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"""
/***************************************************************************
Name : DB Manager
Description : Database manager plugin for QGIS
Date : May 23, 2011
copyright : (C) 2011 by Giuseppe Sucameli
email : brush.tyler@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 Qt, QTimer
from qgis.PyQt.QtGui import QColor, QCursor
from qgis.PyQt.QtWidgets import QApplication
from qgis.gui import QgsMapCanvas, QgsMessageBar
from qgis.core import Qgis, QgsVectorLayer, QgsProject, QgsSettings
from qgis.utils import OverrideCursor
from .db_plugins.plugin import Table
class LayerPreview(QgsMapCanvas):
def __init__(self, parent=None):
super().__init__(parent)
self.parent = parent
self.setCanvasColor(QColor(255, 255, 255))
self.item = None
self.dirty = False
self.current_layer = None
# reuse settings from QGIS
settings = QgsSettings()
self.enableAntiAliasing(
settings.value("/qgis/enable_anti_aliasing", False, type=bool)
)
zoomFactor = settings.value("/qgis/zoom_factor", 2, type=float)
self.setWheelFactor(zoomFactor)
def refresh(self):
self.setDirty(True)
self.loadPreview(self.item)
def loadPreview(self, item):
if item == self.item and not self.dirty:
return
if item is None:
return
self._clear()
if isinstance(item, Table) and item.type in [
Table.VectorType,
Table.RasterType,
]:
# update the preview, but first let the manager chance to show the canvas
def runPrev():
return self._loadTablePreview(item)
QTimer.singleShot(50, runPrev)
else:
return
self.item = item
self.item.aboutToChange.connect(self.setDirty)
def setDirty(self, val=True):
self.dirty = val
def _clear(self):
"""remove any layers from preview canvas"""
if self.item is not None:
# skip exception on RuntimeError fixes #6892
try:
self.item.aboutToChange.disconnect(self.setDirty)
except RuntimeError:
pass
self.item = None
self.dirty = False
self._loadTablePreview(None)
def _loadTablePreview(self, table, limit=False):
"""if has geometry column load to map canvas"""
with OverrideCursor(Qt.CursorShape.WaitCursor):
self.freeze()
vl = None
if table and table.geomType:
# limit the query result if required
if limit and table.rowCount > 1000:
uniqueField = table.getValidQgisUniqueFields(True)
if uniqueField is None:
self.parent.tabs.setCurrentWidget(self.parent.info)
self.parent.infoBar.pushMessage(
QApplication.translate(
"DBManagerPlugin", "Unable to find a valid unique field"
),
Qgis.MessageLevel.Warning,
self.parent.iface.messageTimeout(),
)
return
uri = table.database().uri()
uri.setDataSource(
"",
"(SELECT * FROM %s LIMIT 1000)" % table.quotedName(),
table.geomColumn,
"",
uniqueField.name,
)
provider = table.database().dbplugin().providerName()
vl = QgsVectorLayer(uri.uri(False), table.name, provider)
else:
vl = table.toMapLayer()
if vl and not vl.isValid():
vl.deleteLater()
vl = None
if vl and vl.isValid():
self.current_layer = vl
self.setLayers([self.current_layer])
self.zoomToFullExtent()
else:
self.setLayers([])
self.current_layer = None
self.freeze(False)
super().refresh()
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