Types that animate properties based on data types
| AnchorAnimation | Animates changes in anchor values |
| ColorAnimation | Animates changes in color values |
| NumberAnimation | Animates changes in qreal-type values |
| ParentAnimation | Animates changes in parent values |
| PathAnimation | Animates an item along a path |
| PropertyAnimation | Animates changes in property values |
| RotationAnimation | Animates changes in rotation values |
| Vector3dAnimation | Animates changes in QVector3d values |
Animations are created by applying animation types to property values. Animation types will interpolate property values to create smooth transitions. As well, state transitions may assign animations to state changes.
To create an animation, use an appropriate animation type for the type of the property that is to be animated, and apply the animation depending on the type of behavior that is required.
There are several ways of setting animation to an object.
Animations are created by applying animation objects to property values to gradually change the properties over time. These property animations apply smooth movements by interpolating values between property value changes. Property animations provide timing controls and allows different interpolations through easing curves .
Rectangle { id: flashingblob width: 75; height: 75 color: "blue" opacity: 1.0 MouseArea { anchors.fill: parent onClicked: { animateColor.start() animateOpacity.start() } } PropertyAnimation {id: animateColor; target: flashingblob; properties: "color"; to: "green"; duration: 100} NumberAnimation { id: animateOpacity target: flashingblob properties: "opacity" from: 0.99 to: 1.0 loops: Animation.Infinite easing {type: Easing.OutBack; overshoot: 500} } }
Specialized property animation types have more efficient implementations than the
PropertyAnimation
type. They are for setting animations to different QML types such as
int
,
color
, and rotations. Similarly, the
ParentAnimation
can animate parent changes.
见 Controlling Animations section for more information about the different animation properties.
In the previous example, the PropertyAnimation and NumberAnimation objects needed to specify particular target and properties values to specify the objects and properties that should be animated. This can be avoided by using the <Animation> on <Property> syntax, which specifies the animation is to be applied as a property value source .
Below are two PropertyAnimation objects that are specified using this syntax:
import QtQuick 2.0 Rectangle { id: rect width: 100; height: 100 color: "red" PropertyAnimation on x { to: 100 } PropertyAnimation on y { to: 100 } }
The animation starts as soon as the rectangle is loaded, and will automatically be applied to its
x
and
y
values. Since the
<Animation> on <Property>
syntax has been used, it is not necessary to set the
target
value of the
PropertyAnimation
对象到
rect
, and neither is it necessary to set the
property
values to
x
and
y
.
This can also be used by
grouped animations
to ensure that all animations within a group are applied to the same property. For example, the previous example could instead use
SequentialAnimation
to animate the rectangle's
color
first to yellow, then to blue:
import QtQuick 2.0 Rectangle { width: 100; height: 100 color: "red" SequentialAnimation on color { ColorAnimation { to: "yellow"; duration: 1000 } ColorAnimation { to: "blue"; duration: 1000 } } }
由于
SequentialAnimation
object has been specified on the
color
property using the
<Animation> on <Property>
syntax, its child
ColorAnimation
objects are also automatically applied to this property and do not need to specify
target
or
property
animation values.
Qt Quick 状态 are property configurations where a property may have different values to reflect different states. State changes introduce abrupt property changes; animations smooth transitions to produce visually appealing state changes.
Transition
type can contain animation types to interpolate property changes caused by state changes. To assign the transition to an object, bind it to the
过渡
特性。
A button might have two states, the
pressed
state when the user clicks on the button and a
released
state when the user releases the button. We can assign different property configurations for each state. A transition would animate the change from the
pressed
state to the
released
state. Likewise, there would be an animation during the change from the
released
state to the
pressed
状态。
Rectangle { width: 75; height: 75 id: button state: "RELEASED" MouseArea { anchors.fill: parent onPressed: button.state = "PRESSED" onReleased: button.state = "RELEASED" } states: [ State { name: "PRESSED" PropertyChanges { target: button; color: "lightblue"} }, State { name: "RELEASED" PropertyChanges { target: button; color: "lightsteelblue"} } ] transitions: [ Transition { from: "PRESSED" to: "RELEASED" ColorAnimation { target: button; duration: 100} }, Transition { from: "RELEASED" to: "PRESSED" ColorAnimation { target: button; duration: 100} } ] }
Binding the
to
and
from
properties to the state's name will assign that particular transition to the state change. For simple or symmetric transitions, setting the to
to
property to the wild card symbol, "
*
", denotes that the transition applies to any state change.
transitions:
Transition {
to: "*"
ColorAnimation { target: button; duration: 100}
}
Default property animations are set using
behavior animations
. Animations declared in
Behavior
types apply to the property and animates any property value changes. However, Behavior types have an
enabled
property to purposely enable or disable the behavior animations.
A ball component might have a behavior animation assigned to its
x
,
y
，和
color
properties. The behavior animation could be set up to simulate an elastic effect. In effect, this behavior animation would apply the elastic effect to the properties whenever the ball moves.
Rectangle { width: 75; height: 75; radius: width id: ball color: "salmon" component BounceAnimation : NumberAnimation { easing { type: Easing.OutElastic amplitude: 1.0 period: 0.5 } } Behavior on x { BounceAnimation {} } Behavior on y { BounceAnimation {} } Behavior on color { ColorAnimation { target: ball; duration: 100 } } }
There are several methods of assigning behavior animations to properties. The
Behavior on <property>
declaration is a convenient way of assigning a behavior animation onto a property.
见 Qt Quick Examples - Animation for a demonstration of behavioral animations.
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. Grouping animations in SequentialAnimation and ParallelAnimation will play the animations in sequence or in parallel.
A banner component may have several icons or slogans to display, one after the other. The
opacity
property could transform to
1.0
denoting an opaque object. Using the
SequentialAnimation
type, the opacity animations will play after the preceding animation finishes. The
ParallelAnimation
type will play the animations at the same time.
Rectangle { id: banner width: 150; height: 100; border.color: "black" Column { anchors.centerIn: parent Text { id: code text: "Code less." opacity: 0.01 } Text { id: create text: "Create more." opacity: 0.01 } Text { id: deploy text: "Deploy everywhere." opacity: 0.01 } } MouseArea { anchors.fill: parent onPressed: playbanner.start() } SequentialAnimation { id: playbanner running: false NumberAnimation { target: code; property: "opacity"; to: 1.0; duration: 200} NumberAnimation { target: create; property: "opacity"; to: 1.0; duration: 200} NumberAnimation { target: deploy; property: "opacity"; to: 1.0; duration: 200} } }
Once individual animations are placed into a SequentialAnimation or ParallelAnimation , they can no longer be started and stopped independently. The sequential or parallel animation must be started and stopped as a group.
SequentialAnimation type is also useful for playing transition animations because animations are played in parallel inside transitions.
There are different methods to control animations.
All animation types inherit from the
Animation
type. It is not possible to create
Animation
objects; instead, this type provides the essential properties and methods for animation types. Animation types have
start()
,
stop()
,
resume()
,
pause()
,
restart()
，和
complete()
-- all of these methods control the execution of animations.
Easing curves define how the animation will interpolate between the start value and the end value. Different easing curves might go beyond the defined range of interpolation. The easing curves simplify the creation of animation effects such as bounce effects, acceleration, deceleration, and cyclical animations.
A QML object may have different easing curve for each property animation. There are also different parameters to control the curve, some of which are exclusive to a particular curve. For more information about the easing curves, visit the easing 文档编制。
easing example visually demonstrates each of the different easing types.
In addition, QML provides several other types useful for animation:
These are specialized animation types that animate different property types
Sharing animation instances between Transitions or Behaviors is not supported, and may lead to undefined behavior. In the following example, changes to the Rectangle's position will most likely not be correctly animated.
Rectangle { // NOT SUPPORTED: this will not work correctly as both Behaviors // try to control a single animation instance NumberAnimation { id: anim; duration: 300; easing.type: Easing.InBack } Behavior on x { animation: anim } Behavior on y { animation: anim } }
The easiest fix is to repeat the NumberAnimation for both Behaviors. If the repeated animation is rather complex, you might also consider creating a custom animation component and assigning an instance to each Behavior, for example:
Rectangle { component MyNumberAnimation : NumberAnimation { duration: 300; easing.type: Easing.InBack } Behavior on x { MyNumberAnimation {} } Behavior on y { MyNumberAnimation {} } }