Anti-aliasing leads to visible borders even if borders have "no pen"

[qgib]

Author Name: Johannes Kroeger (Johannes Kroeger)
Original Redmine Issue: 10166
Affected QGIS version: 2.2.0
Redmine category:symbology

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The option "Options -> Rendering -> Rendering Quality: Make lines appear less jagged at the expense of some drawing performance" leads to unwanted visual artifacts when drawing polygons with no borders.

To reproduce:

1. Have some polygons with adjacent/shared borders, eg from a Delaunay/Voronoi.
2. Set "Border style" to "No pen".
3. Set "Options -> Rendering -> Rendering Quality: Make lines appear less jagged at the expense of some drawing performance" to true by ticking the box. If it is ticked, the borders will appear in the color of the background as visible lines. If the option is unticked, there will be no visible borders as intended. See the attached image for an example.

I am on Linux using binary nvidia drivers.
QGIS version 2.3.0-Master
QGIS code revision eacb5bd
Compiled against Qt 4.8.6
Running against Qt 4.8.6
QWT Version 6.1.0
QScintilla2 Version 2.8.1

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• jaggedlinesantialiasingvisibleborders.png (Johannes Kroeger)

[qgib]

Author Name: Martin Dobias (@wonder-sk)

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You can simply keep using border with the border color equal to the fill color - this will make the artifacts disappear.

[qgib]

Author Name: Johannes Kroeger (Johannes Kroeger)

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That hack is only feasible if you use a Single Symbol symbology. Otherwise you would need to update each class to have identical fill and border colors.

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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• category_id was configured as Symbology

[qgib]

Author Name: Sandro Santilli (@strk)

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Maybe there could be an option to make the border style follow the fill style.

[qgib]

Author Name: Sandro Santilli (@strk)

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I shall also mention that for me the artifacts are also visible with "Make lines appear less jagged at the expense of some drawing performance" option unchecked. Just less visible, but occasionally they still emerge.

[qgib]

Author Name: Sandro Santilli (@strk)

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Indeed with a "graduated" symbology it is much harder to fix as you have to go in each and every class, and the default classes all have a black border

[qgib]

Author Name: Johannes Kroeger (Johannes Kroeger)

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Duplicate of #12023

For what it's worth, the fix of adding the same color to the no-stroke border does not work for me in a satisfying way in 2.18.5.

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• status_id was changed from Open to Closed