Pre-multiply alpha for tab decorations

1 files changed, 6 insertions, 3 deletions

diff --git a/sway/desktop/output.c b/sway/desktop/output.c
index 829029a7..551e96fc 100644
--- a/sway/desktop/output.c
+++ b/sway/desktop/output.c
@@ -602,6 +602,7 @@ static void render_container_simple(struct sway_output *output,
 static void render_tab(struct sway_output *output, pixman_region32_t *damage,
                 struct sway_container *parent, int child_index,
                 struct border_colors *colors, struct wlr_texture *title_texture) {
+        struct sway_container *con = parent->children->items[child_index];
         float output_scale = output->wlr_output->scale;
         float color[4];
         struct wlr_box box;
@@ -615,6 +616,7 @@ static void render_tab(struct sway_output *output, pixman_region32_t *damage,
 
         // Single pixel bar above title
         memcpy(&color, colors->border, sizeof(float) * 4);
+        premultiply_alpha(color, con->alpha);
         box.x = x;
         box.y = parent->y;
         box.width = tab_width;
@@ -665,6 +667,7 @@ static void render_tab(struct sway_output *output, pixman_region32_t *damage,
 
         // Title background - above the text
         memcpy(&color, colors->background, sizeof(float) * 4);
+        premultiply_alpha(color, con->alpha);
         box.x = x + 1;
         box.y = parent->y + 1;
         box.width = tab_width - 2;
@@ -707,7 +710,7 @@ static void render_tab_content(struct sway_output *output,
         if (view->border != B_NONE) {
                 if (view->border_left) {
                         memcpy(&color, colors->child_border, sizeof(float) * 4);
-                        color[3] *= con->alpha;
+                        premultiply_alpha(color, con->alpha);
                         box.x = con->x;
                         box.y = con->y + config->border_thickness * 2 + config->font_height;
                         box.width = view->border_thickness;
@@ -718,7 +721,7 @@ static void render_tab_content(struct sway_output *output,
 
                 if (view->border_right) {
                         memcpy(&color, colors->child_border, sizeof(float) * 4);
-                        color[3] *= con->alpha;
+                        premultiply_alpha(color, con->alpha);
                         box.x = view->x + view->width;
                         box.y = con->y + config->border_thickness * 2 + config->font_height;
                         box.width = view->border_thickness;
@@ -729,7 +732,7 @@ static void render_tab_content(struct sway_output *output,
 
                 if (view->border_bottom) {
                         memcpy(&color, colors->child_border, sizeof(float) * 4);
-                        color[3] *= con->alpha;
+                        premultiply_alpha(color, con->alpha);
                         box.x = con->x;
                         box.y = view->y + view->height;
                         box.width = con->width;