Android实现圆形图片的两种方式

在项目中，我们经常会用到圆形图片，但是android本身又没有提供，那我只能我们自己来完成。

第一种方式，自定义CircleImageView:

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(); 
 } 
} 

使用的时候，切记不要引用成V4报下的CircleImageView！！

另一篇文章分享的第二种方式：把图片修剪为圆形，这样给我们视觉上的效果是一样

我们时常会用到圆形图片，那么，是对图片进行裁剪，还是自定义圆形的ImageView，如果没有特殊要求的话，我们肯定选择前者，原因很简单，因为简单！！直接上源码，就是这么粗暴任性~~~

/** 
  * 将图片剪裁为圆形 
  */ 
 public static Bitmap createCircleImage(Bitmap source) { 
  int length = source.getWidth() < source.getHeight() ? source.getWidth() : source.getHeight(); 
  Paint paint = new Paint(); 
  paint.setAntiAlias(true); 
  Bitmap target = Bitmap.createBitmap(length, length, Bitmap.Config.ARGB_8888); 
  Canvas canvas = new Canvas(target); 
  canvas.drawCircle(length / 2, length / 2, length / 2, paint); 
  paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN)); 
  canvas.drawBitmap(source, 0, 0, paint); 
  return target; 
 } 

只需要输入bitmap，然后就给你返回圆形的bitmap，然后设置到ImageView中，是不是很简单。

这里另外提一点，如果从ImageView中拿出来bitmap，只需要一行代码：

//从ImageView中获取bitmap 
  Bitmap bm =((BitmapDrawable) ( imageView).getDrawable()).getBitmap(); 

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持小牛知识库。