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/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
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** $QT_BEGIN_LICENSE:FDL$
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** Documentation License version 1.3 as published by the Free Software
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** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
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****************************************************************************/
/*!
\example widgets/elidedlabel
\group all-examples
\title Elided Label Example
\brief The Elided Label example creates a widget similar to QLabel, that elides the last
visible line, if the text is too long to fit the widget's geometry.
\image elidedlabel-example.png Elided Label example on XPressMusic 5800
When text of varying length has to be displayed in a uniformly sized
area, for instance within a list or grid view where all list items have the
same size, it can be useful to give the user a visual clue when not all
text is visible. QLabel can elide text that doesn't fit within it, but only
in one line. The \c ElidedLabel widget shown in this example word wraps its
text by its width, and elides the last visible line if some text is left
out. \c TestWidget gives control to the features of \c ElidedWidget and
forms the example application.
\section1 ElidedLabel Class Definition
Like QLabel, \c ElidedLabel inherits from QFrame. Here's the definition of
the \c ElidedLabel class:
\snippet examples/widgets/elidedlabel/elidedlabel.h 0
The \c isElided property depends the font, text content and geometry of the
widget. Whenever any of these change, the \c elisionChanged() signal might
trigger. We cache the current elision value in \c elided, so that it
doesn't have to be recomputed every time it's asked for.
\section1 ElidedLabel Class Implementation
Except for initializing the member variables, the constructor sets the size
policy to be horizontally expanding, since it's meant to fill the width of
its container and grow vertically.
\snippet examples/widgets/elidedlabel/elidedlabel.cpp 0
Changing the \c content require a repaint of the widget.
\snippet examples/widgets/elidedlabel/elidedlabel.cpp 1
QTextLayout is used in the \c paintEvent() to divide the \c content into
lines, that wrap on word boundaries. Each line, except the last visible
one, is drawn \c lineSpacing pixels below the previous one. The \c draw()
method of QTextLine will draw the line using the coordinate point as the
top left corner.
\snippet examples/widgets/elidedlabel/elidedlabel.cpp 2
Unfortunately, QTextLayout does not elide text, so the last visible line
has to be treated differently. This last line is elided if it is too wide.
The \c drawText() method of QPainter draws the text starting from the base
line, which is \c ascecnt() pixels below the last drawn line.
Finally, one more line is created to see if everything fit on this line.
\snippet examples/widgets/elidedlabel/elidedlabel.cpp 3
If the text was elided and wasn't before or vice versa, cache it in
\c elided and emit the change.
\snippet examples/widgets/elidedlabel/elidedlabel.cpp 4
\section1 TestWidget Class Definition
\c TestWidget is a QWidget and is the main window of the example. It
contains an \c ElidedLabel which can be resized with two QSlider widgets.
\snippet examples/widgets/elidedlabel/testwidget.h 0
\section1 TestWidget Class Implementation
The constructor initializes the whole widget. Strings of different length
are stored in \c textSamples. The user is able to switch between these.
\snippet examples/widgets/elidedlabel/testwidget.cpp 0
An \c ElidedLabel is created to contain the first of the sample strings.
The frame is made visible to make it easier to see the actual size of the
widget.
\snippet examples/widgets/elidedlabel/testwidget.cpp 1
The buttons and the elision label are created. By connecting the
\c elisionChanged() signal to the \c setVisible() slot of the \c label,
it will act as an indicator to when the text is elided or not. This signal
could, for instance, be used to make a "More" button visible, or similar.
\snippet examples/widgets/elidedlabel/testwidget.cpp 2
The \c widthSlider and \c heightSlider specify the size of the
\c elidedText. Since the y-axis is inverted, the \c heightSlider has to be
inverted to act appropriately.
\snippet examples/widgets/elidedlabel/testwidget.cpp 3
The components are all stored in a QGridLayout, which is made the layout of
the \c TestWidget.
\snippet examples/widgets/elidedlabel/testwidget.cpp 4
On the Maemo platform, windows are stuck in landscape mode by default. With
this attribute set, the window manager is aware that this window can be
rotated.
\snippet examples/widgets/elidedlabel/testwidget.cpp 5
The \c widthSlider and \c heightSlider have the exact same length as the
dimensions of the \c elidedText. The maximum value for both of them is
thus their lengths, and each tick indicates one pixel.
\snippet examples/widgets/elidedlabel/testwidget.cpp 6
The \c switchText() slot simply cycles through all the available sample
texts.
\snippet examples/widgets/elidedlabel/testwidget.cpp 7
These slots set the width and height of the \c elided text, in response to
changes in the sliders.
\section1 The \c main() Function
The \c main() function creates an instance of \c TestWidget fullscreen and
enters the message loop.
\snippet examples/widgets/elidedlabel/main.cpp 0
*/
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