Allow better DPI handling under SDL, handle external resize events in imgui

engine/core/include/imgui_backend.hpp

@@ -16,6 +16,7 @@ namespace prism {
         void render();
 
         void process_move(platform::window_ptr identifier);
+        void process_resize(platform::window_ptr identifier);
 
         void process_mouse_down(int button);
 

engine/core/src/engine.cpp

@@ -425,6 +425,8 @@ void engine::resize(const platform::window_ptr identifier, const prism::Extent e
 
     gfx->recreate_view(identifier, drawable_extent.width, drawable_extent.height);
     current_renderer->resize_render_target(*window->render_target, drawable_extent);
+
+    imgui->process_resize(identifier);
 }
 
 void engine::move(const platform::window_ptr identifier) {

engine/core/src/imgui_backend.cpp

@@ -159,6 +159,12 @@ void imgui_backend::process_move(platform::window_ptr identifier) {
         viewport->PlatformRequestMove = true;
 }
 
+void imgui_backend::process_resize(platform::window_ptr identifier) {
+    auto viewport = ImGui::FindViewportByPlatformHandle(identifier);
+    if(viewport != nullptr)
+        viewport->PlatformRequestResize = true;
+}
+
 void imgui_backend::begin_frame(const float delta_time) {
     ImGuiIO& io = ImGui::GetIO();
 

engine/platform/include/platform.hpp

@@ -101,9 +101,6 @@ namespace platform {
     /// Forces the platform to quit the application. This is not related to Engine::quit().
     void force_quit();
 
-    /// Gets the content scale for the window. 1.0 would be 1x scale, 2.0 would be 2x scale, etc.
-    float get_window_dpi(window_ptr window);
-
     /// Gets the content scale for the monitor. 1.0 would be 1x scale, 2.0 would be 2x scale, etc.
     float get_monitor_dpi();
 

engine/renderer/src/imguipass.cpp

@@ -154,8 +154,8 @@ void ImGuiPass::load_font(const std::string_view filename) {
 
             font_file->read_all();
             
-            io.Fonts->AddFontFromMemoryTTF(font_file->cast_data<unsigned char>(), font_file->size(), 15.0f * platform::get_window_dpi(engine->get_main_window()));
+            io.Fonts->AddFontFromMemoryTTF(font_file->cast_data<unsigned char>(), font_file->size(), 15.0f * platform::get_monitor_dpi());
-            ImGui::GetIO().FontGlobalScale = 1.0f / platform::get_window_dpi(engine->get_main_window());
+            ImGui::GetIO().FontGlobalScale = 1.0f / platform::get_monitor_dpi();
         } else {
             prism::log("Failed to load font file for imgui!");
             return;

platforms/sdl/main.cpp.in

@@ -135,23 +135,26 @@ void platform::force_quit() {
     SDL_Quit();
 }
 
-float platform::get_window_dpi(const platform::window_ptr index) {
-    return 1.0;
-}
-
 float platform::get_monitor_dpi() {
-    return 1.0;
+    float dpi = 1.0f;
+    if (!SDL_GetDisplayDPI(0, &dpi, nullptr, nullptr))
+        dpi = dpi / 96.0f;
+
+    return dpi;
 }
 
 prism::Rectangle platform::get_monitor_resolution() {
-    SDL_DisplayMode DM;
+    SDL_Rect r;
-    SDL_GetCurrentDisplayMode(0, &DM);
+    SDL_GetDisplayBounds(0, &r);
 
-    return {0, 0, (uint32_t)DM.w, (uint32_t)DM.h};
+    return {r.x, r.y, r.w, r.h};
 }
 
 prism::Rectangle platform::get_monitor_work_area() {
-    return platform::get_monitor_resolution();
+    SDL_Rect r = {};
+    SDL_GetDisplayUsableBounds(0, &r);
+
+    return {r.x, r.y, r.w, r.h};
 }
 
 prism::Offset platform::get_window_position(const platform::window_ptr index) {

tools/common/src/commoneditor.cpp

@@ -662,7 +662,7 @@ void CommonEditor::createDockArea() {
 
 void CommonEditor::drawViewport(Scene* scene) {
     const auto size = ImGui::GetContentRegionAvail();
-    const auto real_size = ImVec2(size.x * platform::get_window_dpi(engine->get_main_window()), size.y * platform::get_window_dpi(0));
+    const auto real_size = ImVec2(size.x * platform::get_monitor_dpi(), size.y * platform::get_monitor_dpi());
     
     if(real_size.x <= 0 || real_size.y <= 0)
         return;