android自定义控件ImageView实现圆形图片

android开发中常常涉及到一种情况，就是将用户上传的图片以圆形样式显示，但是用户上传的图片可以有直角、圆角、正方形等多种不确定样式，这时就用到了自定义ImageView控件，在安卓客户端使接收到的图片全部以圆形样式显示

CircleImageView.java

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(); 
 } 
}

activity_main.xml

<?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>

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