如何在 Android 圆形 ImageView 上添加阴影和边框?
androidapps/applicationsmobile development
本示例演示了如何在 Android 圆形 ImageView 上添加阴影和边框
步骤 1 − 在 Android Studio 中创建一个新项目，前往"文件"->"新建项目"，并填写所有必填信息以创建新项目。
步骤 2 − 将以下代码添加到 res/layout/activity_main.xml。
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/rl" android:padding="16dp" tools:context=".MainActivity"> <ImageView android:id="@+id/iv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true"/> <Button android:id="@+id/btn_circular" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Circular It" android:layout_alignParentBottom="true" android:layout_alignParentRight="true"/> </RelativeLayout>
步骤 3 − 将以下代码添加到 src/MainActivity.java
package com.app.sample;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.drawable.RoundedBitmapDrawable;
import androidx.core.graphics.drawable.RoundedBitmapDrawableFactory;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
private Context mContext;
private Resources mResources;
private RelativeLayout mRelativeLayout;
private Button mBTNCircular;
private ImageView mImageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mContext = getApplicationContext();
mResources = getResources();
mRelativeLayout = (RelativeLayout) findViewById(R.id.rl);
mImageView = (ImageView) findViewById(R.id.iv);
mBTNCircular = (Button) findViewById(R.id.btn_circular);
final Bitmap srcBitmap = BitmapFactory.decodeResource(mResources, R.drawable.flower);
mImageView.setImageBitmap(srcBitmap);
mBTNCircular.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Paint paint = new Paint();
int srcBitmapWidth = srcBitmap.getWidth();
int srcBitmapHeight = srcBitmap.getHeight();
int borderWidth = 25;
int shadowWidth = 10;
int dstBitmapWidth = Math.min(srcBitmapWidth,srcBitmapHeight)+borderWidth*2;
Bitmap dstBitmap = Bitmap.createBitmap(dstBitmapWidth,dstBitmapWidth, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(dstBitmap);
canvas.drawColor(Color.WHITE);
canvas.drawBitmap(srcBitmap, (dstBitmapWidth - srcBitmapWidth) / 2, (dstBitmapWidth - srcBitmapHeight) / 2, null);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(borderWidth * 2);
paint.setColor(Color.WHITE);
canvas.drawCircle(canvas.getWidth() / 2, canvas.getHeight() / 2, canvas.getWidth() / 2, paint);
paint.setColor(Color.LTGRAY);
paint.setStrokeWidth(shadowWidth);
canvas.drawCircle(canvas.getWidth()/2,canvas.getHeight()/2,canvas.getWidth()/2,paint);
RoundedBitmapDrawable roundedBitmapDrawable = RoundedBitmapDrawableFactory.create(mResources, dstBitmap);
roundedBitmapDrawable.setCircular(true);
roundedBitmapDrawable.setAntiAlias(true);
mImageView.setImageDrawable(roundedBitmapDrawable);
}
});
}
}
步骤 4 − 将以下代码添加到 Manifests/AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.app.sample"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
让我们尝试运行您的应用程序。假设您已将实际的 Android 移动设备连接到电脑。要从 Android Studio 运行该应用程序，请打开项目的某个 Activity 文件，然后点击工具栏上的"运行"图标 
。选择您的移动设备作为选项，然后检查您的移动设备是否显示您的默认屏幕 −
点击此处下载项目代码。
