Adding button in tab bars

[rjx-ray]

I am using a "+" button after a reorderable tab bar to add a new tab.

if I move the last tab the button's position moves to after the moved tab instead of after the tab bar

I'm using ImGui 1.75 included with https://github.com/jvcleave/ofxImGui

Here's the code outline - a tab is class which has a name variable and I keep the tabs in a C++ vector
`

ImGuiTabBarFlags tab_bar_flags = ImGuiTabBarFlags_AutoSelectNewTabs | ImGuiTabBarFlags_Reorderable;
if (ImGui::BeginTabBar("MyTabBar", tab_bar_flags)) {
    for (auto tab : tabs) {
        string name = tab->name;
        if (ImGui::BeginTabItem(name.c_str())) { 
            // switch to the newly selected tab
            ImGui::EndTabItem();
        }
    }
    ImGui::EndTabBar();
}
ImGui::SameLine();
if (ImGui::Button("+")) {
    // create the new tab and push_back
}

`

[ocornut]

Hello Richard,

I thought we could modify EndTabBar() to set the "last item" information for layout, but this usage pattern would break if the tabs shrinking down or scrolling, so I remember why I explicitly didn't make that change in EndTabBar().

I think instead we should add specific ImGuiTabItemFlags flags to:

• disable reordering on a specific tab
• treat the tab as a button: it would not get selected and return true on click

This would allow implementing this behavior using a tab (and you can alter tab colors in the style if you want it to be red, etc).

[rjx-ray]

Hi Omar, thanks for the quick response.
My + button is a separate ImGui button, outside of the tab bar.
It seemed to me that its just the end point of the tab bar that was calculated wrong.
So I do want to be able to re-order the last tab.

By the way, I had originally tried having a "+" tab after all the others.
I had to do special logic as the new tab wasn't selected until the following cycle so I ended up with two new tabs.
Also I had the issue you describe that the new tab was placed after the "+" tab and the "+" tab then couldn't be re-ordered because any click on it creates a new tab.
So it seemed simpler to have a separate button

[rjx-ray]

I've managed to devise a workaround for this:

If I sort my tabs vector to be in the same order as the ImGui tabs display then the "+" button stays at the end after the last tabItem I call.
That also means that I can save the tab ordering between app invocations which is a requirement for me.

I did the sorting by getting the tabbar tab offsets and names and copying the offset into my tab class. Obviously I'm having to access ImGui internals for this which is not ideal. Also I'm having to sort on every cycle as I don't know when the ordering is changed

But for now its working OK for me.

[ocornut]

Hello Richard,
We are currently working on a proper solution for this.

[rjx-ray]

Fantastic!
It would be great if you could also include some method of notifying a change of ordering and getting the results
Thanks

[ocornut]

You should not need to get a notification of change of ordering. I'd rather work on allowing to preserve that order.

…

On Tue, Jun 16, 2020 at 2:28 PM Richard Jackson ***@***.***> wrote: Fantastic! It would be great if you could also include some method of notifying a change of ordering and getting the results Thanks — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3291 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB6YCIJBD2I6MKXSLFAY3KDRW5QQTANCNFSM4NYMHCWA> .

[rjx-ray]

Could it be preserved between app invocations?

[ocornut]

Well yes that's what we should aim for, but notice it is awkward to preserve order without preserving visibility, and visibility is tied to your code flow, so it's not easy to make something useful out of only preserving order. Anyway this is another topic. If you want to manually save order you can currently query structures in imgui_internal.h, but we won't attempt to provide mid-way public API for this.

…

On Tue, Jun 16, 2020 at 2:34 PM Richard Jackson ***@***.***> wrote: Could it be preserved between app invocations? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3291 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB6YCIME4LWOJZLKWSCEHL3RW5RGTANCNFSM4NYMHCWA> .

[rjx-ray]

OK, I understand, thanks for all the great stuff you do.

[rjx-ray]

Would it be possible to add a favicon to tab - maybe as a optional parameter to BeginTabItem?

[ocornut]

Use fonts icons as described in the docs. Let’s focus on one issue if you have more questions about this please ask on Discord or open a separate issue, thank you!

[ocornut]

This now has been implemented (it was surprisingly lots of work to get it right, done mostly by @Xipiryon, lots of corner cases, resizing/scrolling policy issues)

You can now use TabItemButton() + ImGuiTabItemFlags_Leading, ImGuiTabItemFlags_Trailing flags.
See Demo > Layouts > Tabs for details.

Regular tabs can also be trailing/leading.

The next thing in line is to allow to appends tab using multiple BeginTabBar()/EndTabBar() which would make it possible to add custom buttons into docking nodes created by the docking system.

[ocornut]

Appending to tab bar has been added a bit ago by the way, so closing this as all done.