[Marble-devel] Review Request 123306: Fixes a tile scaling bug that resulted in low level tiles creating a peculiar mosaic on intensive zooming to non-predownloaded areas.

[Torsten Rahn]

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Ship it!


Ship It!

- Torsten Rahn


On April 13, 2015, 7:57 vorm., Adam Dabrowski wrote:
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> https://git.reviewboard.kde.org/r/123306/
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> (Updated April 13, 2015, 7:57 vorm.)
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> Review request for Marble.
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> Repository: marble
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> Description
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> Update: Now fixes the issue by bounding the scaled aread to a minimum of 1 pixel 
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> Doesn't change functionality.
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> Does clarify the code as flow was very non-intuitive previously (especially in case when deltaLevel > 8 for tileSize = 256).
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> if/when the scaledLowerLevelTile "for" loop reached zoom level where 2^deltaLevel > tileSize, a peculiar thing was happening.
> In this situation, in part "// which rect to scale?", the image was copied first from 0 sized-image. Calling the QImage::copy function with null rectangle (or 0 width and 0 height) results in copying a whole image instead. As a result, instead of level_N tile, a level_N-9 (or later) tile was returned unscaled, resulting in curious displays (i.e. multiple copies of the same tile image).
> While for textures that are downloadable this was a temporary case, offline textures would just stop there and display this curious images. Additionally it was very unclear and took me some time to figure out what's happening.
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> This version does clearly what previously was done due to specific QImage::copy behaviour.
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> Let's discuss if this behaviour is desired (or we want to display a full white opaque tile or a tile with a loading icon if there are download urls etc.).
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> Diffs
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>   src/lib/marble/TileLoader.cpp 01994eb 
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> Diff: https://git.reviewboard.kde.org/r/123306/diff/
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> Testing
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> Tested with unbounded second layer (partial) of texture, where the bug formerly was very easy to detect. Also tested with fast zooming to non-predownloaded areas. Works well. 
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> Tested with zooming in and out and two layers of texture as well as one. No change noticed (as intended).
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> Thanks,
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> Adam Dabrowski
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