Feature request #20102

Pre-render canvas outside of visible area

Added by Alexey T about 6 years ago. Updated about 6 years ago.

Status:Feedback
Priority:Normal
Assignee:-
Category:GUI
Pull Request or Patch supplied:No Resolution:
Easy fix?:No Copied to github as #:27924

Description

Moving and zooming a map with many features is slow.
I propose to make some improvements.
1. Prerender some buffer area outside of canvas to make scrolling smoother
2. When zooming show resampled image of current canvas and then change it to rendered image.

test.jpg (253 KB) Alexey T, 2018-10-19 06:26 PM

History

#1 Updated by Saber Razmjooei about 6 years ago

  • Category changed from GUI to Map Canvas

#2 Updated by Saber Razmjooei about 6 years ago

  • Subject changed from Prender canvas outside of visible area to Pre-render canvas outside of visible area

#3 Updated by Giovanni Manghi about 6 years ago

  • Status changed from Open to Feedback
  • Subject changed from Pre-render canvas outside of visible area to Prender canvas outside of visible area
  • Category changed from Map Canvas to GUI

Tried to enable multi-core rendering?

#4 Updated by Alexey T about 6 years ago

Yes.
I have 8-core CPU. Tried to disable and to enable multi-core rendering with 2,4,8 cores. It doesn't help much

#5 Updated by Giovanni Manghi about 6 years ago

  • Subject changed from Prender canvas outside of visible area to Pre-render canvas outside of visible area
  • Status changed from Feedback to Open

#6 Updated by Martin Dobias about 6 years ago

  • Status changed from Open to Feedback

"Prerender some buffer area outside of canvas to make scrolling smoother"

We already do it (turned on by default but you can check "qgis/main_canvas_preview_jobs" advanced setting in options dialog).

"When zooming show resampled image of current canvas and then change it to rendered image."

We do that as well... when you zoom with mouse wheel, it zooms the most recently rendered map in/out - afterwards it starts real map rendering.

#7 Updated by Alexey T about 6 years ago

This screenshot is taken while scrolling canvas in QGis 3.2.3

qgis/main_canvas_preview_jobs is set to true

"When zooming show resampled image of current canvas and then change it to rendered image."
Yes it is, but without buffer area

#8 Updated by Alexey T about 6 years ago

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