旋转图片的几种方式笔记

1.矩阵

private void init(Context context) {   mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);   //加载需要的图片   mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.black_line);   bitmapDisplay = mBitmap;   matrix = new Matrix();   //获取图片的宽高   mWidth = mBitmap.getWidth();   mHeight = mBitmap.getHeight();}

//  设置旋转比例public void setAngle(float fAngle) {    matrix.setRotate(fAngle, mWidth / 2, mHeight / 2);    invalidate();}

@Overrideprotected void onDraw(Canvas canvas) {    super.onDraw(canvas);    canvas.drawBitmap(bitmapDisplay,matrix, mPaint);}

2.旋转canvas

@Overrideprotected void onDraw(Canvas canvas) {    super.onDraw(canvas);    mBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.black_line)).getBitmap();    mBitmapHeight = mBitmap.getHeight();    mBitmapWidth = mBitmap.getWidth();    int left = (screenWidth - mBitmapWidth) / 2;    int top = (screenHeight - mBitmapHeight) / 2;    mSrcRect = new Rect(0, 0, mBitmapWidth, mBitmapHeight);    Log.d("----------", left + ":" + top);    mDesRect = new Rect(0, 150, mBitmapWidth, 150+mBitmapHeight);    canvas.rotate(mDegrees, mBitmapWidth / 2, 150+mBitmapHeight / 2);    canvas.scale(mScale, mScale, mBitmapWidth / 2, 150+mBitmapHeight / 2);    canvas.drawBitmap(mBitmap, mSrcRect, mDesRect, mBitPaint);}