WPF basic animation

1、 Basic animation .
WPF A more advanced model is provided , Through this model, we can only focus on the definition of animation , Regardless of how they are rendered , This model is based on the dependency property infrastructure , Essentially ,WPF Animation is just a way to modify the value of a dependency property over a period of time . But there is another limitation , In order to realize the dynamic of attributes , Animation that supports the corresponding data type is required class , for example Button.Width Property uses the double data type , To realize the dynamic of attributes , Need to use DoubleAnimation class , but Button.Padding The property uses Thickness junction structure , So we need to use ThicknessAnimation class . To animate attributes , You can create your own animation classes for the corresponding data types , You will send present ,System.Windows.Media.Animation Namespaces already provide animation classes for most of the data types you want to use .
2、 Animation class .
There are actually two types of animation , One is an animation that changes attributes in a step-by-step manner between the start value and the end value ( Linear interpolation process ), The other is to suddenly change from one value to another draw ( Keyframe animation ). All keyframe animations use " Type name + AnimationUsingKeyFrames " The form of naming , such as StringAnimationUsingKeyFrames and ObjectAnimationUsingKeyFrames. Some data types have keyframe animation classes , But there is no interpolation animation class . for example , You can use keyframes to animate strings , You cannot use interpolation for words String application animation . However , All data types support keyframe animation , Unless they don't support animation at all . All have ( Use interpolation ) Data type of general animation class , There are also corresponding keys Animation type of frame animation , Such as linear interpolation DoubleAnimation Corresponding DoubleAnimationUsingKyyFrames. There is also a path based animation . therefore ,WPF Animation use three Methods ： linear interpolation 、 Keyframes and paths . stay System.Windows.Media.Animation The following will be found in the namespace ：
7 individual “ Type name +Animation class ” These classes use interpolation animation .
22 individual “ Type name +AnimationUsingKeyFrames” These classes use keyframe animation .
3 individual " Type name +AnimationUsingPath" This class uses path based animation .

3. The life cycle of animation .
From the perspective of Technology ,WPF Animation is only temporary , This means that they can't really change the value of the basic attribute , When animation is active , It just overrides the value of the attribute . One way animation , It will remain active after the animation runs , This is because the animation needs to keep the width of the button at a new value , This can lead to the following common problems , If you try to use code in animation Modify the attribute value after completion , The code will not work , Because the code just specifies a new local value for the property , But we will try out the attribute values after the animation first . In order to solve the problem that the value of the attribute can be modified after the animation is completed , There are the following ways to solve .
a)、 Set up AutoReverse attribute , If this property is set to true, Will move in the opposite direction , Return the original value ( Not suitable for animation after completion , Then set the final value for the attribute , Just revert to animation Previous value ).
b)、 change FillBehavior attribute . Usually ,FillBehavior Property is set to HoldEnd, This means that when the animation ends , Will continue to apply the final value for the target element . If you will FillBehavior Attribute to Stop, As long as the animation is over , Property will return to its original value ( Apply to the end of the animation , Set a new value for it again , Generally not related to AutoReverse Use in conjunction with , These two are used Just one ).