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Add SDL3 surface backend for ImGui example

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- Created imgui_impl_sdlsurface3.h and corresponding implementation file.
- Added Makefile for building the SDL3 surface example on Linux and macOS.
- Included README.md with build instructions for Windows, Linux, and macOS.
- Added build script for Windows (build_win32.bat) and Visual Studio project files.
- Implemented main application logic in main.cpp to demonstrate ImGui with SDL3 and surface rendering.
This commit is contained in:
moonpower
2026-03-13 13:23:18 +01:00
parent 00843f9ece
commit 2f2b8a1226
12 changed files with 1898 additions and 242 deletions
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examples/example_sdl3_surface/main.cpp
+176
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#include "imgui.h"
#include "imgui_impl_sdl3.h"
#include "imgui_impl_sdlsurface3.h"
#include <SDL3/SDL.h>
#include <stdio.h>
int main(int, char**)
{
if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_GAMEPAD))
{
printf("Error: SDL_Init(): %s\n", SDL_GetError());
return 1;
}
float main_scale = SDL_GetDisplayContentScale(SDL_GetPrimaryDisplay());
SDL_WindowFlags window_flags = SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIDDEN | SDL_WINDOW_HIGH_PIXEL_DENSITY;
SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL3+Surface Example", (int)(1280 * main_scale), (int)(800 * main_scale), window_flags);
if (window == nullptr)
{
printf("Error: SDL_CreateWindow(): %s\n", SDL_GetError());
return 1;
}
SDL_SetWindowPosition(window, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED);
SDL_ShowWindow(window);
SDL_Surface* window_surface = SDL_GetWindowSurface(window);
if (window_surface == nullptr)
{
printf("Error: SDL_GetWindowSurface(): %s\n", SDL_GetError());
SDL_DestroyWindow(window);
SDL_Quit();
return 1;
}
SDL_SetWindowSurfaceVSync(window, 1);
int framebuffer_w = window_surface->w;
int framebuffer_h = window_surface->h;
SDL_Surface* framebuffer = SDL_CreateSurface(framebuffer_w, framebuffer_h, SDL_PIXELFORMAT_RGBA32);
if (framebuffer == nullptr)
{
printf("Error: SDL_CreateSurface(): %s\n", SDL_GetError());
SDL_DestroyWindow(window);
SDL_Quit();
return 1;
}
IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO& io = ImGui::GetIO();
io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;
ImGui::StyleColorsDark();
ImGuiStyle& style = ImGui::GetStyle();
style.ScaleAllSizes(main_scale);
style.FontScaleDpi = main_scale;
ImGui_ImplSDL3_InitForOther(window);
ImGui_ImplSDLSurface3_Init(framebuffer);
bool show_demo_window = true;
bool show_another_window = false;
ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
bool done = false;
while (!done)
{
SDL_Event event;
while (SDL_PollEvent(&event))
{
ImGui_ImplSDL3_ProcessEvent(&event);
if (event.type == SDL_EVENT_QUIT)
done = true;
if (event.type == SDL_EVENT_WINDOW_CLOSE_REQUESTED && event.window.windowID == SDL_GetWindowID(window))
done = true;
if ((event.type == SDL_EVENT_WINDOW_RESIZED || event.type == SDL_EVENT_WINDOW_PIXEL_SIZE_CHANGED) && event.window.windowID == SDL_GetWindowID(window))
{
window_surface = SDL_GetWindowSurface(window);
if (window_surface != nullptr)
{
int new_w = window_surface->w;
int new_h = window_surface->h;
if (new_w != framebuffer_w || new_h != framebuffer_h)
{
SDL_DestroySurface(framebuffer);
framebuffer = SDL_CreateSurface(new_w, new_h, SDL_PIXELFORMAT_RGBA32);
if (framebuffer == nullptr)
{
printf("Error: SDL_CreateSurface(): %s\n", SDL_GetError());
done = true;
break;
}
framebuffer_w = new_w;
framebuffer_h = new_h;
ImGui_ImplSDLSurface3_Shutdown();
ImGui_ImplSDLSurface3_Init(framebuffer);
}
}
}
}
if (done)
break;
if (SDL_GetWindowFlags(window) & SDL_WINDOW_MINIMIZED)
{
SDL_Delay(10);
continue;
}
ImGui_ImplSDLSurface3_NewFrame();
ImGui_ImplSDL3_NewFrame();
ImGui::NewFrame();
if (show_demo_window)
ImGui::ShowDemoWindow(&show_demo_window);
{
static float f = 0.0f;
static int counter = 0;
ImGui::Begin("Hello, world!");
ImGui::Text("This is some useful text.");
ImGui::Checkbox("Demo Window", &show_demo_window);
ImGui::Checkbox("Another Window", &show_another_window);
ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
ImGui::ColorEdit3("clear color", (float*)&clear_color);
if (ImGui::Button("Button"))
counter++;
ImGui::SameLine();
ImGui::Text("counter = %d", counter);
ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
ImGui::End();
}
if (show_another_window)
{
ImGui::Begin("Another Window", &show_another_window);
ImGui::Text("Hello from another window!");
if (ImGui::Button("Close Me"))
show_another_window = false;
ImGui::End();
}
ImGui::Render();
SDL_FillSurfaceRect(framebuffer, nullptr, SDL_MapSurfaceRGBA(framebuffer,
(Uint8)(clear_color.x * 255.0f),
(Uint8)(clear_color.y * 255.0f),
(Uint8)(clear_color.z * 255.0f),
(Uint8)(clear_color.w * 255.0f)));
ImGui_ImplSDLSurface3_RenderDrawData(ImGui::GetDrawData());
window_surface = SDL_GetWindowSurface(window);
if (window_surface != nullptr)
{
SDL_BlitSurface(framebuffer, nullptr, window_surface, nullptr);
SDL_UpdateWindowSurface(window);
}
}
ImGui_ImplSDLSurface3_Shutdown();
ImGui_ImplSDL3_Shutdown();
ImGui::DestroyContext();
SDL_DestroySurface(framebuffer);
SDL_DestroyWindowSurface(window);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}