Qt pure c++ adding imgui

[ekato993]

I would like to add imgui into with "pure" c++ code.

I am using Qt5 and win10 and I am using non-qt project, plain c++ application

include\GLFW\glfw3.h
linking\GLFW\glfw3.dll
linking\GLFW\glfw3dll.a
linking\GLFW\libglfw3.a

.pro file

TEMPLATE = app
CONFIG += console c++11
CONFIG -= app_bundle
CONFIG -= qt

HEADERS += \
        imgui.h \
        imconfig.h \
        imgui_internal.h \
        imstb_rectpack.h \
        imstb_textedit.h \
        imstb_truetype.h \

SOURCES += \
        main.cpp \
        imgui.cpp \
        imgui_demo.cpp \
        imgui_draw.cpp \
        imgui_tables.cpp \
        imgui_widgets.cpp

LIBS += -L$$PWD/linking/GLFW/ -lglfw3 -lopengl32
LIBS += -lglu32 -lgdi32

INCLUDEPATH += $$PWD/linking/GLFW
DEPENDPATH += $$PWD/linking/GLFW

INCLUDEPATH += $$PWD/include
DEPENDPATH += $$PWD/include

main.cpp

#include "imgui.h"

#include <stdio.h>

int main(int, char**)
{
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO();

    // Build atlas
    unsigned char* tex_pixels = NULL;
    int tex_w, tex_h;
    io.Fonts->GetTexDataAsRGBA32(&tex_pixels, &tex_w, &tex_h);

    for (int n = 0; n < 20; n++)
    {
        printf("NewFrame() %d\n", n);
        io.DisplaySize = ImVec2(1920, 1080);
        io.DeltaTime = 1.0f / 60.0f;
        ImGui::NewFrame();

        static float f = 0.0f;
        ImGui::Text("Hello, world!");
        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
        ImGui::ShowDemoWindow(NULL);

        ImGui::Render();
    }

    printf("DestroyContext()\n");
    ImGui::DestroyContext();
    return 0;
}

main.cpp is an example file from imgui/example/example-null folder: link

On qt create I click on Rebuild All Project for All Configuration I'am getting the follwoing errors:

...\build-untitled-Desktop_Qt_5_12_11_MinGW_64_bit-Debug\..\untitled\imgui.cpp:10811: error: undefined reference to `ImmGetContext'
debug/imgui.o: In function `ImeSetInputScreenPosFn_DefaultImpl':
...\build-untitled-Desktop_Qt_5_12_11_MinGW_64_bit-Debug/../untitled/imgui.cpp:10811: undefined reference to `ImmGetContext'

...\build-untitled-Desktop_Qt_5_12_11_MinGW_64_bit-Debug\..\untitled\imgui.cpp:10817: error: undefined reference to `ImmSetCompositionWindow'

...\build-untitled-Desktop_Qt_5_12_11_MinGW_64_bit-Debug\..\untitled\imgui.cpp:10818: error: undefined reference to `ImmReleaseContext'

:-1: error: collect2.exe: error: ld returned 1 exit status

:-1: error: [Makefile.Debug:85: debug/untitled.exe] Error 1

[ekato993]

@SGaist

LIBS += -lglu32 -lgdi32 -lshell32 -limm32

Works for me, thanks

[SGaist]

Hi,

Aren't you missing the backend files ?

[ekato993]

@SGaist

I have copyed the imgui_impl_opengl3.h/cpp into my folder and now my .pro looks like this:

TEMPLATE = app
CONFIG += console c++11
CONFIG -= app_bundle
CONFIG -= qt


HEADERS += \
        imgui.h \
        imconfig.h \
        imgui_internal.h \
        imstb_rectpack.h \
        imstb_textedit.h \
        imstb_truetype.h \
        imgui_impl_opengl3.h

SOURCES += \
        main.cpp \
        imgui.cpp \
        imgui_demo.cpp \
        imgui_draw.cpp \
        imgui_tables.cpp \
        imgui_widgets.cpp \
        imgui_impl_opengl3.cpp \
        glad.c

LIBS += -L$$PWD/linking/GLFW/ -lglfw3 -lopengl32
LIBS += -lglu32 -lgdi32

INCLUDEPATH += $$PWD/linking/GLFW
DEPENDPATH += $$PWD/linking/GLFW

INCLUDEPATH += $$PWD/include
DEPENDPATH += $$PWD/include

I need to add the following files as well:

include\glad\glad.h
include\KHR\khrplatform.h

main.cpp

#include "imgui.h"

#include <glad/glad.h>

#include <stdio.h>

int main(int, char**)
{

    gladLoadGL(); //imgui_impl_opengl3.cpp says: Needs to be initialized with gladLoadGL() in user's code

    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO();

    // Build atlas
    unsigned char* tex_pixels = NULL;
    int tex_w, tex_h;
    io.Fonts->GetTexDataAsRGBA32(&tex_pixels, &tex_w, &tex_h);

    for (int n = 0; n < 20; n++)
    {
        printf("NewFrame() %d\n", n);
        io.DisplaySize = ImVec2(1920, 1080);
        io.DeltaTime = 1.0f / 60.0f;
        ImGui::NewFrame();

        static float f = 0.0f;
        ImGui::Text("Hello, world!");
        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
        ImGui::ShowDemoWindow(NULL);

        ImGui::Render();
    }

    printf("DestroyContext()\n");
    ImGui::DestroyContext();
    return 0;
}

I am getting the following errors:

...\build-untitled-Desktop_Qt_5_12_11_MinGW_64_bit-Debug\..\untitled\imgui.cpp:10811: error: undefined reference to `ImmGetContext'
debug/imgui.o: In function `ImeSetInputScreenPosFn_DefaultImpl':
...\build-untitled-Desktop_Qt_5_12_11_MinGW_64_bit-Debug/../untitled/imgui.cpp:10811: undefined reference to `ImmGetContext'

...\build-untitled-Desktop_Qt_5_12_11_MinGW_64_bit-Debug\..\untitled\imgui.cpp:10817: error: undefined reference to `ImmSetCompositionWindow'

...\build-untitled-Desktop_Qt_5_12_11_MinGW_64_bit-Debug\..\untitled\imgui.cpp:10818: error: undefined reference to `ImmReleaseContext'

:-1: error: collect2.exe: error: ld returned 1 exit status

:-1: error: [Makefile.Debug:92: debug/untitled.exe] Error 1

[SGaist]

Where are these methods located ?

[ekato993]

@SGaist

Each methods in the imgui.h except the these methods:

• GetTexDataAsRGBA32 is in the imgui_draw.cpp

• Text and SliderFloat is in the imgui_widgets.cpp

• ShowDemoWindow is in the imgui_demo.cpp

[SGaist]

Do you mean they are used or defined there ?

[ekato993]

@SGaist

They are defined there.

[SGaist]

Looks like you are missing the shell32 and imm32 libraries in your link list.

[ekato993]

@SGaist

LIBS += -lglu32 -lgdi32 -lshell32 -limm32

Works for me, thanks