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I'm asking about how do apply Xiaolin algorithm to have a smooth corner for image in android I've wrote a algorithm that iterate over the pixels and determine wither this pixel should removed or not to have an corner for image also removing pixel by making it transparent 255 for alpha value but the corner isn't smooth and I'm reading about Xiaolin algorithm for smooth line but because I'm in intermediate java programmer I don't know how to apply this algorithm >>> can any one help me on how to apply this algorithm or suggest another algorithm and how to use it this is my code 

int radius = Integer.parseInt(((EditText)MainActivity.this.findViewById(R.id.editTextRadius)).getText().toString());
    int xCenter ;
    int yCenter;
    Bitmap mutableBitmap = BitmapFactory.decodeResource(this.getResources(), R.drawable.h); 
    Bitmap drawaBitmap = mutableBitmap.copy(Bitmap.Config.ARGB_4444, true);


    for (int i = 0; i < radius; i++) {
        xCenter = radius;
        yCenter = radius;
        for (int j = 0; j < radius; j++) {
            if (Math.pow(i - xCenter , 2) + Math.pow(j - yCenter , 2) > Math.pow(radius, 2) ) {

                    drawaBitmap.setPixel(i, j,
                            Color.argb(255, 255, 255, 255));
            }

        }
        xCenter = radius;
        yCenter =  drawaBitmap.getHeight()-radius;
        for (int j = drawaBitmap.getHeight()-1; j > drawaBitmap.getHeight()-radius; j--) {
            if (Math.pow(i - xCenter , 2) + Math.pow(j - yCenter , 2) > Math.pow(radius, 2) ) {

                    drawaBitmap.setPixel(i, j,
                            Color.argb(255, 255, 255, 255));
            }

        }
    }
    for (int i = drawaBitmap.getWidth()-1; i > drawaBitmap.getWidth()-radius; i--) {
        xCenter = drawaBitmap.getWidth() - radius;
        yCenter =  radius;
        for (int j = 0; j < radius; j++) {
            if (Math.pow(i - xCenter , 2) + Math.pow(j - yCenter , 2) > Math.pow(radius, 2)) {

                    drawaBitmap.setPixel(i, j,
                            Color.argb(255, 255, 255, 255));
            }

        }
        xCenter = drawaBitmap.getWidth()-radius;
        yCenter =  drawaBitmap.getHeight()-radius;
        for (int j = drawaBitmap.getHeight()-1; j > drawaBitmap.getHeight()-radius; j--) {
            if (Math.pow(i - xCenter , 2) + Math.pow(j - yCenter , 2) > Math.pow(radius, 2) ) {

                    drawaBitmap.setPixel(i, j,
                            Color.argb(255, 255, 255, 255));
            }

        }
    }
    ((ImageView)this.findViewById(R.id.image)).setImageBitmap(drawaBitmap);

thanks in advance

4

2 回答 2

1

所以，我试了一下你的代码，它对我来说很好用。我确实添加了我向您建议的更改。这是 ImageView 的 xml：

<ImageView
    android:id="@+id/imageView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layerType="hardware"/>

您看到黑色而不是透明像素的原因可能是因为未设置 layerType。更正的代码：

// hardcoded this value for testing purposes
int radius = 120;
int xCenter;
int yCenter;
Bitmap mutableBitmap = BitmapFactory.decodeResource(
                                  this.getResources(), R.drawable.h); 

// ARGB_8888 // ARGB_4444 has been deprecated
Bitmap drawaBitmap = mutableBitmap.copy(Bitmap.Config.ARGB_8888, true);

for (int i = 0; i < radius; i++) {
    xCenter = radius;
    yCenter = radius;

    for (int j = 0; j < radius; j++) {
    if (Math.pow(i - xCenter , 2) + Math.pow(j - yCenter , 2) > Math.pow(radius, 2) ) {

            drawaBitmap.setPixel(i, j,
                            Color.argb(0, 0, 0, 0));
        }

    }

    xCenter = radius;
    yCenter =  drawaBitmap.getHeight()-radius;

    for (int j = drawaBitmap.getHeight()-1; j > drawaBitmap.getHeight()-radius; j--) {

        if (Math.pow(i - xCenter , 2) + Math.pow(j - yCenter , 2) > Math.pow(radius, 2) ) {

            drawaBitmap.setPixel(i, j,
                            Color.argb(0, 0, 0, 0));
        }

    }
}
for (int i = drawaBitmap.getWidth()-1; i > drawaBitmap.getWidth()-radius; i--) {
    xCenter = drawaBitmap.getWidth() - radius;
    yCenter =  radius;

    for (int j = 0; j < radius; j++) {
        if (Math.pow(i - xCenter , 2) + Math.pow(j - yCenter , 2) > Math.pow(radius, 2)) {

        drawaBitmap.setPixel(i, j,
                            Color.argb(0, 0, 0, 0));
    }

}

xCenter = drawaBitmap.getWidth()-radius;
yCenter =  drawaBitmap.getHeight()-radius;

for (int j = drawaBitmap.getHeight()-1; j > drawaBitmap.getHeight()-radius; j--) {
    if (Math.pow(i - xCenter , 2) + Math.pow(j - yCenter , 2) > Math.pow(radius, 2) ) {

        drawaBitmap.setPixel(i, j,
                            Color.argb(0, 0, 0, 0));


    }

}

}

((ImageView) findViewById(R.id.image)).
    setBackgroundColor(getResources().getColor(android.R.color.transparent));

((ImageView) findViewById(R.id.imageView1)).setImageBitmap(drawaBitmap);

顺便说一句，您也可以使用Color.TRANSPARENT.Color.argb(0, 0, 0, 0)

结果：原始和处理

在此处输入图像描述

于 2013-09-09T09:55:52.790 回答
0

这是一个基本的东西：

int radius = 10;
Bitmap b = Bitmap.createBitmap(radius, radius, Config.ARGB_8888);
Bitmap mask = Bitmap.createBitmap(2 * radius, 2 * radius, Config.ARGB_8888);
Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
Canvas c;

// create mask
p.setColor(0xff000000);
c = new Canvas(mask);
c.drawCircle(radius, radius, radius, p);

// draw something on the original bitmap
// skip it if you have original bitmap drawn
c = new Canvas(b);
LinearGradient lg = new LinearGradient(0, 0, radius, radius, 0xffff0000, 0xff00ff00, TileMode.CLAMP);
p.setShader(lg);
c.drawRect(0, 0, radius, radius, p);
// end of skip

for (int x = 0; x < radius; x++) {
    for (int y = 0; y < radius; y++) {
        int maskPixel = mask.getPixel(x, y);
        if ((maskPixel & 0xff000000) != 0xff000000) {
            int bPixel = b.getPixel(x, y);
            bPixel &= 0xffffff;
            bPixel |= (maskPixel & 0xff000000);
            b.setPixel(x, y, bPixel);
        }
    }
}

try {
    OutputStream stream;
    stream = new FileOutputStream("/sdcard/image.png");
    b.compress(CompressFormat.PNG, 100, stream);
    stream = new FileOutputStream("/sdcard/mask.png");
    mask.compress(CompressFormat.PNG, 100, stream);
} catch (FileNotFoundException e) {
    e.printStackTrace();
}
于 2013-09-09T12:43:43.797 回答