SetItemDefaultFocus scroll improvement suggestions

[DomGries]

Hey, I think SetItemDefaultFocus scrolling could be improved due to the following minor issues:

• An item which is barely visible (1px) is not being visibly focused
• Scrolling to an invisible item could be improved to fix the jump between barely visible and completely centered

I think the best behavior would be to copy what the .NET ListView EnsureVisible method does: https://docs.microsoft.com/en-us/dotnet/api/system.windows.forms.listview.ensurevisible?view=netframework-4.8

If the item that you want to ensure is visible is located above the viewable region, calling the EnsureVisible method will scroll the contents until it is the first item in the viewable area. If the item is below the viewable region, calling the EnsureVisible method will scroll the contents until the item is the last item in the viewable area.

Dear ImGui 1.73

[ocornut]

Hello,

Could you provide concrete example/screenshots of both of your case?

If SetItemDefaultFocus() is called on a frame where the window is appearing, I can think of cases where it would be preferable that the be centered. e.g. for a list of items in a combo box.
Perhaps the behavior should differ depending on whether the window is appearing? Would need some more thought..

[DomGries]

Case 1

Popup window does not visibly select 1280x720 button because 1px is already visible (the black line at bottom under 1024x768) when calling SetItemDefaultFocus(). I think the logic should be changed so that it should also scroll when the item is not fully visible:

Case 2

Only centering the view on the item when it is not visible is weird especially combined with suggested fix of case 1.

Assume that the focused item is just barely fully visible then it would be at the very bottom (or top). But if the focused item is just the one below that then it results in it being completely centered which is a jump in behaviour.

I just tested default comboboxes on Windows and they actually simply try to scroll so that the item is at the top or as much as possible at the top. So in SetItemDefaultFocus that would be SetScrollHereY(0.f) without the IsItemVisible() check.

[ocornut]

Case 1: Totally agreeing.

Case 2: I don't think your answer refers to the same idea that I suggested? I suggested using the "IsWindowAppearing" test. Typically behave different on the frame a window is appearing vs if function is called while the window is already up. This is unrelated to the visibility of items within a given window.

Scrolling to the center or to the top is another decision to do. I agree that the behavior of ScrollToBringRectIntoView() is more desirable in some situation. This is also what I asked for a usage scenario here where that behavior is the most desirable (scrolling to make item appear at edge vs centering).

[ocornut]

Closing as per #2814, both cases should be solved. Thanks for your patience!