QGIS

From DreamsteepWiki

UNTESTED

http://wiki.qgis.org/qgiswiki/PythonBindings

Instructions

   1. unpack archive
   2. for every tutorial in mainwindow.py set 'qgis_path' variable to your qgis installation prefix
      (needed for loading providers, projections database etc.)
   3. set environment variables:

      Linux: (when /home/wonder/qgis is used)

      export LD_LIBRARY_PATH=/home/wonder/qgis/lib
      export PYTHONPATH=/home/wonder/qgis/share/qgis/python

      Windows (when c:\qgis is used)

      set PATH=c:\qgis;%PATH%
      set PYTHONPATH=c:\qgis\python

      PYTHONPATH is there to tell python where to search for QGIS Python bindings, LD_LIBRARY_PATH (resp. PATH)
      tells system where to look for QGIS libraries that Python bindings need to work.
   4. run examples: python mainwindow.py 

class MapCoords(object):
  def __init__(self, mainwindow):
    self.mainwindow = mainwindow
    # This one is to capture the mouse move for coordinate display
    QObject.connect(mainwindow.canvas, SIGNAL("xyCoordinates(QgsPoint&)"),
                    self.updateCoordsDisplay)
    self.latlon = QLabel("0.0 , 0.0")
    self.latlon.setFixedWidth(200)

# Original sources Copyright (c) 2006 by Tim Sutton
#
# ported to Python by Martin Dobias
#
# licensed under the terms of GNU GPL 2

from PyQt4 import QtCore, QtGui
from mainwindow_ui import Ui_MainWindow
from qgis.core import *
from qgis.gui import *
import sys
import mainwindow_rc

qgis_prefix = "/opt/projects/qgis/install-cmake"

class MainWindow(QtGui.QMainWindow, Ui_MainWindow):

  def __init__(self):
    QtGui.QMainWindow.__init__(self)

    # required by Qt4 to initialize the UI
    self.setupUi(self)

    # create map canvas
    self.canvas = QgsMapCanvas()
    self.canvas.setCanvasColor(QtGui.QColor(255,255,255))
    self.canvas.enableAntiAliasing(True)
    self.canvas.useQImageToRender(False)
    self.canvas.show()

    # lay our widgets out in the main window
    self.layout = QtGui.QVBoxLayout(self.frameMap)
    self.layout.addWidget(self.canvas)

    # create the actions behaviours
    self.connect(self.mpActionAddLayer, QtCore.SIGNAL("triggered()"), self.addLayer)
    self.connect(self.mpActionZoomIn, QtCore.SIGNAL("triggered()"), self.zoomIn)
    self.connect(self.mpActionZoomOut, QtCore.SIGNAL("triggered()"), self.zoomOut)
    self.connect(self.mpActionPan, QtCore.SIGNAL("triggered()"), self.pan)

    # create a little toolbar
    self.toolbar = self.addToolBar("File");
    self.toolbar.addAction(self.mpActionAddLayer);
    self.toolbar.addAction(self.mpActionZoomIn);
    self.toolbar.addAction(self.mpActionZoomOut);
    self.toolbar.addAction(self.mpActionPan);

    # create the map tools
    self.toolPan = QgsMapToolPan(self.canvas)
    self.toolPan.setAction(self.mpActionPan)
    self.toolZoomIn = QgsMapToolZoom(self.canvas, False) # false = in
    self.toolZoomIn.setAction(self.mpActionZoomIn)
    self.toolZoomOut = QgsMapToolZoom(self.canvas, True) # true = out
    self.toolZoomOut.setAction(self.mpActionZoomOut)

    self.polygon = True
    self.rubberband = QgsRubberBand(self.canvas, self.polygon)


  def zoomIn(self):
    self.canvas.setMapTool(self.toolZoomIn)

  def zoomOut(self):
    self.canvas.setMapTool(self.toolZoomOut)

  def pan(self):
    self.canvas.setMapTool(self.toolPan)

  def addLayer(self):
    """add a (hardcoded) layer and zoom to its extent"""

    info = QtCore.QFileInfo("data/Abarema_jupunba_projection.tif")

    # create layer
    layer = QgsRasterLayer(info.filePath(), info.completeBaseName())

    if not layer.isValid():
      return

    layer.setColorRampingType(QgsRasterLayer.BLUE_GREEN_RED)
    layer.setDrawingStyle(QgsRasterLayer.SINGLE_BAND_PSEUDO_COLOR)
    
    # add layer to the registry
    QgsMapLayerRegistry.instance().addMapLayer(layer);

    # set extent to the extent of our layer
    self.canvas.setExtent(layer.extent())

    # set the map canvas layer set
    cl = QgsMapCanvasLayer(layer)
    layers = [cl]
    self.canvas.setLayerSet(layers)

  def transform(self, x, y):
    return QgsPoint(self.canvas.getCoordinateTransform().toMapCoordinates(x,y))

  def on_mpToolShowRubberBand_clicked(self):
    self.rubberband.reset(self.polygon)
    self.rubberband.addPoint( self.transform(10,10) )
    self.rubberband.addPoint( self.transform(20,10) )
    self.rubberband.addPoint( self.transform(20,20) )
    self.rubberband.addPoint( self.transform(10,20) )

  def on_mpToolHideRubberBand_clicked(self):
    self.rubberband.reset(self.polygon)


def main(argv):
  # create Qt application
  app = QtGui.QApplication(argv)

  # initialize qgis libraries
  QgsApplication.setPrefixPath(qgis_prefix, True)
  QgsApplication.initQgis()

  # create main window
  wnd = MainWindow()
  wnd.show()

  # run!
  retval = app.exec_()
  
  # exit
  QgsApplication.exitQgis()
  sys.exit(retval)


if __name__ == "__main__":
  main(sys.argv)