自定义ImageView图片切角，切指定的边圆角

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.ImageView;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;

/**
* 自定义图片切角，切指定的边。
* Created by czz on 2015/11/3.
*/
public class SemicircleImageView extends ImageView {
private Paint paint;

public SemicircleImageView(Context context) {
this(context, null);
}

public SemicircleImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}

public SemicircleImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
paint = new Paint();
}

/**
* 绘制圆角矩形图片
*
* @author caizhiming
*/
@Override
protected void onDraw(Canvas canvas) {

Drawable drawable = getDrawable();
if (null != drawable) {
Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
//设置图片上半部图片圆角
Bitmap b = SemicircleImageView.fillet(SemicircleImageView.TOP,bitmap,dp2px(5));
final Rect rectSrc = new Rect(0, 0, b.getWidth(), b.getHeight());
final Rect rectDest = new Rect(0, 0, getWidth(), getHeight());
paint.reset();
canvas.drawBitmap(b, rectSrc, rectDest, paint);

} else {
super.onDraw(canvas);
}
}

private int dp2px(int dp) {
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp,
getContext().getResources().getDisplayMetrics());
}

public static final int ALL = 347120;
public static final int TOP = 547120;
public static final int LEFT = 647120;
public static final int RIGHT = 747120;
public static final int BOTTOM = 847120;

/**
*
* @param type
* @param bitmap
* @param roundPx
* @return
*/
public static Bitmap fillet(int type, Bitmap bitmap, int roundPx) {
try {
final int width = bitmap.getWidth();
final int height = bitmap.getHeight();

Bitmap paintingBoard = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(paintingBoard);
canvas.drawARGB(Color.TRANSPARENT, Color.TRANSPARENT, Color.TRANSPARENT, Color.TRANSPARENT);

final Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.BLACK);

if (TOP == type) {
clipTop(canvas, paint, roundPx, width, height);
} else if (LEFT == type) {
clipLeft(canvas, paint, roundPx, width, height);
} else if (RIGHT == type) {
clipRight(canvas, paint, roundPx, width, height);
} else if (BOTTOM == type) {
clipBottom(canvas, paint, roundPx, width, height);
} else {
clipAll(canvas, paint, roundPx, width, height);
}

paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
//帖子图
final Rect src = new Rect(0, 0, width, height);
final Rect dst = src;
canvas.drawBitmap(bitmap, src, dst, paint);
return paintingBoard;
} catch (Exception exp) {
return bitmap;
}
}

private static void clipLeft(final Canvas canvas, final Paint paint, int offset, int width, int height) {
final Rect block = new Rect(offset, 0, width, height);
canvas.drawRect(block, paint);
final RectF rectF = new RectF(0, 0, offset * 2, height);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

private static void clipRight(final Canvas canvas, final Paint paint, int offset, int width, int height) {
final Rect block = new Rect(0, 0, width - offset, height);
canvas.drawRect(block, paint);
final RectF rectF = new RectF(width - offset * 2, 0, width, height);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

private static void clipTop(final Canvas canvas, final Paint paint, int offset, int width, int height) {
final Rect block = new Rect(0, offset, width, height);
canvas.drawRect(block, paint);
final RectF rectF = new RectF(0, 0, width, offset * 2);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

private static void clipBottom(final Canvas canvas, final Paint paint, int offset, int width, int height) {
final Rect block = new Rect(0, 0, width, height - offset);
canvas.drawRect(block, paint);
final RectF rectF = new RectF(0, height - offset * 2, width, height);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

private static void clipAll(final Canvas canvas, final Paint paint, int offset, int width, int height) {
final RectF rectF = new RectF(0, 0, width, height);
canvas.drawRoundRect(rectF, offset, offset, paint);
}

}