GUI: add CMYK painting support

This commit adds a CMYK 8bpp format to QImage. The idea is to enable the
transport of CMYK images inside Qt, for instance to be loaded/saved from
files or painted on CMYK capable paint devices (e.g. PDF).

Also, rasterization support *from* a CMYK image is added (on top of a
RGB surface), as well as CMYK image scaling/conversion.

Conversion and rasterization between CMYK and RGB isn't particularly
optimized nor it honors any colorspaces yet. The overall idea is to
match 1:1 the existing behavior of CMYK QColor (which get naively
changed to RGB; there isn't colorspace support in QPainter yet).

There are no plans to add rasterization *towards* CMYK.

Image save/load in native CMYK formats will be added in future commits.

This work has been kindly sponsored by the QGIS project
(https://qgis.org/).

[ChangeLog][QtGui] Support for 8-bit CMYK images has been added.

Change-Id: I4b024cd4c15119c669b6ddd450418a9e425587f8
Reviewed-by: Allan Sandfeld Jensen <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/tests/baseline/shared/paintcommands.cpp b/tests/baseline/shared/paintcommands.cpp
index a1d2b9e4972..20201b66b0d 100644
--- a/tests/baseline/shared/paintcommands.cpp
+++ b/tests/baseline/shared/paintcommands.cpp
@@ -173,6 +173,7 @@ const char *PaintCommands::imageFormatTable[] = {
     "RGBx32FPx4",
     "RGBA32FPx4",
     "RGBA32FPx4_Premultiplied",
+    "CMYK32",
 };
 
 const char *PaintCommands::renderHintTable[] = {