我有一个位图，我想从该位图中裁剪一个圆形区域。圆外的所有像素均应透明。我该怎么办？
<< img src =“ https://image.soinside.com/eyJ1cmwiOiAiaHR0cHM6Ly9pLnN0YWNrLmltZ3VyLmNvbS9TR2xWcy5qcGcifQ==” alt =“在此处输入图像描述”>
经过长时间的头脑风暴，我找到了解决方法
public Bitmap getCroppedBitmap(Bitmap bitmap) {
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
// canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
canvas.drawCircle(bitmap.getWidth() / 2, bitmap.getHeight() / 2,
bitmap.getWidth() / 2, paint);
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
//Bitmap _bmp = Bitmap.createScaledBitmap(output, 60, 60, false);
//return _bmp;
return output;
}
对于想要矩形（me）中心的豌豆，在切割前添加它：
bitmap.recycle()[基于[Jachumbelechao Unto Mantekilla]的答案，此代码对于正在寻找Kotlin解决方案的人们来说就像一个魅力：
Android Crop Center of Bitmap
这里是使用扩展方法的Kotlin变体
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，正确答案：
/**
* Creates new circular bitmap based on original one.
*/
fun Bitmap.getCircularBitmap(config: Bitmap.Config = Bitmap.Config.ARGB_8888): Bitmap {
// circle configuration
val circlePaint = Paint().apply { isAntiAlias = true }
val circleRadius = Math.max(width, height) / 2f
// output bitmap
val outputBitmapPaint = Paint(circlePaint).apply { xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN) }
val outputBounds = Rect(0, 0, width, height)
val output = Bitmap.createBitmap(width, height, config)
return Canvas(output).run {
drawCircle(circleRadius, circleRadius, circleRadius, circlePaint)
drawBitmap(this@getCircularBitmap, outputBounds, outputBounds, outputBitmapPaint)
output
}
}
科丁功能
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;
}
holder.itemFriendImage.setImageBitmap(ImageConverter.getRoundedCornerBitmap(bitmap,600))
[我相信最简单的解决方案是创建您的Bitmap的BitmapShader，将其传递到绘画对象，然后简单地调用canvas.drawCircle（cx，cy，radius，paint）；]]
例如
**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，您将必须计算哪些像素不在圆内，并相应地设置Alpha（对于完全透明，Alpha = 0）。
public static Bitmap getCircularBitmap(Bitmap bitmap) {
Bitmap output;
if (bitmap.getWidth() > bitmap.getHeight()) {
output = Bitmap.createBitmap(bitmap.getHeight(), bitmap.getHeight(), Config.ARGB_8888);
} else {
output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getWidth(), Config.ARGB_8888);
}
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
float r = 0;
if (bitmap.getWidth() > bitmap.getHeight()) {
r = bitmap.getHeight() / 2;
} else {
r = bitmap.getWidth() / 2;
}
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawCircle(r, r, r, paint);
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return output;
}
您可以使用RoundedBitmapDrawable使图像视图变为圆形
这里是用于实现roundedImageview的代码：
ImageView profilePic=(ImageView)findViewById(R.id.user_image);
//get bitmap of the image
Bitmap imageBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.large_icon);
RoundedBitmapDrawable roundedBitmapDrawable=RoundedBitmapDrawableFactory.create(getResources(), imageBitmap);
//setting radius
roundedBitmapDrawable.setCornerRadius(50.0f);
roundedBitmapDrawable.setAntiAlias(true);
profilePic.setImageDrawable(roundedBitmapDrawable);
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以下是此内容的清晰实现：
我认为此解决方案适用于任何类型的矩形，如果要缩小或放大图像，请更改像素大小：
这也可以在xml中轻松完成，而无需裁剪实际的位图，您只需要创建一个圆形图像蒙版并将其放置在实际图像上即可。这是我使用的一段代码：
您可以使用此代码，它将起作用
<dimen name="icon">36dp</dimen>
<dimen name="icon_mask">55dp</dimen>
您可以使用此代码，它将起作用
private Bitmap getCircleBitmap(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.RED;
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;
}
我建议添加public Bitmap getRoundedShape(Bitmap scaleBitmapImage) {
int targetWidth = 110;
int targetHeight = 110;
Bitmap targetBitmap = Bitmap.createBitmap(targetWidth,
targetHeight,Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(targetBitmap);
Path path = new Path();
path.addCircle(((float) targetWidth - 1) / 2,
((float) targetHeight - 1) / 2,
(Math.min(((float) targetWidth),
((float) targetHeight)) / 2),
Path.Direction.CCW);
canvas.clipPath(path);
Bitmap sourceBitmap = scaleBitmapImage;
canvas.drawBitmap(sourceBitmap,
new Rect(0, 0, sourceBitmap.getWidth(),
sourceBitmap.getHeight()),
new Rect(0, 0, targetWidth, targetHeight), new Paint(Paint.FILTER_BITMAP_FLAG));
return targetBitmap;
}
，如果您不再需要它，它将防止OutOfMemory错误。