Add items to context menu

[Tymoteusz-Mroczkowski]

Is it possible to define additional options from the right-click menu?
I looked through the code and I can't find a solution other than modifying the ImPlot code.
I think it would be a useful feature to allow us to expose extra functionality to the users.

[PapaNaxos]

As it turns out, I also needed this functionality. So I implemented it (possibly less than ideal solution)

Usage Example

if (ImPlot::BeginPlot("My Plot", ImVec2(-1, 0), ImPlotFlags_NoCentralMenu))
{
    // ... plot stuff here ...
    if (ImPlot::BeginCustomContext())
    {
        if (ImGui::MenuItem("My Custom Item")) doThing();
        ImPlot::EndCustomContext(true); // true = append standard menu
    }
    ImPlot::EndPlot();
}

Please note that it is critical to:

• use ImPlotFlags_NoCentralMenu in your BeginPlot() call
• call BeginCustomContext() AFTER BeginPlot() and BEFORE EndPlot()

And if you want to use it:

implot.h changes

- Add flag to enum ImPlotFlags_

ImPlotFlags_NoCentralMenu = 1 << 9,  // disable the central menu, but allow other menus (such as legends and axis)

- Add function declarations

//-----------------------------------------------------------------------------
// [SECTION] Context Menu
//-----------------------------------------------------------------------------

// Begin a custom central plot context menu
IMPLOT_API bool BeginCustomContext();
// End a custom central plot context menu
IMPLOT_API void EndCustomContext(bool include_default = false); // if include_default is true, the normal context menu will be appended

implot.cpp changes

- Modify EndPlot()

    // if (can_ctx && plot.Hovered) <-- old line
    if (can_ctx && !ImHasFlag(plot.Flags, ImPlotFlags_NoCentralMenu) && plot.Hovered) // <-- new line

- Add function definitions

//-----------------------------------------------------------------------------
// [SECTION] Context Menu
//-----------------------------------------------------------------------------

bool BeginCustomContext()
{
    ImPlotContext& gp = *GImPlot;

    if (gp.CurrentPlot == nullptr) return false;

    ImPlotPlot &plot  = *gp.CurrentPlot;

    const bool can_ctx = plot.Hovered &&
                         !plot.Items.Legend.Hovered &&
                         ImGui::IsMouseReleased(ImGuiMouseButton_Right);

    // main ctx menu
    if (can_ctx)
        ImGui::OpenPopup("##CustomPlotContext");

    return ImGui::BeginPopup("##CustomPlotContext");
}

void EndCustomContext(bool include_default)
{
    if (include_default)
        ShowPlotContextMenu(*(GImPlot->CurrentPlot));
    ImGui::EndPopup();
}

[PapaNaxos]

This has a bug when box selecting. Looking into it.

[PapaNaxos]

Fix:
Change the definition of BeginCustomContext() to:

bool BeginCustomContext()
{
    ImPlotContext& gp = *GImPlot;

    if (gp.CurrentPlot == nullptr) return false;

    ImPlotPlot &plot  = *gp.CurrentPlot;

    const bool can_ctx = plot.Hovered &&
                         !plot.Items.Legend.Hovered &&
                         !plot.ContextLocked && // <-- added
                         ImGui::IsMouseReleased(ImGuiMouseButton_Right);

    // main ctx menu
    if (can_ctx)
        ImGui::OpenPopup("##CustomPlotContext");

    return ImGui::BeginPopup("##CustomPlotContext");
}

[Karm]

Hey there, @PapaNaxos, it works for me too. Thanks.

Are you about to draft a PR?

[PapaNaxos]

@Karm I hadn't planned on it. Was hoping maybe the maintainers would make a proper version (mine feels like a hack job).

Also I don't actually know how to make a pull request 😅

[Karm]

@PapaNaxos If you don't mind, I'll polish your solution into a PR and attribute the credit to @PapaNaxos.
To quote our lord and savior Mike Acton, "if it solves the problem, it is the solution".

[PapaNaxos]

@Karm that's totally fine with me, appreciated even!