如何在Android中从位图中裁剪圆形区域

如果您不再需要位图，请添加bitmap.recycle()，这将防止内存溢出错误。

对于想要矩形中心点（即我）的人，在裁剪之前加入以下内容：

    public static Bitmap cropBitmapToBlock(Bitmap bitmap) {
    if (bitmap.getWidth() >= bitmap.getHeight()){
        return Bitmap.createBitmap(
                bitmap,
                bitmap.getWidth()/2 - bitmap.getHeight()/2,
                0,
                bitmap.getHeight(),
                bitmap.getHeight()
        );
    }else{
        return Bitmap.createBitmap(
                bitmap,
                0,
                bitmap.getHeight()/2 - bitmap.getWidth()/2,
                bitmap.getWidth(),
                bitmap.getWidth()
        );
    }
} 

Android 裁剪位图的中心

根据 [Jachumbelechao Unto Mantekilla] 提供的答案，这段代码非常适合寻找 Kotlin 解决方案的人：

fun cropCircleFromBitmap(originalBitmap: Bitmap): Bitmap {
    val size = Math.min(originalBitmap.width, originalBitmap.height)
    val bitmap = ThumbnailUtils.extractThumbnail(originalBitmap, size, size)
    var output = Bitmap.createBitmap(bitmap.width, bitmap.height, Bitmap.Config.ARGB_8888)
    val canvas = Canvas(output)
    val paint = Paint()
    val rect = Rect(0, 0, bitmap.width, bitmap.height)
    val rectF = RectF(rect)
    paint.isAntiAlias = true
    paint.isDither = true
    paint.isFilterBitmap = true
    canvas.drawARGB(0, 0, 0, 0)
    paint.color = 0xffff0000.toInt()
    canvas.drawOval(rectF, paint)
    paint.color = Color.BLUE
    paint.style = Paint.Style.STROKE
    paint.strokeWidth = 4f
    paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN);
    canvas.drawBitmap(bitmap, rect, rect, paint)
    return output
}

现在，正确的答案：

private Bitmap getCroppedBitmap(Bitmap bitmap, Integer cx, Integer cy, Integer radius) {
    int diam = radius << 1;
    Bitmap targetBitmap = Bitmap.createBitmap(diam, diam, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(targetBitmap);
    final int color = 0xff424242;
    final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    canvas.drawCircle(radius, radius, radius, paint);
    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(bitmap, -cx+radius, -cy+radius, paint);
    return targetBitmap;
}

Kotlin函数

 fun getRoundedCornerBitmap(bitmap: Bitmap, pixels: Int): Bitmap {
            val output = Bitmap.createBitmap(bitmap.width, bitmap.height, Bitmap.Config.ARGB_8888)
            val canvas = Canvas(output)

            val color = -0xbdbdbe
            val paint = Paint()
            val rect = Rect(0, 0, bitmap.width, bitmap.height)
            val rectF = RectF(rect)
            val roundPx = pixels.toFloat()

            paint.isAntiAlias = true
            canvas.drawARGB(0, 0, 0, 0)
            paint.color = color
            canvas.drawRoundRect(rectF, roundPx, roundPx, paint)

            paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN)
            canvas.drawBitmap(bitmap, rect, rect, paint)

            return output
        }

使用以下代码进行调用：

 holder.itemFriendImage.setImageBitmap(ImageConverter.getRoundedCornerBitmap(bitmap,600))

在Ext.kt文件中放置kotlin代码

 private fun Bitmap.getCircledBitmap(): Bitmap {
    val output = Bitmap.createBitmap(this.width, this.height, Bitmap.Config.ARGB_8888)
    val canvas = Canvas(output)
    val paint = Paint()
    val rect = Rect(0, 0, this.width, this.height)
    paint.isAntiAlias = true
    canvas.drawARGB(0, 0, 0, 0)
    canvas.drawCircle(this.width / 2f, this.height / 2f, this.width / 2f, paint)
    paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN)
    canvas.drawBitmap(this, rect, rect, paint)
    return output
}

对于kotlin：

private fun getCircularBitmap(bitmap: Bitmap): Bitmap? {
        val output = Bitmap.createBitmap(
            bitmap.width,
            bitmap.height, Bitmap.Config.ARGB_8888
        )
        val canvas = Canvas(output)
        val color = -0xbdbdbe
        val paint = Paint()
        val rect = Rect(0, 0, bitmap.width, bitmap.height)
        paint.isAntiAlias = true
        canvas.drawARGB(0, 0, 0, 0)
        paint.color = color
        canvas.drawCircle(
            (bitmap.width / 2).toFloat(), (bitmap.height / 2).toFloat(), (
                    bitmap.width / 2).toFloat(), paint
        )
        paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN)
        canvas.drawBitmap(bitmap, rect, rect, paint)
        return output
    }

**Jst Add this to your image Id and get the circuler image.**

 imgUserProfile.setImageBitmap(getCircularCenterCropBitmap(bitmap, (int) (150 * denisty)));

Method:-

public void Bitmap getCircularCenterCropBitmap(Bitmap originalBmp, int diameter) {
        Bitmap resizedBmp = BitmapUtils.getScaledCroppedBitmap(originalBmp, diameter, diameter);
        return BitmapUtils.getRoundedCircularBitmap(resizedBmp, diameter / 2);
    }

不确定这是否是一个编程问题，但是...

最简单的解决方案是在源位图中使外部区域透明。否则，您将不得不计算哪些像素在圆形外部，并相应地设置 alpha 值（alpha = 0 表示完全透明）。