Dostawca widoku

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Revision as of 13:19, 25 January 2024 by Kaktus (talk | contribs) (Created page with "==Dostawcy widoków Python==")

Wprowadzenie

Viewproviders are classes that define the way objects will look like in the tree view and the 3D view, and how they will interact with certain graphical actions such as selection.

They complement the scripted objects. While the base class of the scripted object defines its data properties, the viewprovider defines it view properties. These view properties are not essential information of the object, as they only indicate superficial information like line width, line color, face color, etc. In a terminal only session, the viewprovider is not loaded because there will be no interface to manipulate those visible properties.

Like with data properties, view properties are accessible from the property editor.

Dostawcy widoków Python

The viewproviders classes usually include ViewProvider in their name. They are assigned on the ViewObject attribute of the base object.

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)

Ikonki użytkownika

Implementując metodę getIcon, można zdefiniować ikonkę, która będzie wyświetlana w widok drzewa w górnej części widoku połączonego.

Wartością zwrotną może być pełna ścieżka do ikony.

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

class ViewProviderCustom:
    ...

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

Względna ścieżka do ikony w skompilowanym pliku zasobów.

import MyModule_rc.py

class ViewProviderCustom:
    ...

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

Nieobrobiona Ikona XPM, która jest zasadniczo grafiką ASCII.

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 */
               "                ",
               "  +          +  ",
               " +.+        +.+ ",
               "  +.+      +.+  ",
               "   +        +   ",
               "      ++++      ",
               "     +....+     ",
               "     +...++     ",
               "     +..+++     ",
               "     +.++.+     ",
               "      ++++      ",
               "   +        +   ",
               "  +.+      +.+  ",
               " +.+        +.+ ",
               "  +          +  ",
               "                "
               };
               """

Zobacz różne przykłady na stronie Własna ikona w widoku drzewa.