白色圆圈内的位图 [英] Bitmap inside white circle

问题描述

我正在尝试在白色圆圈内填充Bitmap，更具体地说:

I'm trying to fill Bitmap inside white circle, more specifically:

例如，我有一个Bitmap:

我想要这个:

我将背景设为灰色以了解图像.

I've make background gray for understand image.

我使用这种方法，但是不能满足我的要求.

I use this method, but it doesn't make what I want..

public static Bitmap getRoundedBitmap(Bitmap bitmap)
{
    final Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
    final Canvas canvas = new Canvas(output);

    final int color = Color.WHITE;
    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
    final RectF rectF = new RectF(rect);

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    canvas.drawOval(rectF, paint);
    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(bitmap, rect, rect, paint);

    bitmap.recycle();

    return output;
}

推荐答案

我猜您用来绘制椭圆的颜色的ALPHA =0.尝试用Color(1.0f，1.0f，1.0f，1.0替换Color.WHITE F).告诉我这是否解决了您的问题，然后看一下: PorterDuff.Mode在android中是什么意思图形.它有什么作用?

I guess the color you use to paint the oval has ALPHA = 0. Try replacing Color.WHITE with Color(1.0f, 1.0f, 1.0f, 1.0f). Tell me if that solved your problem, and take a look at: What does PorterDuff.Mode mean in android graphics.What does it do?

在这种情况下，对于SRC_IN:[Sa * Da，Sc * Da](摘自android reference，PorterDuff.Mode)

In this case, for SRC_IN: [Sa * Da, Sc * Da] (Taken from android reference, PorterDuff.Mode)

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