pyqgis - Adding textbox to QGIS plugin toolbar?

I am trying to write a plugin with a input control such as textbox on it. I looked around quite a bit for building plugins. But I can only find examples of how to build a plugin with buttons/icons in its toolbar.

How can I add other widgets such as a textbox on my plugin's toolbar?

For the button, there isn't much to handle except for a callback when it's clicked. I imagine it would be quite different for a textbox as one needs to associate the input control to e.g. a global variable??

For now, I need interaction with the textbox (QLineEdit). I want to implement a plugin for going to the next feature where I can display the row number of the current record, and jump to any given row by entering its row number.

I am using QGIS2.99 and Qt5, the standard Plugin Builder and pb_tool to create and deploy the plugin template. I suppose I need to add the QLineEdit in initGui() of the main py file(as shown below). I don't know much about Qt5, and only figured I might need addUserInputWidget() and/or connect it with the add_action() function? But I don't know how to put the pieces together, and register the events etc.

Here is what I have so far:

def initGui(self):
    """Create the menu entries and toolbar icons inside the QGIS GUI."""

    # Create & add a textbox
    self.textbox = QLineEdit(self.iface.mainWindow())
    self.textbox.resize(80,20)


    self.txtAction = self.toolbar.addWidget(self.textbox)
    #should I use addUserInputWidget(self.textbox) #??

    self.txtAction.setToolTip(self.tr(u'Current Row Number'))
    #callback=self.runTextChange   how to register an event handler?

The UI shows but there is no interaction.

Can someone help explain how to link the QLineEdit to the toolbar so that I can get/change the text value?

Also, a minor issue I can't figure out is that the textbox takes up the full width of the toolbar no matter what I use in its .resize() method. How should I limit its width?

Answer

Nice answer by @mgri (don't delete it as it is useful to use within QGIS!). I tested the following on QGIS 2.18 also with Qt4 but perhaps it might be useful too as the other answer. A couple of things to note:

• You can use self.textbox.setFixedWidth(80) to set the width of the textbox.


• You can use self.textbox.textChanged.connect(self.runTextChange) to connect the textbox to a function whenever the text is changed.

Here is the code used:

def initGui(self):
    """Create the menu entries and toolbar icons inside the QGIS GUI."""
    # Create & add a textbox

    self.textbox = QLineEdit(self.iface.mainWindow())
    # Set width
    self.textbox.setFixedWidth(80)
    # Add textbox to toolbar
    self.txtAction = self.toolbar.addWidget(self.textbox)
    # Set tooltip
    self.txtAction.setToolTip(self.tr(u'Current Row Number'))
    # Set callback
    self.textbox.textChanged.connect(self.runTextChange)



def runTextChange(self, rownum):
    # Set active layer
    layer = iface.activeLayer()
    # If textbox is empty or 0 then deselect all features
    if rownum == '' or int(rownum) == 0:
        layer.deselect([feat.id() for feat in layer.getFeatures()])
    else:
        # Else select row number matching the entered value
        for feat in layer.getFeatures():

            if feat.id() == int(rownum) - 1:
                layer.setSelectedFeatures([feat.id()])

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Example: