A Desktop UI with QtQuick

A Desktop UI with QtQuick
How QtQuick encouraged us to totally rethink a Desktop
User Interface

1

Freitag, 25. November 2011

my Qt mileage

Nils Jeisecke
saltation GmbH & Co. KG / Bielefeld / Germany
http://www.saltation.de

Qt developer > 10 years (since Qt 2)

2


The Use Case Computer Telephony Integration

The Use Case is called „TK-Suite Client“, a CTI and PIM
application for a PBX.
Personal Information Management

Business telephone system

That Application went through nearly all Qt iterations:
• Qt 2 used for prototype
• Qt 3 used for 1.0, 2.0, 3.0 and the !rst Mac Version
• Qt 4 used for 4.x 1st (!rst rewrite)

3


Evolution of TK-Suite Client
Version 1 and 2

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Version 3

5


Version 4

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Highlighting some UI problems

* Live Demo of Version 4 *

7


Building a UI with Qt Widgets
What does a Qt programmer do if he must implement a
UI?

1. I look for the widget that is the nearest match for the
requirements
2. I tune the widget by
• doing some CSS styling
• subclassing and changing behavior
• writing a custom delegate for item views
3. If that’s not possible, I’ll write a widget from scratch

8


A customized TreeView

In order to navigate through contacts and
numbers, we use an expanded tree view

A custom delegate will draw a
special selection

But a customized QTreeView is still a
QTreeView and will always be.

9


A Problem with Toolbars

This is a long distance!
There’s no visual connection.

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The Problems with Popups

That’s 0x0c (12) entries!

1

2
We repeat the item Text

3

4

5
6

7
8

9

a

b
c

1

+1 completely unrelated to the item

11


Using QMainWindow as a Dashboard

Everything is arranged around a
Screen 1 2 3 4 5 6 central widget that deﬁnes the
“main” functionality of each screen

Resizing a Dockwidget inﬂuences
other dockwidgets

12


Resizing a QMainWindow

sm
al
le
r

ol
d
si
Oh no! My lovely arranged Favorite
ze
Views are totally messed up!

13


I have a certain feeling that we
need to do something about
this!

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So this is what our interface designer had in mind...

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...and this was our programmer’s reaction:

If I will have to code this with
QWidgets and CSS styling
I’m going to shoot myself.

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Short Break for a commercial

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Whatever the future of Qt on mobile
phones will be...

Nokia gave us a precious gift:

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...so this is what we have built using QtQuick:

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* Live Demo of Version 5 *

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A User Interface with Qml

This is a ListView with a delegate

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A Contact Delegate
Column {
id: data
anchors.left: parent.left
anchors.leftMargin: 30
anchors.right: parent.right
spacing: 4
clip: true

Text {
visible: text.length > 0
width: data.width
color: "#efefef"
text: model.displayName
Not that exiting:
elide: Text.ElideMiddle
font.bold: true
This could easily be done within
font.pixelSize: 14
QItemDelegate::paint
}
Text {
width: data.width
text: model.company
color: "#a7a07a"
font.pixelSize: model.displayName.length === 0 ? 14 : 10
elide: Text.ElideMiddle
}

Image { source: "images/contact_separator.png" }
}

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Qml Delegates have a state
CtiExtensionStateProvider {
id: contactExtensionState
contactId: model.objectId
}

Rectangle {
anchors.fill: extensionNo
anchors.margins: -2
color: contactExtensionState.stateColor
Now it’s getting more interesting: opacity: 0.7
visible: contactExtensionState.extensionId != ""
This is a custom C++ QObject based class }
that is created from within Qml and Text {
implements business logic. id: extensionNo
anchors.verticalCenter: parent.verticalCenter
x: 6
color: "white"
text: contactExtensionState.extensionNo
}
In this case we display the status of a PBX
extension (that’s a telephone) by binding
to properties of that object.

I need no longer put logic in a
model where it does not belong to.
23


Putting actions in context

ActionMenu {
id: actionMenu
}

The ActionMenu item extends a Qml
ListView

This is the ActionMenu’s delegate

So you can really have delegates in
ListViews in delegates! How cool is
that. And actually useful!
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Qml based Dashboard

#2
#3
Repeater {

model: QsltDashboardModel {
id: dashboardModel
canvasRect: Qt.rect(root.x, root.y, root.width, isMaximized ? maximizedSize : 10000)
spacing: 10

#1 }

delegate: DashboardDelegate {}
}

#4
This is the C++ model that cares
about the layout
All these delegates are created by a
Qml Repeater item

This delegate implements all the
animation and manages the content
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DashboardDelegate caption

Rectangle {
id: captionRect
color: captionColor
width: parent.width
height: 28
radius: 10

Row {
id: captionButtons
DashboardCaptionButton {
imageSource: trashIcon; visible: __settingsItem !== null; onClicked: { removeItem() } }
imageSource: showSettingsIcon; visible: __settingsItem === null; onClicked: { toggleSettings() } }
imageSource: hideSettingsIcon; visible: __settingsItem !== null; onClicked: { toggleSettings() } }
imageSource: maximizeIcon; onClicked: { toggleMaximize() } }
}
}
Text { /* ... */ }

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Moving a DashboardDelegate around

MouseArea {
id: dragArea
anchors.fill: captionRect

onPressed: root.dragging = true

onPositionChanged: {
if (root.dragging) {
var p = mapToItem(root, mouse.x, mouse.y)
dashboardModel.moveTo(model.index, Qt.point(p.x, p.y))
}
}
}

We let our C++ model do all the hard work
of recalculating the layout.

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DashboardDelegate content

Loader {
id: content
anchors.left: parent.left
anchors.top: settingsContainer.bottom
anchors.bottom: parent.bottom
source: model.componentPath // the model will tell us which Qml file implements the DashboardItem
opacity: dragArea.pressed && dragArea.pressedButton == Qt.LeftButton ? 0.3 : 1

Behavior on opacity { NumberAnimation { duration: 200 } }

/* ... */
}
I’m going to watch TV
now.

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Wireframing

If time permits: Demo the Workspace Wireframe

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Best Practices with QtQuick
• Use the power of Qt and C++ to implement
– Business logic
– Data models
– Network communication
• Use QObject and QAbstractItemModel to interface
between C++ and Qml
• Limit the use of Qml to implement
– Data presentation
– User Interaction
• Don‘t forget to contact a Designer

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Thanks to QtQuick we can !nally
develop state of the art cross platform
User Interfaces.

Thank your very much for your
Attention and have fun at Qt
DevDays 2011!
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