imgui/misc/stl/imgui_stl.cpp

// imgui_stl.cpp
// Wrappers for C++ standard library (STL) types (std::string, etc.)
// This is also an example of how you may wrap your own similar types.

// Compatibility:
// - std::string support is only guaranteed to work from C++11. 
//   If you try to use it pre-C++11, please share your findings (w/ info about compiler/architecture)

#include "imgui.h"
#include "imgui_stl.h"

struct InputTextCallback_UserData
{
    std::string*            Str;
    ImGuiInputTextCallback  ChainCallback;
    void*                   ChainCallbackUserData;
};

static int InputTextCallback(ImGuiInputTextCallbackData* data)
{
    InputTextCallback_UserData* user_data = (InputTextCallback_UserData*)data->UserData;
    if (data->EventFlag == ImGuiInputTextFlags_CallbackResize)
    {
        // Resize string callback
        // If for some reason we refuse the new length (BufTextLen) and/or capacity (BufSize) we need to set them back to what we want.
        std::string* str = user_data->Str;
        IM_ASSERT(data->Buf == str->c_str());
        str->resize(data->BufTextLen);
        data->Buf = (char*)str->c_str();
    }
    else if (user_data->ChainCallback)
    {
        // Forward to user callback, if any
        data->UserData = user_data->ChainCallbackUserData;
        return user_data->ChainCallback(data);
    }
    return 0;
}

bool ImGui::InputText(const char* label, std::string* str, ImGuiInputTextFlags flags, ImGuiInputTextCallback callback, void* user_data)
{
    IM_ASSERT((flags & ImGuiInputTextFlags_CallbackResize) == 0);
    flags |= ImGuiInputTextFlags_CallbackResize;

    InputTextCallback_UserData cb_user_data;
    cb_user_data.Str = str;
    cb_user_data.ChainCallback = callback;
    cb_user_data.ChainCallbackUserData = user_data;
    return InputText(label, (char*)str->c_str(), str->capacity() + 1, flags, InputTextCallback, &cb_user_data);
}

bool ImGui::InputTextMultiline(const char* label, std::string* str, const ImVec2& size, ImGuiInputTextFlags flags, ImGuiInputTextCallback callback, void* user_data)
{
    IM_ASSERT((flags & ImGuiInputTextFlags_CallbackResize) == 0);
    flags |= ImGuiInputTextFlags_CallbackResize;

    InputTextCallback_UserData cb_user_data;
    cb_user_data.Str = str;
    cb_user_data.ChainCallback = callback;
    cb_user_data.ChainCallbackUserData = user_data;
    return InputTextMultiline(label, (char*)str->c_str(), str->capacity() + 1, size, flags, InputTextCallback, &cb_user_data);
}