Android 自定义圆角头像

在自己项目中新建文件夹views,在该目录下新建类CircleImageView （圆角图片）。

CircleImageView 类的实现如下。

相关注释代码已经标注，可以直接复制即可。

package com.xie.com.imoocmusic.views;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.support.annotation.Nullable;
import android.support.v7.widget.AppCompatImageView;
import android.util.AttributeSet;

public class CircleImageView extends AppCompatImageView {
private float width;
private float height;
private float radius;
private Paint paint;
private Matrix matrix;

public CircleImageView(Context context) {
this(context, null);
}

public CircleImageView(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}

public CircleImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
paint = new Paint();
paint.setAntiAlias(true);   //设置抗锯齿
matrix = new Matrix();      //初始化缩放矩阵
}

/**
* 测量控件的宽高，并获取其内切圆的半径
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
width = getMeasuredWidth();
height = getMeasuredHeight();
radius = Math.min(width, height) / 2;
}

@Override
protected void onDraw(Canvas canvas) {
Drawable drawable = getDrawable();
if (drawable == null) {
super.onDraw(canvas);
return;
}
if (drawable instanceof BitmapDrawable) {
paint.setShader(initBitmapShader((BitmapDrawable) drawable));//将着色器设置给画笔
canvas.drawCircle(width / 2, height / 2, radius, paint);//使用画笔在画布上画圆
return;
}
super.onDraw(canvas);
}

/**
* 获取ImageView中资源图片的Bitmap，利用Bitmap初始化图片着色器,通过缩放矩阵将原资源图片缩放到铺满整个绘制区域，避免边界填充
*/
private BitmapShader initBitmapShader(BitmapDrawable drawable) {
Bitmap bitmap = drawable.getBitmap();
BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
float scale = Math.max(width / bitmap.getWidth(), height / bitmap.getHeight());
matrix.setScale(scale, scale);//将图片宽高等比例缩放，避免拉伸
bitmapShader.setLocalMatrix(matrix);
return bitmapShader;
}
}

在布局中的引用自定义View。

<com.xie.com.imoocmusic.views.CircleImageView
android:id="@+id/iv_icon"
android:layout_width="56dp"
android:layout_height="56dp"
android:src="@mipmap/img1"/>

效果如下：