如何使机器人带有圆角的视图 [英] How to make a view in android with rounded corners

问题描述

我试图在Android的视图与圆边。我迄今发现的解决方案是定义一个圆角的形状，并用它作为视图的背景。

I am trying to make a view in android with rounded edges. The solution I found so far is to define a shape with rounded corners and use it as the background of that view.

下面是我做的，定义绘制下面给出

Here is what I did,define a drawable as given below

    

<padding
android:top="2dp"
android:bottom="2dp"/>
<corners android:bottomRightRadius="20dp"
android:bottomLeftRadius="20dp"
android:topLeftRadius="20dp"
android:topRightRadius="20dp"/>

现在我以此为背景对我的布局如下

Now I used this as the background for my layout as below

<LinearLayout
        android:orientation="vertical"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginBottom="10dp"
        android:clipChildren="true"
        android:background="@drawable/rounded_corner">

这工作完全正常，我可以看到，观点圆边。

This works perfectly fine, I can see that the view has rounded edges.

但我的布局得到了它说，一个ImageView的或MapView的许多其他孩子的意见。当我把上面的布局中的ImageView的，图像的角不修剪/裁剪，而是出现爆满。

But my layout has got many other child views in it Say an ImageView or a MapView. When I place an ImageView inside the above layout, the corners of image are not clipped/cropped, instead it appears full.

我看到其他的解决办法，使工作像一个解释<一个href="http://www.techrepublic.com/article/pro-tip-round-corners-on-an-android-imageview-with-this-hack/">here.

I have seen other workarounds to make it work like the one explained here.

但有一个方法来设置圆角的视图，其所有   子视图包含已圆形的主视图中   角落？

But is there a method to set rounded corners for a view and all its child views are contained within that main view that has rounded corners?

感谢。

推荐答案

另一种方法是创建一个自定义布局类类似下面。这种布局首先绘制它的内容到屏幕外的位图，掩盖了屏幕外的位图带圆角的矩形，然后绘制实际的画布上的屏幕外的位图。

Another approach is to make a custom layout class like the one below. This layout first draws its contents to an offscreen bitmap, masks the offscreen bitmap with a rounded rect and then draws the offscreen bitmap on the actual canvas.

我尝试过了，似乎工作（至少对于我的简单的测试用例）。相比于常规的布局它当然将影响性能。

I tried it and it seems to work (at least for my simple testcase). It will of course affect performance compared to a regular layout.

package com.example;

import android.content.Context;
import android.graphics.*;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.widget.FrameLayout;

public class RoundedCornerLayout extends FrameLayout {
    private final static float CORNER_RADIUS = 40.0f;

    private Bitmap maskBitmap;
    private Paint paint, maskPaint;
    private float cornerRadius;

    public RoundedCornerLayout(Context context) {
        super(context);
        init(context, null, 0);
    }

    public RoundedCornerLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs, 0);
    }

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

    private void init(Context context, AttributeSet attrs, int defStyle) {
        DisplayMetrics metrics = context.getResources().getDisplayMetrics();
        cornerRadius = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, CORNER_RADIUS, metrics);

        paint = new Paint(Paint.ANTI_ALIAS_FLAG);

        maskPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
        maskPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));

        setWillNotDraw(false);
    }

    @Override
    public void draw(Canvas canvas) {
        Bitmap offscreenBitmap = Bitmap.createBitmap(canvas.getWidth(), canvas.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas offscreenCanvas = new Canvas(offscreenBitmap);

        super.draw(offscreenCanvas);

        if (maskBitmap == null) {
            maskBitmap = createMask(canvas.getWidth(), canvas.getHeight());
        }

        offscreenCanvas.drawBitmap(maskBitmap, 0f, 0f, maskPaint);
        canvas.drawBitmap(offscreenBitmap, 0f, 0f, paint);
    }

    private Bitmap createMask(int width, int height) {
        Bitmap mask = Bitmap.createBitmap(width, height, Bitmap.Config.ALPHA_8);
        Canvas canvas = new Canvas(mask);

        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setColor(Color.WHITE);

        canvas.drawRect(0, 0, width, height, paint);

        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
        canvas.drawRoundRect(new RectF(0, 0, width, height), cornerRadius, cornerRadius, paint);

        return mask;
    }
}

使用这种像一个正常的布局：

Use this like a normal layout:

<com.example.RoundedCornerLayout
    android:layout_width="200dp"
    android:layout_height="200dp">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/test"/>

    <View
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:background="#ff0000"
        />

</com.example.RoundedCornerLayout>

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