A scrollable list of items with too many elements

[sairus7]

I want to show an array of 100000 strings into a listbox with single item selection and scrolling.
But it is very inefficient to render them all every frame.
So, I should somehow:

• Draw only current visible items:
  • get number of elements that can fit into the current listbox height
  • get first and last index of visible elements from scrollbar position and draw only them
• Draw a cusom scrollbar, since I am filling listbox only with few items and built-it scrollbar would not show properly:
  • add VSlider at the same line
  • revert its min-max values, and recalc first and last visible index

Are there some ready-to use widgets with these optimizations enabled?
Or maybe I can modify widget scrollbar behaviour without adding vertical slider?

[ocornut]

This problem is already solved by ImGuiListClipper and demonstrated in multiple places of the demo.

[sairus7]

Thanks! You saved my day!