Viewprovider

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Revision as of 20:09, 29 October 2022 by FBXL5 (talk | contribs) (Created page with "Die Klassen der Viewprovider haben normalerweise {{incode|ViewProvider}} im Namen. Sie sind dem {{incode|ViewObject}} Attribut des Basisobjekts zugeordnet.")

Einleitung

Viewprovider sind Klassen, die festlegen, wie Objekte in der Baumansicht und der 3D-Ansicht aussehen und wie sie mit bestimmten grafischen Aktionen, wie z.B Auswahl zusammenarbeiten.

Sie ergänzen die skriptgenerierten Objekte. Während die Basis-Klasse des skriptgenerierten Objekts seine Daten- Eigenschaften festlegt, definiert der viewprovider seine Ansichts- Eigenschaften. Diese Ansichts-Eigenschaften stellen keine wesentlichen Informationen des Objekts dar, da sie nur Informatione zur Darstellung enthalten, wie Linienbreite, Linienfarbe, Flächenfarbe usw. Für eine reine Terminal-Sitzung wird der Viewprovider nicht geladen, da keine Schnittstelle zum Bearbeiten dieser sichtbaren Eigenschaften vorhanden ist.

Wie auch Daten-Eigenschaften sind die Ansichts-Eigenschaften durch den Eigenschafteneditor erreichbar.

Python-Viewprovider

Die Klassen der Viewprovider haben normalerweise ViewProvider im Namen. Sie sind dem ViewObject Attribut des Basisobjekts zugeordnet.

In this example, we define two properties for the viewprovider, only if the properties don't already exist, and assign their default values. We also define the onChanged method that runs every time a property changes. We need to test the property by name, and then we will call one of two methods that will do the actual work of updating the pattern or setting its size.

# views/view_custom.py
class ViewProviderCustom:
    """Viewprovider of the custom object."""

    def __init__(self, vobj):
        self.Object = vobj.Object

        self._set_properties(vobj)
        vobj.Proxy = self

    def _set_properties(self, vobj):
        if not hasattr(vobj, "Pattern"):
            vobj.addProperty("App::PropertyEnumeration",
                             "Pattern",
                             "Custom",
                             "Defines a hatch pattern for this object.")
            vobj.Pattern = ["None", "diagonals", "cross", "brick"]

        if not hasattr(vobj, "PatternSize"):
            vobj.addProperty("App::PropertyFloat",
                             "PatternSize",
                             "Custom",
                             "Defines the size of the hatch pattern.")
            vobj.PatternSize = 1

    def onChanged(self, vobj, prop):
        if prop in "Pattern":
            self._set_pattern(vobj.Pattern)
        if prop in "PatternSize":
            self._set_size(vobj.PatternSize)

    def _set_pattern(self, pattern):
        ...

    def _set_size(self, size):
        ...

The normal workflow is to first add the object proxy class, for example, CustomObject, and then the viewprovider, for example, ViewProviderCustom. The viewprovider can only be assigned when we have verified that the graphical interface is available, as otherwise the ViewObject attribute doesn't exist, and it will be an error to use this element as input for our class.

import FreeCAD as App
import objects.custom as custom
import views.view_custom as view_custom

doc = App.newDocument()
obj = doc.addObject("Part::FeaturePython", "Custom")

custom.CustomObject(obj)

if App.GuiUp:
    view_custom.ViewProviderCustom(obj.ViewObject)

Custom icons

By implementing the getIcon method, you can specify the icon that will be shown in the tree view in the upper part of the combo view.

The return value can be the full path to an icon.

import os
some_path = "/home/user/.FreeCAD/custom_icons"

class ViewProviderCustom:
    ...

    def getIcon(self):
        return os.path.join(some_path, "my_icon.svg")

The relative path to an icon inside a compiled resource file.

import MyModule_rc.py

class ViewProviderCustom:
    ...

    def getIcon(self):
        return ":/icons/my_icon.svg"

A raw XPM icon, which is essentially ASCII art.

import MyModule_rc.py

class ViewProviderCustom:
    ...

    def getIcon(self):
        return """
               /* XPM */
               static char *Some_icon_xpm[] = {
               /* columns rows colors chars-per-pixel */
               "16 16 3 1 ",
               "  c None",
               ". c #D71414",
               "+ c #AA1919",
               /* pixels */
               "                ",
               "  +          +  ",
               " +.+        +.+ ",
               "  +.+      +.+  ",
               "   +        +   ",
               "      ++++      ",
               "     +....+     ",
               "     +...++     ",
               "     +..+++     ",
               "     +.++.+     ",
               "      ++++      ",
               "   +        +   ",
               "  +.+      +.+  ",
               " +.+        +.+ ",
               "  +          +  ",
               "                "
               };
               """

See various examples in Custom icon in tree view.