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author | Leena Miettinen <riitta-leena.miettinen@qt.io> | 2020-09-29 14:28:27 +0200 |
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committer | Leena Miettinen <riitta-leena.miettinen@qt.io> | 2020-09-29 12:33:30 +0000 |
commit | 168c3df4c652c6dba58a635c90e93e4ec371d91c (patch) | |
tree | 3cfb70f68b7938010f09d3ad7a9c0510610a9c75 /doc | |
parent | 67bc45ebcd221dfc3da8a589d2a84cc6b0c13cb4 (diff) |
Doc: Add missing file
This content was moved to a new file, but the file was
not submitted as a part of the change.
Change-Id: I44246688f5d8b0baf83069475fbd3c0a5c9a4c7d
Reviewed-by: Topi Reiniƶ <topi.reinio@qt.io>
Diffstat (limited to 'doc')
-rw-r--r-- | doc/qtcreator/src/qtquick/qtquick-placeholder-data.qdoc | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/doc/qtcreator/src/qtquick/qtquick-placeholder-data.qdoc b/doc/qtcreator/src/qtquick/qtquick-placeholder-data.qdoc new file mode 100644 index 0000000000..b620a6e57b --- /dev/null +++ b/doc/qtcreator/src/qtquick/qtquick-placeholder-data.qdoc @@ -0,0 +1,123 @@ +/**************************************************************************** +** +** Copyright (C) 2020 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the Qt Creator documentation. +** +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Free Documentation License Usage +** Alternatively, this file may be used under the terms of the GNU Free +** Documentation License version 1.3 as published by the Free Software +** Foundation and appearing in the file included in the packaging of +** this file. Please review the following information to ensure +** the GNU Free Documentation License version 1.3 requirements +** will be met: https://www.gnu.org/licenses/fdl-1.3.html. +** +****************************************************************************/ + +/*! + \page qtquick-placeholder-data.html + \if defined(qtdesignstudio) + \previouspage studio-simulation-overview.html + \nextpage studio-javascript.html + \else + \previouspage qtquick-annotations.html + \nextpage creator-quick-ui-forms.html + \endif + + \title Loading Placeholder Data + + The Design mode supports views, models, and delegates, so that when you add + a Grid View, List View, or Path View item, the ListModel and the delegate + item are added automatically. + + However, the missing context of the application presents a challenge. + Specific models defined in C++ are the most obvious case. Often, + the context is missing simple properties, which are either defined in C++, + or in other QML files. A typical example is an item that uses the + properties of its parent, such as \c parent.width. + + \section1 Using Dummy Models + + If you open a file in the Design mode that references a C++ model, you see + nothing on the canvas. If the data in the model is fetched from the + internet, you have no control over it. To get reliable data, \e {dummy data} + was introduced. + + For example, the following code snippet describes the file example.qml that + contains a ListView that in turn specifies a C++ model: + + \qml + ListView { + model: dataModel + delegate: ContactDelegate { + name: name + } + } + \endqml + + Create a directory named \e dummydata in the root directory of the project, + so that it is not deployed to the device. In the \c dummydata directory, + create a QML file that has the same name as the value of \c model: + + \code + qml/exampleapp/example.qml + dummydata/dataModel.qml + \endcode + + Then create the dataModel.qml file that contains the dummy data: + + \qml + import QtQuick 2.0 + + ListModel { + ListElement { + name: "Ariane" + } + ListElement { + name: "Bella" + } + ListElement { + name: "Corinna" + } + } + \endqml + + \section1 Creating Dummy Context + + The following example presents a common pattern in QML: + + \qml + Item { + width: parent.width + height: parent.height + } + \endqml + + This works nicely for applications but the Design mode displays a zero-sized + item. A parent for the opened file does not exist, because the context is + missing. To get around the missing context, the idea of a \e {dummy + context} is introduced. If you place a file with the same name as the + application (here, example.qml) in the \c {dummydata/context} directory, + you can fake a parent context: + + \qml + import QtQuick 2.0 + import QmlDesigner 1.0 + + DummyContextObject { + parent: Item { + width: 640 + height: 300 + } + } + \endqml +*/ |