util: add util_format_is_luminance/intensity/rgb(), etc

Reviewed-by: José Fonseca <jfonseca@vmware.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/util/u_format.c b/src/gallium/auxiliary/util/u_format.c
index 34922ab18ab..700382a0f5e 100644
--- a/src/gallium/auxiliary/util/u_format.c
+++ b/src/gallium/auxiliary/util/u_format.c
@@ -67,6 +67,100 @@ util_format_is_float(enum pipe_format format)
 }
 
 
+/**
+ * Return the number of logical channels in the given format by
+ * examining swizzles.
+ * XXX this could be made into a public function if useful elsewhere.
+ */
+static unsigned
+nr_logical_channels(const struct util_format_description *desc)
+{
+   boolean swizzle_used[UTIL_FORMAT_SWIZZLE_MAX];
+
+   memset(swizzle_used, 0, sizeof(swizzle_used));
+
+   swizzle_used[desc->swizzle[0]] = TRUE;
+   swizzle_used[desc->swizzle[1]] = TRUE;
+   swizzle_used[desc->swizzle[2]] = TRUE;
+   swizzle_used[desc->swizzle[3]] = TRUE;
+
+   return (swizzle_used[UTIL_FORMAT_SWIZZLE_X] +
+           swizzle_used[UTIL_FORMAT_SWIZZLE_Y] +
+           swizzle_used[UTIL_FORMAT_SWIZZLE_Z] +
+           swizzle_used[UTIL_FORMAT_SWIZZLE_W]);
+}
+
+
+/** Test if the format contains RGB, but not alpha */
+boolean
+util_format_is_rgb_no_alpha(enum pipe_format format)
+{
+   const struct util_format_description *desc =
+      util_format_description(format);
+
+   if ((desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB ||
+        desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB) &&
+       nr_logical_channels(desc) == 3) {
+      return TRUE;
+   }
+   return FALSE;
+}
+
+
+boolean
+util_format_is_luminance(enum pipe_format format)
+{
+   const struct util_format_description *desc =
+      util_format_description(format);
+
+   if ((desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB ||
+        desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB) &&
+       desc->swizzle[0] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[1] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[2] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[3] == UTIL_FORMAT_SWIZZLE_1) {
+      return TRUE;
+   }
+   return FALSE;
+}
+
+
+boolean
+util_format_is_luminance_alpha(enum pipe_format format)
+{
+   const struct util_format_description *desc =
+      util_format_description(format);
+
+   if ((desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB ||
+        desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB) &&
+       desc->swizzle[0] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[1] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[2] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[3] == UTIL_FORMAT_SWIZZLE_Y) {
+      return TRUE;
+   }
+   return FALSE;
+}
+
+
+boolean
+util_format_is_intensity(enum pipe_format format)
+{
+   const struct util_format_description *desc =
+      util_format_description(format);
+
+   if ((desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB ||
+        desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB) &&
+       desc->swizzle[0] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[1] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[2] == UTIL_FORMAT_SWIZZLE_X &&
+       desc->swizzle[3] == UTIL_FORMAT_SWIZZLE_X) {
+      return TRUE;
+   }
+   return FALSE;
+}
+
+
 boolean
 util_format_is_supported(enum pipe_format format, unsigned bind)
 {