Hi Leyan
>Why is the ellipse marker separated from the simple marker ?
It was the original plan to merge the two approaches, but was never
finished.
Btw., there is an ongoing Google summer of code project about improving
the symbology system, mentored by Alexander Bruy and Martin Dobias
(http://www.arunmozhi.in/devlog/june-2012/). Maybe it is of interest for
you.
Regards,
Marco
Am 17.06.2012 09:29, schrieb 欧阳乐岩:
Hi all,
Now that I am confident that bug reports and patches are considered
(good response time on the mailing-list by the way !) I started to
look a bit more in the code.
I am currently mostly interested in the symbology code as it is
central to my use of QGis and still has a lot of room for improvement
in my opinion.
I have mainly three questions:
* Why is the ellipse marker separated from the simple marker?
* What is the logic behind the two level of properties? (global
properties for the symbol and then for each symbol layer)
* Can we change the default values for increment?
Why is the ellipse marker separated from the simple marker ? Isn't it
possible to just replace size by sizeX, sizeY (or keep size and add a
ratio if it is judged more intuitive ?) and merge ellipse marker ?
Right now, the situation is that both have advantages and drawbacks.
Ellipse markers allow to control the outline width (but a 0 width does
not work), to use data-defined color, but they do not obey the global
color choice (before going into the symbol properties dialog. This
means for example that they cannot be used for graduated symbology.
They also have less shapes available and cannot be offset like simple
symbols.
Is it a temporary situation and both will develop in different
directions later ? Should we merge them ?
Second, what is the logic behind the symbol layers ? I like the
concept as it allows to construct complex symbols easily, but right
now the whole thing is a bit shaky: if I make a symbol with two layers
using some offset and rotations (real-world use case : a valve symbol
by using two triangles touching by one corner), the resulting symbol
shape is affected when I manipulate the angle or the size:
* changing the main rotation will reset all the layers rotation (that
was the object of my first patch http://hub.qgis.org/issues/4453)
* changing the size will scale all layers accordingly and respect
their relative size, but the offset will not be modified so elements
that were just touching each others will start overlapping.
Third, is it possible to change the values for increment of line width
and border width? I know that when I want to increase a line width
from the default 0.26, I very rarely want 1.26, 2.26, 3.26 ... I would
love to have 0.26, 0.3, 0.4, 0.5, etc.
Sorry for the long blurb ! Should I ask someone in particular if I
have subsequent questions ?
Regards,
Leyan
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Dr. Marco Hugentobler
Sourcepole - Linux& Open Source Solutions
Weberstrasse 5, CH-8004 Zürich, Switzerland
[email protected] http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee
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