render/drm_format_set: introduce wlr_drm_format_intersect

Intersects modifiers from two wlr_drm_format structs. If either format
doesn't support modifiers, the resulting format won't support modifiers.
This commit is contained in:
Simon Ser 2020-11-25 15:58:37 +01:00 committed by Ilia Bozhinov
parent 237c2cf2fb
commit 82443ea46b
2 changed files with 45 additions and 0 deletions

View file

@ -4,5 +4,14 @@
#include <wlr/render/drm_format_set.h>
struct wlr_drm_format *wlr_drm_format_dup(const struct wlr_drm_format *format);
/**
* Intersect modifiers for two DRM formats.
*
* Both arguments must have the same format field. If the formats aren't
* compatible, NULL is returned. If either format doesn't support any modifier,
* a format that doesn't support any modifier is returned.
*/
struct wlr_drm_format *wlr_drm_format_intersect(
const struct wlr_drm_format *a, const struct wlr_drm_format *b);
#endif

View file

@ -137,3 +137,39 @@ struct wlr_drm_format *wlr_drm_format_dup(const struct wlr_drm_format *format) {
memcpy(duped_format, format, format_size);
return duped_format;
}
struct wlr_drm_format *wlr_drm_format_intersect(
const struct wlr_drm_format *a, const struct wlr_drm_format *b) {
assert(a->format == b->format);
size_t format_cap = a->len < b->len ? a->len : b->len;
size_t format_size = sizeof(struct wlr_drm_format) +
format_cap * sizeof(a->modifiers[0]);
struct wlr_drm_format *format = calloc(1, format_size);
if (format == NULL) {
wlr_log_errno(WLR_ERROR, "Allocation failed");
return NULL;
}
format->format = a->format;
format->cap = format_cap;
for (size_t i = 0; i < a->len; i++) {
for (size_t j = 0; j < b->len; j++) {
if (a->modifiers[i] == b->modifiers[j]) {
assert(format->len < format->cap);
format->modifiers[format->len] = a->modifiers[i];
format->len++;
break;
}
}
}
// If both formats support modifiers, but the intersection is empty, then
// the formats aren't compatible with each other
if (format->len == 0 && a->len > 0 && b->len > 0) {
free(format);
return NULL;
}
return format;
}