new FileOutputStream(tempFile);
					} catch (FileNotFoundException e) {
						e.printStackTrace();
					}
					bmp.compress(Bitmap.CompressFormat.PNG, 100, fOut);
					try {
						fOut.flush();
						fOut.close();
					} catch (IOException e) {
						// TODO: handle exception
						e.printStackTrace();
					}

					Toast.makeText(this, getString(R.string.save_succ),
							Toast.LENGTH_SHORT).show();

				} catch (Exception e) {
					e.printStackTrace();
				}
			} else {
				Toast.makeText(this, getString(R.string.no_iamge_save_fail),
						Toast.LENGTH_SHORT).show();
			}
		} else {
			Toast.makeText(this, getString(R.string.no_sdcard_save_fail),
					Toast.LENGTH_SHORT).show();
		}
		String release = android.os.Build.VERSION.RELEASE;
		String tempID = release.substring(0, 3);
		if (Double.parseDouble(tempID) >= 4.4) {// 安卓4.4以上版本的时候使用这个，以下的使用else语句里面的
			MediaScannerConnection.scanFile(
					this,
					new String[] { Environment
							.getExternalStoragePublicDirectory(
									Environment.DIRECTORY_DCIM).getPath()
							+ "/" }, null, null);
		} else {
			sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
					Uri.parse("file://"
							+ Environment.getExternalStorageDirectory())));
			MediaScannerConnection.scanFile(
					this,
					new String[] { Environment
							.getExternalStoragePublicDirectory(
									Environment.DIRECTORY_DCIM).getPath()
							+ "/" }, null, null);
		}

	}

	private class TouchListener implements OnTouchListener {

		private PointF startPoint = new PointF();
		private Matrix matrix = new Matrix();
		private Matrix currentMaritx = new Matrix();

		private int mode = 0; // 用于标记模式
		private static final int DRAG = 1; // 拖动
		private static final int ZOOM = 2; // 放大
		private float startDis = 0;
		private PointF midPoint; // 中心点

		@Override
		public boolean onTouch(View v, MotionEvent event) {
			switch (event.getAction() & MotionEvent.ACTION_MASK) {
			case MotionEvent.ACTION_DOWN:
				mode = DRAG; // 拖拽
				currentMaritx.set(mFullImageView.getImageMatrix()); // 记录ImageView当前移动位置
				startPoint.set(event.getX(), event.getY()); // 开始点
				break;
			case MotionEvent.ACTION_MOVE:// 移动事件
				float tempX = event.getX() - startPoint.x;
				float tempY = event.getY() - startPoint.y;
				/**
				 * 控制移动小于1.0的情况下，视为没有移动，执行点击事件		
				 */
				if(Math.abs(tempX) < 1.0 && Math.abs(tempY) < 1.0){
					isShutDownPic = true;
				}else {
					isShutDownPic = false;
				}
				mFullImageView.setScaleType(ImageView.ScaleType.MATRIX);
				if (mode == DRAG) { // 图片拖动事件
					float dx = event.getX() - startPoint.x; // x轴移动距离
					float dy = event.getY() - startPoint.y;
					matrix.set(currentMaritx); // 在当前的位置基础上移动
					matrix.postTranslate(dx, dy);
				} else if (mode == ZOOM) { // 图片放大事件
					float endDis = distance(event); // 结束距离
					if (endDis > 10f) {
						float scale = endDis / startDis; // 放大倍数
						matrix.set(currentMaritx);
						matrix.postScale(scale, scale, midPoint.x, midPoint.y);
					}

				}
				break;
			case MotionEvent.ACTION_UP:
				mode = 0;
				break;
			// 有手指离开屏幕，但屏幕还有触点（手指）
			case MotionEvent.ACTION_POINTER_UP:
				mode = 0;
				break;
			// 当屏幕上已经有触点（手指），再有一个手指压下屏幕
			case MotionEvent.ACTION_POINTER_DOWN:
				mode = ZOOM;
				startDis = distance(event);
				if (startDis > 10f) { // 避免手指上有两个
					midPoint = mid(event);
					currentMaritx.set(mFullImageView.getImageMatrix()); // 记录当前的缩放倍数
				}
				break;
			}

			// 显示缩放后的图片
			mFullImageView.setImageMatrix(matrix);
			return false;
		}

	}

	/**
	 * 计算两点之间的距离
	 * 
	 * @param event
	 * @return
	 */
	public static float distance(MotionEvent event) {
		float dx = event.getX(1) - event.getX(0);
		float dy = event.getY(1) - event.getY(0);
		return FloatMath.sqrt(dx * dx + dy * dy);
	}

	/**
	 * 计算两点之间的中间点
	 * 
	 * @param event
	 * @return
	 */
	public static PointF mid(MotionEvent event) {
		float midX = (event.getX(1) + event.getX(0)) / 2;
		float midY = (event.getY(1) + event.getY(0)) / 2;
		return new PointF(midX, midY);
	}

}

高仿新浪点击图片放大(可以拖动，动态缩小放大，以及再次点击图片消失和保存图片的功能)