绘制图像时绘制外部阴影

Question

我目前通过绘制到画布在我的应用程序中创建一个圆形版本的图像.我想在图像周围画一个微弱的outershadow,但我不能完全正确.我有两个问题:1.如何绘制外部阴影(我似乎只能用ax或y偏移绘制阴影)2.如何绘制阴影,使其没有附加图像中显示的瑕疵.码:

![public Bitmap getRoundedCornerBitmap(Bitmap bitmap, float cornerRadius) {
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth()+6, bitmap.getHeight() +6, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        final int color = 0xff424242;
        int shadowRadius = getDipsFromPixel(3);
        final Rect imageRect = new Rect(shadowRadius, shadowRadius, bitmap.getWidth(), bitmap.getHeight());
        final RectF rectF = new RectF(imageRect);

        // This does not achieve the desired effect
        Paint shadowPaint = new Paint();
        shadowPaint.setAntiAlias(true);
        shadowPaint.setColor(Color.BLACK);
        shadowPaint.setShadowLayer((float)shadowRadius, 2.0f, 2.0f,Color.BLACK);
        canvas.drawOval(rectF, shadowPaint);

        canvas.drawARGB(0, 0, 0, 0);
        final Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(color);

        canvas.drawRoundRect(rectF, cornerRadius, cornerRadius, paint);

        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, imageRect, imageRect, paint);

        return output;
    }][1]

这是我想要实现的效果的一个例子:

Answer 1

我想要一个类似的效果,但在AppWidget上,不幸的是我无法使用@ EvelioTarazona的解决方案.这就是我提出的,它应该适用于任何形状的位图.

    final Bitmap src = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
    final Bitmap shadow = addShadow(src, src.getHeight(), src.getWidth(), Color.BLACK, 3, 1, 3);
    final ImageView iv = (ImageView)findViewById(R.id.image);
    iv.setImageBitmap(shadow);

 public Bitmap addShadow(final Bitmap bm, final int dstHeight, final int dstWidth, int color, int size, float dx, float dy) {
    final Bitmap mask = Bitmap.createBitmap(dstWidth, dstHeight, Config.ALPHA_8);

    final Matrix scaleToFit = new Matrix();
    final RectF src = new RectF(0, 0, bm.getWidth(), bm.getHeight());
    final RectF dst = new RectF(0, 0, dstWidth - dx, dstHeight - dy);
    scaleToFit.setRectToRect(src, dst, ScaleToFit.CENTER);

    final Matrix dropShadow = new Matrix(scaleToFit);
    dropShadow.postTranslate(dx, dy);

    final Canvas maskCanvas = new Canvas(mask);
    final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    maskCanvas.drawBitmap(bm, scaleToFit, paint);
    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_OUT));
    maskCanvas.drawBitmap(bm, dropShadow, paint);

    final BlurMaskFilter filter = new BlurMaskFilter(size, Blur.NORMAL);
    paint.reset();
    paint.setAntiAlias(true);
    paint.setColor(color);
    paint.setMaskFilter(filter);
    paint.setFilterBitmap(true);

    final Bitmap ret = Bitmap.createBitmap(dstWidth, dstHeight, Config.ARGB_8888);
    final Canvas retCanvas = new Canvas(ret);
    retCanvas.drawBitmap(mask, 0,  0, paint);
    retCanvas.drawBitmap(bm, scaleToFit, null);
    mask.recycle();
    return ret;
}

Answer 2

开始了

是的,我还在挖掘Nexus S.

首先,请停止屏蔽位图是这样,你可以做到这一点不分配另一个Bitmap,结帐这个博客帖子有关如何绘制圆角(实际上任何形状)的图像.

第二次使用Drawable你可能会弄清楚如何添加你的阴影,只是确保它不会被剪裁,在18岁以上你可以使用ViewOverlays,同时请记住,硬件加速层有几个不受支持的绘图操作,包括setShadowLayer和BlurMaskFilter,如果性能是不是你的问题,你可以一如既往禁用它:

if (SDK_INT >= HONEYCOMB) {
  view.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}

并setShadowLayer按照您的尝试使用:

somePaint.setShadowLayer(shadowSize, deltaX, deltaY, shadowColor);

有关示例,请查看最后的链接.

如果你仍然想要硬件加速,你将不得不伪装它有过度绘制的风险,你可以使用径向渐变或绘制另一个椭圆模糊它(如前所述不能使用BlurMaskFilter)或使用预模糊Bitmap(更多掩蔽) ).

对于这样一个微妙的阴影,如果需要性能,我宁愿只是平放,完整的酱汁在香蕉架上.

更新:从L开始,您可以使用真实阴影.

Answer 3

           ImageView imageView=findViewById(R.id.iv);
                    Bitmap icon = BitmapFactory.decodeResource(getResources(), R.drawable.images);
                    imageView.setImageBitmap(doHighlightImage(icon));   


           public static Bitmap doHighlightImage(Bitmap src) {
                    Bitmap bmOut = Bitmap.createBitmap(src.getWidth() + 96, src.getHeight() + 96, Bitmap.Config.ARGB_8888);
                    Canvas canvas = new Canvas(bmOut);
                    canvas.drawColor(0, Mode.CLEAR);
                    Paint ptBlur = new Paint();
                    ptBlur.setMaskFilter(new BlurMaskFilter(15, BlurMaskFilter.Blur.NORMAL));
                    int[] offsetXY = new int[2];
                    Bitmap bmAlpha = src.extractAlpha(ptBlur, offsetXY);
                    Paint ptAlphaColor = new Paint();
                    ptAlphaColor.setColor(Color.BLACK);
                    canvas.drawBitmap(bmAlpha, offsetXY[0], offsetXY[1], ptAlphaColor);
                    bmAlpha.recycle();
                    canvas.drawBitmap(src, 0, 0, null);
                    return bmOut;
                }