图片转圆角（saveLayer、restore）
public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {
int x = bitmap.getWidth();
int y = bitmap.getHeight();
float[] mOuter = new float[] { roundPx, roundPx, roundPx, roundPx,
roundPx, roundPx, roundPx, roundPx };
// 根据源文件新建一个darwable对象
Drawable imageDrawable = new BitmapDrawable(bitmap);
// 新建一个新的输出图片
Bitmap output = Bitmap.createBitmap(x, y, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(output);
// 新建一个矩形
RectF outerRect = new RectF(0, 0, x, y);
Path mPath = new Path();
// 创建一个圆角矩形路径
mPath.addRoundRect(outerRect, mOuter, Path.Direction.CW);
// 画出一个红色的圆角矩形
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.RED);
paint.setAntiAlias(true);
canvas.drawPath(mPath, paint);
// 设置绘图两层交汇时的模式
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
// 设置绘图区域（在那个区域内绘图）
imageDrawable.setBounds(0, 0, x, y);
// 将用于绘制图片的图层拷贝到单独图层并压入图层栈
canvas.saveLayer(outerRect, paint, Canvas.ALL_SAVE_FLAG);
// 将源图片绘制到这个拷贝的图片图层上
imageDrawable.draw(canvas);
// 将图片图层退出栈并将图像绘制到矩形的那一层
canvas.restore();
return output;
}【图片转圆角（saveLayer、restore）】
public static Bitmap getCircleBitmap(Bitmap bitmap, float roundPx) {
Drawable imageDrawable = new BitmapDrawable(bitmap);
// 新建一个新的输出图片
Bitmap output = Bitmap.createBitmap((int)roundPx, (int)roundPx, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(output);
Path mPath = new Path();
mPath.addCircle(roundPx/2, roundPx/2, roundPx/2, Path.Direction.CW);
// 画出一个红色的圆角矩形
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.RED);
paint.setAntiAlias(true);
canvas.drawPath(mPath, paint);
// 设置绘图两层交汇时的模式
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
// 设置绘图区域（在那个区域内绘图）
imageDrawable.setBounds(0, 0, (int)roundPx, (int)roundPx);
// 将用于绘制图片的图层压入图层栈
canvas.saveLayer(0, 0, (int)roundPx, (int)roundPx, paint, Canvas.ALL_SAVE_FLAG);
// 将源图片绘制到这个圆角矩形上
imageDrawable.draw(canvas);
// 将图片图层退出栈并将图像绘制到矩形的那一层
canvas.restore();
return output;
}public static Bitmap getRoundCornerImage(Bitmap bitmap, int roundPixels) {
// 创建一个和原始图片一样大小位图
Bitmap roundConcerImage = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
// 创建带有位图roundConcerImage的画布
Canvas canvas = new Canvas(roundConcerImage);
// 创建画笔
Paint paint = new Paint();
// 创建一个和原始图片一样大小的矩形
Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
RectF rectF = new RectF(rect);
// 去锯齿
paint.setAntiAlias(true);
// 画一个和原始图片一样大小的圆角矩形
canvas.drawRoundRect(rectF, roundPixels, roundPixels, paint);
// 设置相交模式
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
// 把图片画到矩形去
canvas.drawBitmap(bitmap, null, rect, paint);
return roundConcerImage;
}
