自定义View 之ImageView（二） 圆角ImageView

很多场景下我们需要ImageView带有圆角，这样布局看上去会更漂亮。官方ImageView没有默认该项属性，所以需要我们自定义一个ImageView

具体代码如下：

import android.content.Context;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.PorterDuff;import android.graphics.PorterDuffXfermode;import android.graphics.Rect;import android.graphics.RectF;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.Drawable;import android.util.AttributeSet;import android.widget.ImageView;/** * Created by sunwenbin on 2017/6/8. */public class RoundRectImageView extends ImageView {    private Paint paint;    public RoundRectImageView(Context context) {        this(context,null);    }    public RoundRectImageView(Context context, AttributeSet attrs) {        this(context, attrs,0);    }    public RoundRectImageView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        paint  = new Paint();    }    /**     * 绘制圆角矩形图片     * @author sunwenbin     */    @Override    protected void onDraw(Canvas canvas) {        Drawable drawable = getDrawable();        if (null != drawable) {            Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();            Bitmap b = getRoundBitmap(bitmap, 10); // 该函数中的bitmap就是被修改的图片，后面的int值，就是圆角的半径。            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);        }    }    /**     * 获取圆角矩形图片方法     * @param bitmap     * @param roundPx,一般设置成14     * @return Bitmap     * @author sunwenbin     */    private Bitmap getRoundBitmap(Bitmap bitmap, int roundPx) {        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),                bitmap.getHeight(), Bitmap.Config.ARGB_8888);        Canvas canvas = new Canvas(output);        final int color = 0xff424242;        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());        final RectF rectF = new RectF(rect);        paint.setAntiAlias(true);        canvas.drawARGB(0, 0, 0, 0);        paint.setColor(color);        int x = bitmap.getWidth();        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));        canvas.drawBitmap(bitmap, rect, rect, paint);        return output;    }}