libgimpcolor: Enable LCMS2 Fast Float plug-in

Adds support for loading and using the Little CMS
Fast Float plug-in. This plug-in should speed up
color conversions for 8/16 bit and floating point
precision operations. It can be turned off by changing
the "Optimize for" setting from Speed to Quality.

libgimpcolor/gimpcolortransform.c

@@ -26,6 +26,9 @@
 #include <string.h>
 
 #include <lcms2.h>
+#ifdef HAVE_LCMS_FAST_FLOAT_PLUGIN
+#include <lcms2_fast_float.h>
+#endif
 
 #include <gio/gio.h>
 #include <gegl.h>
@@ -128,6 +131,10 @@ gimp_color_transform_class_init (GimpColorTransformClass *klass)
                   G_TYPE_NONE, 1,
                   G_TYPE_DOUBLE);
 
+#ifdef HAVE_LCMS_FAST_FLOAT_PLUGIN
+  cmsPlugin (cmsFastFloatExtensions ());
+#endif
+
   cmsSetLogErrorHandler (lcms_error_handler);
 }
 

meson.build

@@ -442,6 +442,10 @@ json_glib_minver  = '1.2.6'
 json_glib         = dependency('json-glib-1.0',      version: '>='+json_glib_minver)
 lcms_minver       = '2.8'
 lcms              = dependency('lcms2',              version: '>='+lcms_minver)
+if cc.has_header('lcms2_fast_float.h')
+  conf.set('HAVE_LCMS_FAST_FLOAT_PLUGIN', 1)
+endif
+
 libmypaint_minver = '1.5.0'
 libmypaint        = dependency('libmypaint',         version: '>='+libmypaint_minver)
 mypaint_brushes   = dependency('mypaint-brushes-2.0')