ShadowGenerator.java 文件源码

public static Bitmap createPillWithShadow(int rectColor, int width, int height) {

        float shadowRadius = height * 1f / 32;
        float shadowYOffset = height * 1f / 16;

        int radius = height / 2;

        Canvas canvas = new Canvas();
        Paint blurPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
        blurPaint.setMaskFilter(new BlurMaskFilter(shadowRadius, Blur.NORMAL));

        int centerX = Math.round(width / 2 + shadowRadius);
        int centerY = Math.round(radius + shadowRadius + shadowYOffset);
        int center = Math.max(centerX, centerY);
        int size = center * 2;
        Bitmap result = Bitmap.createBitmap(size, size, Config.ARGB_8888);
        canvas.setBitmap(result);

        int left = center - width / 2;
        int top = center - height / 2;
        int right = center + width / 2;
        int bottom = center + height / 2;

        // Draw ambient shadow, center aligned within size
        blurPaint.setAlpha(AMBIENT_SHADOW_ALPHA);
        canvas.drawRoundRect(left, top, right, bottom, radius, radius, blurPaint);

        // Draw key shadow, bottom aligned within size
        blurPaint.setAlpha(KEY_SHADOW_ALPHA);
        canvas.drawRoundRect(left, top + shadowYOffset, right, bottom + shadowYOffset,
                radius, radius, blurPaint);

        // Draw the circle
        Paint drawPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
        drawPaint.setColor(rectColor);
        canvas.drawRoundRect(left, top, right, bottom, radius, radius, drawPaint);

        return result;
    }