Custom Window Resizing

Syntec

I am working on a CustomUI Framework and while it does function for window resizing it isn't as good as it could be. The issue is currently in Objo there is no way to set window dimensions all at the same time, resulting in up to 4 different calls to resize a window (Left, Top, Width, Height) this results in jitter when resizing windows (because modifying left/width and top/height in two calls causes things to bounce a little).

I am on Windows 11 and I know the OS supports SetWindowPos in user32.dll but right now Objo does not have a way to Declare functions from external libraries.

I am wondering if there is a way to either suspend window updates while modifying its position and resume once all its properties have been updated. Or if some sort of Window.SetPosition(Left,Top,Width,Height) could be added that makes all the changes in a single window manager call vs. a maximum of 4.

I thought about writing a helper to run in the background that handles window resizing but I also do not think I can obtain hWnd currently in ObjoStudio, and this feels like a bad hack anyways that complicates cross-platform development.

For now, I think I just have to live with the jitter I've optimized it as much as I think I can and it isn't horrible just not ideal.

Garry

Hi @Syntec. Thanks for the detailed report. Your diagnosis is exactly right: each of Left, Top, Width, and Height is currently applied to the operating-system window as a separate operation, so a combined move-and-resize passes through intermediate states - that's the bounce you're seeing. There's nothing wrong with your framework code; the gap is on Objo's side.

I've accepted the feature and tracked it here: https://feedback.objo.dev/feature/1577

What I'm adding

A new Window.SetBounds(Left As Integer, Top As Integer, Width As Integer, Height As Integer) method that applies position and size in a single update, so the window moves and resizes in one visual step with no intermediate states. I went with SetBounds rather than your suggested SetPosition since it sets the complete bounds (position and size) but it's otherwise exactly what you proposed.
Batching for the individual properties too: consecutive assignments like

Win.Left = l
Win.Top = t
Win.Width = w
Win.Height = h

will be applied together in one update, so your existing code will improve without any changes once this ships.

What I'm deliberately not adding

Suspend/resume of window updates: the UI framework Objo is built on has no cross-platform way to suppress window updates. Emulating it per-OS requires exactly the platform-specific tricks you were trying to avoid, tends to leave drawing artefacts, and risks a permanently frozen window if code fails between the suspend and resume calls. The combined call removes the intermediate states at the source rather than papering over them, so it's simply the better fix.
Declare access to external libraries such as SetWindowPos in user32.dll: this stays out by design. Objo apps remain cross-platform precisely because they can't reach into OS internals - your instinct that a background helper "feels like a bad hack that complicates cross-platform development" matches the exact reason.
Exposing the native window handle (hWnd): same reasoning; it would invite code that only works on one platform.

One extra thing worth knowing when building a custom-drawn framework: Moved and Resized are deliberately "settled" events. They fire about a quarter of a second after the window stops changing, so bursts of changes coalesce into a single event. Resize is the continuous one. Live redraws belong in Paint, which follows every change immediately, so make sure nothing in your framework tracks geometry from the settled events or it will lag behind the drag.

Thanks again for the clear write-up - it made this easy to act on. You can follow progress on the Feedback item above.

rgb

Garry

Hi,
Great feature if same thing for control

control.SetBounds(x,y,w,h)

Syntec

Garry Thank you Garry! Amazingly fast as always, it is greatly appreciated!

Garry

Hi @rgb - good call.

Control.SetBounds(Left As Integer, Top As Integer, Width As Integer, Height As Integer) will work just like its Window counterpart: position and size are applied together in a single update, so a control that moves and resizes at the same time no longer bounces through intermediate layouts. That should be especially useful in frameworks like the one @SSyntec is building, where several controls get re-anchored on every window resize.

Two details worth knowing:

This one is desktop-only. Controls on web pages don't have settable absolute Left/Top positions - their layout is responsive and owned by the page - so there is no web equivalent to align with.
Unlike the Window feature, consecutive individual property assignments won't be batched. Control property setters each apply immediately - which is also why reading back a value you have just set always works - and that rules out the deferred batching the window side uses. When you need an atomic move-and-resize, SetBounds is the way to do it.

It shares its design with the Window method, so expect the two to land together. Tracked here: https://feedback.objo.dev/feature/1579

Thanks for the suggestion 🙂

Garry

Both of these features have been added to the next release 🙂