有没有办法在
Android中的位图上绘制圆形梯度蒙版？试图生产类似于雾窗的东西.点击窗口,透明的圆圈显示窗口后面的内容.优雅地使用渐变,所以圆的中心是完全透明的,从中心越远透明度越低.这可能吗？
我是Android的新手,所以任何代码示例将不胜感激.
谢谢.
解决方法
- private void drawFoggyWindowWithTransparentCircle(Canvas canvas,float circleX,float circleY,float radius) {
- // Get the "foggy window" bitmap
- BitmapDrawable foggyWindow =
- (BitmapDrawable) getResources().getDrawable(R.drawable.foggy_window);
- Bitmap foggyWindowBmp = foggyWindow.getBitmap();
- // Create a temporary bitmap
- Bitmap tempBitmap = Bitmap.createBitmap(
- foggyWindowBmp.getWidth(),foggyWindowBmp.getHeight(),Bitmap.Config.ARGB_8888);
- Canvas tempCanvas = new Canvas(tempBitmap);
- // Copy foggyWindowBmp into tempBitmap
- tempCanvas.drawBitmap(foggyWindowBmp,null);
- // Create a radial gradient
- RadialGradient gradient = new android.graphics.RadialGradient(
- circleX,circleY,radius,0xFF000000,0x00000000,android.graphics.Shader.TileMode.CLAMP);
- // Draw transparent circle into tempBitmap
- Paint p = new Paint();
- p.setShader(gradient);
- p.setColor(0xFF000000);
- p.setXfermode(new PorterDuffXfermode(Mode.DST_OUT));
- tempCanvas.drawCircle(circleX,p);
- // Draw tempBitmap onto the screen (over what's already there)
- canvas.drawBitmap(tempBitmap,null);
- }
