Android编程实现自定义ImageView圆图功能的方法

本文实例讲述了Android编程实现自定义ImageView圆图功能的方法。分享给大家供大家参考，具体如下：

首先很感谢开源项目Universal Image Loader图片加载框架。之前也看过一段时间框架源码，但是却没有时间进行知识点的总结。

今天项目遇到了需要实现圆头像的编辑显示，Universal就已经提供了这个显示RoundedBitmapDisplayer这个类实现了圆图功能。看它的代码可以发现是实现的Drawable

public static class RoundedDrawable extends Drawable {    protected final float cornerRadius;    protected final int margin;    protected final RectF mRect = new RectF(),        mBitmapRect;    protected final BitmapShader bitmapShader;    protected final Paint paint;    public RoundedDrawable(Bitmap bitmap, int cornerRadius, int margin) {      this.cornerRadius = cornerRadius;      this.margin = margin;      bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);      mBitmapRect = new RectF (margin, margin, bitmap.getWidth() - margin, bitmap.getHeight() - margin);      paint = new Paint();      paint.setAntiAlias(true);      paint.setShader(bitmapShader);    }    @Override    protected void onBoundsChange(Rect bounds) {      super.onBoundsChange(bounds);      mRect.set(margin, margin, bounds.width() - margin, bounds.height() - margin);      // Resize the original bitmap to fit the new bound      Matrix shaderMatrix = new Matrix();      shaderMatrix.setRectToRect(mBitmapRect, mRect, Matrix.ScaleToFit.FILL);      bitmapShader.setLocalMatrix(shaderMatrix);    }    @Override    public void draw(canvas canvas) {      canvas.drawRoundRect(mRect, cornerRadius, cornerRadius, paint);    }    @Override    public int getOpacity() {      return PixelFORMat.TRANSLUCENT;    }    @Override    public void setAlpha(int alpha) {      paint.setAlpha(alpha);    }    @Override    public void setColorFilter(ColorFilter cf) {      paint.setColorFilter(cf);    }  }