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moonpower
2026-03-15 12:33:32 +01:00
parent af86719c5a
commit 31c2e522f5
21 changed files with 3571 additions and 1 deletions
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examples/example_sdl2_cpu/main.cpp
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// main.cpp
// Example program using imgui_impl_cpu backend
#include "imgui.h"
#include "imgui_impl_cpu.h"
#include "imgui_impl_sdl2.h"
#include <SDL.h>
#include <chrono>
#include <stdio.h>
#include <string.h>
#ifdef __EMSCRIPTEN__
#include "../libs/emscripten/emscripten_mainloop_stub.h"
#endif
struct ExampleTimingHistory
{
double Samples[120];
int Count;
int Offset;
ExampleTimingHistory() : Count(0), Offset(0) { memset(Samples, 0, sizeof(Samples)); }
void AddSample(double value_ms)
{
Samples[Offset] = value_ms;
Offset = (Offset + 1) % IM_ARRAYSIZE(Samples);
if (Count < IM_ARRAYSIZE(Samples))
Count++;
}
double GetAverageMs() const
{
if (Count == 0)
return 0.0;
double total = 0.0;
for (int i = 0; i < Count; i++)
total += Samples[i];
return total / (double)Count;
}
};
struct ExampleFramebuffer
{
ImVector<unsigned char> Storage;
ImVector<ImU32> Palette;
ImGui_ImplCPU_PixelFormat Format;
ImGui_ImplCPU_Framebuffer CPU;
SDL_Surface* Surface;
Uint32 SDLFormat;
ExampleFramebuffer() { memset((void*)this, 0, sizeof(*this)); }
};
static double ExampleGetTimeMs()
{
typedef std::chrono::steady_clock Clock;
return std::chrono::duration<double, std::milli>(Clock::now().time_since_epoch()).count();
}
static void InitCPUFormatFromSDL(ImGui_ImplCPU_PixelFormat* out, ImVector<ImU32>* out_palette, const SDL_PixelFormat* format)
{
memset(out, 0, sizeof(*out));
out->BitsPerPixel = format->BitsPerPixel;
out->BytesPerPixel = format->BytesPerPixel;
out->Rmask = format->Rmask;
out->Gmask = format->Gmask;
out->Bmask = format->Bmask;
out->Amask = format->Amask;
out->Rshift = (ImU8)format->Rshift;
out->Gshift = (ImU8)format->Gshift;
out->Bshift = (ImU8)format->Bshift;
out->Ashift = (ImU8)format->Ashift;
out->Rloss = (ImU8)format->Rloss;
out->Gloss = (ImU8)format->Gloss;
out->Bloss = (ImU8)format->Bloss;
out->Aloss = (ImU8)format->Aloss;
out->Palette = nullptr;
out->PaletteSize = 0;
out->MapColorFn = nullptr;
out_palette->clear();
if (format->palette != nullptr && format->palette->colors != nullptr && format->palette->ncolors > 0)
{
out_palette->resize(format->palette->ncolors);
for (int i = 0; i < format->palette->ncolors; i++)
{
const SDL_Color& c = format->palette->colors[i];
(*out_palette)[i] = IM_COL32(c.r, c.g, c.b, c.a);
}
out->Palette = out_palette->Data;
out->PaletteSize = out_palette->Size;
}
}
static bool RecreateFramebuffer(ExampleFramebuffer* framebuffer, SDL_Surface* window_surface)
{
if (framebuffer->Surface != nullptr)
{
SDL_FreeSurface(framebuffer->Surface);
framebuffer->Surface = nullptr;
}
const int width = window_surface->w;
const int height = window_surface->h;
const int bytes_per_pixel = window_surface->format->BytesPerPixel;
if (width <= 0 || height <= 0 || bytes_per_pixel <= 0)
return false;
InitCPUFormatFromSDL(&framebuffer->Format, &framebuffer->Palette, window_surface->format);
framebuffer->Storage.resize(width * height * bytes_per_pixel);
framebuffer->CPU.Pixels = framebuffer->Storage.Data;
framebuffer->CPU.Width = width;
framebuffer->CPU.Height = height;
framebuffer->CPU.Pitch = width * bytes_per_pixel;
framebuffer->CPU.Format = &framebuffer->Format;
framebuffer->SDLFormat = window_surface->format->format;
framebuffer->Surface = SDL_CreateRGBSurfaceWithFormatFrom(framebuffer->CPU.Pixels, width, height, window_surface->format->BitsPerPixel, framebuffer->CPU.Pitch, window_surface->format->format);
return framebuffer->Surface != nullptr;
}
int main(int, char**)
{
// Setup SDL
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0)
{
printf("Error: %s\n", SDL_GetError());
return -1;
}
// From 2.0.18: Enable native IME.
#ifdef SDL_HINT_IME_SHOW_UI
SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");
#endif
// Create window
float main_scale = ImGui_ImplSDL2_GetContentScaleForDisplay(0);
SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_SHOWN);
SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+CPU Example",
SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
(int)(1280 * main_scale), (int)(720 * main_scale), window_flags);
if (!window)
{
printf("Error creating window: %s\n", SDL_GetError());
return -1;
}
SDL_Surface* window_surface = SDL_GetWindowSurface(window);
if (!window_surface)
{
printf("Error getting window surface: %s\n", SDL_GetError());
return -1;
}
int win_w = window_surface->w;
int win_h = window_surface->h;
ExampleFramebuffer framebuffer;
if (!RecreateFramebuffer(&framebuffer, window_surface))
{
printf("Error creating framebuffer: %s\n", SDL_GetError());
return -1;
}
// Setup Dear ImGui context
IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO& io = ImGui::GetIO(); (void)io;
io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls
#ifdef __EMSCRIPTEN__
io.IniFilename = nullptr;
#endif
// Setup Dear ImGui style
ImGui::StyleColorsDark();
// Setup scaling
ImGuiStyle& style = ImGui::GetStyle();
style.ScaleAllSizes(main_scale); // Bake a fixed style scale.
style.FontScaleDpi = main_scale;
// Setup Platform/Renderer backends
ImGui_ImplSDL2_InitForOther(window);
ImGui_ImplSDL2_SetGamepadMode(ImGui_ImplSDL2_GamepadMode_AutoFirst, nullptr, 0);
ImGui_ImplCPU_Init();
// Our state
bool show_demo_window = true;
bool show_another_window = false;
ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
ExampleTimingHistory raster_times;
ExampleTimingHistory present_times;
// Main loop
bool done = false;
#ifdef __EMSCRIPTEN__
EMSCRIPTEN_MAINLOOP_BEGIN
#else
while (!done)
#endif
{
// Poll and handle events (inputs, window resize, etc.)
SDL_Event event;
while (SDL_PollEvent(&event))
{
ImGui_ImplSDL2_ProcessEvent(&event);
if (event.type == SDL_QUIT)
done = true;
if (event.type == SDL_WINDOWEVENT)
{
if (event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
done = true;
if (event.window.event == SDL_WINDOWEVENT_SIZE_CHANGED || event.window.event == SDL_WINDOWEVENT_RESIZED)
{
// Recreate framebuffer at new size
window_surface = SDL_GetWindowSurface(window);
int new_w = window_surface->w;
int new_h = window_surface->h;
if (new_w != win_w || new_h != win_h || window_surface->format->format != framebuffer.SDLFormat)
{
if (!RecreateFramebuffer(&framebuffer, window_surface))
{
printf("Error creating framebuffer after resize: %s\n", SDL_GetError());
return -1;
}
win_w = new_w;
win_h = new_h;
}
}
}
}
// Skip rendering when minimized to avoid busy-looping
if (SDL_GetWindowFlags(window) & SDL_WINDOW_MINIMIZED)
{
SDL_Delay(10);
continue;
}
// Start the Dear ImGui frame
ImGui_ImplCPU_NewFrame();
ImGui_ImplSDL2_NewFrame();
ImGui::NewFrame();
int logical_w = 0;
int logical_h = 0;
SDL_GetWindowSize(window, &logical_w, &logical_h);
// 1. Show the big demo window
if (show_demo_window)
ImGui::ShowDemoWindow(&show_demo_window);
// 2. Show a simple window that we create ourselves. Mirror the SDL_Renderer example.
{
static float f = 0.0f;
static int counter = 0;
ImGui::Begin("Hello, world!"); // Create a window called "Hello, world!" and append into it.
ImGui::Text("This is some useful text."); // Display some text
ImGui::Checkbox("Demo Window", &show_demo_window); // Edit bools storing our window open/close state
ImGui::Checkbox("Another Window", &show_another_window);
ImGui::SliderFloat("float", &f, 0.0f, 1.0f); // Edit 1 float using a slider from 0.0f to 1.0f
ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
if (ImGui::Button("Button")) // Buttons return true when clicked
counter++;
ImGui::SameLine();
ImGui::Text("counter = %d", counter);
ImGui::Text("Raster %.3f ms | Present %.3f ms", raster_times.GetAverageMs(), present_times.GetAverageMs());
ImGui::Text("Window %d x %d | Framebuffer %d x %d", logical_w, logical_h, framebuffer.CPU.Width, framebuffer.CPU.Height);
ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
ImGui::End();
}
// 3. Show another simple window.
if (show_another_window)
{
ImGui::Begin("Another Window", &show_another_window); // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
ImGui::Text("Hello from another window!");
if (ImGui::Button("Close Me"))
show_another_window = false;
ImGui::End();
}
// Rendering
ImGui::Render();
const double raster_start_ms = ExampleGetTimeMs();
SDL_FillRect(framebuffer.Surface, nullptr, SDL_MapRGBA(framebuffer.Surface->format,
(Uint8)(clear_color.x * 255),
(Uint8)(clear_color.y * 255),
(Uint8)(clear_color.z * 255),
(Uint8)(clear_color.w * 255)));
ImGui_ImplCPU_RenderDrawData(ImGui::GetDrawData(), &framebuffer.CPU);
raster_times.AddSample(ExampleGetTimeMs() - raster_start_ms);
const double present_start_ms = ExampleGetTimeMs();
SDL_BlitSurface(framebuffer.Surface, nullptr, window_surface, nullptr);
SDL_UpdateWindowSurface(window);
present_times.AddSample(ExampleGetTimeMs() - present_start_ms);
}
#ifdef __EMSCRIPTEN__
EMSCRIPTEN_MAINLOOP_END;
#endif
ImGui_ImplCPU_Shutdown();
ImGui_ImplSDL2_Shutdown();
ImGui::DestroyContext();
if (framebuffer.Surface != nullptr)
SDL_FreeSurface(framebuffer.Surface);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}