I can think of two options which only use the functionality that is currently available in the racket GUI library:
One option is to use a `pasteboard%` instead of the `canvas%` and use an `editor-snip%` for the text input, with the snip being moved where you need it. This solution will be limited to the text input widget only, unless you want to write additional widgets, which will have to be implemented as `snip%` instances. Another option is to write your own panel widget by deriving from `panel%` and overriding `container-size` and `place-children` -- this will give full control over the placement of child items inside the panel: e.g. the canvas could be placed at 0,0 and fill the entire client area, while the text input will be placed on top of the canvas at the correct position. This solution allows placing arbitrary controls on the canvas. For scrolling, I would suggest making the canvas itself scrollable and have the panel update the position of the text input: a scrollable panel works, but the canvas will not know its viewing area and will have to draw all the rows and let the underlying draw routines clip them -- this might be a performance issue for very large number of rows. Good luck with your project, Alex. On Monday, August 5, 2019 at 7:28:17 PM UTC+8, Neil Van Dyke wrote: > > For a million-rows spreadsheet GUI widget that's based on a canvas, and > wants to overlay a single normal widget like a `text-field%` at a time, > over the canvas, for cell value editing... what's the best way to get > that overlay to happen in Racket `gui`? > > One idea: in the implementation of `panel%`, looks like I can force it > to be implemented as a canvas (`wx-vertical-canvas-panel%`). If I could > draw the spreadsheet viewport to that same canvas, as well as parent > overlaid widgets to it, I suppose I could use panes to position and size > the editing widget. I don't know whether that would work at all, on all > platforms, and in future Racket releases. > > Or is there a better way? > > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/3b932c2d-c6c2-48ea-8906-605695579fe2%40googlegroups.com.
