Почему мое изображение не показано, пока я перетаскиваю фоновое окно, чтобы изменить размер в Imgui? ⇐ C++

[Anonymous]

Я разрабатываю настольную программу на основе ветки imgui docking в Ubuntu 22.04, чтобы добавлять изображение в фоновое окно и всегда центрировать его при изменении размера окна:
(Также обратите внимание: перед запуском программы поместите произвольное изображение в формате PNG в папку значков)

Код: Выделить всё

#include 
#define GL_SILENCE_DEPRECATION
#if defined(IMGUI_IMPL_OPENGL_ES2)
#include 
#endif
#include  // Will drag system OpenGL headers
#include "imgui.h"
#include "imgui_impl_glfw.h"
#include "imgui_impl_opengl3.h"
#include "IconsFontAwesome6.h"  // from https://github.com/juliettef/IconFontCppHeaders.git

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"          // from https://github.com/nothings/stb.git

static void glfw_error_callback(int error, const char* description)
{
fprintf(stderr, "GLFW Error %d: %s\n", error, description);
}

// Simple helper function to load an image into a OpenGL texture with common settings
bool LoadTextureFromMemory(const void* data, size_t data_size, GLuint* out_texture, int* out_width, int* out_height)
{
// Load from file
int image_width = 0;
int image_height = 0;
unsigned char* image_data = stbi_load_from_memory((const unsigned char*)data, (int)data_size, &image_width, &image_height, NULL, 4);
if (image_data == NULL)
return false;

// Create a OpenGL texture identifier
GLuint image_texture;
glGenTextures(1, &image_texture);
glBindTexture(GL_TEXTURE_2D, image_texture);

// Setup filtering parameters for display
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

// Upload pixels into texture
glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image_width, image_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image_data);
stbi_image_free(image_data);

*out_texture = image_texture;
*out_width = image_width;
*out_height = image_height;

return true;
}

// Open and read a file, then forward to LoadTextureFromMemory()
bool LoadTextureFromFile(const char* file_name, GLuint* out_texture, int* out_width, int* out_height)
{
FILE* f = fopen(file_name, "rb");
if (f == NULL)
return false;
fseek(f, 0, SEEK_END);
auto file_size = ftell(f);
if (file_size == -1)
return false;
fseek(f, 0, SEEK_SET);
void* file_data = IM_ALLOC(file_size);
fread(file_data, 1, file_size, f);
bool ret = LoadTextureFromMemory(file_data, file_size, out_texture, out_width, out_height);
IM_FREE(file_data);
return ret;
}

void setupImgui()
{
// 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
io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
//io.ConfigViewportsNoAutoMerge = true;
//io.ConfigViewportsNoTaskBarIcon = true;

// Setup Dear ImGui style
ImGui::StyleColorsDark();
//ImGui::StyleColorsLight();

// When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
ImGuiStyle& style = ImGui::GetStyle();
if (io.ConfigFlags &  ImGuiConfigFlags_ViewportsEnable)
{
style.WindowRounding = 0.0f;
style.Colors[ImGuiCol_WindowBg].w = 1.0f;
}
}

int main(int argc, char ** argv)
{
(void)(argc), (void)(argv);
glfwSetErrorCallback(glfw_error_callback);
if (!glfwInit())
return 1;
// Decide GL+GLSL versions
#if defined(IMGUI_IMPL_OPENGL_ES2)
// GL ES 2.0 + GLSL 100 (WebGL 1.0)
const char* glsl_version = "#version 100";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
#elif defined(IMGUI_IMPL_OPENGL_ES3)
// GL ES 3.0 + GLSL 300 es (WebGL 2.0)
const char* glsl_version = "#version 300 es";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
#elif defined(__APPLE__)
// GL 3.2 + GLSL 150
const char* glsl_version = "#version 150";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);            // Required on Mac
#else
// GL 3.0 + GLSL 130
const char* glsl_version = "#version 130";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
//glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
//glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);            // 3.0+ only
#endif

// Create window with graphics context
GLFWwindow* window = glfwCreateWindow(1280, 720, "Main Window", nullptr, nullptr);
if (window == nullptr)
return 1;
glfwMakeContextCurrent(window);
glfwSwapInterval(1); // Enable vsync

setupImgui();

// Setup Platform/Renderer backends
ImGui_ImplGlfw_InitForOpenGL(window, true);
#ifdef __EMSCRIPTEN__
ImGui_ImplGlfw_InstallEmscriptenCallbacks(window, "#canvas");
#endif
ImGui_ImplOpenGL3_Init(glsl_version);

ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

int my_image_width = 0;
int my_image_height = 0;
GLuint my_image_texture = 0;
bool ret = LoadTextureFromFile("icons/test.png", &my_image_texture, &my_image_width, &my_image_height);
if(!ret) return 0;

ImGuiIO& io = ImGui::GetIO();
// Main loop
#ifdef __EMSCRIPTEN__
// For an Emscripten build we are disabling file-system access, so let's not attempt to do a fopen() of the imgui.ini file.
// You may manually call LoadIniSettingsFromMemory() to load settings from your own storage.
io.IniFilename = nullptr;
EMSCRIPTEN_MAINLOOP_BEGIN
#else
while(!glfwWindowShouldClose(window))
#endif
{
// Poll and handle events (inputs, window resize, etc.)
// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
glfwPollEvents();
if (glfwGetWindowAttrib(window, GLFW_ICONIFIED) != 0)
{
ImGui_ImplGlfw_Sleep(10);
continue;
}

// Start the Dear ImGui frame
ImGui_ImplOpenGL3_NewFrame();
ImGui_ImplGlfw_NewFrame();

ImGui::NewFrame();

const ImGuiViewport* viewport = ImGui::GetMainViewport();
ImDrawList* draw_list = ImGui::GetBackgroundDrawList();
ImVec2 logoSz(200,200);
ImVec2 tl, br;
tl.x = (viewport->Size.x - logoSz.x) / 2.f + viewport->Pos.x;
tl.y = (viewport->Size.y - logoSz.y) / 2.f + viewport->Pos.y;
br.x = tl.x + logoSz.x;
br.y = tl.y + logoSz.y;

draw_list->AddImage(my_image_texture, tl, br);

// Rendering
ImGui::Render();
int display_w, display_h;
glfwGetFramebufferSize(window, &display_w, &display_h);
glViewport(0, 0, display_w, display_h);
glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
glClear(GL_COLOR_BUFFER_BIT);
ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

// Update and Render additional Platform Windows
// (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
//  For this specific demo app we could also call glfwMakeContextCurrent(window) directly)
if(io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
{
GLFWwindow* backup_current_context = glfwGetCurrentContext();
ImGui::UpdatePlatformWindows();
ImGui::RenderPlatformWindowsDefault();
glfwMakeContextCurrent(backup_current_context);
}

glfwSwapBuffers(window);
}
#ifdef __EMSCRIPTEN__
EMSCRIPTEN_MAINLOOP_END;
#endif
std::cout 

Подробнее здесь: [url]https://stackoverflow.com/questions/79386868/why-is-my-image-not-shown-while-im-dragging-background-window-to-resize-it-in-i[/url]