android - 使用毕加索绘制白色背景的圆形图像

Question

我有一些白色背景的图像和一些透明背景的图像。在创建它们的圆形图像时，我希望它们都具有白色背景，所以基本上我想用白色像素替换图像的透明像素。

有没有办法在不求助于一个一个像素的情况下实现这一点？这是我用于创建圆形图像的转换：

package com.mobilefootie.util;

import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;

public class RoundedTransformation implements com.squareup.picasso.Transformation {

public RoundedTransformation() {

}

@Override
public Bitmap transform(final Bitmap source) {
    int size = Math.min(source.getWidth(), source.getHeight());

    int x = (source.getWidth() - size) / 2;
    int y = (source.getHeight() - size) / 2;

    Bitmap squaredBitmap = Bitmap.createBitmap(source, x, y, size, size);          
    if (squaredBitmap != source) {
        source.recycle();
    }

    Bitmap bitmap = Bitmap.createBitmap(size, size, source.getConfig());

    Canvas canvas = new Canvas(bitmap);

    Paint paint = new Paint();

    BitmapShader shader = new BitmapShader(squaredBitmap, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP);
    paint.setShader(shader);
    paint.setAntiAlias(true);

    float r = size/2f;
    canvas.drawCircle(r, r, r, paint);

    squaredBitmap.recycle();
    return bitmap;

}

@Override
public String key() {
    return "rounded";
}
}

Answer 1

你必须ColorFilter为你设置一个Paint（我应用了绿色以获得更好的可视化）：

BitmapShader shader = new BitmapShader(squaredBitmap, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP);
paint.setShader(shader);
paint.setAntiAlias(true);

PorterDuff.Mode mMode = PorterDuff.Mode.OVERLAY;
paint.setColorFilter(new PorterDuffColorFilter(Color.GREEN, mMode));