downscaleHalf() [1/2]

void fl::downscaleHalf	(	const CRGB *	src,
		const XYMap &	srcXY,
		CRGB *	dst,
		const XYMap &	dstXY )

Definition at line 47 of file downscale.cpp.

                                       {
    fl::u16 dstWidth = dstXY.getWidth();
    fl::u16 dstHeight = dstXY.getHeight();
 
    FASTLED_ASSERT(srcXY.getWidth() == dstXY.getWidth() * 2,
                   "Source width must be double the destination width");
    FASTLED_ASSERT(srcXY.getHeight() == dstXY.getHeight() * 2,
                   "Source height must be double the destination height");
 
    for (fl::u16 y = 0; y < dstHeight; ++y) {
        for (fl::u16 x = 0; x < dstWidth; ++x) {
            // Map to top-left of the 2x2 block in source
            fl::u16 srcX = x * 2;
            fl::u16 srcY = y * 2;
 
            // Fetch 2x2 block
            const CRGB &p00 = src[srcXY.mapToIndex(srcX, srcY)];
            const CRGB &p10 = src[srcXY.mapToIndex(srcX + 1, srcY)];
            const CRGB &p01 = src[srcXY.mapToIndex(srcX, srcY + 1)];
            const CRGB &p11 = src[srcXY.mapToIndex(srcX + 1, srcY + 1)];
 
            // Average each color channel
            fl::u16 r =
                (p00.r + p10.r + p01.r + p11.r + 2) / 4; // +2 for rounding
            fl::u16 g = (p00.g + p10.g + p01.g + p11.g + 2) / 4;
            fl::u16 b = (p00.b + p10.b + p01.b + p11.b + 2) / 4;
 
            // Store result
            dst[dstXY.mapToIndex(x, y)] =
                CRGB((fl::u8)r, (fl::u8)g, (fl::u8)b);
        }
    }
}

References fl::XYMap::getHeight(), fl::XYMap::getWidth(), fl::XYMap::mapToIndex(), x, and y.

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