Examples: GLFW+OpenGL2: Fixed not applying content scale. (#8921)

Note that this requires GLFW 3.3.

docs/CHANGELOG.txt

@@ -107,6 +107,7 @@ Other Changes:
   while navigating and to not close popup automatically.
 - CI: Updates Windows CI to use a more recent VulkanSDK. (#8925, #8778) [@yaz0r]
 - Examples: Android: Android+OpenGL3: update Gradle project (#8888, #8878) [@scribam]
+- Examples: GLFW+OpenGL2: Fixed not applying content scale. (#8921)
 - Backends: SDL_GPU: Added ImGui_ImplSDLGPU3_InitInfo::SwapchainComposition and
   PresentMode to configure how secondary viewports are created. Currently only used
   multi-viewport mode. (#8892) [@PTSVU]

examples/example_glfw_opengl2/main.cpp

@@ -40,7 +40,8 @@ int main(int, char**)
         return 1;
 
     // Create window with graphics context
-    GLFWwindow* window = glfwCreateWindow(1280, 720, "Dear ImGui GLFW+OpenGL2 example", nullptr, nullptr);
+    float main_scale = ImGui_ImplGlfw_GetContentScaleForMonitor(glfwGetPrimaryMonitor()); // Valid on GLFW 3.3+ only
+    GLFWwindow* window = glfwCreateWindow((int)(1280 * main_scale), (int)(800 * main_scale), "Dear ImGui GLFW+OpenGL2 example", nullptr, nullptr);
     if (window == nullptr)
         return 1;
     glfwMakeContextCurrent(window);
@@ -57,6 +58,11 @@ int main(int, char**)
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsLight();
 
+    // Setup scaling
+    ImGuiStyle& style = ImGui::GetStyle();
+    style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
+    style.FontScaleDpi = main_scale;        // Set initial font scale. (using io.ConfigDpiScaleFonts=true makes this unnecessary. We leave both here for documentation purpose)
+
     // Setup Platform/Renderer backends
     ImGui_ImplGlfw_InitForOpenGL(window, true);
     ImGui_ImplOpenGL2_Init();