this message "QPropertyAnimation::updateState: starting an animation without
end value" came from Qt.

This  is happening because of wrong type in property.

You need change this lines:

  animation.setStartValue(QVariant("0, 0, 100, 30"))
  animation.setEndValue(QVariant("250, 250, 100, 30"))

to:

  animation.setStartValue(QVariant(QRect(0, 0, 100, 30)))
  animation.setEndValue(QVariant(QRect(250, 250, 100, 30)))


using QVariant("0, 0, 100, 30") you will create a QVariant whit QString
the correct is use QVariant(QRect(250, 250, 100, 30)).

Strange, When I make the requested changes, I see no errors, but still see no
animation. I will play with it using different properties (as I suspect I am
not seeing anything because of being on a Maemo platform)

Also, why is there the need for QVariants when the original C++ code doesn't
require them?

Never mind, I understand why QVariant is needed now. Still not understanding
why animations are showing as expected, but I'm sure it is not related to
PySide itself.

Thanks renato

Take that  back, Running the following:

import sys
from PySide.QtCore import *
from PySide.QtGui import *


app = QApplication(sys.argv)

button = QPushButton("Animated Button")
button.show()

animation = QPropertyAnimation(button, "text")
animation.setDuration(10000)
animation.setStartValue(QVariant(QRect(0, 0, 100, 30)))
animation.setEndValue(QVariant(QRect(250, 250, 100, 30)))

animation.start()

app.exec_()

yields the following output in my N900:
$ python simple_animation.py
QPropertyAnimation::updateState: starting an animation without end value

However, setEndValue() is clearly used before animation.start().

If you are changing the property text, you need create QVariants compatible
with this property.

In this case you are trying change the property "text", with QRect values, the
correct is QString, you only can change some proprieties with valid values for
this property.


in this case:

animation = QPropertyAnimation(button, "text")
animation.setDuration(10000)
animation.setStartValue(QVariant(QString("start")))
animation.setEndValue(QVariant(QString("end")))

(In reply to comment #5)
> If you are changing the property text, you need create QVariants compatible
> with this property.

I believe the reporter made a typo on that last example.

Anyway, I just tried it here locally (adding the missing code for the full C++
example to run, such as a parent for the button), and indeed the C++ example
works, where equivalent Python code does not.

I printed the startValue() and endValue() return values before and after
animation.start(), and looks like on Python the QVariant is being invalidated
for some reason. Make some parenting issue?

I did the same test for C++ and the QVariants returned by startValue() and
endValue() stayed the same before/after animation.start().

Created attachment 29 [details]
Simple animation example (complete)

My mistake. I just noticed I pasted exactly the buggy code in comment #4
instead of the correct one.

After fixing the example, it worked exactly as on C++.

I attached my (working) code for reference.

(In reply to comment #6)
> (In reply to comment #5)
> > If you are changing the property text, you need create QVariants compatible
> > with this property.
> 
> I believe the reporter made a typo on that last example.

Right. I was trying to see if maybe I tried to animate a different property I
would get a different answer and never changed that portion of code back.

Thanks for the working code. It does seem to clearly be user error.

this works fine, if you use correct QVariant type as a arg in animation
functions.