FreeType, Loading Emoji Font freezes window

[Advik-B]

Version/Branch of Dear ImGui:

Version: v1.90
Branch: docking

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_glfw.cpp + imgui_impl_opengl3.cpp
Compiler: MSVC 2022 64x
Operating System: Windows 11

My Issue/Question:

Why does my GUI freeze, I have pinpointed the problem here:

cfg.FontBuilderFlags |= ImGuiFreeTypeBuilderFlags_LoadColor;

If I comment out the line, it works perfectly

Screenshots/Video

The output generated by cmake

C++ file

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <imgui.h>
#include <imgui_impl_glfw.h>
#include <imgui_impl_opengl3.h>
#include <filesystem>
#include "misc/freetype/imgui_freetype.h"

#define resPath "resources/"
#define defaultFont "Satoshi-Bold.otf"
#define emojiFont "NotoColorEmoji.ttf"
namespace fs = std::filesystem;

int windowWidth = 1280;
int windowHeight = 720;


// On Resize
void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
    glViewport(0, 0, width, height);
}

void setupStyle(ImGuiStyle& style) {
    ImGui::StyleColorsDark();
    style.WindowRounding = 8.f;
//    style.Colors[ImGuiCol_WindowBg] = ImVec4(0.1f, 0.1f, 0.1f, 1.f);
}

void loadFonts() {
    // Make a path object for the font directory
    fs::path fontDir = fs::path(resPath) / "fonts";

    // The default font is Satoshi-Bold.otf
    fs::path fontPath = fontDir / defaultFont;

    // Check if the font exists
    if (!fs::exists(fontPath)) {
        std::cout << "Font file (default) does not exist: " << fontPath << std::endl;
        return;
    }

    // Load the font
    ImGuiIO& io = ImGui::GetIO();

    // Set the default font
    io.FontDefault = io.Fonts->AddFontFromFileTTF(fontPath.string().c_str(), 18.f);

    // Then, add the emoji font
    fontPath = fontDir / emojiFont;
    if (!fs::exists(fontPath)) {
        std::cout << "Font file (emoji) does not exist: " << fontPath << std::endl;
        return;
    }
    static ImWchar ranges[] = { 0x1, static_cast<ImWchar>(0x1FFFF), 0 };
    static ImFontConfig cfg;
    cfg.OversampleH = cfg.OversampleV = 1;
    cfg.MergeMode = true;
    cfg.FontBuilderFlags |= ImGuiFreeTypeBuilderFlags_LoadColor;
    std::cout << "Loading font: " << fontPath << std::endl;
    io.Fonts->AddFontFromFileTTF(fontPath.string().c_str(), 18.f, &cfg, ranges);

    // Build the font atlas
    io.Fonts->Build();
    ImGui_ImplOpenGL3_CreateFontsTexture();

}

int main() {
    // Initialize GLFW
    if (!glfwInit()) {
        std::cout << "Failed to initialize GLFW" << std::endl;
        return -1;
    }

    // Set GLFW window hints
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    GLFWwindow* window;
    window = glfwCreateWindow(windowWidth, windowHeight, "My Window", NULL, NULL);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

    // Check for window creation failure
    if (!window) {
        // Terminate GLFW
        glfwTerminate();
        // Exit program
        std::cout << "Failed to create GLFW window" << std::endl;
        return -1;
    }

    glfwMakeContextCurrent(window);
    gladLoadGLLoader((GLADloadproc)glfwGetProcAddress);
    glfwSwapInterval(1); // Enable vsync

    // Set the viewport
    glViewport(0, 0, windowWidth, windowHeight);

    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO(); (void)io;
    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
    io.IniFilename = nullptr;

    ImGui_ImplGlfw_InitForOpenGL(window, true);
    ImGui_ImplOpenGL3_Init("#version 330");

    setupStyle(ImGui::GetStyle());
    loadFonts();
    // Loop until the user closes the window
    while (!glfwWindowShouldClose(window)) {
        // Poll for and process events
        glfwPollEvents();

        // ImGUI frame
        ImGui_ImplOpenGL3_NewFrame();
        ImGui_ImplGlfw_NewFrame();

        ImGui::NewFrame();
        ImGui::SetNextWindowPos(ImVec2(100, 100), ImGuiCond_FirstUseEver);
        ImGui::SetNextWindowSize(ImVec2(500, 500), ImGuiCond_FirstUseEver);
        ImGui::Begin("Hello, world!");
        ImGui::Text("This is some useful text.");
        ImGui::End();
        ImGui::ShowDemoWindow();

        // Render here
        glClear(GL_COLOR_BUFFER_BIT); // Clear the color buffer
        ImGui::Render();
        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

        // Swap front and back buffers
        glfwSwapBuffers(window);

    }
    ImGui_ImplOpenGL3_Shutdown();
    ImGui_ImplGlfw_Shutdown();
    ImGui::DestroyContext();

    // Terminate GLFW
    glfwTerminate();
    return 0;
}

Cmake

cmake_minimum_required(VERSION 3.26)
project(LightWeightUI)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_COMPILER_LAUNCHER ccache)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)

set(GLFW_BUILD_DOCS OFF CACHE BOOL "" FORCE)
set(GLFW_BUILD_TESTS OFF CACHE BOOL "" FORCE)
set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)

#option(BUILD_SHARED_LIBS "Build shared libraries" OFF)

add_subdirectory(glfw)
add_subdirectory(lunasvg)
#add_subdirectory(harfbuzz)
#add_subdirectory(freetype)

find_package(Freetype REQUIRED)


# ImGui
include_directories(imgui)

# Glob all the ImGui source files
file(GLOB IMGUI_SOURCES
        imgui/*.cpp
        imgui/imgui_impl_glfw.cpp
        imgui/imgui_impl_opengl3.cpp
        imgui/misc/freetype/imgui_freetype.cpp
)

add_executable(LightWeightUI main.cpp ${IMGUI_SOURCES})

# Glad
add_library(glad STATIC glad/src/glad.c)
target_include_directories(glad PUBLIC glad/include)
# KHR
target_include_directories(LightWeightUI PUBLIC glad/include/KHR)


target_link_libraries(LightWeightUI PUBLIC glfw glad Freetype::Freetype lunasvg)

# Copy over the resources folder
## First, delete the old resources folder (if it exists)
add_custom_command(TARGET LightWeightUI POST_BUILD
        COMMAND ${CMAKE_COMMAND} -E remove_directory
        ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/resources)

## Then, copy over the new resources folder
add_custom_command(TARGET LightWeightUI POST_BUILD
        COMMAND ${CMAKE_COMMAND} -E copy_directory
        ${CMAKE_SOURCE_DIR}/resources
        ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/resources)


# If on Release, disable console window and enable optimizations
if (CMAKE_BUILD_TYPE STREQUAL "Release")
    if (MSVC)
        set_target_properties(LightWeightUI PROPERTIES LINK_FLAGS "/SUBSYSTEM:WINDOWS /ENTRY:mainCRTStartup")
        # Enable optimizations
        target_compile_options(LightWeightUI PRIVATE /O2)
    endif()
endif()

# If on Debug, enable debug symbols
if (CMAKE_BUILD_TYPE STREQUAL "Debug")
    if (MSVC)
        target_compile_options(LightWeightUI PRIVATE /Zi)
        target_link_options(LightWeightUI PRIVATE /DEBUG)
    endif()
endif()

[PathogenDavid]

Does it freeze forever or just take a really long time to load?

static ImWchar ranges[] = { 0x1, static_cast<ImWchar>(0x1FFFF), 0 };

This is a huge range. Dear ImGui currently rasterizes all glyphs up front, so this will take quite a long time.

You probably need to be more selective about the ranges your app actually needs.

[Advik-B]

Hang on. I thought I am supposed add that line because of this
I want to add emoji support, thats why i've loaded up that font.

[ocornut]

It may be ok to load a large range if the fonts only has part of it.
You should clarify what you mean by "freezing". You can break in debugger to find what's its doing.

[PathogenDavid]

Omar is right, I might've jumped the gun with that remark. I second though that you need to clarify what you mean by freezing and where it is getting stuck.

[Advik-B]

"Freezing" as in, taking a longgg time to load and literally using more ram as we speak

[ocornut]

Try to break in debugger a few times randomly to see where the execution is, to see where that time goes.
It might be related to that LunaSVG issue that Pascal mentioned below.

[pthom]

This issue is probably the same as sammycage/lunasvg#150

[ocornut]

Also your issue #7187