怎么在Android中利用ImageView实现一个放大缩小动画-创新互联

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1.配置文件直接添加

当直接在布局文件中添加图片的话，可以在自定义View代码中用getDrawable（）获取图片资源，然后通过DrawBitmap绘制图片。通过不断绘制图片的位置，达到放大缩小的功能。
第一种情况实在XML布局文件中直接添加的：

public class CoolImageView extends ImageView {

  private int mLeft = 0;
  private int mTop = 0;
  private Handler mHandler;
  private Bitmap bitmap;
  private Rect srcRect = new Rect();
  private Rect dstRect = new Rect();
  private int imgWidth;
  private int imgHeight;
  private boolean flag;
  private boolean istart;

  public CoolImageView(Context context) {
    super(context);
  }

  public CoolImageView(Context context, AttributeSet attrs) {
    super(context, attrs);
    setUp(context, attrs);
  }

  public CoolImageView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    setUp(context, attrs);
  }


  private void setUp(Context context, AttributeSet attrs) {
    mHandler = new MoveHandler();
    mHandler.sendEmptyMessageDelayed(1, 220L);
    istart = true;
  }

  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    int width = getWidth();
    int height = getHeight();
    //获取图片资源
    BitmapDrawable drawable = (BitmapDrawable) getDrawable();
    bitmap = drawable.getBitmap();
    dstRect.left = 0;
    dstRect.top = 0;
    dstRect.right = width;
    dstRect.bottom = height;
    if (bitmap != null) {
      if (istart) {
//        获取图片的宽高
        imgWidth = bitmap.getWidth();
        imgHeight = bitmap.getHeight();
        srcRect.left = 0 + mLeft;
        srcRect.right = imgWidth - mLeft;
        srcRect.top = 0 + mTop;
        srcRect.bottom = imgHeight - mTop;
        canvas.drawBitmap(bitmap, srcRect, dstRect, null);
      } else {
        canvas.drawBitmap(bitmap, null, dstRect, null);
      }
    }

  }

  private class MoveHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {
      switch (msg.what) {
        case 1:
          if (imgHeight != 0) {
            if (mTop == 0) {
              mTop += 5;
              mLeft += 5;
            } else if (mTop == 120) {
              mTop -= 5;
              mLeft -= 5;
            }
          }
          postInvalidate();
          mHandler.sendEmptyMessageDelayed(1, 250);
          break;
      }
    }
  }

  public void start() {
    mTop = 0;
    mLeft = 0;
    istart = true;
    mHandler.sendEmptyMessageDelayed(1, 220L);
  }

  public void stop() {
    istart = false;
  }
}