Android Bitmap 常见的几个操作：缩放，裁剪，旋转，偏移

@H_906_54@mSCALE_X MSKEW_X  MTRANS_X
MSKEW_Y  MSCALE_Y MTRANS_Y
MPERSP_0 MPERSP_1 MPERSP_2

    /**
     * 根据给定的宽和高进行拉伸
     *
     * @param origin    原图
     *  newWidth  新图的宽
     *  newHeight 新图的高
     * @return new Bitmap
     */
    private Bitmap scaleBitmap(Bitmap origin,int newWidth,1)">int newHeight) {
        if (origin == null) {
            return ;
        }
        int height = origin.getHeight();
        int width = origin.getWidth();
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;
        Matrix matrix = new Matrix();
        matrix.postScale(scaleWidth,scaleHeight);// 使用后乘
        Bitmap newBM = Bitmap.createBitmap(origin,width,height,matrix,1)">false);
        if (!origin.isRecycled()) {
            origin.recycle();
        }
        return newBM;
    }

    
     * 按比例缩放图片
     *
     *  origin 原图
     *  ratio  比例
     *  新的bitmap
     float ratio) {
         origin.getHeight();
        Matrix matrix =  Matrix();
        matrix.preScale(ratio,ratio);
        Bitmap newBM = Bitmap.createBitmap(origin,1)">if (newBm.equals(origin)) {
             newBM;
        }
        origin.recycle();
        
     * 裁剪
     *
     *  bitmap 原图
     *  裁剪后的图像
     private Bitmap cropBitmap(Bitmap bitmap) {
        int w = bitmap.getWidth();  得到图片的宽，高
        int h = bitmap.getHeight();
        int cropWidth = w >= h ? h : w; 裁切后所取的正方形区域边长
        cropWidth /= 2;
        int cropHeight = (int) (cropWidth / 1.2return Bitmap.createBitmap(bitmap,w / 3,cropWidth,cropHeight,1)">null,1)">);
    }

    
     * 选择变换
     *
     *  alpha  旋转角度，可正可负
     *  旋转后的图片
     private Bitmap rotateBitmap(Bitmap origin,1)"> alpha) {
         Matrix();
        matrix.setRotate(alpha);
         围绕原地进行旋转
        Bitmap newBM = Bitmap.createBitmap(origin,1)">
     * 偏移效果
     *  偏移后的bitmap
      Bitmap skewBitmap(Bitmap origin) {
         Matrix();
        matrix.postSkew(-0.6f,-0.3f);
        Bitmap newBM = Bitmap.createBitmap(origin,1)"> newBM;
    }

    @Override
    public void onClick(View v) {
        Bitmap originBM = BitmapFactory.decoderesource(getresources(),R.drawable.littleboygreen_x128);
        switch (v.getId()) {
            case R.id.btn1: { 按尺寸缩放
                effectTextView.setText(R.String.scalE);
                Bitmap nBM = scaleBitmap(originBM,100,72);
                effectView.setImageBitmap(nBM);
                break;
            }
            case R.id.btn2: { 按比例缩放，每次点击缩放比例都会不同
                effectTextView.setText(R.String.scale_ratio);
                if (ratio < 3) {
                    ratio += 0.05f;
                } else {
                    ratio = 0.1f;
                }
                Bitmap nBM = scaleBitmap(originBM,ratio);
                effectView.setImageBitmap(nBM);
                case R.id.btn3: { 裁剪
                effectTextView.setText("剪个头");
                Bitmap cropBitmap = cropBitmap(originBM);
                effectView.setImageBitmap(cropBitmap);
                case R.id.btn4: { 顺时针旋转效果；每次点击更新旋转角度
                if (alpha < 345) {
                    alpha += 15 {
                    alpha = 0;
                }
                effectTextView.setText("旋转");
                Bitmap rotateBitmap = rotateBitmap(originBM,alpha);
                effectView.setImageBitmap(rotateBitmap);
                case R.id.btn5: { 逆时针旋转效果；每次点击更新旋转角度
                if (beta > 15) {
                    beta -= 15 {
                    beta = 360);
                effectView.setImageBitmap(rotateBitmap);
                case R.id.btn6: { 偏移效果；偏移量在方法中
                Bitmap skewBM = skewBitmap(originBM);
                effectView.setImageBitmap(skewBM);
                ;
            }
        }
    }