CODEWITHSUNDEEP
c#wpfwpf-animation
SysKorn
SysKorn

Reputation: 3

How to reverse or repeat RotateTransform?

I followed a tutorial on rotating a picture bound to a button and it should be pretty simple, yet I can't figure it out. 

private void rotateMenu()
{
    int rotateAngle;

    if (menuState) rotateAngle = -90;
    else rotateAngle = 90;

    DoubleAnimation myanimation = new DoubleAnimation(0, rotateAngle, new Duration(TimeSpan.FromMilliseconds(222)));

    var rotateTransform = new RotateTransform(rotateAngle, 24.5, 24.5);
    menuButtonImage.RenderTransform = rotateTransform;

    rotateTransform.BeginAnimation(RotateTransform.AngleProperty, myanimation);

}

First button press - rotate the picture by 90 degrees. Simple, works.

Now I want to either reverse the rotation or rotate another 90 degrees. Animation works fine but the outcome always switches back to the picture being rotated 90 degrees, no matter what I set the second rotateAngle to.

Basically what I get is in the first part of the picture, want I need in the second part.

Basically what I get is in the first part of the Pic, want I need in the second part.

What am I doing wrong here? Why can't I rotate the picture again? I tried with -90, 90 and lots of other values, e.g. 45 degrees, yet no rotation happening?

Upvotes: 0

Views: 549

Answers (1)

Jeroen van Langen
Jeroen van Langen

Reputation: 22073

That's because the picture isn't actually rotated, but it's only rendered rotated. Until the rendertransform gets a new transform, it will stay rotated.

This will rotate it back, So you could try:

DoubleAnimation myanimation2 = 
    new DoubleAnimation(0, new Duration(TimeSpan.FromMilliseconds(222)));

only use the toValue parameter overload to rotate it back.

I would make something like:

// initial angle is 0
RotateTransform _rotateTransform = new RotateTransform(0.0, 24.5, 24.5);
Duration _rotationSpeed;

private void CreateRotation()
{
    _rotationSpeed = new Duration(TimeSpan.FromMilliseconds(222));
    menuButtonImage.RenderTransform = _rotateTransform;
}


private void rotateToSide()
{
    DoubleAnimation myanimation = new DoubleAnimation(90, _rotationSpeed);

    _rotateTransform.BeginAnimation(RotateTransform.AngleProperty, myanimation);

}

private void rotateToDefault()
{
    DoubleAnimation myanimation = new DoubleAnimation(0, _rotationSpeed);

    _rotateTransform.BeginAnimation(RotateTransform.AngleProperty, myanimation);

}

For your information (as I can read from your code) You don't have to change the Angle property of the rotateTransform object. The rotateTransform.BeginAnimation will alter the property.

Upvotes: 1

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