Observations about DrawJig behavior (sampler/update/worldDraw)

[gswifort]

I observed the following behavior when using Ed.DrawJig. @CEXT-Dan — could you confirm whether these are intended?

Observations:

1. jig.drag() usually returns the same status returned by sampler(), with exceptions:
   If the user presses Esc: sampler() runs to completion, but drag() returns kCancel regardless; update() and worldDraw() are not called.
   If sampler() returns kNoChange → drag() still returns eOk.
   Behavior by sampler() status:
   eOk → update() and worldDraw() are called (normal).
   kCancel → jig ends immediately.
   kNull → jig runs; worldDraw() and update() are called (effectively same as eOk).
   kOther → mouse movement does not call update()/worldDraw(); zoom calls update() and worldDraw(); panning calls only worldDraw() (not update()); zoom while panning behaves like panning.
   kModeless → behaves like kCancel.

2. After clicking a point or pressing Enter, depending on what we return from sampler() we can distinguish the following end cases for the Jig:
   eOk → after sampler() update() is called but not worldDraw(),
   kNull → after sampler() neither update() nor worldDraw() is called,
   kOther → same as eOk, i.e. after sampler() update() is called but not worldDraw().

3. If update() returns False, then drag() returns kOther (note, update() must be called, so for example, this won't happen when kNull is returned from sampler()); returning False from update() has no effect on Jig's behavior when moving the mouse around the screen.

4. If worldDraw() returns False, then Jig terminates immediately and drag() returns kCancel

Repro code:

def test_jig():

    class MyJig(Ed.DrawJig):
        def __init__(self):
            super().__init__()
            self._line = Db.Line()

        def sampler(self) -> Ed.DragStatus:
            self.setUserInputControls(Ed.UserInputControls.kNullResponseAccepted)
            status, point = self.acquirePoint()
            self.point = point
            print("sampler", status, point)
            return status
            # return Ed.DragStatus.eOk
            # return Ed.DragStatus.kCancel
            # return Ed.DragStatus.kNull
            # return Ed.DragStatus.kOther
            # return Ed.DragStatus.kModeless
            # return Ed.DragStatus.kNoChange

        def update(self) -> bool:
            print("update")
            self._line.setEndPoint(self.point)
            return True
            # return False

        def worldDraw(self, wd: Gi.WorldDraw):
            print("worldDraw")
            geom = wd.geometry()
            geom.draw(self._line)
            return True
            # return False

    jig = MyJig()
    jig.setDispPrompt("Click a point or press Enter: ")
    status = jig.drag()
    print("Jig finished with status:", status)

[CEXT-Dan]

No, it’s a bug! Oof! But, also returning false from worldDraw should forward the call to viewportDraw, so you must override viewportDraw.

However, I have a typo, I made viewportDraw, ViewportDraw with a capital V You can test with

        def worldDraw(self, wd: Gi.WorldDraw):
            print("worldDraw")
            geom = wd.geometry()
            geom.draw(self._line)
            #return True
            return False
            
        def ViewportDraw(self, wd: Gi.ViewportDraw) -> None:
            print("viewportDraw")

[CEXT-Dan]

actually, better to draw in viewportDraw, if that is your intention

class MyJig(Ed.DrawJig):
    def __init__(self):
        super().__init__()
        self._line = Db.Line()

    def sampler(self) -> Ed.DragStatus:
        self.setUserInputControls(Ed.UserInputControls.kNullResponseAccepted)
        status, point = self.acquirePoint()
        self.point = point
        print("sampler", status, point)
        return Ed.DragStatus.eOk

    def update(self) -> bool:
        print("update")
        self._line.setEndPoint(self.point)
        return True
        # return False

    def worldDraw(self, wd: Gi.WorldDraw):
        print("worldDraw")
        return False

    def viewportDraw(self, wd: Gi.ViewportDraw) -> None:
        print("viewportDraw")
        geom = wd.geometry()
        geom.draw(self._line) 

mind the V

thanks for pointing this out.

[CEXT-Dan]

Note that there is no DrawJig in ObjectARX. It’s a custom implementation similar to this

I used a slightly different approach to make it work in better in Python

class PyDrawJig : public AcEdJig, public AcDbEntity, public boost::python::wrapper<PyDrawJig>

then hijacked AcDbEntity::subWorldDraw and AcDbEntity::subViewportDraw

[gswifort]

So the other behaviors are intentional?

[CEXT-Dan]

From a AcedJig perspective, pretty sure you’re getting the API (ARX) behavior.
There’s no implementation. As you can see, I pass the return values from the Python class.

Now DrawJig may be behave differently in that worldDraw, viewportDraw are called via the virtual methods of AcDbEntity, which may be called outside of the jigging cycle, which explains why Draw is called during panning. These methods are not aware of Jig methods like update() or returning kNoChange, so you may have to store your own flag(s) to control draw behavior.