58.圆角图片

绘制流程：

1.根据获取的属性值，判断显示模式，并设置圆形图片、外边框、内边框的半径值

2.画边框

3.画图片内容

（1）获取原图

（2）得到正方形图

（3）得到缩放图

（4）得到圆形图

public class MyRoundImageView extends ImageView {

private int defaultColor = 0xffffffff;    private ShowType mShowType = ShowType.NoBorder;    private int mBorderThickness = 0;    private int mBorderInsideColor;    private int mBorderOutsideColor;    private int mRadius = 0;

enum ShowType {InsideBorder,OutsideBorder,InsideAndOutsideBorder,NoBorder}

public MyRoundImageView(Context context) {super(context);}

public MyRoundImageView(Context context, AttributeSet attrs) {super(context, attrs);readAttrs(attrs);}

public MyRoundImageView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);readAttrs(attrs);}

private void readAttrs(AttributeSet attrs) {        TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.RoundImageView);mBorderThickness = a.getDimensionPixelSize(R.styleable.RoundImageView_border_thickness, 0);mBorderInsideColor = a.getColor(R.styleable.RoundImageView_border_inside_color, defaultColor);mBorderOutsideColor = a.getColor(R.styleable.RoundImageView_border_outside_color, defaultColor);readShowType();}

private void readShowType() {if (mBorderInsideColor != defaultColor && mBorderOutsideColor != defaultColor) {mShowType = ShowType.InsideAndOutsideBorder;} else if (mBorderInsideColor != defaultColor && mBorderOutsideColor == defaultColor) {mShowType = ShowType.InsideBorder;} else if (mBorderInsideColor == defaultColor && mBorderOutsideColor != defaultColor) {mShowType = ShowType.OutsideBorder;} else {mShowType = ShowType.NoBorder;}    }

@Overrideprotected void onDraw(Canvas canvas) {switch (mShowType) {case InsideBorder:mRadius = (getWidth() < getHeight() ? getWidth() : getHeight()) / 2 - mBorderThickness;drawRoundBorder(canvas, mRadius + mBorderThickness / 2, mBorderInsideColor);                break;            case OutsideBorder:mRadius = (getWidth() < getHeight() ? getWidth() : getHeight()) / 2 - mBorderThickness;drawRoundBorder(canvas, mRadius + mBorderThickness / 2, mBorderOutsideColor);                break;            case InsideAndOutsideBorder:mRadius = (getWidth() < getHeight() ? getWidth() : getHeight()) / 2 - mBorderThickness * 2;drawRoundBorder(canvas, mRadius + mBorderThickness / 2, mBorderInsideColor);drawRoundBorder(canvas, mRadius + mBorderThickness / 2 + mBorderThickness, mBorderOutsideColor);                break;            case NoBorder:mRadius = (getWidth() < getHeight() ? getWidth() : getHeight()) / 2;                break;            default:        }        drawBitmapContent(canvas);}

private void drawRoundBorder(Canvas canvas, int radius, int color) {        Paint paint = new Paint();paint.setAntiAlias(true);paint.setFilterBitmap(true);paint.setDither(true);paint.setColor(color);paint.setStyle(Paint.Style.STROKE);paint.setStrokeWidth(mBorderThickness);canvas.drawCircle(getWidth() / 2, getHeight() / 2, radius, paint);}

private void drawBitmapContent(Canvas canvas) {        canvas.drawBitmap(bitmapToRound(bitmapToScale(bitmapToSquare(readBitmap()))), getWidth() / 2 - mRadius, getHeight() / 2 - mRadius, null);}

private Bitmap readBitmap() {        Drawable drawable = getDrawable();        if (drawable == null) {return null;}if (drawable instanceof NinePatchDrawable) {return null;}if (drawable instanceof BitmapDrawable) {return ((BitmapDrawable) drawable).getBitmap().copy(Bitmap.Config.ARGB_8888, true);}return null;}

private Bitmap bitmapToSquare(Bitmap bitmap) {int w = bitmap.getWidth();        int h = bitmap.getHeight();        int x = w > h ? (w - h) / 2 : 0;        int y = w > h ? 0 : (h - w) / 2;        int sideLength = w > h ? h : w;        return Bitmap.createBitmap(bitmap, 0, 0, sideLength, sideLength);}

private Bitmap bitmapToScale(Bitmap bitmap) {return Bitmap.createScaledBitmap(bitmap, mRadius * 2,mRadius * 2, true);}

public Bitmap bitmapToRound(Bitmap bitmap) {        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),bitmap.getHeight(), Bitmap.Config.ARGB_8888);Canvas canvas = new Canvas(output);Paint paint = new Paint();Rect rect = new Rect(0, 0, output.getWidth(),output.getHeight());paint.setAntiAlias(true);canvas.drawRoundRect(new RectF(rect), rect.width()/2, rect.height()/2, paint);//取output的图层与bitmap的图层的交集paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));//参数2是截取原图区域，可以不是全部图片，参数3是显示位置区域canvas.drawBitmap(bitmap, rect, rect, paint);        return output;}

}

附1.设置两张图片相交时的模式

/**     * setXfermode 设置两张图片相交时的模式*///    PorterDuff.Mode.CLEAR 清除画布上图像//    PorterDuff.Mode.SRC 显示上层图像//    PorterDuff.Mode.DST 显示下层图像//    PorterDuff.Mode.SRC_OVER上下层图像都显示，上层居上显示//    PorterDuff.Mode.DST_OVER 上下层都显示,下层居上显示//    PorterDuff.Mode.SRC_IN 取两层图像交集部门,只显示上层图像//    PorterDuff.Mode.DST_IN 取两层图像交集部门,只显示下层图像//    PorterDuff.Mode.SRC_OUT 取上层图像非交集部门//    PorterDuff.Mode.DST_OUT 取下层图像非交集部门//    PorterDuff.Mode.SRC_ATOP 取下层图像非交集部门与上层图像交集部门//    PorterDuff.Mode.DST_ATOP 取上层图像非交集部门与下层图像交集部门//    PorterDuff.Mode.XOR 取两层图像的非交集部门

参考资料：

http://blog.csdn.net/alan_biao/article/details/17379925

来自为知笔记(Wiz)