android圖片縮放、放大demo

樣本

原圖：

 

拖動查看其他部分：

 

 

放大仔細查看

 

程式碼範例，注釋比較詳細，其他不多講了

 

package com.study.drascale;import android.os.Bundle;import android.app.Activity;import android.graphics.Matrix;import android.graphics.PointF;import android.util.FloatMath;import android.view.MotionEvent;import android.view.View;import android.view.View.OnTouchListener;import android.widget.ImageView;public class MainActivity extends Activity {ImageView imageView;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                imageView = (ImageView) findViewById(R.id.img);        imageView.setOnTouchListener(new TounchListener());    }    private class TounchListener implements OnTouchListener{        private PointF startPoint = new PointF();    private Matrix matrix = new Matrix();    private Matrix currentMaritx = new Matrix();        private int mode = 0;//用於標記模式    private static final int DRAG = 1;//拖動    private static final int ZOOM = 2;//放大    private float startDis = 0;    private PointF midPoint;//中心點public boolean onTouch(View v, MotionEvent event) {switch (event.getAction() & MotionEvent.ACTION_MASK) {case MotionEvent.ACTION_DOWN:mode = DRAG;currentMaritx.set(imageView.getImageMatrix());//記錄ImageView當期的移動位置startPoint.set(event.getX(),event.getY());//開始點break;case MotionEvent.ACTION_MOVE://移動事件if (mode == DRAG) {//圖片拖動事件float dx = event.getX() - startPoint.x;//x軸移動距離float dy = event.getY() - startPoint.y;matrix.set(currentMaritx);//在當前的位置基礎上移動matrix.postTranslate(dx, dy);} else if(mode == ZOOM){//圖片放大事件float endDis = distance(event);//結束距離if(endDis > 10f){float scale = endDis / startDis;//放大倍數matrix.set(currentMaritx);matrix.postScale(scale, scale, midPoint.x, midPoint.y);}}break;case MotionEvent.ACTION_UP:mode = 0;break;//有手指離開螢幕，但螢幕還有觸點(手指)case MotionEvent.ACTION_POINTER_UP:mode = 0;break;//當螢幕上已經有觸點（手指）,再有一個手指壓下螢幕case MotionEvent.ACTION_POINTER_DOWN:mode = ZOOM;startDis = distance(event);if(startDis > 10f){//避免手指上有兩個繭midPoint = mid(event);currentMaritx.set(imageView.getImageMatrix());//記錄當前的縮放倍數}break;}imageView.setImageMatrix(matrix);return true;}        }    /**     * 兩點之間的距離     * @param event     * @return     */    private static float distance(MotionEvent event){    //兩根線的距離    float dx = event.getX(1) - event.getX(0);    float dy = event.getY(1) - event.getY(0);    return FloatMath.sqrt(dx*dx + dy*dy);    }    /**     * 計算兩點之間中心點的距離     * @param event     * @return     */    private static PointF mid(MotionEvent event){    float midx = event.getX(1) + event.getX(0);    float midy = event.getY(1) - event.getY(0);        return new PointF(midx/2, midy/2);    }}

 

樣本下載：

http://download.csdn.net/detail/sdefzhpk/4542576