Fix map grid decoration bottom vertical labels placement and vertical labels background placement

[agiudiceandrea]

Description

Fixes the position of the bottom vertical label of a map grid decoration when a non zero "Distance to map frame" is set (regression introduced with #37133 since 3.14).

Fixes the vertical labels background placement of a map grid decoration.
(It seems to me the QgsTextRenderer::drawText function has an issue with a rotated background placement, but I couldn't find the cause) Now fixed with #45425.

Fixes #44907.

This PR needs to be backported to 3.20 and 3.16 branches.

Before:

After:

Edited after #45425.

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[agiudiceandrea]

I think this bugfix should be merged and backported.

[nyalldawson]

@agiudiceandrea

It seems to me the QgsTextRenderer::drawText function has an issue with a rotated background placement, but I couldn't find the cause

I'd rather track this down instead -- we use QgsTextRenderer a LOT in qgis now, so the underlying issue would affect other code paths...

[nyalldawson]

The background issue is fixed in #45425 -- can you drop that commit so we can merge the other?

[agiudiceandrea]

The background issue is fixed in #45425 -- can you drop that commit so we can merge the other?

Yes, of course. Commit dropped. Thanks a lot @nyalldawson! So, does your fix makes no longer needed a similar "patch" used for map layout grid in QgsLayoutItemMapGrid::drawCoordinateAnnotation?

QGIS/src/core/layout/qgslayoutitemmapgrid.cpp

Lines 1390 to 1395 in de20bca

	const QgsScopedQPainterState painterState( context.painter() );
	context.painter()->translate( QPointF( xpos, ypos ) );
	context.painter()->rotate( rotation );
	context.painter()->translate( -anchor );
	const QgsScopedRenderContextScaleToPixels scale( context );
	QgsTextRenderer::drawText( QPointF( 0, 0 ), 0, QgsTextRenderer::AlignLeft, QStringList() << annotationString, context, mAnnotationFormat );

[nyalldawson]

Hmm... Probably. I suspect that's been in place there from before the grids were drawn using the text renderer. There's good tests coverage there -- you could try removing and see if everything passes