generalizer.py

"""
/***************************************************************************
 generalizer
                                 A QGIS plugin
 Lines generalization (smooth and simplify) based on v.generalize GRASS module
                              -------------------
        begin                : 2011-08-17
        copyright            : (C) 2011 by Piotr Pociask
        email                : ppociask (at) o2 pl
        adapted to QGIS 3    : 2019-11-10 by Sylvain POULAIN
        email				 : sylvain.poulain (at) giscan.com
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
"""
from __future__ import absolute_import
# Import the PyQt and QGIS libraries
from builtins import object
from PyQt5.QtCore import *
from PyQt5.QtGui import *

from PyQt5.QtWidgets import QAction, QMessageBox


from qgis.core import *
# Initialize Qt resources from file resources.py
from .resources import *
# Import the code for the dialog
from .generalizerdialog import generalizerDialog, getLayersNames
import os.path


class generalizer:

    def __init__(self, iface):
        # Save reference to the QGIS interface
        self.iface = iface
        
        self.canvas = iface.mapCanvas()

        # initialize plugin directory
        self.plugin_dir = os.path.dirname(__file__)

        # Declare instance attributes
        self.actions = []
        self.menu = self.tr(u'&Generalizer')
        # TODO: We are going to let the user set this up in a future iteration
        self.toolbar = self.iface.addToolBar(u'Generalizer')
        self.toolbar.setObjectName(u'Generalizer')

        #print "** INITIALIZING Generalizer"

        self.pluginIsActive = False
        self.dockwidget = None

        self.output_layer = None

    # noinspection PyMethodMayBeStatic
    def tr(self, message):
        """Get the translation for a string using Qt translation API.

        We implement this ourselves since we do not inherit QObject.

        :param message: String for translation.
        :type message: str, QString

        :returns: Translated version of message.
        :rtype: QString
        """
        # noinspection PyTypeChecker,PyArgumentList,PyCallByClass
        return QCoreApplication.translate('Generalizer', message)
        
    def add_action(
        self,
        icon_path,
        text,
        callback,
        enabled_flag=True,
        add_to_menu=True,
        add_to_toolbar=True,
        status_tip=None,
        whats_this=None,
        parent=None):
        """Add a toolbar icon to the toolbar.

        :param icon_path: Path to the icon for this action. Can be a resource
            path (e.g. ':/plugins/foo/bar.png') or a normal file system path.
        :type icon_path: str

        :param text: Text that should be shown in menu items for this action.
        :type text: str

        :param callback: Function to be called when the action is triggered.
        :type callback: function

        :param enabled_flag: A flag indicating if the action should be enabled
            by default. Defaults to True.
        :type enabled_flag: bool

        :param add_to_menu: Flag indicating whether the action should also
            be added to the menu. Defaults to True.
        :type add_to_menu: bool

        :param add_to_toolbar: Flag indicating whether the action should also
            be added to the toolbar. Defaults to True.
        :type add_to_toolbar: bool

        :param status_tip: Optional text to show in a popup when mouse pointer
            hovers over the action.
        :type status_tip: str

        :param parent: Parent widget for the new action. Defaults None.
        :type parent: QWidget

        :param whats_this: Optional text to show in the status bar when the
            mouse pointer hovers over the action.

        :returns: The action that was created. Note that the action is also
            added to self.actions list.
        :rtype: QAction
        """

        icon = QIcon(icon_path)
        text = "Generalizer"
        action = QAction(icon, text, parent)
        action.triggered.connect(callback)
        action.setEnabled(enabled_flag)

        if status_tip is not None:
            action.setStatusTip(status_tip)

        if whats_this is not None:
            action.setWhatsThis(whats_this)

        if add_to_toolbar:
            self.toolbar.addAction(action)

        if add_to_menu:
            self.iface.addPluginToVectorMenu(
                self.menu,
                action)

        self.actions.append(action)

        return action


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

        icon_path = ':/plugins/Generalizer3/icon.png'
        self.add_action(
            icon_path,
            text=self.tr(u''),
            callback=self.run,
            parent=self.iface.mainWindow())


    def unload(self):
        """Removes the plugin menu item and icon from QGIS GUI."""

        #print "** UNLOAD Generalizer"

        for action in self.actions:
            self.iface.removePluginVectorMenu(
                self.tr(u'&Generalizer'),
                action)
            self.iface.removeToolBarIcon(action)
        # remove the toolbar
        del self.toolbar

    # run method that performs all the real work
    def run(self):
        #check if there are loaded line layers
        if len(getLayersNames()) == 0:
            QMessageBox.critical(None, 'Generalizer', 'Load line layer!')
            return

          # create and show the dialog
        dlg = generalizerDialog(self.iface)
        # show the dialog
        dlg.show()
        result = dlg.exec_()
        # See if OK was pressed
        if result == 1:
            # do something useful (delete the line containing pass and
            # substitute with your code
            pass