swaybar: Lift background clearing out of main rendering function

This avoids us from using a bogus background_color value that
mutates as swaybar renders things and deciding opacity depending on
that.

Also remove a redundant full surface clear. Just directly write our
desired background color.

1 files changed, 14 insertions, 13 deletions

diff --git a/swaybar/render.c b/swaybar/render.c
index a296112a..1113ca44 100644
--- a/swaybar/render.c
+++ b/swaybar/render.c
@@ -693,15 +693,6 @@ static uint32_t render_to_cairo(struct render_context *ctx) {
         struct swaybar_output *output = ctx->output;
         struct swaybar *bar = output->bar;
         struct swaybar_config *config = bar->config;
-        cairo_set_operator(cairo, CAIRO_OPERATOR_SOURCE);
-        if (output->focused) {
-                ctx->background_color = config->colors.focused_background;
-        } else {
-                ctx->background_color = config->colors.background;
-        }
-
-        cairo_set_source_u32(cairo, ctx->background_color);
-        cairo_paint(cairo);
 
         int th;
         get_text_size(cairo, config->font_description, NULL, &th, NULL, 1, false, "");
@@ -763,8 +754,17 @@ void render_frame(struct swaybar_output *output) {
 
         free_hotspots(&output->hotspots);
 
+        uint32_t background_color;
+        if (output->focused) {
+                background_color = output->bar->config->colors.focused_background;
+        } else {
+                background_color = output->bar->config->colors.background;
+        }
+
         struct render_context ctx = { 0 };
         ctx.output = output;
+        // initial background color used for deciding the best way to antialias text
+        ctx.background_color = background_color;
 
         cairo_surface_t *recorder = cairo_recording_surface_create(
                         CAIRO_CONTENT_COLOR_ALPHA, NULL);
@@ -786,10 +786,11 @@ void render_frame(struct swaybar_output *output) {
                 ctx.textaa_sharp = fo;
         }
 
-        cairo_save(cairo);
-        cairo_set_operator(cairo, CAIRO_OPERATOR_CLEAR);
+
+        cairo_set_operator(cairo, CAIRO_OPERATOR_SOURCE);
+        cairo_set_source_u32(cairo, background_color);
         cairo_paint(cairo);
-        cairo_restore(cairo);
+
         uint32_t height = render_to_cairo(&ctx);
         int config_height = output->bar->config->height;
         if (config_height > 0) {
@@ -834,7 +835,7 @@ void render_frame(struct swaybar_output *output) {
                 wl_surface_damage(output->surface, 0, 0,
                                 output->width, output->height);
 
-                uint32_t bg_alpha = ctx.background_color & 0xFF;
+                uint32_t bg_alpha = background_color & 0xFF;
                 if (bg_alpha == 0xFF) {
                         struct wl_region *region =
                                 wl_compositor_create_region(output->bar->compositor);