Android改造CardView为圆形View，Kotlin

偏执的太偏执、 2024-02-29 03:02 14阅读 0赞

### Android改造CardView为圆形View，Kotlin ###

可以利用androidx.cardview.widget.CardView的cardCornerRadius特性，将CardView改造成一个圆形的View，技术实现的关键首先设定CardView为一个宽高相等的View（正方形），然后将radius特意设置成宽度（或高度，一样，因为正方形，宽高相等）的1/2，此时CardView自然就变成一个圆。

（1）kotlin代码运行时生成：

import android.content.Context
    import android.graphics.Color
    import android.os.Bundle
    import androidx.appcompat.app.AppCompatActivity
    import androidx.cardview.widget.CardView
    
    class MainActivity : AppCompatActivity() {
        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
    
            val circularCardView = CircularCardView(this)
            circularCardView.setCardBackgroundColor(Color.BLUE)
            setContentView(circularCardView)
        }
    }
    
    class CircularCardView(ctx: Context) : CardView(ctx) {
        override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec)
            val width = measuredWidth
            setMeasuredDimension(width, width)
            radius = (width / 2).toFloat()
        }
    }

![323a1e2955794a8bb3c14f5337be448c.png][]

（2）在xml布局中实现：

<?xml version="1.0" encoding="utf-8"?>
    <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    
        <androidx.cardview.widget.CardView
            android:layout_width="200dp"
            android:layout_height="200dp"
            app:cardBackgroundColor="@android:color/holo_orange_light"
            app:cardCornerRadius="100dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">
    
        </androidx.cardview.widget.CardView>
    
    </androidx.constraintlayout.widget.ConstraintLayout>

![12908f66eb6341578c6485422ccee7fe.png][]

[Android RoundedBitmapDrawable：Android官方的圆角图形图象实现方案\_android 官方圆角-CSDN博客Android RoundedBitmapDrawable：Android官方的圆角图形图象实现方案RoundedBitmapDrawable是Android在support v4的扩展包中新增的实现圆角图形的关键类，借助RoundedBitmapDrawable的帮助，可以轻松的以Android标准方式实现圆角图形图象。写一个简单的例子。写一个线性布局，竖直方向放三个Im\_android 官方圆角![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/51829650][Android RoundedBitmapDrawable_Android_android _-CSDN_Android RoundedBitmapDrawable_Android_RoundedBitmapDrawable_Android_support v4_RoundedBitmapDrawable_Android_Im_android _favicon32.ico_https_blog.csdn.net_zhangphil_article_details_51829650][Android CardView设置成普通的Framelayout-CSDN博客比如可以这样写代码，CardView就变成普通的FrameLayout：![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/52911922][Android CardView_Framelayout-CSDN_CardView_FrameLayout_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_52911922]

[323a1e2955794a8bb3c14f5337be448c.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/29/03077b675e394ebaa096ec65ae682403.png
[12908f66eb6341578c6485422ccee7fe.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/29/10a8c39c48cd4b27958db7e5b55d246f.png
[favicon32.ico]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/29/bcb7b719ec214963bf438e03d95274da.png
[Android RoundedBitmapDrawable_Android_android _-CSDN_Android RoundedBitmapDrawable_Android_RoundedBitmapDrawable_Android_support v4_RoundedBitmapDrawable_Android_Im_android _favicon32.ico_https_blog.csdn.net_zhangphil_article_details_51829650]: https://blog.csdn.net/zhangphil/article/details/51829650
[Android CardView_Framelayout-CSDN_CardView_FrameLayout_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_52911922]: https://blog.csdn.net/zhangphil/article/details/52911922