How to Get Docked Status of a Window before Begin()

[Malkierian]

Version/Branch of Dear ImGui:

1.91.6 docking

Back-ends:

n/a

Compiler, OS:

Win10 MSVC 2022

Details:

I've seen a couple of options for trying to get a window's docked status on the web, but only after the window has been opened. I'm trying to be able to modify a given user-defined color for the window background based on whether it's docked or not, so I need to know the docked status beforehand. However, using ImGui::GetID() with the same string that I use later to open the window with Begin() doesn't return anything useful (I feel like it's a garbage ID). Is there any way to get the raw data that would be stored in the .ini for that status, or some other way I'm missing?

[ocornut]

Using imgui_internal.h:

ImGuiWindow* window = ImGui::FindWindowByName(name);
return window && window->DockIsActive;

However, using ImGui::GetID()

GetID() is stacked (here using the previous window id which would likely be the implicit Debug Window) so wouldn't be an absolute ID. I just realized this isn't actually properly exposed in the public API, but if you use GetIDWithSeed() with a seed of 0, or ImHashStr() you'll get the correct identifier which you can feed into FindWindowByID(id) but there's no value using this instead of FindWindowByName().

[Malkierian]

Hmm, I tried implementing that, but window->DockIsActive is never true, even when it's actually docked, and I verified the window returned by that before Begin was the same Ctx and everything as the window returned by GetCurrentWindow() after Begin(). In addition, though, DockIsActive for that window becomes true if another window is docked with it in another tab, and when it's on its own, DockNodeIsVisible and DockTabIsVisible are true despite DockIsActive being false.

[Malkierian]

Interestingly, I originally dove into this because of some framebuffer ghosting I was getting because this particular window's background color was transparent when supposedly docked:

However, when I add another window such that DockIsActive then registers as true for this window, the framebuffer ghosting is no longer an issue:

[ocornut]

nterestingly, I originally dove into this because of some framebuffer ghosting I was getting because this particular window's background color was transparent when supposedly docked:

Then this is a XY Problem. Please don’t do this. I would happily help you investigate that problem, but the question you asked about I now consider to be void.

Please investigate the actual initial problem. you can use Metrics to browse the draw calls, and try to manufacture a repro then you can open a new issue with details. Thanks.

[Malkierian]

I'm not sure which part you're saying is void at this point. I knew the initial problem came about because of the color, that's why I wanted to know if it was docked beforehand to apply the right opacity, but it seems, with the other investigations, it's supposed to do that automatically if it's docked anyway (as evidenced by the fact that a second window being docked changes its actual docked status and thus automatically fixes the ghosting).

[ocornut]

I meant if you have a bug where the docked window background doesn't appear, we should investigate that rather than investigate how to detect being docked.

Why not simply setting the WindowBg color to always be opaque, regardless of docking state?

[Malkierian]

Because it's a user-specified color, and the opacity option makes sense when it's hovering over the main window but not docked.

Anyway, yeah, since this is beyond the scope of just getting the docked status (as DockNodeIsVisible still works for my purposes), I'll see if I can get a reproduceable state on the demo or something so that code is easily trackable and open another one.