Android 图片缩放与旋转的实现详解

package com.android.matrix;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ImageView.ScaleType;
/**
 * Android实现图片缩放与旋转。
 * @author Administrator
 *
 */
public class MatixActivity extends Activity {
    public void onCreate(Bundle icicle) {

        super.onCreate(icicle);

        setTitle("Android实现图片缩放与旋转。");
        LinearLayout linLayout = new LinearLayout(this);

        //加载需要操作的图片，这里是一张图片
        Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),R.drawable.r);

        //获取这个图片的宽和高
        int width = bitmapOrg.getWidth();
        int height = bitmapOrg.getHeight();

        //定义预转换成的图片的宽度和高度
        int newWidth = 200;
        int newHeight = 200;

        //计算缩放率，新尺寸除原始尺寸
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;

        // 创建操作图片用的matrix对象
        Matrix matrix = new Matrix();

        // 缩放图片动作
        matrix.postScale(scaleWidth, scaleHeight);

        //旋转图片 动作
        matrix.postRotate(45);

        // 创建新的图片
        Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0,
        width, height, matrix, true);

        //将上面创建的Bitmap转换成Drawable对象，使得其可以使用在ImageView, ImageButton中
        BitmapDrawable bmd = new BitmapDrawable(resizedBitmap);

        //创建一个ImageView
        ImageView imageView = new ImageView(this);

        // 设置ImageView的图片为上面转换的图片
        imageView.setImageDrawable(bmd);

        //将图片居中显示
        imageView.setScaleType(ScaleType.CENTER);

        //将ImageView添加到布局模板中
        linLayout.addView(imageView,
        new LinearLayout.LayoutParams(
        LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT
        )
        );

        // 设置为本activity的模板
        setContentView(linLayout);
     } 
}

package com.android.zooming;
import android.view.View;
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.drawable.Drawable; 
import android.view.KeyEvent; 
public class Zoom extends View {
     private Drawable image; 
     private int zoomControler=20; 

     public Zoom(Context context){ 
         super(context); 
         image=context.getResources().getDrawable(R.drawable.x); 
         setFocusable(true); 
     } 

     @Override 
     protected void onDraw(Canvas canvas) { 
         // TODO Auto-generated method stub 
         super.onDraw(canvas); 
         //控制图像的宽度和高度
         image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler); 
         image.draw(canvas); 
     } 

     @Override 
     public boolean onKeyDown(int keyCode, KeyEvent event) { 

             if(keyCode==KeyEvent.KEYCODE_DPAD_UP)//放大
                     zoomControler+=10; 

             if(keyCode==KeyEvent.KEYCODE_DPAD_DOWN) //缩小
                     zoomControler-=10; 

             if(zoomControler<10) 
                     zoomControler=10; 

             invalidate(); 
             return true; 
     } 
}