/
natural_earth_raster.py
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/
natural_earth_raster.py
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from PyQt4.QtCore import (Qt, QCoreApplication, QSettings, QThread,
QTranslator, qVersion, SIGNAL)
from PyQt4.QtGui import (QAction, QDialog, QIcon, QLabel, QPixmap,
QProgressBar, QPushButton)
from qgis.core import (QgsContrastEnhancement, QgsMapLayerRegistry,
QgsMessageLog, QgsRasterLayer)
from qgis.gui import QgsMessageBar
from natural_earth_raster_dialog import NaturalEarthRasterDialog
from natural_earth_raster_worker import NaturalEarthRasterWorker
import csv
import os.path
import resources_rc
class NaturalEarthRaster:
"""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)
self.themes = {'high': [], 'medium': [], 'low': []}
# read theme metadata from local file
csv_file = os.path.join(self.plugin_dir, 'data', 'natural_earth.csv')
with open(csv_file, 'rb') as csvfile:
reader = csv.reader(csvfile, delimiter=';')
for row in reader:
self.themes[row[0]].append({'id': row[1], 'name': row[2],
'preview': row[3], 'url': row[4]})
# declare instance attributes
self.action = None
self.menu = self.tr('&Natural Earth')
def initGui(self):
"""Create the menu entries inside the QGIS GUI."""
# create action to display the settings dialog
self.action = QAction(
QIcon(':/plugins/natural_earth_raster/assets/icon.png'),
self.tr('Add theme...'),
self.iface.mainWindow())
# connect the actions to their respective methods
self.action.triggered.connect(self.run)
# add toolbar button and menu items
self.iface.addPluginToRasterMenu(self.menu, self.action)
def unload(self):
"""Removes the plugin menu item from the QGIS GUI."""
self.iface.removePluginRasterMenu('&Natural Earth', self.action)
def run(self):
"""Makes a few sanity checks and prepares the worker thread."""
# create the dialog (after translation) and keep reference
self.dialog = NaturalEarthRasterDialog()
# connect some odds and ends
self.dialog.scaleCombo.currentIndexChanged.connect(self.update_theme)
self.dialog.themeCombo.currentIndexChanged.connect(self.update_preview)
# make sure we have themes to choose from
self.update_theme(0)
# show the dialog
self.dialog.show()
result = self.dialog.exec_()
if result == QDialog.Rejected:
return False
# get the indices of the selected combobox items
scale = self.get_scale()
theme = self.dialog.themeCombo.currentIndex()
# build the path to the local copy of the theme
id = self.themes[scale][theme]['id']
theme_path = os.path.join(self.plugin_dir, 'data', id, id + '.tif')
if os.path.isfile(theme_path):
# we have a local copy of the theme, just add it to the workspace
self.add_raster_layer(theme_path, id)
else:
# we don't have a local copy, use a worker thread to download it
url = self.themes[scale][theme]['url']
self.worker_start(self.plugin_dir, url, id)
def worker_start(self, dir, url, id):
"""Start a worker instance on a background thread."""
worker = NaturalEarthRasterWorker(dir, url, id)
message_bar = self.iface.messageBar().createMessage('')
label = QLabel('Downloading theme {}...'.format(id))
label.setAlignment(Qt.AlignLeft | Qt.AlignVCenter)
progress_bar = QProgressBar()
progress_bar.setAlignment(Qt.AlignLeft | Qt.AlignVCenter)
progress_bar.setMaximum(100)
cancel_button = QPushButton()
cancel_button.setText(self.tr('Cancel'))
cancel_button.clicked.connect(worker.kill)
message_bar.layout().addWidget(label)
message_bar.layout().addWidget(progress_bar)
message_bar.layout().addWidget(cancel_button)
self.iface.messageBar().pushWidget(message_bar,
self.iface.messageBar().INFO)
self.message_bar = message_bar
# start the worker in a new thread
thread = QThread()
worker.moveToThread(thread)
# connect some odds and ends
worker.finished.connect(self.worker_finished)
worker.error.connect(self.worker_error)
worker.progress.connect(progress_bar.setValue)
thread.started.connect(worker.run)
thread.start()
self.thread = thread
self.worker = worker
def worker_finished(self, id):
"""Clean up after the worker and the thread."""
# kill the thread
self.worker.deleteLater()
self.thread.quit()
self.thread.wait()
self.thread.deleteLater()
# remove the progress bar
self.iface.messageBar().popWidget(self.message_bar)
if id is not None:
# add the downloaded layer to the workspace
path = os.path.join(self.plugin_dir, 'data', id, id + '.tif')
self.add_raster_layer(path, id)
else:
# display an error message in the message bar
message = self.tr('Theme download cancelled by user.')
self.iface.messageBar().pushMessage(message,
level=QgsMessageBar.INFO, duration=3)
def worker_error(self, e, exception_string):
"""Handle errors from the worker thread."""
# add the error message to the general log
message = 'Worker thread exception: {}'.format(exception_string)
QgsMessageLog.logMessage(message, level=QgsMessageLog.CRITICAL)
def update_theme(self, index):
"""Update the theme selection combobox."""
# remove all existing items from the combobox
self.dialog.themeCombo.clear()
# add items from the selected scale to the combobox
scale = self.get_scale()
for theme in self.themes[scale]:
self.dialog.themeCombo.addItem(theme['name'])
def update_preview(self, index):
"""Update the preview label image."""
# get the filename of the preview image
scale = self.get_scale()
preview = self.themes[scale][index]['preview']
# load the image
path = os.path.join(self.plugin_dir, 'assets', 'previews', preview)
image = QPixmap(path)
# add the image to the label
self.dialog.previewLabel.setPixmap(image)
def add_raster_layer(self, path, id):
"""Add a downloaded raster layer to the workspace."""
# create a new rasterlayer from the supplied TIF file
layer = QgsRasterLayer(path, id)
# load layer style based on number of bands
bands = layer.bandCount()
if bands == 1:
path = os.path.join(self.plugin_dir, 'styles', 'singleband.qml')
else:
path = os.path.join(self.plugin_dir, 'styles', 'multiband.qml')
layer.loadNamedStyle(path)
# add the layer to the workspace
QgsMapLayerRegistry.instance().addMapLayer(layer)
def get_scale(self):
"""Get the name of a scale based on a combobox index."""
index = self.dialog.scaleCombo.currentIndex()
try:
return ['high', 'medium', 'low'][index]
except IndexError:
return default
# noinspection PyMethodMayBeStatic
def tr(self, message):
"""Get the translation for a string using Qt translation API."""
# noinspection PyTypeChecker,PyArgumentList,PyCallByClass
return QCoreApplication.translate('Natural Earth Raster', message)