android 图片旋转

android图片旋转是老话题了，但如何简单迅速无BUG的解决它是需要想一想的。

首先回顾一下android 图片旋转提供的API有哪些

1.Matrix

2.Animation

说白了 Animation的核心也是Matrix。 而且Animation真是扩展性不强也不好用，用过的应该都知道。

那我们开始走Matrix路线吧。下面是游戏中用到的箭头选择并动画在原地来回偏移。

核心代码如下

package com.laahaa.view.extension;

import com.laahaa.R;
import com.laahaa.config.ExtensionLayoutConfig;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.drawable.BitmapDrawable;
import android.view.Gravity;
import android.widget.FrameLayout;
import android.widget.FrameLayout.LayoutParams;
import android.widget.ImageView;

/**
 * 
 * <p>class name:中间箭头</p>
 * <p>class instruction:</p>
 * @author Mercury  Create in 2012-2-7
 */
public class CenterArrow extends ImageView{
    FrameLayout.LayoutParams lp;
    private Bitmap bitmap;
    private Matrix matrix = new Matrix(); 
    
    public CenterArrow(Context context) {
        super(context);
         lp=new FrameLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT,Gravity.CENTER);
    }
    /**
     * 线程每次间隔时间调用
     * @param dir
     */
    public void onTick(int dir)
    {
        switch (dir) {
        case 0:
            if(lp.bottomMargin==(ExtensionLayoutConfig.CenterArrowWidth+ExtensionLayoutConfig.CenterCircleWidth))
                lp.bottomMargin+=ExtensionLayoutConfig.ArrowOffset;
            else
                lp.bottomMargin-=ExtensionLayoutConfig.ArrowOffset;
            break;
        case 1:            
            if(lp.leftMargin==(ExtensionLayoutConfig.CenterArrowWidth+ExtensionLayoutConfig.CenterCircleWidth))
                lp.leftMargin+=ExtensionLayoutConfig.ArrowOffset;
            else
                lp.leftMargin-=ExtensionLayoutConfig.ArrowOffset;
            break;
        case 2:        
            if(lp.bottomMargin==-(ExtensionLayoutConfig.CenterArrowWidth+ExtensionLayoutConfig.CenterCircleWidth))
                lp.bottomMargin-=ExtensionLayoutConfig.ArrowOffset;
            else
                lp.bottomMargin+=ExtensionLayoutConfig.ArrowOffset;
            break;
        case 3:
            if(lp.leftMargin==-(ExtensionLayoutConfig.CenterArrowWidth+ExtensionLayoutConfig.CenterCircleWidth))
                lp.leftMargin-=ExtensionLayoutConfig.ArrowOffset;
            else
                lp.leftMargin+=ExtensionLayoutConfig.ArrowOffset;
            break;
        }
        this.setLayoutParams(lp);
        this.setImageBitmap(bitmap);
    }
    public void setRotate(int dir)
    {
        int degrees=0;
        switch (dir) {
        case 0:
            degrees=90;
            lp.leftMargin=0;
            lp.rightMargin=0;
            lp.bottomMargin=ExtensionLayoutConfig.CenterArrowWidth+ExtensionLayoutConfig.CenterCircleWidth;
            lp.topMargin=0;
            break;
        case 1:
            degrees=0;
            lp.leftMargin=ExtensionLayoutConfig.CenterArrowWidth+ExtensionLayoutConfig.CenterCircleWidth;
            lp.rightMargin=0;
            lp.bottomMargin=0;
            lp.topMargin=0;
            break;
        case 2:
            degrees=270;
            lp.leftMargin=0;
            lp.rightMargin=0;
            lp.bottomMargin=-(ExtensionLayoutConfig.CenterArrowWidth+ExtensionLayoutConfig.CenterCircleWidth);
            lp.topMargin=0;
            break;
        case 3:
            degrees=180;
            lp.leftMargin=-(ExtensionLayoutConfig.CenterArrowWidth+ExtensionLayoutConfig.CenterCircleWidth);
            lp.rightMargin=0;
            lp.bottomMargin=0;
            lp.topMargin=0;
            break;
        }
         bitmap=((BitmapDrawable) getResources().getDrawable(R.drawable.arrow)).getBitmap();  
          this.setLayoutParams(lp);
          //设置图像的旋转角度    
          matrix.setRotate(degrees);
          //旋转图像，并生成新的Bitmap对像  
          bitmap=Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
          //重新在ImageView组件中显示旋转后的图像  
          this.setImageBitmap(bitmap); 
    }
}