我在 Android 中有一个动态生成的位图,我想从顶部边缘开始羽化,这样边界区域在顶部完全透明,并逐渐在下面稍微变为完全不透明。
创建均匀的完全透明的顶部边缘
transparentPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
transparentPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OUT));
Shader shader = new LinearGradient(0, 0, 0, 20,
Color.TRANSPARENT, Color.TRANSPARENT, Shader.TileMode.CLAMP);
transparentPaint.setShader(shader);
// the bitmap is dynamically generated beforehand
Canvas c = new Canvas(bitmap);
c.drawRect(0, 0, bitmapWidth, 20, transparentPaint);
Alpha 渐变而不是完全透明的孔?
你会如何实现这样的目标:
[本例中只是顶部边缘]
看看这个例子:使位图的某些区域在触摸时透明
这是使用渐变绘画的一种方法:
Paint framePaint = new Paint();
for(int i = 1; i < 5; i++){
setFramePaint(framePaint, i, imageW, imageH);
myCanvas.drawPaint(framePaint);
}
...
private void setFramePaint(Paint p, int side, float iw, float ih){
// paint, side of rect, image width, image height
p.setShader(null);
p.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
float borderSize = 0.1f; //relative size of border
//use the smaller image size to calculate the actual border size
float bSize = (iw > ih)? ih * borderSize: ih * borderSize;
float g1x = 0;
float g1y = 0;
float g2x = 0;
float g2y = 0;
int c1 = 0, c2 = 0;
if (side == 1){
//left
g1x = 0;
g1y = ih/2;
g2x = bSize;
g2y = ih/2;
c1 = Color.TRANSPARENT;
c2 = Color.BLACK;
}else if(side == 2){
//top
g1x = iw/2;
g1y = 0;
g2x = iw/2;
g2y = bSize;
c1 = Color.TRANSPARENT;
c2 = Color.BLACK;
}else if(side == 3){
//right
g1x = iw;
g1y = ih/2;
g2x = iw - bSize;
g2y = ih/2;
c1 = Color.TRANSPARENT;
c2 = Color.BLACK;
}else if(side == 4){
//bottom
g1x = iw/2;
g1y = ih;
g2x = iw/2;
g2y = ih - bSize;
c1 = Color.TRANSPARENT;
c2 = Color.BLACK;
}
p.setShader(new LinearGradient(g1x, g1y, g2x, g2y, c1, c2, Shader.TileMode.CLAMP));
}
本文内容由网友自发贡献,版权归原作者所有,本站不承担相应法律责任。如您发现有涉嫌抄袭侵权的内容,请联系:hwhale#tublm.com(使用前将#替换为@)