make use of the RasterWindow from the \l {Raster Window Example}
and reimplement the \c render function to draw the clock face:
- \snippet gui/analogclock/main.cpp 5
+ \snippet analogclock/main.cpp 5
\section1 AnalogClock Class Implementation
- \snippet gui/analogclock/main.cpp 6
+ \snippet analogclock/main.cpp 6
We set a title on the window and resize to a reasonable size. Then
we start a timer which we will use to redraw the clock every
second.
- \snippet gui/analogclock/main.cpp 7
+ \snippet analogclock/main.cpp 7
The timerEvent function is called every second as a result of
our startTimer call. Making use of the convenience in the base
one active timer in this instance, but it is good practice to do
so.
- \snippet gui/analogclock/main.cpp 14
- \snippet gui/analogclock/main.cpp 8
+ \snippet analogclock/main.cpp 14
+ \snippet analogclock/main.cpp 8
Before we set up the painter and draw the clock, we first define
two lists of \l {QPoint}s and two \l{QColor}s that will be used
for the hour and minute hands. The minute hand's color has an
alpha component of 191, meaning that it's 75% opaque.
- \snippet gui/analogclock/main.cpp 9
+ \snippet analogclock/main.cpp 9
We call QPainter::setRenderHint() with QPainter::Antialiasing to
turn on antialiasing. This makes drawing of diagonal lines much
smoother.
- \snippet gui/analogclock/main.cpp 10
+ \snippet analogclock/main.cpp 10
The translation moves the origin to the center of the window, and
the scale operation ensures that the following drawing operations
hour and minute. This means that the hand will be shown rotated clockwise
by the required amount.
- \snippet gui/analogclock/main.cpp 11
+ \snippet analogclock/main.cpp 11
We set the pen to be Qt::NoPen because we don't want any outline,
and we use a solid brush with the color appropriate for
displaying hours. Brushes are used when filling in polygons and
other geometric shapes.
- \snippet gui/analogclock/main.cpp 2
+ \snippet analogclock/main.cpp 2
We save and restore the transformation matrix before and after the
rotation because we want to place the minute hand without having to
take into account any previous rotations.
- \snippet gui/analogclock/main.cpp 12
+ \snippet analogclock/main.cpp 12
We draw markers around the edge of the clock for each hour. We
draw each marker then rotate the coordinate system so that the
painter is ready for the next one.
- \snippet gui/analogclock/main.cpp 13
- \snippet gui/analogclock/main.cpp 3
+ \snippet analogclock/main.cpp 13
+ \snippet analogclock/main.cpp 3
The minute hand is rotated in a similar way to the hour hand.
- \snippet gui/analogclock/main.cpp 4
+ \snippet analogclock/main.cpp 4
Again, we draw markers around the edge of the clock, but this
time to indicate minutes. We skip multiples of 5 to avoid drawing
you will not have to worry about resolving those functions if you want your
application to work with OpenGL as well as OpenGL ES 2.0.
- \snippet gui/openglwindow/openglwindow.h 1
+ \snippet openglwindow/openglwindow.h 1
The window's surface type must be set to QSurface::OpenGLSurface to
indicate that the window is to be used for OpenGL rendering and not for
rendering raster content with QPainter using a QBackingStore.
- \snippet gui/openglwindow/openglwindow.cpp 1
+ \snippet openglwindow/openglwindow.cpp 1
Any OpenGL initialization needed can be done by overriding the initialize()
function, which is called once before the first call to render(), with a
whereas the default render() implementation initializes a
QOpenGLPaintDevice and then calls into render(QPainter *).
- \snippet gui/openglwindow/openglwindow.cpp 2
+ \snippet openglwindow/openglwindow.cpp 2
The renderLater() function simply puts an update request event on
the event loop, which leads to renderNow() being called once the event
size might be unknown, and in addition what is rendered might not even end
up on the screen.
- \snippet gui/openglwindow/openglwindow.cpp 3
+ \snippet openglwindow/openglwindow.cpp 3
In renderNow() we return if we are not currently exposed, in which case
rendering is delayed until we actually get an expose event. If we have not
If animation has been enabled with OpenGLWindow::setAnimating(true), we
call renderLater() to put another update request on the event loop.
- \snippet gui/openglwindow/openglwindow.cpp 4
+ \snippet openglwindow/openglwindow.cpp 4
Enabling animation also triggers an update request as shown in the
following code snippet.
- \snippet gui/openglwindow/openglwindow.cpp 5
+ \snippet openglwindow/openglwindow.cpp 5
\section1 Example OpenGL rendering sub class
rotating triangle. By indirectly sub classing QOpenGLFunctions we gain
access to all OpenGL ES 2.0 level functionality.
- \snippet gui/openglwindow/main.cpp 1
+ \snippet openglwindow/main.cpp 1
In our main function we initialize QGuiApplication and instantiate our
TriangleOpenGLWindow. We give it a QSurfaceFormat specifying that we want
Since we want to have animation we call the above mentioned setAnimating()
function with an argument of true.
- \snippet gui/openglwindow/main.cpp 2
+ \snippet openglwindow/main.cpp 2
The following code snippet shows the OpenGL shader program used in this
example. The vertex and fragment shaders are relatively simple, doing
vertex transformation and interpolated vertex coloring.
- \snippet gui/openglwindow/main.cpp 3
+ \snippet openglwindow/main.cpp 3
Here is the code that loads the shaders and initializes the shader program
By using QOpenGLShaderProgram instead of raw OpenGL we get the convenience
locations in member variables to avoid having to do the location lookup
each frame.
- \snippet gui/openglwindow/main.cpp 4
+ \snippet openglwindow/main.cpp 4
Finally, here is our render() function, where we use OpenGL to set up the
viewport, clear the background, and render a rotating triangle.
- \snippet gui/openglwindow/main.cpp 5
+ \snippet openglwindow/main.cpp 5
*/
\section1 Application Entry Point
- \snippet gui/rasterwindow/main.cpp 1
+ \snippet rasterwindow/main.cpp 1
The entry point for a QWindow based application is the \l
QGuiApplication class. It manages the GUI application's control
\section1 RasterWindow Declaration
- \snippet gui/rasterwindow/rasterwindow.h 1
+ \snippet rasterwindow/rasterwindow.h 1
We first start by including the the QtGui headers. This means we
can use all classes in the Qt GUI module. Classes can also be
\section1 RasterWindow Implementation
- \snippet gui/rasterwindow/rasterwindow.cpp 1
+ \snippet rasterwindow/rasterwindow.cpp 1
The constructor first of all calls \l QWindow::create(). This will
create the window in the windowing system. Without calling create,
Then we create the backingstore and pass it the window instance it
is supposed to manage.
- \snippet gui/rasterwindow/rasterwindow.cpp 2
+ \snippet rasterwindow/rasterwindow.cpp 2
Shortly after calling \l QWindow::show() on a created window, the
virtual function \l QWindow::exposeEvent() will be called to
system with some visual content.
- \snippet gui/rasterwindow/rasterwindow.cpp 5
+ \snippet rasterwindow/rasterwindow.cpp 5
The resize event is guaranteed to be called prior to the window
being shown on screen and will also be called whenever the window
and call renderNow() if we are visible to immediately update the
visual representation of the window on screen.
- \snippet gui/rasterwindow/rasterwindow.cpp 3
+ \snippet rasterwindow/rasterwindow.cpp 3
The renderNow function sets up what is needed for a \l QWindow to
render its content using QPainter. As obscured windows have will
using \l QBackingStore::flush().
- \snippet gui/rasterwindow/rasterwindow.cpp 4
+ \snippet rasterwindow/rasterwindow.cpp 4
The render function contains the drawing code for the window. In
this minial example, we only draw the string "QWindow" in the
\section1 Rendering Asynchronously
- \snippet gui/rasterwindow/rasterwindow.cpp 6
+ \snippet rasterwindow/rasterwindow.cpp 6
We went through a few places where the window needed to repainted
immediately. There are some cases where this is not desierable,
is already pending, we store this state in the \c m_update_pending
variable.
- \snippet gui/rasterwindow/rasterwindow.cpp 7
+ \snippet rasterwindow/rasterwindow.cpp 7
We reimplement the virtual \l QObject::event() function to handle
the update event we posted to ourselves. When the event comes in
TEMPLATE = subdirs
+CONFIG += no_docs_target
SUBDIRS += analogclock
SUBDIRS += rasterwindow
headerdirs += ..
-sourcedirs += ..
+sourcedirs += .. \
+ ../../../examples/gui/doc
-exampledirs += ../../../examples \
+exampledirs += ../../../examples/gui \
+ ../../../doc/src/snippets \
../ \
snippets
-excludedirs += ../../../examples/widgets/doc
+excludedirs += snippets
-imagedirs += images
+imagedirs += images \
+ ../../../doc/src/images \
+ ../../../examples/gui/doc/images
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