qt-creator/doc/qtcreator/src/qtquick/qtquick-animation-overview.qdoc

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/*!
    \page quick-animation-overview.html
    \previouspage qtquick-motion-design.html

    \title Introduction to Animation Techniques

    \QDS supports the following types of animation techniques that are suitable
    for different purposes:

    \list
        \li Common motion design techniques for 2D and 3D
        \li Screen-to-screen or state-to-state animations
        \li Data-driven UI logic animations
    \endlist

    \section1 Common Motion Design Techniques

    The following table summarizes common motion design techniques for 2D and
    3D and their typical use cases.

    \table
    \header
        \li Technique
        \li Use Case
    \row
        \li \l{Timeline}{Timeline animation}
        \li Linear interpolation through intermediate values at specified
            keyframes instead of immediately changing to the target value.
    \row
        \li \l{Editing Easing Curves}{Easing curves} attached to keyframes
        \li Nonlinear interpolation between keyframes to make components
            appear to pick up speed, slow down, or bounce back at the end
            of the animation.
    \row
        \li \l{Curve Editor}{Animation curves} attached to keyframes
        \li Complex 3D animations that require several keyframes so it becomes
            necessary to visualize the value and the interpolation of a keyframe
            simultaneously.
    \endtable

    \section2 Timeline and Keyframe Based Animation

    Timeline animation is based on \e keyframes. In \QC, keyframes determine the
    value of the property of a \l{glossary_component}{component} at a certain
    time. Animating properties enables their values to move through intermediate
    values instead of immediately changing to the target value.

    For example, you can set the y position property of a rectangle to 0 at the
    start of your animation and to 100 at the end of the animation. When the
    animation is run, the rectangle moves from position 0 to 100 on the y axis.
    In the middle of the animation, the y property has the value of 50 since
    keyframes are interpolated linearly by default.

    \section2 Easing Curves

    Sometimes you don't want linear movement but would rather like the rectangle
    to move faster at the beginning and slower at the end of the animation. To
    achieve this effect, you could insert a large number of keyframes between
    the start frame and the end frame. To avoid this effort, you can specify
    \e {easing curves} for nonlinear interpolation between keyframes. The
    easing curves can make components appear to pick up speed, slow down, or
    bounce back at the end of the animation.

    \section2 Animation Curves

    While easing curves work well for most simple UI animations, more complex
    3D animations require several keyframes so it becomes necessary to visualize
    the value and the interpolation of a keyframe simultaneously. The
    \l {Curve Editor} visualizes the whole animation of a property at once and
    shows the effective values of a keyframe together with the interpolation
    between keyframes. It can also show animations of different properties
    simultaneously so that you can see the animation for the x position
    and the animation for the y position side-by-side.

    \section1 Screen-to-Screen or State-to-State Animations

    The following table summarizes techniques used for navigating between
    screens and UI states.

    \table
    \header
        \li Technique
        \li Use Case
    \if defined(qtdesignstudio)
    \row
        \li \l{Designing Application Flows}{Application flows}
        \li An interactive prototype that can be clicked through to simulate
            the user experience of the application.
    \endif
    \row
        \li \l{Transition Editor}{Transitions between states}
        \li Transitions between different states of the UI using a transition
            timeline that is based on keyframes. You can apply easing curves
            to the keyframes.
    \endtable

    \if defined(qtdesignstudio)
    \section2 Application Flows

    You can design an application in the form of a \e {schematic diagram}
    that shows all the significant components of the application UI and their
    interconnections by means of symbols. This results in an interactive
    prototype that can be clicked through to simulate the user experience of
    the application. Code is created in the background and can be used
    as the base of the production version of the application.

    For more information, see \l{Designing Application Flows}.
    \endif

    \section2 Transitions Between States

    UIs are designed to present different UI configurations in different
    scenarios, or to modify their appearances in response to user
    interaction. Often, several changes are made concurrently so that the
    UI can be seen to be internally changing from one \e state to another.

    This applies generally to UIs regardless of their complexity. A photo
    viewer may initially present images in a grid, and when an image is clicked,
    change to a detailed state where the individual image is expanded and the
    interface is changed to present new options for image editing. At the other
    end of the scale, when a button is pressed, it may change to a
    \e pressed state in which its color and position are modified so that it
    appears to be pressed down.

    Any component can change between different states to apply sets of
    changes that modify the properties of relevant components. Each state can
    present a different configuration that can, for example:

    \list
        \li Show some UI components and hide others.
        \li Present different available actions to the user.
        \li Start, stop, or pause animations.
        \li Execute some script required in the new state.
        \li Change a property value for a particular component.
        \li Show a different view.
    \endlist

    State changes introduce abrupt motion that you can make visually appealing
    by using \e transitions. Transitions are animation types that interpolate
    property changes caused by state changes.

    In \l {Transition Editor}, you can set the start frame, end frame,
    and duration for the transition of each property. You can also set
    an \l{Editing Easing Curves}{easing curve} for each animation and
    the maximum duration of the whole transition.

    \section1 Data-Driven UI Logic Animations

    The following table summarizes techniques used for animating the UI logic
    by using real or mock data from a backend.

    \table
    \header
        \li Technique
        \li Use Case
    \row
        \li Data-driven timeline animation
        \li Using real or mock data from a backend to control motion.
    \row
        \li Programmatic property animation
        \li Interpolating property values programmatically to create smooth
            transitions.
    \endtable

    \section2 Data-Driven Timeline Animation

    You can connect property values to data backends to drive timeline
    animation. You can fetch data from various sources, such as data models,
    JavaScript files, and backend services. You can also connect your UI to
    Simulink to load live data from a Simulink simulation.

    You can connect these data sources to the current frame of a timeline,
    creating animation when the backend changes the current frame property.

    For example, you could connect the speed value from a backend to a
    tachometer dial in a cluster. As the speed value is increased or
    decreased from the backend, it moves the needle animation from one
    end of the timeline to the other.

    For more information, see \l{Simulating Complex Experiences}.

    \section2 Programmatic Animation

    You can control property animation programmatically. Property animations
    are created by binding \l{Animations}{Animation} components to property
    values of component instances to gradually change the properties values
    over time. The property animations apply smooth movement by interpolating
    values between property value changes. They provide timing controls and
    enable different interpolations through easing curves.

    Developers can control the execution of property animations by using the
    \c start(), \c stop(), \c resume(), \c pause(), \c restart(), and
    \c complete() functions.

    You can create instances of preset animation components available in
    \l Library > \uicontrol Components > \uicontrol {Default Components} >
    \uicontrol Animation to create \l{Animations}{animations} depending on
    the type of the property that is to be animated and the behavior that
    you want.

    \table
    \header
        \li Animation Type
        \li Use Case
    \row
        \li Property animation
        \li Applying animation when the value of a property changes. Color
            and number animations are property animation types for specific
            purposes.
    \row
        \li Property action
        \li Setting non-animated property values during an animation.
    \row
        \li Color animation
        \li Applying animation when a color value changes.
    \row
        \li Number animation
        \li Applying animation when a numerical value changes.
    \row
        \li Parallel animation
        \li Running animations in parallel.
    \row
        \li Sequential Animation
        \li Running animations sequentially.
    \row
        \li Pause animation
        \li Creating a step in a sequential animation where nothing happens for
            a specified duration.
    \row
        \li Script action
        \li Executing JavaScript during an animation.
    \endtable

    \section3 Property Animation and Action

    A property animation is applied when the value of a property changes.

    To immediately change a property value during an animation without
    animating the property change, use a property action instead. This
    is useful for setting non-animated property values during an animation.

    For example, you can use a sequential animation that contains two property
    actions around a number animation to set the value of the opacity property
    of an \l{Images}{Image} to \c 0.5, animate the width of the image, and then
    set the opacity back to \c 1.

    \section3 Color Animation

    A color animation is a specialized property animation that defines an
    animation to be applied when a color value changes.

    For example, you can apply animation to the color property of a \l Rectangle
    to change its value from its current color to another color over a period
    of time specified in milliseconds.

    \section3 Number Animation

    A number animation is a specialized property animation that defines an
    animation to be applied when a numerical value changes.

    For example, you can apply animation to the x property of a \l Rectangle
    to make it appear to move from its current position on the x axis to another
    position over a period of time specified in milliseconds.

    \section3 Parallel and Sequential Animation

    Animations can run in parallel or in sequence. Parallel animations will
    play a group of animations at the same time while sequential animations
    play a group of animations in order, one after the other.

    For example, a banner component may have several icons or slogans to
    display, one after the other. The opacity property could change to
    \c 1.0 denoting an opaque object. Using a sequential animation, the
    opacity animations will play after the preceding animation finishes,
    whereas a parallel animation will play the animations at the same time.

    Once individual animations are placed into a group of parallel or sequential
    animations, they can no longer be started and stopped independently. The
    sequential or parallel animations must be started and stopped as a group.

    \section3 Pause Animation

    When used in a sequential animation, a pause animation is a step when
    nothing happens, for a specified duration.

    For example, you could specify a 500-millisecond animation sequence, with
    a 100-millisecond pause between two animations.
*/