第一种是生成圆角背景:
Button mView = (Button)findViewById(R.id.mView);
Bitmap myCoolBitmap = ((BitmapDrawable) getResources().getDrawable(
R.drawable.icon)).getBitmap();
int w = myCoolBitmap.getWidth(), h = myCoolBitmap.getHeight();
Bitmap rounder = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(rounder);
Paint xferPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
xferPaint.setColor(Color.RED);
canvas.drawRoundRect(new RectF(0, 0, w, h), 20.0f, 20.0f, xferPaint);
xferPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
canvas.drawBitmap(myCoolBitmap, 0, 0, null);
canvas.drawBitmap(rounder, 0, 0, xferPaint);
Drawable drawable = new BitmapDrawable(rounder);
mView.setBackgroundDrawable(drawable);
第二种是真的圆角的位图:
public Bitmap getRoundedCornerBitmap(Bitmap bitmap) {
// 创建一个指定宽度和高度的空位图对象
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
// 用该位图创建画布
Canvas canvas = new Canvas(output);
// 画笔对象
final Paint paint = new Paint();
// 画笔的颜色
final int color = 0xff424242;
// 矩形区域对象
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
// 未知
final RectF rectF = new RectF(rect);
// 拐角的半径
final float roundPx = 30;
// 消除锯齿
paint.setAntiAlias(true);
// 画布背景色
canvas.drawARGB(0, 0, 0, 0);
// 设置画笔颜色
paint.setColor(color);
// 绘制圆角矩形
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
// 未知
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
// 把该图片绘制在该圆角矩形区域中
canvas.drawBitmap(bitmap, rect, rect, paint);
// 最终在画布上呈现的就是该圆角矩形图片,然后我们返回该Bitmap对象
return output;
}