Android利用CircleImageView实现圆形头像的方法

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="CircleImageView">
 <attr name="border_width" format="dimension" />
 <attr name="border_color" format="color" />
 </declare-styleable>
</resources>

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.widget.ImageView;
public class CircleImageView extends ImageView {
 private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP;
 private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888;
 private static final int COLORDRAWABLE_DIMENSION = 1;
 private static final int DEFAULT_BORDER_WIDTH = 0;
 private static final int DEFAULT_BORDER_COLOR = Color.BLACK;
 private final RectF mDrawableRect = new RectF();
 private final RectF mBorderRect = new RectF();
 private final Matrix mShaderMatrix = new Matrix();
 private final Paint mBitmapPaint = new Paint();
 private final Paint mBorderPaint = new Paint();
 private int mBorderColor = DEFAULT_BORDER_COLOR;
 private int mBorderWidth = DEFAULT_BORDER_WIDTH;
 private Bitmap mBitmap;
 private BitmapShader mBitmapShader;
 private int mBitmapWidth;
 private int mBitmapHeight;
 private float mDrawableRadius;
 private float mBorderRadius;
 private boolean mReady;
 private boolean mSetupPending;
 public CircleImageView(Context context) {
 super(context);
 }
 public CircleImageView(Context context, AttributeSet attrs) {
 this(context, attrs, 0);
 }
 public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 super.setScaleType(SCALE_TYPE);
 TypedArray a = context.obtainStyledAttributes(attrs,
 R.styleable.CircleImageView, defStyle, 0);
 mBorderWidth = a.getDimensionPixelSize(
 R.styleable.CircleImageView_border_width, DEFAULT_BORDER_WIDTH);
 mBorderColor = a.getColor(R.styleable.CircleImageView_border_color,
 DEFAULT_BORDER_COLOR);
 a.recycle();
 mReady = true;
 if (mSetupPending) {
 setup();
 mSetupPending = false;
 }
 }
 @Override
 public ScaleType getScaleType() {
 return SCALE_TYPE;
 }
 @Override
 public void setScaleType(ScaleType scaleType) {
 if (scaleType != SCALE_TYPE) {
 throw new IllegalArgumentException(String.format(
 "ScaleType %s not supported.", scaleType));
 }
 }
 @Override
 protected void onDraw(Canvas canvas) {
 if (getDrawable() == null) {
 return;
 }
 canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius,
 mBitmapPaint);
 if (mBorderWidth != 0) {
 canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius,
 mBorderPaint);
 }
 }
 @Override
 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
 super.onSizeChanged(w, h, oldw, oldh);
 setup();
 }
 public int getBorderColor() {
 return mBorderColor;
 }
 public void setBorderColor(int borderColor) {
 if (borderColor == mBorderColor) {
 return;
 }
 mBorderColor = borderColor;
 mBorderPaint.setColor(mBorderColor);
 invalidate();
 }
 public int getBorderWidth() {
 return mBorderWidth;
 }
 public void setBorderWidth(int borderWidth) {
 if (borderWidth == mBorderWidth) {
 return;
 }
 mBorderWidth = borderWidth;
 setup();
 }
 @Override
 public void setImageBitmap(Bitmap bm) {
 super.setImageBitmap(bm);
 mBitmap = bm;
 setup();
 }
 @Override
 public void setImageDrawable(Drawable drawable) {
 super.setImageDrawable(drawable);
 mBitmap = getBitmapFromDrawable(drawable);
 setup();
 }
 @Override
 public void setImageResource(int resId) {
 super.setImageResource(resId);
 mBitmap = getBitmapFromDrawable(getDrawable());
 setup();
 }
 private Bitmap getBitmapFromDrawable(Drawable drawable) {
 if (drawable == null) {
 return null;
 }
 if (drawable instanceof BitmapDrawable) {
 return ((BitmapDrawable) drawable).getBitmap();
 }
 try {
 Bitmap bitmap;
 if (drawable instanceof ColorDrawable) {
 bitmap = Bitmap.createBitmap(COLORDRAWABLE_DIMENSION,
  COLORDRAWABLE_DIMENSION, BITMAP_CONFIG);
 } else {
 bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),
  drawable.getIntrinsicHeight(), BITMAP_CONFIG);
 }
 Canvas canvas = new Canvas(bitmap);
 drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
 drawable.draw(canvas);
 return bitmap;
 } catch (OutOfMemoryError e) {
 return null;
 }
 }
 private void setup() {
 if (!mReady) {
 mSetupPending = true;
 return;
 }
 if (mBitmap == null) {
 return;
 }
 mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
 mBitmapPaint.setAntiAlias(true);
 mBitmapPaint.setShader(mBitmapShader);
 mBorderPaint.setStyle(Paint.Style.STROKE);
 mBorderPaint.setAntiAlias(true);
 mBorderPaint.setColor(mBorderColor);
 mBorderPaint.setStrokeWidth(mBorderWidth);
 mBitmapHeight = mBitmap.getHeight();
 mBitmapWidth = mBitmap.getWidth();
 mBorderRect.set(0, 0, getWidth(), getHeight());
 mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2,
 (mBorderRect.width() - mBorderWidth) / 2);
 mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width()
 - mBorderWidth, mBorderRect.height() - mBorderWidth);
 mDrawableRadius = Math.min(mDrawableRect.height() / 2,
 mDrawableRect.width() / 2);
 updateShaderMatrix();
 invalidate();
 }
 private void updateShaderMatrix() {
 float scale;
 float dx = 0;
 float dy = 0;
 mShaderMatrix.set(null);
 if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width()
 * mBitmapHeight) {
 scale = mDrawableRect.height() / (float) mBitmapHeight;
 dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f;
 } else {
 scale = mDrawableRect.width() / (float) mBitmapWidth;
 dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f;
 }
 mShaderMatrix.setScale(scale, scale);
 mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth,
 (int) (dy + 0.5f) + mBorderWidth);
 mBitmapShader.setLocalMatrix(mShaderMatrix);
 }
}

 <com.example.suqh.drop.CircleImageView
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:src="@drawable/img3" />