poly_strip.py

# -*- coding: utf-8 -*-
"""
/***************************************************************************
 PolyStrip
                                 A QGIS plugin
 Polygons along lines 
                              -------------------
        begin                : 2017-07-29
        git sha              : $Format:%H$
        copyright            : (C) 2017 by Werner Macho
        email                : werner.macho@gmail.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 qgis.PyQt.QtCore import (
    QSettings,
    QTranslator,
    qVersion,
    QCoreApplication
)
from qgis.PyQt.QtGui import (
    QIcon
)
from qgis.PyQt.QtWidgets import (
    QAction,
)
from qgis.core import (
    Qgis,
    QgsMapLayer,
    QgsWkbTypes,
    QgsUnitTypes
)
# Import the code for the dialog
from .poly_strip_dialog import PolyStripDialog
# Initialize Qt resources from file resources.py
from . import resources


import os.path


def show_warning(self, message):
    text = QCoreApplication.translate('Polystrip', message)
    mb = self.iface.messageBar()
    mb.pushWidget(mb.createMessage(text),
                  Qgis.Warning, 5)


class PolyStrip:
    """QGIS Plugin Implementation."""

    def __init__(self, iface):
        """Constructor.

        :param iface: An interface instance that will be passed to this class
            which provides the hook by which you can manipulate the QGIS
            application at run time.
        :type iface: QgsInterface
        """
        # Save reference to the QGIS interface
        self.iface = iface
        # initialize plugin directory
        self.plugin_dir = os.path.dirname(__file__)
        # initialize locale
        locale = QSettings().value('locale/userLocale')[0:2]
        locale_path = os.path.join(
            self.plugin_dir,
            'i18n',
            '{}.qm'.format(locale))

        if os.path.exists(locale_path):
            self.translator = QTranslator()
            self.translator.load(locale_path)

            if qVersion() > '4.3.3':
                QCoreApplication.installTranslator(self.translator)

        # Declare instance attributes
        self.actions = []
        self.menu = self.tr(u'&PolyStrip')
        self.toolbar = self.iface.addToolBar(u'PolyStrip')
        self.toolbar.setObjectName(u'PolyStrip')

    # 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('PolyStrip', 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
        """

        # Create the dialog (after translation) and keep reference
        self.dlg = PolyStripDialog()
        icon = QIcon(icon_path)
        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/PolyStrip/img/polystrip.svg'
        self.add_action(
            icon_path,
            text=self.tr(u'PolyStrip'),
            callback=self.run)

    def unload(self):
        """Removes the plugin menu item and icon from QGIS GUI."""
        for action in self.actions:
            self.iface.removePluginVectorMenu(
                self.tr(u'&PolyStrip'),
                action)
            self.iface.removeToolBarIcon(action)
        # remove the toolbar
        del self.toolbar

    def run(self):
        """Run method that performs all the real work"""
        leave = -1

        for layer in self.iface.mapCanvas().layers():
            if layer.type() == QgsMapLayer.VectorLayer and \
               layer.geometryType() == QgsWkbTypes.LineGeometry:
                leave += 1

            if layer == self.iface.activeLayer() and \
                    layer.type() != QgsMapLayer.VectorLayer:
                message = self.tr(u'Select a Feature in a Vectorlayer')
                show_warning(self, message)
                return
            if layer == self.iface.activeLayer() and \
                    layer.geometryType() != QgsWkbTypes.LineGeometry:
                message = self.tr(u'Select a Feature in a Linelayer')
                show_warning(self, message)
                return
            if layer == self.iface.activeLayer() and \
                    layer.selectedFeatureCount() == 0:
                message = self.tr('No feature in active Layer selected!')
                show_warning(self, message)
                return

        if leave < 0:
            message = self.tr(u'No layers with line features - polystrip needs a selected line feature!')
            show_warning(self, message)
            return

        # show the dialog
        # First get Units from current Canvas
        unit = self.iface.mapCanvas().mapUnits()
        unit_strg = QgsUnitTypes.encodeUnit(unit)
        self.dlg.labelwriter(unit_strg)

        self.dlg.show()

        # Run the dialog event loop
        result = self.dlg.exec_()

        # See if OK was pressed
        if result:
            layer = self.iface.activeLayer()
            self.dlg.polystrip(layer)