package com.example.myapi.pictobig;import com.example.myapi.R;import android.content.Context;  import android.graphics.Bitmap;  import android.graphics.BitmapFactory;  import android.graphics.BitmapShader;  import android.graphics.Canvas;  import android.graphics.Matrix;  import android.graphics.Shader.TileMode;  import android.graphics.drawable.ShapeDrawable;  import android.graphics.drawable.shapes.OvalShape;  import android.view.MotionEvent;  import android.view.View;  import android.widget.ImageView;  /**  * 图片放大镜工具类  * @author yw-tony  *  */  public class PicToBigTools extends ImageView{      private Bitmap bitmap;      private ShapeDrawable drawable;      /*放大镜的半径*/      private static final int RADIUS = 80;      /*放大倍数*/      private static final int FACTOR = 3;      private Matrix matrix = new Matrix();      /**     * 构造方法     * @param context     */    public PicToBigTools(Context context) {          super(context);          Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.pictobig_icon);          bitmap = bmp;                 BitmapShader shader = new BitmapShader(                  Bitmap.createScaledBitmap(bmp, bmp.getWidth()*FACTOR,                          bmp.getHeight()*FACTOR, true), TileMode.CLAMP, TileMode.CLAMP);          //圆形的drawable          drawable = new ShapeDrawable(new OvalShape());                  drawable.getPaint().setShader(shader);         /*设置放大的区域*/        drawable.setBounds(0, 0, RADIUS*2, RADIUS*2);      }               @Override      public boolean onTouchEvent(MotionEvent event) {          final int x = (int) event.getX();          final int y = (int) event.getY();                          /**设置图片等比例缩放*/        // 获得图片的宽高        int width = bitmap.getWidth();        int height = bitmap.getHeight();         // 计算缩放比例        float scaleWidth = ((float) RADIUS*2) / width;        float scaleHeight = ((float) RADIUS*2) / height;        matrix.postScale(scaleWidth,scaleHeight);                        //这个位置表示的是，画shader的起始位置          matrix.setTranslate(RADIUS-x*FACTOR, RADIUS-y*FACTOR);          drawable.getPaint().getShader().setLocalMatrix(matrix);          //bounds，就是那个圆的外切矩形          drawable.setBounds(x-RADIUS, y-RADIUS, x+RADIUS, y+RADIUS);          invalidate();//更新UI        return true;      }            @Override      public void onDraw(Canvas canvas) {          super.onDraw(canvas);          canvas.drawBitmap(bitmap, 0, 0, null);          drawable.draw(canvas);//绘制图片      }  }