[Qgis-developer] Help needed for 1st dive into Qgis C++ - Access and modify the Scale List combo box

Nathan Woodrow madmanwoo at gmail.com
Mon May 7 01:31:47 PDT 2012


This is how I would do it.


I would create a signal on the project properties dialog that gets emitted
when the scale change, which you then connect to a slot in the scale edit
object in qgisapp.cpp.  Once the signal fires you read the new scales from
where every they are stored into the scale bar widget.

- Nathan

On Mon, May 7, 2012 at 6:03 PM, kimaidou <kimaidou at gmail.com> wrote:

> Hi devs,
> I would like to learn C++ and understand Qgis code organisation, in order
> to participate in making a better Qgis. This is why I am trying to propose
> a simple new feature : in the project properties dialog, let the user
> choose the scales he vould like to use for the current project. Then, use
> these scales to replace the predefined scales in the status bar scales
> list. The next step would be to optionnaly force Qgis to stick to these
> scales when zooming in/out/extent, etc.
> I have already coded the "project properties dialog" part : manage a list
> of scales, with add/delete buttons, and read/save in the project xml file.
> Now I need to interact with the scale list, wich is normally added by
> src/app/qgisapp.cpp by the method
>    QgisApp::createStatusBar()
> The scale list is creating using the class QgsScaleComboBox :
> mScaleEdit = new QgsScaleComboBox( statusBar() );
> Now, I need som help. I tried to access the scale list directly using
> QgisApp::instance()->statusBar() , but with no success.
> I think what I should do is to add a method
> QgsScaleComboBox::update(QStringList)  in qgsscalecombobox.cpp which change
> the content of the list. But then, how can I access this method from
> qgsprojectproperties.cpp ?
> Thanks in advance
> Michael
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