RENDERING_BBOX calculation blocks Inkscape if export dialog is kept open

[Jukka Korhonen]

If the export dialog is left open and you continue to edit your work, Inkscape stops responding for 10-15 seconds. Switching between objects is really slow.

This is on Windows 7 Professional using NVIDIA Quadro 4000.

[su_v (suv-lp)]

Does it make a different if you have the Export Area set to 'Selection' or 'Page'?

If you have it set to 'Selection', Inkscape does have to live-update the values for the current selection in the dialog, which might cause an obvious slow-down in complex drawings (huge paths, lots of objects, filter effects) because for export Inkscape uses a more precise and costly (performance-wise) method to calculate the exact dimensions of the current selection than is used for the visual selection bbox drawn on canvas.

[Jukka Korhonen (loadus)]

The export area is usually "Selection" - so yea, that might be it. Still very annoying and costing a bit of time when you have to wait for Inkscape to come around again. This happens very often, when exporting multiple objects, like game buttons etc.

[su_v (suv-lp)]

Possibly related to the changes to fix bug #166659 “Bounding box does not include long miters”
<https://bugs.launchpad.net/inkscape/+bug/166659>

Johan Engelen wrote on 2010-04-10:
«although it is expensive to calculate the bbox precisely, it is necessary for png export. And since it is not an interactive thing that has to be done 1000 times, I think it is not a big issue to request extra precision for bitmap exporting.
Since 9307 the RENDERING_BBOX type includes strokes.
Fixed bug in r9309.»
<https://bugs.launchpad.net/inkscape/+bug/166659/comments/6>

[su_v (suv-lp)]

Reproduced with Inkscape 0.48+devel r10191 on OS X 10.5.8 (i386):
Compared to Inkscape 0.47, keeping the 'Export Bitmap…' dialog opened while try to continue working on the drawing is impracticable with new bbox calculation mode, mainly because the calculation blocks the main window and because the automatic switch to 'Selection' mode in the export dialog can't be turned off.

[su_v (suv-lp)]

Comparison between 0.47 and 0.48 done with SVG file attached to bug #180495:
<https://bugs.launchpad.net/inkscape/+bug/180495/+attachment/186845/+files/vertov01.svg>

[Jon A. Cruz (jon-joncruz)]

The general lag solution approach used to fix the delay when sliding colorbars might help here.

[su_v (suv-lp)]

A 'general lag solution' IMHO would not really help addressing the performance issues with the new bbox calculation when exporting to bitmap. The export dialog should no longer be in constant interactive mode (only _optionally_ auto-update the export area if the selection in the main window changes) nor try to calculate the export area before even showing the dialog, or the performance of the bbox calculation must be improved to match the old less precise mode (e.g. by using cached values if possible).

See for example the related report:
Bug #871000 “Inkscape hangs on Export Bitmap or Print”
<https://bugs.launchpad.net/inkscape/+bug/871000>

[su_v (suv-lp)]

Reported delay / blocking of the main window no longer reproduced with current trunk builds - tested with r11398 (32bit) and 113404 (64bit) - possibly due to caching of the (visual) bbox values?

[Beluga (buovjaga)]

Jukka: what is the current situation for you with 0.91 or 0.92?

[Jukka Korhonen (loadus)]

Beluga: This issue is resolved - just tested with a workfile that consists of hundreds or pieces and there is no freezing or lagging when unselecting or selecting objects.

[jazzynico (jazzynico)]

Reproduced on Windows XP (32-bit) with Inkscape 0.48.5.
Not reproduced with 0.91.