add setting to config_skia.h whether to use 32bpp bitmaps

As said in previous Skia commits about BackendCapabilities::mbSupportsBitmap32
this should be preferrably enabled, but there are still parts of LO code
that have a problem with it, so make it easier to enable/disable this.

Change-Id: Iae7a8d5fc77a27372c00f6745317d168e8b2a05b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/86489
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/config_host/config_skia.h.in b/config_host/config_skia.h.in
index 75b1e099ce8e..1a8b64a1dfd6 100644
--- a/config_host/config_skia.h.in
+++ b/config_host/config_skia.h.in
@@ -8,6 +8,23 @@ are the same.
 #ifndef CONFIG_SKIA_H
 #define CONFIG_SKIA_H
 
+// This a setting that should be set manually and it affects LO
+// code rather than Skia itself. It basically controls setting
+// BackendCapabilities::mbSupportsBitmap32.
+// Since Skia does not natively support 24bpp, the preferred setup is
+// that the setting should be enabled, it makes the code faster and cleaner.
+// Unfortunately VCL historically splits alpha into a whole separate
+// bitmap and works with 24bpp+8bpp, which is generally more complicated,
+// more error-prone and just worse, but that's how LO code has been
+// written and so there are many places in LO that expect this and
+// do not work correctly with true 32bpp bitmaps.
+// So ultimately the 24+8 split should be dumped (preferably in all of LO,
+// not just the Skia-related code), but until all of LO works correctly
+// with 32bpp disabling this will avoid such breakages.
+#define SKIA_USE_BITMAP32 1
+//#define SKIA_USE_BITMAP32 0
+
+
 /* TODO SKIA check all these */
 
 #define SK_SUPPORT_GPU 1