drawinglayer/source/processor2d/cairopixelprocessor2d.cxx | 79 +++++++++++---
1 file changed, 67 insertions(+), 12 deletions(-)
New commits:
commit e68715944f26cf3171dde12c4a2dfef64f0e684a
Author: Armin Le Grand (Collabora) <armin.le.gr...@me.com>
AuthorDate: Tue Aug 27 22:14:09 2024 +0200
Commit: Armin Le Grand <armin.le.gr...@me.com>
CommitDate: Wed Aug 28 21:01:30 2024 +0200
CairoSDPR: Use integer & shifting in LuminanceToAlpha conversion
Change-Id: I8a6b6341295487d7590d166d327ea90b7d1315db
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/172480
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <armin.le.gr...@me.com>
diff --git a/drawinglayer/source/processor2d/cairopixelprocessor2d.cxx
b/drawinglayer/source/processor2d/cairopixelprocessor2d.cxx
index 5379f751f30f..f8a786fa7870 100644
--- a/drawinglayer/source/processor2d/cairopixelprocessor2d.cxx
+++ b/drawinglayer/source/processor2d/cairopixelprocessor2d.cxx
@@ -759,13 +759,64 @@ void LuminanceToAlpha(cairo_surface_t* pMask)
unsigned char* mask_surface_data(cairo_image_surface_get_data(pMask));
- // include/basegfx/color/bcolormodifier.hxx
- constexpr double nRedMul(0.2125 / 255.0);
- constexpr double nGreenMul(0.7154 / 255.0);
- constexpr double nBlueMul(0.0721 / 255.0);
+ // change to unsigned 16bit and shifting. This is not much
+ // faster on modern processors due to nowadays good double/
+ // float HW, but may also be used on smaller HW (ARM, ...).
+ // Since source is sal_uInt8 integer using double (see version
+ // before) is not required numerically either.
+ // scaling values are now put to a 256 entry lookup for R, G and B
+ // thus 768 bytes, so no multiplications have to happen. The values
+ // used to create these are (54+183+18 == 255):
+ // sal_uInt16 nR(0.2125 * 256.0); // -> 54.4
+ // sal_uInt16 nG(0.7154 * 256.0); // -> 183.1424
+ // sal_uInt16 nB(0.0721 * 256.0); // -> 18.4576
+ // and the short loop (for nR, nG and nB resp.) like:
+ // for(unsigned short a(0); a < 256; a++)
+ // std::cout << ((a * nR) / 255) << ", ";
+ constexpr std::array<sal_uInt8, 256> nRArray
+ = { 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3,
3, 3, 4, 4, 4,
+ 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 7, 7, 7, 7, 8,
8, 8, 8, 8, 9,
+ 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 11, 12, 12, 12,
12, 12, 13, 13, 13, 13,
+ 13, 14, 14, 14, 14, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 17,
17, 17, 17, 18, 18, 18,
+ 18, 18, 19, 19, 19, 19, 19, 20, 20, 20, 20, 20, 21, 21, 21, 21,
22, 22, 22, 22, 22, 23,
+ 23, 23, 23, 23, 24, 24, 24, 24, 24, 25, 25, 25, 25, 26, 26, 26,
26, 26, 27, 27, 27, 27,
+ 27, 28, 28, 28, 28, 29, 29, 29, 29, 29, 30, 30, 30, 30, 30, 31,
31, 31, 31, 31, 32, 32,
+ 32, 32, 33, 33, 33, 33, 33, 34, 34, 34, 34, 34, 35, 35, 35, 35,
36, 36, 36, 36, 36, 37,
+ 37, 37, 37, 37, 38, 38, 38, 38, 38, 39, 39, 39, 39, 40, 40, 40,
40, 40, 41, 41, 41, 41,
+ 41, 42, 42, 42, 42, 42, 43, 43, 43, 43, 44, 44, 44, 44, 44, 45,
45, 45, 45, 45, 46, 46,
+ 46, 46, 47, 47, 47, 47, 47, 48, 48, 48, 48, 48, 49, 49, 49, 49,
49, 50, 50, 50, 50, 51,
+ 51, 51, 51, 51, 52, 52, 52, 52, 52, 53, 53, 53, 53, 54 };
+ constexpr std::array<sal_uInt8, 256> nGArray
+ = { 0, 0, 1, 2, 2, 3, 4, 5, 5, 6, 7, 7, 8,
9, 10, 10,
+ 11, 12, 12, 13, 14, 15, 15, 16, 17, 17, 18, 19, 20,
20, 21, 22,
+ 22, 23, 24, 25, 25, 26, 27, 27, 28, 29, 30, 30, 31,
32, 33, 33,
+ 34, 35, 35, 36, 37, 38, 38, 39, 40, 40, 41, 42, 43,
43, 44, 45,
+ 45, 46, 47, 48, 48, 49, 50, 50, 51, 52, 53, 53, 54,
55, 55, 56,
+ 57, 58, 58, 59, 60, 61, 61, 62, 63, 63, 64, 65, 66,
66, 67, 68,
+ 68, 69, 70, 71, 71, 72, 73, 73, 74, 75, 76, 76, 77,
78, 78, 79,
+ 80, 81, 81, 82, 83, 83, 84, 85, 86, 86, 87, 88, 88,
89, 90, 91,
+ 91, 92, 93, 94, 94, 95, 96, 96, 97, 98, 99, 99, 100,
101, 101, 102,
+ 103, 104, 104, 105, 106, 106, 107, 108, 109, 109, 110, 111, 111,
112, 113, 114,
+ 114, 115, 116, 116, 117, 118, 119, 119, 120, 121, 122, 122, 123,
124, 124, 125,
+ 126, 127, 127, 128, 129, 129, 130, 131, 132, 132, 133, 134, 134,
135, 136, 137,
+ 137, 138, 139, 139, 140, 141, 142, 142, 143, 144, 144, 145, 146,
147, 147, 148,
+ 149, 149, 150, 151, 152, 152, 153, 154, 155, 155, 156, 157, 157,
158, 159, 160,
+ 160, 161, 162, 162, 163, 164, 165, 165, 166, 167, 167, 168, 169,
170, 170, 171,
+ 172, 172, 173, 174, 175, 175, 176, 177, 177, 178, 179, 180, 180,
181, 182, 183 };
+ constexpr std::array<sal_uInt8, 256> nBArray
+ = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 3,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4,
4, 4, 4, 4, 4,
+ 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 6, 6, 6,
+ 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10,
10, 10, 10, 10, 10, 10,
+ 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
12, 12, 12, 12, 12, 12,
+ 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13,
13, 13, 13, 13, 13, 13,
+ 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 15,
15, 15, 15, 15, 15, 15,
+ 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16,
16, 16, 16, 16, 16, 17,
+ 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 18 };
- // Only this alpha channel is taken into account by cairo_mask_surface
- // so reuse this surface for the alpha result
for (sal_uInt32 y(0); y < nHeight; ++y)
{
unsigned char* pMaskPixelData = mask_surface_data + (nStride * y);
@@ -777,17 +828,21 @@ void LuminanceToAlpha(cairo_surface_t* pMask)
if (0 != nAlpha)
{
- const double fLuminance = pMaskPixelData[SVP_CAIRO_RED] *
nRedMul
- + pMaskPixelData[SVP_CAIRO_GREEN] *
nGreenMul
- + pMaskPixelData[SVP_CAIRO_BLUE] *
nBlueMul;
+ // get Luminance in range [0..255]
+ const sal_uInt8 nLum(nRArray[pMaskPixelData[SVP_CAIRO_RED]]
+ + nGArray[pMaskPixelData[SVP_CAIRO_GREEN]]
+ +
nBArray[pMaskPixelData[SVP_CAIRO_BLUE]]);
if (255 != nAlpha)
- nAlpha = fLuminance / nAlpha;
+ // remove pre-multiplied alpha (use existing VCL tooling)
+ nAlpha = vcl::bitmap::unpremultiply(nLum, nAlpha);
else
- nAlpha = 255.0 * fLuminance;
+ // already what we need
+ nAlpha = nLum;
+
+ pMaskPixelData[SVP_CAIRO_ALPHA] = 255 - nAlpha;
}
- pMaskPixelData[SVP_CAIRO_ALPHA] = 255 - nAlpha;
pMaskPixelData += 4;
}
}
