Matrix的倾斜和缩放简单使用

1.代码如下：

public class MyView extends View {
    //初始化图片资源
    private Bitmap bitmap;
    //Matrix
    private Matrix matrix = new Matrix();
    //倾斜度
    private float sx = 0.0f;
    //位图宽高
    private int width , height;
    //缩放比例
    private float scale = 1.0f;
    //判断缩放还是倾斜
    private boolean isScale = false;


    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        bitmap = ((BitmapDrawable)context.getResources().getDrawable(R.drawable.a)).getBitmap();
        width = bitmap.getWidth();
        height = bitmap.getHeight();
        this.setFocusable(true);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        matrix.reset();
        if (! isScale){ //倾斜
            matrix.setSkew(sx , 0);
        } else { //缩放
            matrix.setScale(scale , scale);
        }
        //将matix的变换放入之前的位图，得到新的位图，并绘制出来
        Bitmap bitmap2 = Bitmap.createBitmap(bitmap , 0 , 0 , width , height , matrix , true);
        canvas.drawBitmap(bitmap2 , 0 ,0 ,null);

    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        switch (event.getKeyCode()){
            case KeyEvent.KEYCODE_A:
                //向左倾斜
                isScale = false;
                sx += 0.1;
                postInvalidate();

                break;
            case KeyEvent.KEYCODE_D:
                //向右倾斜
                isScale = false;
                sx -= 0.1;
                postInvalidate();
                break;
            case KeyEvent.KEYCODE_W:
                //放大
                isScale = true;
                if (scale < 2.0){
                    scale += 0.1;
                }
                postInvalidate();
                break;
            case KeyEvent.KEYCODE_S:
                //缩小
                isScale = true;
                if (scale > 0.5){
                    scale -= 0.1;
                }
                postInvalidate();
                break;
        }
        return super.onKeyDown(keyCode, event);
    }

}public class MyView extends Vi