现在很多的应用都有设置头像的功能，如QQ、微信、微博等。头像有标准的四方形，也有圆形（如QQ）。现在结合他人的代码加以修改，给出一个以原始图形中心为原点，修剪图片为头像的工具类，此类

可以直接在布局文件中加载使用，比如：

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
        xmlns:tools="http://schemas.android.com/tools"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent" >  
      
        <zhangphil.circle.CircleImageView  
            android:id="@+id/civ"  
            android:layout_width="wrap_content"  
            android:layout_height="wrap_content"  
            android:src="@drawable/pic" />  
      
    </RelativeLayout>  

CircleImageView.java的完整源代码：

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.Paint.Align;  
import android.graphics.Rect;  
import android.graphics.RectF;  
import android.graphics.Shader;  
import android.graphics.SweepGradient;  
import android.graphics.drawable.BitmapDrawable;  
import android.graphics.drawable.ColorDrawable;  
import android.graphics.drawable.Drawable;  
import android.net.Uri;  
import android.text.TextPaint;  
import android.util.AttributeSet;  
import android.util.FloatMath;  
import android.widget.ImageView;  
  
/** 
 * @author Phil 
 * 
 */  
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 = 2;  
  
    // 圆形边框的厚度默认值。  
    // 如果是0，则没有天蓝色渐变的边框。  
    private static final int DEFAULT_BORDER_WIDTH = 20;  
  
    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;  
    private final Paint mFlagBackgroundPaint = new Paint();  
    private final TextPaint mFlagTextPaint = new TextPaint();  
    private String mFlagText;  
    private boolean mShowFlag = false;  
    private Rect mFlagTextBounds = new Rect();  
  
    Shader mSweepGradient = null;  
  
    public CircleImageView(Context context) {  
        super(context);  
  
        init();  
    }  
  
    public CircleImageView(Context context, AttributeSet attrs) {  
        this(context, attrs, 0);  
    }  
  
    public CircleImageView(Context context, AttributeSet attrs, int defStyle) {  
        super(context, attrs, defStyle);  
  
        // 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();  
  
        init();  
    }  
  
    private void init() {  
        super.setScaleType(SCALE_TYPE);  
        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  
    public void setAdjustViewBounds(boolean adjustViewBounds) {  
        if (adjustViewBounds) {  
            throw new IllegalArgumentException(  
                    "adjustViewBounds not supported.");  
        }  
    }  
  
    @Override  
    protected void onDraw(Canvas canvas) {  
        if (getDrawable() == null) {  
            return;  
        }  
  
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius,  
                mBitmapPaint);  
        if (mBorderWidth != 0) {  
            canvas.save();  
            canvas.rotate(20, getWidth() / 2, getHeight() / 2);  
            canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius,  
                    mBorderPaint);  
            canvas.restore();  
        }  
  
        if (mShowFlag && mFlagText != null) {  
            canvas.drawArc(mBorderRect, 40, 100, false, mFlagBackgroundPaint);  
            mFlagTextPaint.getTextBounds(mFlagText, 0, mFlagText.length(),  
                    mFlagTextBounds);  
            canvas.drawText(mFlagText, getWidth() / 2,  
                    (3 + FloatMath.cos((float) (Math.PI * 5 / 18)))  
                            * getHeight() / 4 + mFlagTextBounds.height() / 3,  
                    mFlagTextPaint);  
        }  
  
    }  
  
    @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;  
    }  
  
    /** 
     * @param borderWidth 
     *            圆形的边框厚度。 
     */  
    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();  
    }  
  
    @Override  
    public void setImageURI(Uri uri) {  
        super.setImageURI(uri);  
        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);  
  
        mFlagBackgroundPaint.setColor(Color.BLACK & 0x66FFFFFF);  
        mFlagBackgroundPaint.setFlags(TextPaint.ANTI_ALIAS_FLAG);  
  
        mFlagTextPaint.setFlags(TextPaint.ANTI_ALIAS_FLAG);  
        mFlagTextPaint.setTextAlign(Align.CENTER);  
        mFlagTextPaint.setColor(Color.WHITE);  
        mFlagTextPaint  
                .setTextSize(getResources().getDisplayMetrics().density * 18);  
  
        mSweepGradient = new SweepGradient(getWidth() / 2, getHeight() / 2,  
                new int[] { Color.rgb(255, 255, 255), Color.rgb(1, 209, 255) },  
                null);  
  
        mBorderPaint.setShader(mSweepGradient);  
  
        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);  
    }  
  
    public void setShowFlag(boolean show) {  
        mShowFlag = show;  
        invalidate();  
    }  
  
    public void setFlagText(String text) {  
        mFlagText = text;  
        invalidate();  
    }  
}