CustomDrawable.java

package com.zhoujian.drawable.view;

import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Shader;
import
 
 android.graphics.drawable.Drawable;

/**
 * Created by zhoujian on 2016/12/9.
 */

public class CustomDrawable  extends Drawable
{

    private Paint mPaint;
    private int mWidth;
    private Bitmap mBitmap ;

    public CustomDrawable(Bitmap bitmap)
    {
        mBitmap = bitmap ;
        BitmapShader bitmapShader = new
 
 BitmapShader(bitmap, Shader.TileMode.CLAMP,
                Shader.TileMode.CLAMP);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setShader(bitmapShader);
        mWidth = Math.min(mBitmap.getWidth(), mBitmap.getHeight());
    }

    @Override
    public void draw(Canvas canvas)
    {
        canvas.drawCircle(mWidth / 2
 
, mWidth / 2, mWidth / 2, mPaint);
    }

    @Override
    public int getIntrinsicWidth()
    {
        return mWidth;
    }

    @Override
    public int getIntrinsicHeight()
    {
        return mWidth;
    }

    @Override
    public void setAlpha(int alpha)
    {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf)
    {
        mPaint.setColorFilter(cf);
    }

    @Override
    public int getOpacity()
    {
        return PixelFormat.TRANSLUCENT;
    }
}

activity_main.xml

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

    <ImageView
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:id="@+id/imgView"
        android:layout_width="300dp"
        android:layout_height="300dp"/>
</RelativeLayout>

MainActivity.java

package com.zhoujian.drawable.activity;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
import com.zhoujian.drawable.R;
import com.zhoujian.drawable.view.CustomDrawable;

public class MainActivity extends AppCompatActivity
{

    private ImageView imgeview;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Bitmap bitmap= BitmapFactory.decodeResource(getResources(),R.mipmap.imgeview);
        imgeview= (ImageView) findViewById(R.id.imgView);
        imgeview.setImageDrawable(new CustomDrawable(bitmap));
    }
}

效果圖：

Drawable系列原始碼下載