Redirecting window mouse wheel inputs to parent

[Twinki14]

Currently i'm running into a problem of having Wrapped Text in a child region.

I have a child rregion, which consists of Columns, in those Columns I have another child region which has a TextWrapped of a description.

https://i.imgur.com/kvWAu6h.gif

The Window is intended to have enough items that scrolling will be needed, however when I hover over the Wrapped Text areas, it cannot scroll. I was able to solve it by using ImGuiWindowFlags_NoInputs on the child region inside the column, however if the Description now requires scrolling, users can no longer drag scroll, since all input isn't being cached for the child region.

Is there anyway I can block only specific inputs? or a potentially solution to this problem?

ADMIN Attached your GIF file. Please don't use imgur.com as those images will disappear:

[ocornut]

Hello @Twinki14,

This was discussed in #1245, and while I would personally prefer Windows-style behavior to avoid that sort of issue you are hitting on, other people seemed to like Mac-style behavior.

Note that being used on Mac this means that most applications there who needs embedded scrolling regions tends to leave some space available.

For reference, the patch for Windows-style scrolling may be applied in NewFrame():
https://github.com/ocornut/imgui/blob/master/imgui.cpp#L2398

    // Scale & Scrolling
    if (g.HoveredWindow && g.IO.MouseWheel != 0.0f && !g.HoveredWindow->Collapsed)
    {
        ImGuiWindow* window = g.HoveredWindow;

By changing the 3 occurences of g.HoveredWindow to g.NavWindow here.

A possible solution is when we find the flag ImGuiWindowFlags_NoScrollWithMouse on a window we could search back among its parent until we find one that doesn't have this flag set and scroll that window. I will try that.

PS: Please use github attachment for pictures/gif so that the pictures won't disappear in the future and those threads can be relevant to future readers.

[ocornut]

If you replace:

        else if (!g.IO.KeyCtrl && !(window->Flags & ImGuiWindowFlags_NoScrollWithMouse))
        {
            // Scroll
            const int scroll_lines = (window->Flags & ImGuiWindowFlags_ComboBox) ? 3 : 5;
            SetWindowScrollY(window, window->Scroll.y - g.IO.MouseWheel * window->CalcFontSize() * scroll_lines);
        }

with:

        else if (!g.IO.KeyCtrl)
        {
            // Scrolling
            // If the window has the ImGuiWindowFlags_NoScrollWithMouse flag, we give a chance to scroll its parent
            ImGuiWindow* scroll_window = window;
            while (!(scroll_window->Flags & ImGuiWindowFlags_NoInputs) && (scroll_window->Flags & ImGuiWindowFlags_NoScrollWithMouse) && scroll_window->ParentWindow)
                scroll_window = scroll_window->ParentWindow;

            if (!(scroll_window->Flags & ImGuiWindowFlags_NoScrollWithMouse) && !(scroll_window->Flags & ImGuiWindowFlags_NoInputs))
            {
                const int scroll_lines = (scroll_window->Flags & ImGuiWindowFlags_ComboBox) ? 3 : 5;
                SetWindowScrollY(scroll_window, scroll_window->Scroll.y - g.IO.MouseWheel * scroll_window->CalcFontSize() * scroll_lines);
            }
        }

It would solve your problem when passing ImGuiWindowFlags_NoScrollWithMouse to the child windows. However I'm not sure what would be the other side effects for people already using this flag and perhaps expecting mouse wheel to completely be ignored in that situation.

[ocornut]

@Twinki14 You can now use the ImGuiWindowFlags_NoScrollWithMouse flag and by default on a child window it will forward the mouse wheel to its parent.

"Using the ImGuiWindowFlags_NoScrollWithMouse flag on a child window forwards the mouse wheel event to the parent window, unless either ImGuiWindowFlags_NoInputs or ImGuiWindowFlags_NoScrollbar are also set."

[ocornut]

Note that I have amended this behavior today:

• Mouse wheel scrolling while hovering a child window is automatically forwarded to parent window if ScrollMax is zero on the scrolling axis (so in a same position vertical mouse wheel can apply to a different window than the horizontal mouse wheel).
• Also still he case if ImGuiWindowFlags_NoScrollWithMouse is set (not new), but previously the forwarding would be disabled if ImGuiWindowFlags_NoScrollbar was set on the child window, which is not the case any more. Forwarding can still be disabled by setting ImGuiWindowFlags_NoInputs.