Raster calculator freezes the GUI with big rasters

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Author Name: Alessandro Pasotti (@elpaso)
Original Redmine Issue: 20583
Affected QGIS version: 3.5(master)
Redmine category:raster_calculator
Assignee: Alessandro Pasotti

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Raster is a dem 40000x40000 and even with a simple expression it takes ages and the GUI completely freezes (no cancellation is possible: it is disabled in code)

This makes the tool completely unusable for large rasters.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Hi Alessandro, likely duplicate of #21389 ?

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• status_id was changed from Open to Feedback

[qgib]

Author Name: Alessandro Pasotti (@elpaso)

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Yeah, related but not the same bug.

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• assigned_to_id was configured as Alessandro Pasotti

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Author Name: Anónimo (Anónimo)

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Applied in changeset d3d1805.

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• done_ratio was changed from 0 to 100
• status_id was changed from Feedback to Closed

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Thanks Alessandro for tackling this, it was MUCH needed.

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Author Name: Alessandro Pasotti (@elpaso)

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I actually fixed the "big" issue (the crash #21389) but I couldn't do much for the first part of GUI freeze: this is happening because the rasters are read as a whole and that operation is not interruptable.

But, once the raster are read and the computation starts, the progress bar now appears and the operation can be interrupted.

So, since this is a partial fix, I'm going to leave this open.

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• status_id was changed from Closed to Reopened

[qgib]

Author Name: Alessandro Pasotti (@elpaso)

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A small step forward: #8564

[qgib]

Author Name: Alessandro Pasotti (@elpaso)

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Applied in changeset 273a71a.

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• status_id was changed from Reopened to Closed