InvisibleButton: add a way to optionally call RenderNavHighlight inside?

[achabense]

Version/Branch of Dear ImGui:

Version 1.91.2

Back-ends:

imgui_impl_sdl2.cpp + imgui_impl_sdlrenderer2.cpp

Compiler, OS:

Windows 10 + MSVC 2022

Full config/build information:

No response

Details:

ImGui::InVisibleButton is useful for defining custom widgets. However, when ImGuiConfigFlags_NavEnableKeyboard is specified, the keyboard navigation will work on them in an invisible way.
Take the code below for example. If not calling RenderNavHighlight, the effect would be like this. It's hard to tell where the navigation goes.

It will work well if calling RenderNavHighlight. However, as RenderNavHighlight is an internal function, I think it will be helpful to add a way to call RenderNavHighlight inside InvisibleButton. A new button flag may be fine for this change.

Screenshots/Video:

No response

Minimal, Complete and Verifiable Example code:

// ImGui::GetIO().ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;

static void example() {
    if (ImGui::Begin("Example", 0, ImGuiWindowFlags_NoSavedSettings)) {
        const int c = 5;
        static bool vals[c]{};
        for (int i = 0; i < c; ++i) {
            if (i != 0) {
                ImGui::SameLine();
            }
            ImGui::PushID(i);
            if (ImGui::InvisibleButton("In", {20, 20})) {
                vals[i] = !vals[i];
            }
            ImGui::PopID();

            // Custom rendering:
            const auto min = ImGui::GetItemRectMin();
            const auto max = ImGui::GetItemRectMax();
            // ImGui::RenderNavHighlight({min, max}, ImGui::GetItemID()); // "imgui_internal.h"
            ImGui::GetWindowDrawList()->AddRectFilled(min, max, vals[i] ? IM_COL32_WHITE : IM_COL32_BLACK);
            ImGui::GetWindowDrawList()->AddRect(min, max, IM_COL32_WHITE);
        }
    }
    ImGui::End();
}

[ocornut]

You are right. I'm surprised that this hasn't been brought before.

I believe the most correct approach would be to add this call in InvisibleButton().
The problem being that large invisible button calls are used in many place and in those cases the lack of nav highlight was accidentally desirable.

So we'd need make sure that the user know they can use e..g PushItemFlag(ImGuiItemFlags_NoNav, ...); Or we may add a public ImGuiButtonFlags_NoNav shortcut for this purpose too.

[ocornut]

A convenient default may to do the opposite:

• Change InvisibleButton() to use _NoNav by default and so it is correct that it doesn't render highlight. (we need to bundle those two properties together to be consistent)
• And you can opt-out aka re-enable navigation.
  It's a little bit inconsistent but no breakage and might be a better default. I will be polling a few large users.

[ocornut]

I have been agonizing a little too much over this...
It would be consistent to enable nav by default, but with the fix of rendering highlight this is going to create many more issues (e.g. ctrl+tabbing back to a window with a large invisible button).

I also polled some users, and as one in particular said "we have 595 calls to InvisibleButton() in our codebase" I though I would play it safe 😆

Pushed 67e5f35, disable nav by default + added ImGuiButtonFlags_EnableNav.

There is a possibility that someone would want to use InvisibleButton() with nav but no highlight (drawing a custom one). In which case we could decide to specifically add a ImGuiItemFlags_NoNavHighlight item flag. But I suspect most people are going to use lower-level ButtonBehavior() in this situation anyhow.