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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
/*!
\example progressbar
\ingroup studioexamples
\title Progress Bar
\brief Illustrates how to use timelines to create an animated progress bar.
\image progressbar.png "Progress Bar example application"
\e {Progress Bar} animates rectangles and numbers using timelines.
\section1 Creating the Progress Bar
First, we create an empty project, as described in \l {Creating Projects}.
For the purposes of this example, we call the project \e progressbar.
In this example, we use two overlapping instances of the preset
\l{basic-rectangle}{Rectangle} component and an instance of the preset
\l{Text} component to create the progress bar. There is also a preset
\l {progress-bar-control}{Progress Bar} component available in
\uicontrol Components > \uicontrol {Qt Quick Controls}.
In the \uicontrol Design mode, we drag-and-drop a \uicontrol Rectangle from
\uicontrol Components > \uicontrol {Default Components} >
\uicontrol Basic to \l {Form Editor} and modify its size to create the
background for the progress bar. We change its ID to \e pb_back in
\l Properties.
We want to be able to control the background rectangle and the text label
that was added by the project wizard, so we will use an \uicontrol Item
component for that. We drag-and-drop the Item from \uicontrol Components >
\uicontrol {Default Components} > \uicontrol Basic
to \uicontrol {Form Editor} and change its ID to \e root in
\uicontrol Properties.
To make the background and text children of the Item, we drag-and-drop them
to the Item in \l Navigator. This enables us to use the anchor
buttons in \uicontrol Properties > \uicontrol Layout to anchor them to their
parent. We anchor the background to its parent on all edges, with a 30-pixel
margin at the top to leave space for the text. We then anchor the text to
the top of the Item.
\image progressbar-rectangle.png "Progress bar background in the Form Editor"
We now drag-and-drop another rectangle on top of the background rectangle in
\uicontrol Navigator and change its ID to \e pb_front in
\uicontrol Properties.
We then anchor the left, top, and bottom of the indicator to its parent with
5-pixel margins. We leave the right side free because its value needs to
change for the animation.
For more information about creating and positioning components, see
\l {Using Components} and \l {Scalable Layouts}.
\section1 Animating Progress Bar Elements
The text label will indicate the progress in numbers and changing color,
while the indicator rectangle will indicate it by getting wider and
changing color. To animate the label and indicator, we'll add timelines
in the \l Timeline view.
For more information about using the timeline, see
\l {Creating Timeline Animations}.
\section2 Adding Color Animation
First, we add a color animation to the \e root component in the \e Root.qml
file. We select the \inlineimage icons/plus.png
button to add a 100-frame timeline to root. You can use the default
values for all other fields.
\image progressbar-timeline-settings.png "Timeline settings"
To start recording a color animation on the timeline, we check that the
playhead is at frame 0 and then select the \inlineimage icons/recordfill.png
(\uicontrol {Auto Key (K)}) button (or press \key k).
\image progressbar-timeline.png "Color animation timeline"
We then set the color at frame 0 to green (\e {#8de98d}) in
\uicontrol Properties > \uicontrol Text > \uicontrol {Text Color}.
We can either \l{Picking Colors}{pick a color} from the color selector
or use the \uicontrol {Set Binding} command in the
\inlineimage icons/action-icon.png
(\uicontrol Actions) menu to open the \uicontrol {Binding Editor}.
We then move the playhead to frame 50 and set the text color to red
(\e {#de4f4f}). Finally, we move the playhead to frame 100 and set
the color to yellow (\e {#f0c861}).
When we deselect the record button to stop recording the timeline, the
new timeline appears in the view.
We can drag the playhead along the timeline to see the color animation.
\section2 Animating the Indicator
We select \e pb_front in \uicontrol Navigator and then select the record
button again to animate the width of the indicator. At frame 0, we set the
width to 0 in \uicontrol Properties > \uicontrol {Geometry - 2D} >
\uicontrol Size. We then move the playhead to 100 frames and set the width
to 590.
\image progressbar-timeline-indicator.png "Indicator timeline"
We will now copy the color animation from the text label to the indicator.
First, we right-click the text component in the \uicontrol Timeline view to
open a context menu and select \uicontrol {Copy All Keyframes from Item} to
copy the keyframe values we specified for the text label.
Next, we select the indicator in the \uicontrol Navigator, and then select
\uicontrol {Insert Keyframes for Item} to paste the keyframe
values to the indicator.
\image progressbar-timeline-indicator-color.png "Indicator timeline with color animation"
When we move the playhead, we can see that the color animation is also
applied to the indicator.
\section1 Creating a Reusable Component
We want the progress bar to be reusable, so we'll move it to a separate
component file. To make sure that the component will contain the timeline,
we select \uicontrol {Filter Tree} in \uicontrol Navigator and then
deselect the \uicontrol {Show Only Visible Items} check box to show the
timeline component in \uicontrol Navigator. We then move the timeline
component to \e root to have it moved as a part of the root component.
Now we can right-click root to open a context menu and select
\uicontrol {Move Component into Separate File}. We can see the
properties that will be available from outside of the component.
\image progressbar-move-component.png "Move Component into Separate File dialog"
\section1 Exporting Properties
We now select the root component in \uicontrol Navigator, and
then select \uicontrol {Go into Component} in the context menu to
open \e Root.qml in \uicontrol {Form Editor}.
We want to be able to use the keyframe value as the value of the text label,
so we will export it as a \l{Adding Property Aliases}{property alias}. We
select \e timeline in \uicontrol Navigator and then \uicontrol Properties >
\uicontrol Timeline > \uicontrol {Current frame} > \uicontrol Actions >
\uicontrol {Export Property as Alias}.
\image progressbar-root-export-property.png "Export keyframe group as a property"
When we select \e root in \uicontrol Navigator, we can see the
\e timelineCurrentFrame property in \l {Connection View} >
\uicontrol Bindings. We double-click it to change its name to \e progress.
\image progressbar-bindings-progress.png "Connection View Bindings tab"
We will bind some JavaScript to the value of the text label to turn
it into a running number that reflects the number of the keyframe on the
timeline. We select the text label in \uicontrol Navigator and then
select \uicontrol Properties > \uicontrol Text > \uicontrol {Set Binding}
to open the \uicontrol {Binding Editor}. We set
\c {Math.round(root.progress)} as the value of the text label.
When we move back to the top-level file, we can see that the number of the
current keyframe (0) is displayed as the value of the text label.
\section1 Animating Progress Bar Instances
We want to experiment with different start and end values and easing curves,
so we copy-paste the progress bar instance twice in the top-level file. We
use a column layout to lay out the progress bar instances.
We can now add timelines for each progress bar instance, with different
settings. We select the \inlineimage icons/plus.png
button to add a 4000-frame timeline to the first progress bar instance
(\e root). We select the \uicontrol Continuous check box so that the
animation will loop.
In \uicontrol Properties > \uicontrol Root, we can see the
\uicontrol progress property that we can animate. If we had
called the component and property something else, we would
see the names we gave them here.
With the playhead in the first frame, we select the record button and
give the \uicontrol progress property the initial value of \e 5. We then
move the playhead to frame 2000 and give it the value of \e 95. We
continue to the last frame and set the value back to \e 5 to have a
smooth looping animation.
When we select the \uicontrol {Show Live Preview} button on the
\uicontrol {Form Editor} toolbar, we see a running number and moving
progress indicator of the animated progress bar instance.
\image progressbar-animated.png
We now change the settings of the other two progress bar instances. We
make one of the indicators move from right to left by starting from frame
100. When all our progress bar instances have been animated, we'll continue
by specifying easing curves for them.
For more information about previewing UIs, see
\l {Validating with Target Hardware}.
\section1 Specifying Easing Curves
We can add custom easing curves to every keyframe in the animations. First,
we select the keyframe to add the easing curve to, and then select
\uicontrol {Edit Easing Curve} in the context menu. We can select several
keyframes simultaneously if we want to use the same easing curve for them.
We select the easing curve in the \uicontrol {Easing Curve Editor}.
\image studio-easing-curve-editor.png "Easing Curve Editor"
When we apply easing curves to animations, the shape of the keyframe
marker changes from \inlineimage icons/keyframe_linear_active.png
to \inlineimage icons/keyframe_manualbezier_active.png
.
For more information, see \l{Editing Easing Curves}.
*/
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