Communiquer avec l’utilisateur¶

Showing messages. The QgsMessageBar class.¶

Using mesages boxes can be a bad idea from a user experience point of view. For showing a small info line or a warning/error messages, the QGIS message bar is usually a better option

Using the reference to the QGIS interface object, you can show a message in the message bar with the following code.

iface.messageBar().pushMessage("Error", "I'm sorry Dave, I'm afraid I can't \
  do that", level=QgsMessageBar.CRITICAL)

Barre de message de QGis

You can set a duration to show it for a limited time.

iface.messageBar().pushMessage("Error", ""Ooops, the plugin is not working as \
  it should", level=QgsMessageBar.CRITICAL, duration=3)

Barre de message de Qgis avec décompte

The examples above show an error bar, but the level parameter can be used to creating warning messages or info messages, using the QgsMessageBar.WARNING and QgsMessageBar.INFO constants repectively.

QGIS Message bar (warning)

Barre de message QGis (info)

Des Widgets peuvent être ajoutés à la barre de message comme par exemple un bouton pour montrer davantage d’information

def showError():
pass

widget = iface.messageBar().createMessage("Missing Layers", "Show Me")
button = QPushButton(widget)
button.setText("Show Me")
button.pressed.connect(showError)
widget.layout().addWidget(button)
iface.messageBar().pushWidget(widget, QgsMessageBar.WARNING)

Barre de message QGis avec un bouton

You can even use a message bar in your own dialog so you don’t have to show a message box, or if it doesn’t make sense to show it in the main QGIS window.

class MyDialog(QDialog):
    def __init__(self):
        QDialog.__init__(self)
        self.bar = QgsMessageBar()
        self.bar.setSizePolicy( QSizePolicy.Minimum, QSizePolicy.Fixed )
        self.setLayout(QGridLayout())
        self.layout().setContentsMargins(0,0,0,0)
        self.buttonbox = QDialogButtonBox(QDialogButtonBox.Ok)
        self.buttonbox.accepted.connect(self.run)
        self.layout().addWidget(self.buttonbox , 0,0,2,1)
        self.layout().addWidget(self.bar, 0,0,1,1)

    def run(self):
        self.bar.pushMessage("Hello", "World", level=QgsMessageBar.INFO)

Barre de message QGis avec une boîte de dialogue personnalisée

Afficher la progression¶

Les barres de progression peuvent également être insérées dans la barre de message QGis car, comme nous l’avons déjà vu, cette dernière accepte les widgets. Voici un exemple que vous pouvez utilisez dans la console.

import time
from PyQt4.QtGui import QProgressBar
from PyQt4.QtCore import *
progressMessageBar = iface.messageBar().createMessage("Doing something boring...")
progress = QProgressBar()
progress.setMaximum(10)
progress.setAlignment(Qt.AlignLeft|Qt.AlignVCenter)
progressMessageBar.layout().addWidget(progress)
iface.messageBar().pushWidget(progressMessageBar, iface.messageBar().INFO)
for i in range(10):
        time.sleep(1)
        progress.setValue(i + 1)
iface.messageBar().clearWidgets()

Also, you can use the built-in status bar to report progress, as in the next example.

::

count = layers.featureCount() for i, feature in enumerate(features):

#do something time-consuming here ... percent = i / float(count) * 100 iface.mainWindow().statusBar().showMessage(“Processed {} %”.format(int(percent)))

iface.mainWindow().statusBar().clearMessage()

Journal¶

Vous pouvez utiliser le système de journal de QGis pour enregistrer toute information à conserver sur l’exécution de votre code.

QgsMessageLog.logMessage("Your plugin code has been executed correctly", \
  QgsMessageLog.INFO)
QgsMessageLog.logMessage("Your plugin code might have some problems", \
  QgsMessageLog.WARNING)
QgsMessageLog.logMessage("Your plugin code has crashed!", \
  QgsMessageLog.CRITICAL)