wxGUI/datacatalog: enable lazy loading of maps (#1434)

* reload mapset when new item is added to not loaded mapset
* suggest turning on lazyloading in infobar if loading took more than 5 s

gui/wxpython/core/settings.py

@@ -159,6 +159,7 @@ def _defaultSettings(self):
             "datacatalog": {
                 # grassdb string
                 "grassdbs": {"listAsString": ""},
+                "lazyLoading": {"enabled": False, "asked": False},
             },
             "manager": {
                 # show opacity level widget

gui/wxpython/datacatalog/catalog.py

@@ -26,9 +26,11 @@
 from datacatalog.infomanager import DataCatalogInfoManager
 from gui_core.wrap import Menu
 from gui_core.forms import GUI
-from grass.script import gisenv
+from core.settings import UserSettings
 
 from grass.pydispatch.signal import Signal
+from grass.script.utils import clock
+from grass.script import gisenv
 
 from grass.grassdb.manage import split_mapset_path
 from grass.grassdb.checks import (
@@ -55,6 +57,7 @@ def __init__(
         self.parent = parent
         self.baseTitle = title
         self.giface = giface
+        self._startLoadingTime = 0
         wx.Panel.__init__(self, parent=parent, id=id, **kwargs)
         self.SetName("DataCatalog")
 
@@ -77,6 +80,7 @@ def __init__(
             infobar=self.infoBar, giface=self.giface
         )
         self.tree.showImportDataInfo.connect(self.showImportDataInfo)
+        self.tree.loadingDone.connect(self._loadingDone)
 
         # some layout
         self._layout()
@@ -126,15 +130,59 @@ def showImportDataInfo(self):
         )
 
     def LoadItems(self):
-        self.tree.ReloadTreeItems()
+        """Reload tree - full or lazy - based on user settings"""
+        self._startLoadingTime = clock()
+        self.tree.ReloadTreeItems(full=False)
+
+    def _loadingDone(self):
+        """If loading took more time, suggest lazy loading"""
+        if clock() - self._startLoadingTime > 5 and not self.tree._useLazyLoading():
+            asked = UserSettings.Get(
+                group="datacatalog", key="lazyLoading", subkey="asked"
+            )
+            if not asked:
+                wx.CallAfter(
+                    self.infoManager.ShowLazyLoadingOn,
+                    setLazyLoadingOnHandler=self._saveLazyLoadingOnSettings,
+                    doNotAskHandler=self._saveDontAskLazyLoadingSettings,
+                )
+
+    def _saveLazyLoadingOnSettings(self, event):
+        """Turn on lazy loading in settings"""
+        UserSettings.Set(
+            group="datacatalog", key="lazyLoading", subkey="enabled", value=True
+        )
+        UserSettings.Set(
+            group="datacatalog", key="lazyLoading", subkey="asked", value=True
+        )
+        self._saveLazyLoadingSettings()
+        event.Skip()
+
+    def _saveDontAskLazyLoadingSettings(self, event):
+        """Save in settings that decision on lazy loading was done to not ask again"""
+        UserSettings.Set(
+            group="datacatalog", key="lazyLoading", subkey="asked", value=True
+        )
+        self._saveLazyLoadingSettings()
+        event.Skip()
+
+    def _saveLazyLoadingSettings(self):
+        dcSettings = {}
+        UserSettings.ReadSettingsFile(settings=dcSettings)
+        if "datacatalog" not in dcSettings:
+            dcSettings["datacatalog"] = UserSettings.Get(group="datacatalog")
+        dcSettings["datacatalog"]["lazyLoading"] = UserSettings.Get(
+            group="datacatalog", key="lazyLoading"
+        )
+        UserSettings.SaveToFile(dcSettings)
 
     def dismissInfobar(self):
         if self.infoBar.IsShown():
             self.infoBar.Dismiss()
 
     def OnReloadTree(self, event):
         """Reload whole tree"""
-        self.LoadItems()
+        self.tree.ReloadTreeItems(full=True)
 
     def OnReloadCurrentMapset(self, event):
         """Reload current mapset tree only"""

gui/wxpython/datacatalog/infomanager.py

@@ -64,6 +64,19 @@ def ShowImportDataInfo(self, OnImportOgrLayersHandler, OnImportGdalLayersHandler
         ).format(loc=gisenv()["LOCATION_NAME"])
         self.infoBar.ShowMessage(message, wx.ICON_INFORMATION, buttons)
 
+    def ShowLazyLoadingOn(self, setLazyLoadingOnHandler, doNotAskHandler):
+        """Show info about lazy loading"""
+        message = _(
+            "Loading of Data catalog content took rather long. "
+            "To prevent delay, you can enable loading of current mapset only. "
+            "You can change that later in GUI Settings, General tab."
+        )
+        buttons = [
+            (_("Enable loading current mapset only"), setLazyLoadingOnHandler),
+            (_("No change, don't ask me again"), doNotAskHandler),
+        ]
+        self.infoBar.ShowMessage(message, wx.ICON_INFORMATION, buttons)
+
     def ShowFallbackSessionInfo(self, reason_id):
         """Show info when last used mapset is not usable"""
         string = self._text_from_reason_id(reason_id)