How to make a view with rounded corners?

问题

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.

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\"/>

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\">

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

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.

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

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?

回答1:

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.

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;
    }
}

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>

回答2:

Or you can use a android.support.v7.widget.CardView like so:

<android.support.v7.widget.CardView
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    card_view:cardBackgroundColor="@color/white"
    card_view:cardCornerRadius="4dp">

    <!--YOUR CONTENT-->
</android.support.v7.widget.CardView>

回答3:

shape.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <solid android:color="#f6eef1" />

    <stroke
        android:width="2dp"
        android:color="#000000" />

    <padding
        android:bottom="5dp"
        android:left="5dp"
        android:right="5dp"
        android:top="5dp" />

    <corners android:radius="5dp" />

</shape>

and inside you layout

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

        <ImageView
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:src="@drawable/your image"
             android:background="@drawable/shape">

</LinearLayout>

回答4:

If you are having problem while adding touch listeners to the layout. Use this layout as parent layout.

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.graphics.Region;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.View;
import android.widget.FrameLayout;

public class RoundedCornerLayout extends FrameLayout {
    private final static float CORNER_RADIUS = 6.0f;
    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);
        setLayerType(View.LAYER_TYPE_SOFTWARE, null);
    }


    @Override
    protected void dispatchDraw(Canvas canvas) {
        int count = canvas.save();

        final Path path = new Path();
        path.addRoundRect(new RectF(0, 0, canvas.getWidth(), canvas.getHeight()), cornerRadius, cornerRadius, Path.Direction.CW);
        canvas.clipPath(path, Region.Op.REPLACE);

        canvas.clipPath(path);
        super.dispatchDraw(canvas);
        canvas.restoreToCount(count);
    }


}

<?xml version="1.0" encoding="utf-8"?>
<com.example.view.RoundedCornerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <RelativeLayout
        android:id="@+id/patentItem"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingRight="20dp">
        ... your child goes here
    </RelativeLayout>
</com.example.view.RoundedCornerLayout>

回答5:

Jaap van Hengstum's answer works great however I think it is expensive and if we apply this method on a Button for example, the touch effect is lost since the view is rendered as a bitmap.

For me the best method and the simplest one consists in applying a mask on the view, like that:

@Override
protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight) {
    super.onSizeChanged(width, height, oldWidth, oldHeight);

    float cornerRadius = <whatever_you_want>;
    this.path = new Path();
    this.path.addRoundRect(new RectF(0, 0, width, height), cornerRadius, cornerRadius, Path.Direction.CW);
}

@Override
protected void dispatchDraw(Canvas canvas) {
    if (this.path != null) {
        canvas.clipPath(this.path);
    }
    super.dispatchDraw(canvas);
}

回答6:

Create a xml file called round.xml in the drawable folder and paste this content:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
  <solid android:color="#FFFFFF" />
  <stroke android:width=".05dp" android:color="#d2d2d2" />
  <corners android:topLeftRadius="5dp" android:topRightRadius="5dp" android:bottomRightRadius="5dp" android:bottomLeftRadius="5dp"/>
</shape>

then use the round.xml as background to any item. Then it will give you rounded corners.

回答7:

In Android L you will be able to just use View.setClipToOutline to get that effect. In previous versions there is no way to just clip the contents of a random ViewGroup in a certain shape.

You will have to think of something that would give you a similar effect:

If you only need rounded corners in the ImageView, you can use a shader to 'paint' the image over the shape you are using as background. Take a look at this library for an example.
If you really need every children to be clipped, maybe you can another view over your layout? One with a background of whatever color you are using, and a round 'hole' in the middle? You could actually create a custom ViewGroup that draws that shape over every children overriding the onDraw method.

回答8:

follow this tutorial and all the discussion beneath it - http://www.curious-creature.org/2012/12/11/android-recipe-1-image-with-rounded-corners/

according to this post written by Guy Romain, one of the leading developers of the entire Android UI toolkit, it is possible to make a container (and all his child views) with rounded corners, but he explained that it too expensive (from performances of rendering issues).

I'll recommend you to go according to his post, and if you want rounded corners, then implement rounded corners ImageView according to this post. then, you could place it inside a container with any background, and you'll get the affect you wish.

that's what I did also also eventually.

回答9:

The CardView worked for me in API 27 in Android Studio 3.0.1. The colorPrimary was referenced in the res/values/colors.xml file and is just an example. For the layout_width of 0dp it will stretch to the width of the parent. You'll have to configure the constraints and width/height to your needs.

<android.support.v7.widget.CardView
    android:id="@+id/cardView"
    android:layout_width="0dp"
    android:layout_height="200dp"
    android:layout_marginEnd="8dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    app:cardCornerRadius="4dp"
    app:cardBackgroundColor="@color/colorPrimary">

    <!-- put your content here -->

</android.support.v7.widget.CardView>

回答10:

Create a xml file under your drawable folder with following code. (The name of the file I created is rounded_corner.xml)

rounded_corner.xml

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

        <!-- view background color -->
        <solid
            android:color="#a9c5ac" >
        </solid>

        <!-- view border color and width -->
        <stroke
            android:width="3dp"
            android:color="#1c1b20" >
        </stroke>

        <!-- If you want to add some padding -->
        <padding
            android:left="4dp"
            android:top="4dp"
            android:right="4dp"
            android:bottom="4dp"    >
        </padding>

        <!-- Here is the corner radius -->
        <corners
            android:radius="10dp"   >
        </corners>
    </shape>

And keep this drawable as background for the view to which you want to keep rounded corner border. Let’s keep it for a LinearLayout

    <LinearLayout android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/rounded_corner"
            android:layout_centerInParent="true">

            <TextView android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:text="Hi, This layout has rounded corner borders ..."
                android:gravity="center"
                android:padding="5dp"/>

    </LinearLayout>

回答11:

Difference from Jaap van Hengstum's answer:

Use BitmapShader instead of mask bitmap.
Create bitmap only once.

public class RoundedFrameLayout extends FrameLayout {
    private Bitmap mOffscreenBitmap;
    private Canvas mOffscreenCanvas;
    private BitmapShader mBitmapShader;
    private Paint mPaint;
    private RectF mRectF;

    public RoundedFrameLayout(Context context) {
        super(context);
        init();
    }

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

    public RoundedFrameLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        setWillNotDraw(false);
    }

    @Override
    public void draw(Canvas canvas) {
        if (mOffscreenBitmap == null) {
            mOffscreenBitmap = Bitmap.createBitmap(canvas.getWidth(), canvas.getHeight(), Bitmap.Config.ARGB_8888);
            mOffscreenCanvas = new Canvas(mOffscreenBitmap);
            mBitmapShader = new BitmapShader(mOffscreenBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
            mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mPaint.setShader(mBitmapShader);
            mRectF = new RectF(0f, 0f, canvas.getWidth(), canvas.getHeight());
        }
        super.draw(mOffscreenCanvas);

        canvas.drawRoundRect(mRectF, 8, 8, mPaint);
    }
}

回答12:

public class RoundedCornerLayout extends FrameLayout {
    private double mCornerRadius;

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

    public RoundedCornerLayout(Context context, AttributeSet attrs) {
        this(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();
        setLayerType(View.LAYER_TYPE_SOFTWARE, null);
    }

    public double getCornerRadius() {
        return mCornerRadius;
    }

    public void setCornerRadius(double cornerRadius) {
        mCornerRadius = cornerRadius;
    }

    @Override
    public void draw(Canvas canvas) {
        int count = canvas.save();

        final Path path = new Path();
        path.addRoundRect(new RectF(0, 0, canvas.getWidth(), canvas.getHeight()), (float) mCornerRadius, (float) mCornerRadius, Path.Direction.CW);
        canvas.clipPath(path, Region.Op.REPLACE);

        canvas.clipPath(path);
        super.draw(canvas);
        canvas.restoreToCount(count);
    }
}

回答13:

The tutorial link you provided seems to suggest that you need to set the layout_width and layout_height properties, of your child elements to match_parent.

<ImageView
    android:layout_width="match_parent"
    android:layout_height="match_parent">

回答14:

try this property with your linear layout it will help
tools:context=".youractivity"

回答15:

public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, int pixels) {

        Bitmap roundedBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap
                .getHeight(), Config.ARGB_8888);
        Canvas canvas = new Canvas(roundedBitmap);

        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
        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(bitmap, rect, rect, paint);

        return roundedBitmap;
    }

回答16:

Use shape in xml with rectangle.set the property of bottom or upper radius as want.then apply that xml as background to ur view....or...use gradients to do it from code.

来源：https://stackoverflow.com/questions/26074784/how-to-make-a-view-with-rounded-corners

标签

android

android-layout

android-view

android-shape