Label pre-rotation #1757
Label pre-rotation #1757
Conversation
|
\cc @nirvn Note for everybody: the need to change the matrix has been satisfied in an hacky way in this PR, with known memory leaks left in the code. |
| @@ -572,6 +578,12 @@ class CORE_EXPORT QgsGeometry | |||
| @param hasZValue 25D type?*/ | |||
| void translateVertex( QgsWkbPtr &wkbPtr, double dx, double dy, bool hasZValue ); | |||
|
|
|||
| /**Rotate a single vertex around Z axis | |||
There was a problem hiding this comment.
comment needs to be fixed, this is not restricted to "rotate" a vertex, but can be used for any affine transformation (could actually also replace the translateVertex method)
|
@strk I can't comment on the label changes, but the geometry work looks good to me (requires sip bindings though, and inclusion of unit tests would be preferable). It will be very handy to have this rotate method available - I've needed something similar in the past. Thanks! |
|
@strk nice! The more I was thinking of my hackish pull request which was create a situation where labels' distance from the labelled points was variable, the more uneasy I was becoming. This fixes it, and more. |
|
A more complex labelling scenario works flawlessly. Zero-rotation: -55 degrees rotation: |
|
Thanks for testing, I'll be first pushing a commit with the QgsGeometry::rotate function, including SIP bindings and unit test, and then get back to the labeling part |
|
e2e47d7 does the QgsGeometry::rotate part (and friends) |
Revert custom rotation handling in label placement. Drop rotation component from the transformation used to determine placement as rotation was applied up-front.
strk
force-pushed
the
label_prerotation
branch
from
c7ad785
to
9c63d4f
Compare
|
squash-rebased, now looking at manually placed labels |
|
The fact that manually-placed labels are defined by their upper-left corner makes for funny effects. |
Also add a comment with the rationale for the need to reset rotation. There is still another leak to fix, for the matrix set in the pal layer.
Drops the other QgsMapToPixel leak.
|
The code is now leak-less. What I found is that often the PAL based label engine inappropriately uses the trick of computing the hortogonal distance between two corners of a rectangle to scale down a distance from map to device units. Of course when rotation is in charge hortogonal distance may be zero, messing up all computations. The last commit directly uses the "mapUnitsPerPixel" value instead. |
Pre-rotate vectors for placing labels.
This was suggested by @dakcarto in http://hub.qgis.org/issues/11814
Limiting pre-transformation to rotation requires later dropping rotation from the transform matrix used to get to device coordinates. This mixed approach would be fixed by directly acting at the device (pixel) level, as suggested in http://hub.qgis.org/issues/11856
\cc @dakcarto @wonder-sk