Active Tools Break Custom Gizmos #60289

New Issue

Julian Eisel · 2019-01-07T19:27:04+01:00

Julian Eisel commented

2019-01-07 19:27:04 +01:00

Blender Version
Broken: 3d2ff33c26

Short description of error

Using an active tool gizmo at the same time as a custom (as in Python defined) gizmo may entirely break gizmos.
This happens when the custom gizmo sets internal gizmo properties on redraws. We basically put Blender into a redraw + reinitialize loop then.

Exact steps for others to reproduce the error

Enter Scripting Workspace
In Text Editor, select {nav Templates > Python > Gizmo Custom Geometry}
Press "Run Script"
Select the light object (custom gizmo should appear)
Open toolbar, activate some transform gizmo

The transform gizmo will appear and disappear immediately. This should happen again after selecting a different object, and then the light again. The custom light gizmo won't function properly (glitchy hover highlight, dragging doesn't work).

Cause
The root cause is the gizmo properties sending a (NC_SCREEN | NA_EDITED) notifier when set.
If a custom gizmo sets any of these properties (e.g. alpha, matrix_basis, hide, etc.) in a redraw callback - something that should definitely supported -, that triggers such notifiers to be send on every redraw. While sending this notifer seems reasonable, that causes ED_screen_refresh & ED_area_initialize to be executed on every redraw too! These are not supposed to be used that way. The latter also reinitializes tools, causing a redraw which again causes the gizmo properties to send a notifier. Hence, this is a redraw + reinitialize loop.

Fixing
Gizmos properties should update the UI without causing ED_screen_refresh calls. AFAICS we only need to redraw the region the gizmo is in. A few options:

Add a new notifier type triggering a region redraw.
Use new message bus to tag region redraw.
Use property setter to tag region redraw.

Not sure which way we should go for fixing. I also don't have much time for this, so opening a report to ensure it's not forgotten.

**Blender Version** Broken: 3d2ff33c261593 **Short description of error** Using an active tool gizmo at the same time as a custom (as in Python defined) gizmo may entirely break gizmos. This happens when the custom gizmo sets internal gizmo properties on redraws. We basically put Blender into a redraw + reinitialize loop then. **Exact steps for others to reproduce the error** * Enter *Scripting* Workspace * In Text Editor, select {nav Templates > Python > Gizmo Custom Geometry} * Press "Run Script" * Select the light object (custom gizmo should appear) * Open toolbar, activate some transform gizmo - > The transform gizmo will appear and disappear immediately. This should happen again after selecting a different object, and then the light again. The custom light gizmo won't function properly (glitchy hover highlight, dragging doesn't work). **Cause** The root cause is the gizmo properties sending a `(NC_SCREEN | NA_EDITED)` notifier when set. If a custom gizmo sets any of these properties (e.g. `alpha`, `matrix_basis`, `hide`, etc.) in a redraw callback - something that should definitely supported -, that triggers such notifiers to be send **on every redraw**. While sending this notifer seems reasonable, that causes `ED_screen_refresh` & `ED_area_initialize` to be executed on every redraw too! These are **not** supposed to be used that way. The latter also reinitializes tools, causing a redraw which again causes the gizmo properties to send a notifier. Hence, this is a redraw + reinitialize loop. **Fixing** Gizmos properties should update the UI without causing `ED_screen_refresh` calls. AFAICS we only need to redraw the region the gizmo is in. A few options: * Add a new notifier type triggering a region redraw. * Use new message bus to tag region redraw. * Use property setter to tag region redraw. ---- Not sure which way we should go for fixing. I also don't have much time for this, so opening a report to ensure it's not forgotten.

Julian Eisel commented

2019-01-07 19:27:04 +01:00

Added subscriber: @JulianEisel