在Android中,ImageView默认是一个矩形。如何使它成为一个圆角矩形(剪辑我的位图的所有4个角为圆角矩形)在ImageView?


请注意,从2021年起,只需使用ShapeableImageView


当前回答

尝试材质组件库并使用ShapeableImageView。 大概是这样的:

Java:

imageView=new ShapeableImageView(context);
imageView.setShapeAppearanceModel(
        imageView.getShapeAppearanceModel()
                 .toBuilder()
                 .setAllCornerSizes(20)
                 .build());

芬兰湾的科特林:

val imageView = ShapeableImageView(context)
imageView.setShapeAppearanceModel(
        imageView.getShapeAppearanceModel()
                 .toBuilder()
                 .setAllCornerSizes(20f)
                 .build())

其他回答

对于上面提到的乔治·沃尔特斯二世,我只是把他的答案扩展了一下,以支持不同的圆角。这可以进一步优化(一些目标矩形重叠),但不是很多。

我知道这个线程有点老了,但它是谷歌上关于如何在Android上圆角ImageViews的查询的顶级结果之一。

/**
 * Use this method to scale a bitmap and give it specific rounded corners.
 * @param context Context object used to ascertain display density.
 * @param bitmap The original bitmap that will be scaled and have rounded corners applied to it.
 * @param upperLeft Corner radius for upper left.
 * @param upperRight Corner radius for upper right.
 * @param lowerRight Corner radius for lower right.
 * @param lowerLeft Corner radius for lower left.
 * @param endWidth Width to which to scale original bitmap.
 * @param endHeight Height to which to scale original bitmap.
 * @return Scaled bitmap with rounded corners.
 */
public static Bitmap getRoundedCornerBitmap(Context context, Bitmap bitmap, float upperLeft,
        float upperRight, float lowerRight, float lowerLeft, int endWidth,
        int endHeight) {
    float densityMultiplier = context.getResources().getDisplayMetrics().density;

    // scale incoming bitmap to appropriate px size given arguments and display dpi
    bitmap = Bitmap.createScaledBitmap(bitmap, 
            Math.round(endWidth * densityMultiplier),
            Math.round(endHeight * densityMultiplier), true);

    // create empty bitmap for drawing
    Bitmap output = Bitmap.createBitmap(
            Math.round(endWidth * densityMultiplier),
            Math.round(endHeight * densityMultiplier), Config.ARGB_8888);

    // get canvas for empty bitmap
    Canvas canvas = new Canvas(output);
    int width = canvas.getWidth();
    int height = canvas.getHeight();

    // scale the rounded corners appropriately given dpi
    upperLeft *= densityMultiplier;
    upperRight *= densityMultiplier;
    lowerRight *= densityMultiplier;
    lowerLeft *= densityMultiplier;

    Paint paint = new Paint();
    paint.setAntiAlias(true);
    paint.setColor(Color.WHITE);

    // fill the canvas with transparency
    canvas.drawARGB(0, 0, 0, 0);

    // draw the rounded corners around the image rect. clockwise, starting in upper left.
    canvas.drawCircle(upperLeft, upperLeft, upperLeft, paint);
    canvas.drawCircle(width - upperRight, upperRight, upperRight, paint);
    canvas.drawCircle(width - lowerRight, height - lowerRight, lowerRight, paint);
    canvas.drawCircle(lowerLeft, height - lowerLeft, lowerLeft, paint);

    // fill in all the gaps between circles. clockwise, starting at top.
    RectF rectT = new RectF(upperLeft, 0, width - upperRight, height / 2);
    RectF rectR = new RectF(width / 2, upperRight, width, height - lowerRight);
    RectF rectB = new RectF(lowerLeft, height / 2, width - lowerRight, height);
    RectF rectL = new RectF(0, upperLeft, width / 2, height - lowerLeft);

    canvas.drawRect(rectT, paint);
    canvas.drawRect(rectR, paint);
    canvas.drawRect(rectB, paint);
    canvas.drawRect(rectL, paint);

    // set up the rect for the image
    Rect imageRect = new Rect(0, 0, width, height);

    // set up paint object such that it only paints on Color.WHITE
    paint.setXfermode(new AvoidXfermode(Color.WHITE, 255, AvoidXfermode.Mode.TARGET));

    // draw resized bitmap onto imageRect in canvas, using paint as configured above
    canvas.drawBitmap(bitmap, imageRect, imageRect, paint);

    return output;
}

我认为最简单的解决方法是这样的:-

步骤1 -创建一个形状绘图文件如下所示

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >

    <solid android:color="@color/white" />

    <corners android:radius="@dimen/dimen_10dp" />

    <stroke
        android:width="1dp"
        android:color="@color/white" />
</shape>

步骤2 -在代码中使用上述绘图。

Drawable drawable = ContextCompat.getDrawable(mActivity, R.drawable.photos_round_shape);
            drawable.mutate().setColorFilter(randomColor, PorterDuff.Mode.SRC_ATOP);
            imageView.setBackground(drawable);
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
               imageView.setClipToOutline(true);
            }

Glide.with(mContext)
                .setDefaultRequestOptions(getNoAnimationOptions())
                .load(url)
                .into(imageView);

希望这能有所帮助。

在支持库的v21中,现在有了一个解决方案:它被称为RoundedBitmapDrawable。

它基本上就像一个普通的Drawable,除了你给它一个角半径的剪辑:

setCornerRadius(float cornerRadius)

所以,从Bitmap src和一个目标ImageView开始,它看起来像这样:

RoundedBitmapDrawable dr = RoundedBitmapDrawableFactory.create(res, src);
dr.setCornerRadius(cornerRadius);
imageView.setImageDrawable(dr);

应用一个形状到你的imageView如下所示:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >
    <solid android:color="#faf5e6" />
    <stroke
        android:width="1dp"
        android:color="#808080" />
    <corners android:radius="15dp" />
    <padding
        android:bottom="5dp"
        android:left="5dp"
        android:right="5dp"
        android:top="5dp" />
</shape>

这可能对你的朋友有帮助。

我发现这两种方法在提出可行的解决方案时都非常有用。这是我的合成版本,它与像素无关,允许你有一些正方形的角,其余的角具有相同的半径(这是通常的用例)。 感谢以上两种解决方案:

public static Bitmap getRoundedCornerBitmap(Context context, Bitmap input, int pixels , int w , int h , boolean squareTL, boolean squareTR, boolean squareBL, boolean squareBR  ) {

    Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);
    Canvas canvas = new Canvas(output);
    final float densityMultiplier = context.getResources().getDisplayMetrics().density;

    final int color = 0xff424242;
    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, w, h);
    final RectF rectF = new RectF(rect);

    //make sure that our rounded corner is scaled appropriately
    final float roundPx = pixels*densityMultiplier;

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    canvas.drawRoundRect(rectF, roundPx, roundPx, paint);


    //draw rectangles over the corners we want to be square
    if (squareTL ){
        canvas.drawRect(0, h/2, w/2, h, paint);
    }
    if (squareTR ){
        canvas.drawRect(w/2, h/2, w, h, paint);
    }
    if (squareBL ){
        canvas.drawRect(0, 0, w/2, h/2, paint);
    }
    if (squareBR ){
        canvas.drawRect(w/2, 0, w, h/2, paint);
    }


    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(input, 0,0, paint);

    return output;
}

我重写了ImageView,把这个放进去,这样我就可以用xml定义它了。 您可能想在这里添加一些super调用所做的逻辑,但我已经对其进行了注释,因为它对我的情况没有帮助。

    @Override
protected void onDraw(Canvas canvas) {
    //super.onDraw(canvas);
        Drawable drawable = getDrawable();

        Bitmap b =  ((BitmapDrawable)drawable).getBitmap() ;
        Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true);

        int w = getWidth(), h = getHeight();


        Bitmap roundBitmap =  CropImageView.getRoundedCornerBitmap( getContext(), bitmap,10 , w, h , true, false,true, false);
        canvas.drawBitmap(roundBitmap, 0,0 , null);
}

希望这能有所帮助!