Android DragImageView实现下拉拖动图片放大效果

package com.example.dragimagescale;  import android.annotation.SuppressLint; import android.app.Activity; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Matrix; import android.graphics.PointF; import android.os.Handler; import android.os.Message; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.util.Log; import android.view.MotionEvent; import android.view.WindowManager; import android.widget.ImageView; import android.widget.ImageView.ScaleType; import android.widget.RelativeLayout;  public class DragScaleImageView extends RelativeLayout {  private String TAG = "DragScaleImageView";  private static final int BACK_SCALE = 1010;   private Context mContext;  private AttributeSet attrs;  private int displayWidth = 0;  private int displayHeight = 0;  private int mImageId;  private Bitmap bmp;  private ImageView imageView;   /** 是否处在回弹状态 */  private boolean isBacking = false;   /** 用于记录拖拉图片移动的坐标位置 */  private Matrix matrix = new Matrix();  /** 用于记录图片要进行拖拉时候的坐标位置 */  private Matrix currentMatrix = new Matrix();  private Matrix defaultMatrix = new Matrix();  /** 图片的宽高 */  private float imgHeight, imgWidth;  /** 初始状态 */  private int mode = 0;  /** 拖拉照片模式 */  private final int MODE_DRAG = 1;   private float scaleY = 0;   /** 用于记录开始时候的坐标位置 */  private PointF startPoint = new PointF();   /** 用于记录开始时候的在整个屏幕中的Y坐标位置 */  private float startRawY = 0;  float scale = 1;      private TouchEventListener touchEventListener = null;  private BackScaleListener backScaleListener = null;   public DragScaleImageView(Context context, AttributeSet attrs) {   super(context, attrs);   // TODO Auto-generated constructor stub   this.mContext = context;   this.attrs = attrs;   initView();  }   public DragScaleImageView(Context context) {   super(context);   // TODO Auto-generated constructor stub   this.mContext = context;   initView();  }   public DragScaleImageView(Activity activity, Bitmap resBitmap, int width,    int height) {   super(activity);  }   /**   * 初始化图片   */  private void initView() {   /* 取得屏幕分辨率大小 */   DisplayMetrics dm = new DisplayMetrics();   WindowManager mWm = (WindowManager) mContext     .getSystemService(Context.WINDOW_SERVICE);   mWm.getDefaultDisplay().getMetrics(dm);   displayWidth = dm.widthPixels;   displayHeight = dm.heightPixels;    TypedArray a = mContext.obtainStyledAttributes(attrs,     R.styleable.DragScaleImageView);   mImageId = a.getResourceId(R.styleable.DragScaleImageView_scale_image,     0);   a.recycle();   if (null == bmp && mImageId != 0) {    bmp = BitmapFactory.decodeResource(getResources(), mImageId);    float scale = (float) displayWidth / (float) bmp.getWidth();// 1080/1800    matrix.postScale(scale, scale, 0, 0);    imgHeight = scale * bmp.getHeight();    imgWidth = scale * bmp.getWidth();   } else {    imgHeight = displayWidth;    imgWidth = displayWidth;   }   initImageView();  }   private void initImageView() {   imageView = new ImageView(mContext);   imageView.setImageMatrix(matrix);   defaultMatrix.set(matrix);   Log.w(TAG, "imgWidth :" + imgWidth);   Log.w(TAG, "imgHeight :" + imgHeight);    RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(     (int) imgWidth, (int) imgHeight);   imageView.setLayoutParams(layoutParams);   imageView.setImageBitmap(bmp);   imageView.setScaleType(ScaleType.CENTER_CROP);   this.addView(imageView);  }   /**   * 设置ImageView的宽高   *   * @param width   * @param height   */  public void setImageWidthAndHeight(int width, int height) {   imgWidth = width;   imgHeight = height;   RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(     (int) imgWidth, (int) imgHeight);   imageView.setLayoutParams(layoutParams);  }   public boolean onTouchEvent(MotionEvent event) {   Log.w(TAG, "onTouchEvent :" + event.getAction());   // 当该View放置在ScrollView里面时，会与父控件Touch事件冲突，所以touch该控件区域时，父控件不可用   if (event.getAction() == MotionEvent.ACTION_UP) {    getParent().requestDisallowInterceptTouchEvent(false);   } else {    getParent().requestDisallowInterceptTouchEvent(true);// true表示父类的不可用;   }   switch (event.getAction() & MotionEvent.ACTION_MASK) {   // 手指压下屏幕   case MotionEvent.ACTION_DOWN:    if (isBacking) {     return super.onTouchEvent(event);    }    int[] location = new int[2];    imageView.getLocationInWindow(location);    if (location[1] >= 0) {     mode = MODE_DRAG;     // 记录ImageView当前的移动位置     currentMatrix.set(imageView.getImageMatrix());     startPoint.set(event.getX(), event.getY());     startRawY = event.getRawY();     Log.w(TAG, "onTouchEvent startRawY:" + startRawY);    }    break;   // 手指在屏幕上移动，改事件会被不断触发   case MotionEvent.ACTION_MOVE:    // 拖拉图片    if (mode == MODE_DRAG) { //    float dx = event.getX() - startPoint.x; // 得到x轴的移动距离     float dy = event.getY() - startPoint.y; // 得到y轴的移动距离     // 在没有移动之前的位置上进行移动     if (dy > 0) {      matrix.set(currentMatrix);      Log.w(TAG, "onTouchEvent dy:" + dy);      scale = ((dy / (displayHeight - startRawY) * (displayHeight - imgHeight)) + imgHeight)        / imgHeight; // 得到缩放倍数，当手指移动到屏幕底部时，图片也达到屏幕底部      Log.w(TAG, "onTouchEvent scale:" + scale);           scaleY = dy;      RelativeLayout.LayoutParams relativeLayout = new RelativeLayout.LayoutParams(        (int) (scale * imgWidth), (int) (scale * imgHeight));      imageView.setLayoutParams(relativeLayout);      matrix.postScale(scale, scale, imgWidth / 2, 0);      imageView.setImageMatrix(matrix);     }    }    break;   // 手指离开屏幕   case MotionEvent.ACTION_UP:    // 当触点离开屏幕，图片还原    mHandler.sendEmptyMessage(BACK_SCALE);   case MotionEvent.ACTION_POINTER_UP:    // 当两个手指移动时，取消移动图片    mode = 0;    break;   }   // 设置的Touch监听事件   if (touchEventListener != null) {    touchEventListener.onTouchEvent(event);   }   return true;  }    /** 逐步回弹 */  @SuppressLint("HandlerLeak")  private Handler mHandler = new Handler() {   @Override   public void handleMessage(Message msg) {    // TODO Auto-generated method stub    switch (msg.what) {    case BACK_SCALE:     scale = (scaleY / 2 + imgHeight) / (imgHeight);// 得到缩放倍数     if (scaleY > 0) {      isBacking = true;      matrix.set(currentMatrix);      RelativeLayout.LayoutParams relativeLayout = new RelativeLayout.LayoutParams(        (int) (scale * imgWidth), (int) (scale * imgHeight));      imageView.setLayoutParams(relativeLayout);      matrix.postScale(scale, scale, imgWidth / 2, 0);      imageView.setImageMatrix(matrix);      scaleY = (float) (scaleY / 2 - 1);      mHandler.sendEmptyMessageDelayed(BACK_SCALE, 20);// 逐步回弹     } else {      scaleY = 0;      RelativeLayout.LayoutParams relativeLayout = new RelativeLayout.LayoutParams(        (int) imgWidth, (int) imgHeight);      imageView.setLayoutParams(relativeLayout);      matrix.set(defaultMatrix);      imageView.setImageMatrix(matrix);      isBacking = false;     }     if (backScaleListener != null) {      backScaleListener.onBackScale();     }     break;    default:     break;    }    super.handleMessage(msg);   }  };    public void setTouchEventListener(TouchEventListener touchEventListener) {   this.touchEventListener = touchEventListener;  }    public void setBackScaleListener(BackScaleListener backScaleListener) {   this.backScaleListener = backScaleListener;  }   /** Touch事件监听 */  public interface TouchEventListener {   public void onTouchEvent(MotionEvent event);  }  /** 回弹事件监听 */  public interface BackScaleListener {   public void onBackScale();  } } 

package com.example.dragimagescale;  import com.example.dragimagescale.DragScaleImageView.BackScaleListener; import com.example.dragimagescale.DragScaleImageView.TouchEventListener;  import android.app.Activity; import android.os.Bundle; import android.view.MotionEvent;  public class MainActivity extends Activity {     DragScaleImageView mDragScaleImageView;    @Override  protected void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   setContentView(R.layout.activity_main);    mDragScaleImageView = (DragScaleImageView) findViewById(R.id.dragScaleImageView);   /** 自定义ImageView的宽高，若不设置则按图片宽高压缩至屏幕宽度 */ //  mDragScaleImageView.setImageWidthAndHeight(720, 300);   // Touch事件监听   mDragScaleImageView.setTouchEventListener(new TouchEventListener() {        @Override    public void onTouchEvent(MotionEvent event) {     // TODO Auto-generated method stub     // do something here    }   });   // 回弹事件监听   mDragScaleImageView.setBackScaleListener(new BackScaleListener() {        @Override    public void onBackScale() {     // TODO Auto-generated method stub     // do something here    }   });  }         } 

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools"  xmlns:dragscaleimageview="http://schemas.android.com/apk/res/com.example.dragimagescale"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:background="#ffffff" >   <com.example.dragimagescale.DragScaleImageView   android:id="@+id/dragScaleImageView"   android:layout_width="match_parent"     android:layout_height="wrap_content"   dragscaleimageview:scale_image="@drawable/image"   >  </com.example.dragimagescale.DragScaleImageView>  </RelativeLayout>