罗曼盖伊就在那里。

缩小版如下。

Bitmap bitmap = ((BitmapDrawable) getResources().getDrawable(R.drawable.image)).getBitmap();

Bitmap bitmapRounded = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
Canvas canvas = new Canvas(bitmapRounded);
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));
canvas.drawRoundRect((new RectF(0.0f, 0.0f, bitmap.getWidth(), bitmap.getHeight())), 10, 10, paint);

imageView.setImageBitmap(bitmapRounded);

为什么不在draw()中进行剪辑?

以下是我的解决方案:

用剪切扩展RelativeLayout 将ImageView(或其他视图)放入布局中:

代码:

public class RoundRelativeLayout extends RelativeLayout {

    private final float radius;

    public RoundRelativeLayout(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray attrArray = context.obtainStyledAttributes(attrs,
                R.styleable.RoundRelativeLayout);
        radius = attrArray.getDimension(
                R.styleable.RoundRelativeLayout_radius, 0);
    }

    private boolean isPathValid;
    private final Path path = new Path();

    private Path getRoundRectPath() {
        if (isPathValid) {
            return path;
        }

        path.reset();

        int width = getWidth();
        int height = getHeight();
        RectF bounds = new RectF(0, 0, width, height);

        path.addRoundRect(bounds, radius, radius, Direction.CCW);
        isPathValid = true;
        return path;
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        canvas.clipPath(getRoundRectPath());
        super.dispatchDraw(canvas);
    }

    @Override
    public void draw(Canvas canvas) {
        canvas.clipPath(getRoundRectPath());
        super.draw(canvas);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        int oldWidth = getMeasuredWidth();
        int oldHeight = getMeasuredHeight();
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        int newWidth = getMeasuredWidth();
        int newHeight = getMeasuredHeight();
        if (newWidth != oldWidth || newHeight != oldHeight) {
            isPathValid = false;
        }
    }

}

我的ImageView圆角小部件的实现，(下||上)大小图像到所需的尺寸。它利用了CaspNZ的代码形式。

public class ImageViewRounded extends ImageView {

    public ImageViewRounded(Context context) {
        super(context);
    }

    public ImageViewRounded(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public ImageViewRounded(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        BitmapDrawable drawable = (BitmapDrawable) getDrawable();

        if (drawable == null) {
            return;
        }

        if (getWidth() == 0 || getHeight() == 0) {
            return; 
        }

        Bitmap fullSizeBitmap = drawable.getBitmap();

        int scaledWidth = getMeasuredWidth();
        int scaledHeight = getMeasuredHeight();

        Bitmap mScaledBitmap;
        if (scaledWidth == fullSizeBitmap.getWidth() && scaledHeight == fullSizeBitmap.getHeight()) {
            mScaledBitmap = fullSizeBitmap;
        } else {
            mScaledBitmap = Bitmap.createScaledBitmap(fullSizeBitmap, scaledWidth, scaledHeight, true /* filter */);
        }

        Bitmap roundBitmap = ImageUtilities.getRoundedCornerBitmap(getContext(), mScaledBitmap, 5, scaledWidth, scaledHeight,
                false, false, false, false);
        canvas.drawBitmap(roundBitmap, 0, 0, null);

    }

}

如果你的图片在互联网上，最好的方法是使用glide和RoundedBitmapDrawableFactory(来自API 21 -但在支持库中可用)，如下所示:

 Glide.with(ctx).load(url).asBitmap().centerCrop().into(new BitmapImageViewTarget(imageView) {
    @Override
    protected void setResource(Bitmap res) {
        RoundedBitmapDrawable bitmapDrawable =
             RoundedBitmapDrawableFactory.create(ctx.getResources(), res);
        bitmapDrawable.setCircular(true);//comment this line and uncomment the next line if you dont want it fully cricular
        //circularBitmapDrawable.setCornerRadius(cornerRadius);
        imageView.setImageDrawable(bitmapDrawable);
    }
});

以下是我的解决方案:

<com.myproject.ui.RadiusCornerImageView
        android:id="@+id/imageViewPhoto"
        android:layout_width="160dp"
        android:layout_height="160dp"
        app:corner_radius_dp="5"
        app:corner_radius_position="top"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

在java代码中:

public class RadiusCornerImageView extends android.support.v7.widget.AppCompatImageView {
    private int cornerRadiusDP = 0; // dp
    private int corner_radius_position;

    public RadiusCornerImageView(Context context) {
        super(context);
    }

    public RadiusCornerImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public RadiusCornerImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        TypedArray typeArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.RadiusCornerImageView, 0, 0);
        try {
            cornerRadiusDP = typeArray.getInt(R.styleable.RadiusCornerImageView_corner_radius_dp, 0);
            corner_radius_position = typeArray.getInteger(R.styleable.RadiusCornerImageView_corner_radius_position, 0);
        } finally {
            typeArray.recycle();
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        float radiusPx = AndroidUtil.dpToPx(getContext(), cornerRadiusDP);
        Path clipPath = new Path();
        RectF rect = null;
        if (corner_radius_position == 0) { // all
            // round corners on all 4 angles
            rect = new RectF(0, 0, this.getWidth(), this.getHeight());
        } else if (corner_radius_position == 1) {
            // round corners only on top left and top right
            rect = new RectF(0, 0, this.getWidth(), this.getHeight() + radiusPx);

    } else {
        throw new IllegalArgumentException("Unknown corner_radius_position = " + corner_radius_position);
    }
    clipPath.addRoundRect(rect, radiusPx, radiusPx, Path.Direction.CW);
    canvas.clipPath(clipPath);
    super.onDraw(canvas);
 }
}

您可以尝试这个库- RoundedImageView

它是:

一个快速的ImageView，支持圆角，椭圆形和圆形。CircleImageView的完整超集。

我在我的项目中使用了它，它非常简单。