Android应用中如何将头像图片变圆形

package com.common.base.util;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;import com.common.base.R;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);  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); }}