如何制作带有圆角的ImageView？

在Android中，默认情况下，ImageView是一个矩形。如何在ImageView中使其成为一个圆角矩形（将Bitmap的所有4个角都切掉为圆角矩形）？

#1楼

非常感谢您首先回答。这是修改后的版本，可将矩形图像转换为正方形图像（并四舍五入），并通过填充颜色作为参数。

public static Bitmap getRoundedBitmap(Bitmap bitmap, int pixels, int color) {

    Bitmap inpBitmap = bitmap;
    int width = 0;
    int height = 0;
    width = inpBitmap.getWidth();
    height = inpBitmap.getHeight();

    if (width <= height) {
        height = width;
    } else {
        width = height;
    }

    Bitmap output = Bitmap.createBitmap(width, height, Config.ARGB_8888);
    Canvas canvas = new Canvas(output);

    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, width, height);
    final RectF rectF = new RectF(rect);
    final float roundPx = pixels;

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

    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
    canvas.drawBitmap(inpBitmap, rect, rect, paint);

    return output;
}

#2楼

为什么不对draw()进行裁剪？

这是我的解决方案：

通过裁剪扩展RelativeLayout
将ImageView（或其他视图）放入布局中：

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;
        }
    }

}

#3楼

虽然上述答案有效，但Romain Guy（Android的核心开发人员）在他的博客中展示了一种更好的方法，该方法通过使用着色器而不创建位图的副本来使用更少的内存。该功能的基本要点如下：

BitmapShader shader;
shader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);

Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setShader(shader);

RectF rect = new RectF(0.0f, 0.0f, width, height);

// rect contains the bounds of the shape
// radius is the radius in pixels of the rounded corners
// paint contains the shader that will texture the shape
canvas.drawRoundRect(rect, radius, radius, paint);

与其他方法相比，它的优点是：

不会创建位图的单独副本，因为它会占用大量内存和大图像[与此处的大多数其他答案相比]
支持抗锯齿 [vs clipPath方法]
支持alpha [vs xfermode + porterduff方法]
支持硬件加速 [vs clipPath方法]
只能在画布上绘制一次 [vs xfermode和clippath方法]

我基于此代码创建了RoundedImageView ，该代码将该逻辑包装到ImageView中，并添加了适当的ScaleType支持和可选的圆角边框。

#4楼

罗曼·盖（Romain Guy）就在这里。

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);

#5楼

将形状应用于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>

这可能对您的朋友有帮助。

来源：oschina

链接：https://my.oschina.net/stackoom/blog/3156366

标签

android

RoundedImageView