app: some comments and erorrs regarding IDs configuration

Signed-off-by: Marcus Fritzsch <marcus_fritzsch@mentor.com>

diff --git a/src/app.cpp b/src/app.cpp
index 461ac35..1c9b3c2 100644 (file)
--- a/src/app.cpp
+++ b/src/app.cpp
@@ -144,6 +144,11 @@ int App::init() {
       return -1;
    }
 
+   if (this->surface2layer.mapping.empty()) {
+      logerror("No surface -> layer mapping loaded");
+      return -1;
+   }
+
    this->display->add_global_handler(
       "wl_output", [this](wl_registry *r, uint32_t name, uint32_t v) {
          this->outputs.emplace_back(std::make_unique<wl::output>(r, name, v));
@@ -269,6 +274,8 @@ void App::surface_created(uint32_t surface_id) {
             int w = rect.w;
             int h = rect.h;
 
+            // less-than-0 values refer to MAX + 1 - $VALUE
+            // e.g. MAX is either screen width or height
             if (w < 0) {
                w = c->output_size.w + 1 + w;
             }
@@ -277,8 +284,11 @@ void App::surface_created(uint32_t surface_id) {
             }
             logdebug("Computed rect={ %d, %d, %d, %d }", x, y, w, h);
 
+            // configure surface to wxh dimensions
             s->set_configuration(w, h);
+            // set source rect to "entire surface"
             s->set_source_rectangle(0, 0, w, h);
+            // set destination to the display rectangle
             s->set_destination_rectangle(x, y, w, h);
 
             s->set_visibility(1);