package com.customview.widget;

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;
import android.support.annotation.IntRange;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;

/**
 * 自定義Drawable 實現圓形圖片
 * Created by hust_twj on 2017/9/26.
 */

public class CircleDrawable extends Drawable {
  private Paint mPaint;
  private int mWidth; //寬/高，直徑
  private Bitmap mBitmap;

  public CircleDrawable(Bitmap bitmap) {
    this.mBitmap = bitmap;
    BitmapShader bitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);//著色器 水平和豎直都需要填充滿
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setShader(bitmapShader);
    mWidth = Math.min(mBitmap.getWidth(), mBitmap.getHeight()); //寬高的最小值作為直徑
  }

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

  @Override
  public void setAlpha(@IntRange(from = 0, to = 255) int i) {
    mPaint.setAlpha(i);
  }

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

  @Override
  public int getOpacity() {
    return PixelFormat.TRANSLUCENT; //設置系統默認，讓drawable支持和窗口一樣的透明度
  }

  //還需要從重寫以下2個方法，返回drawable實際寬高
  @Override
  public int getIntrinsicWidth() {
    return mWidth;
  }

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


}

package com.customview.widget;

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.RectF;
import android.graphics.Shader;
import android.graphics.drawable.Drawable;
import android.support.annotation.IntRange;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;

/**
 * 自定義Drawable 實現圓角圖片
 * Created by hust_twj on 2017/9/26.
 */

public class RoundCornerDrawable extends Drawable {
  private Paint mPaint;
  private RectF rectF;//定義矩形區域
  private Bitmap mBitmap;

  public RoundCornerDrawable(Bitmap bitmap) {
    this.mBitmap = bitmap;
    BitmapShader bitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);//著色器 水平和豎直都需要填充滿
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setShader(bitmapShader);
    //rectF = new RectF(0, 0, bitmap.getWidth(), bitmap.getHeight());
  }

  @Override
  public void draw(@NonNull Canvas canvas) {
    //RectF:圓角矩形區域
    canvas.drawRoundRect(new RectF(0, 0, mBitmap.getWidth(), mBitmap.getHeight()),100, 100, mPaint);//rx：x方向上的圓角半徑; ry：y方向上的圓角半徑。
  }

/*  @Override
  public void setBounds(int left, int top, int right, int bottom) {
    super.setBounds(left, top, right, bottom);
    rectF = new RectF(left, top, right, bottom);
  }*/

  @Override
  public void setAlpha(@IntRange(from = 0, to = 255) int i) {
    mPaint.setAlpha(i);
  }

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

  @Override
  public int getOpacity() {
    return PixelFormat.TRANSLUCENT; //設置系統默認，讓drawable支持和窗口一樣的透明度
  }

  //還需要從重寫以下2個方法，返回drawable實際寬高
  @Override
  public int getIntrinsicWidth() {
    return mBitmap.getWidth();
  }

  @Override
  public int getIntrinsicHeight() {
    return mBitmap.getHeight();
  }

}

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.XXX);
imageView.setImageDrawable(new RoundCornerDrawable(bitmap));