android自定义控件ImageView实现圆形图片

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 = 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; 
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); 
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, 
(float) ((3 + Math.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(); 
} 
}

<?xml version="1.0" encoding="utf-8"? 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
<com.example.view.CircleImageView
android:layout_width="match_parent"
android:layout_height="match_parent"/ 
<／LinearLayout