1QDirectPainter(3qt) QDirectPainter(3qt)
2
6 QDirectPainter - Direct access to the video hardware
7
9 #include <qdirectpainter_qws.h>
10 Inherits QPainter.
12 Public Members
14 QDirectPainter ( const QWidget * w )
15 ~QDirectPainter ()
16 uchar * frameBuffer ()
17 int lineStep ()
18 int transformOrientation ()
19 int numRects () const
20 const QRect & rect ( int i ) const
21 QRegion region () const
22 int depth () const
23 int width () const
24 int height () const
25 int xOffset () const
26 int yOffset () const
27 QPoint offset () const
28 QSize size () const
29 void setAreaChanged ( const QRect & r )
30
32 The QDirectPainter class provides direct access to the video hardware.
33 Only available in Qt/Embedded.
35 When the hardware is known and well defined, as is often the case with
37 software for embedded devices, it may be useful to manipulate the
38 underlying video hardware directly. In order to do this in a way that
39 is co-operative with other applications, you must lock the video
40 hardware for exclusive use for a small time while you write to it, and
41 you must know the clipping region which is allocated to a widget.
42 QDirectPainter provides this functionality.
44 In the simplest case, you make a QDirectPainter on a widget and then,
46 observing the clip region, perform some platform-specific operation.
47 For example:
48 void MyWidget::updatePlatformGraphics()
50 {
51 QDirectPainter dp( this );
52 for ( int i = 0; i < dp.numRects; i++ ) {
53 const QRect& clip = dp.rect(i);
54 ... // platform specific operation
55 }
56 }
57 The platform-specific code has access to the display, but should only
59 modify graphics in the rectangles specified by numRects() and rect().
60 Note that these rectangles are relative to the entire display.
61 The offset() function returns the position of the widget relative to
63 the entire display, allowing you to offset platform-specific operations
64 appropriately. The xOffset() and yOffset() functions merely return the
65 component values of offset().
66 For simple frame-buffer hardware, the frameBuffer(), lineStep(), and
68 depth() functions provide basic access, though some hardware
69 configurations are insufficiently specified by such simple parameters.
70 Note that while a QDirectPainter exists, the entire Qt/Embedded window
72 system is locked from use by other applications. Always construct the
73 QDirectPainter as an auto (stack) variable, and be very careful to
74 write robust and stable code within its scope.
75 See also Graphics Classes.
77
80 Construct a direct painter on w. The display is locked and the mouse
81 cursor is hidden if it is above w.
82
84 Destroys the direct painter. The mouse cursor is revealed if necessary
85 and the display is unlocked.
86
88 Returns the bit-depth of the display.
89
91 Returns a pointer to the framebuffer memory if available.
92
94 Returns the height of the widget drawn upon.
95
97 Returns the spacing in bytes from one framebuffer line to the next.
98
100 Returns the number of rectangles in the drawable region.
101 See also rect() and region().
103
105 Returns the position of the widget relative to the entire display.
106
108 Returns a reference to rectangle i of the drawable region. Valid values
109 for i are 0..numRects()-1.
110 See also region().
112
114 Returns the region of the framebuffer which represents the exposed area
115 of the widget being painted on. Note that this may be a sub-area of the
116 clip region, because of child widgets and overlapping cousin widgets.
117 See also numRects() and rect().
119
121 Sets the area changed by the transaction to r. By default, the entire
122 widget is assumed to have changed. The area changed is only used by
123 some graphics drivers, so often calling this function for a smaller
124 area will make no difference to performance.
125
127 Returns the size of the widget drawn upon.
128 See also width() and height().
130
132 Returns a number that signifies the orientation of the framebuffer.
133 <center>.nf
134 </center>
136
138 Returns the width of the widget drawn upon.
139
141 Returns the X-position of the widget relative to the entire display.
142
144 Returns the Y-position of the widget relative to the entire display.
145
148 http://doc.trolltech.com/qdirectpainter.html
149 http://www.trolltech.com/faq/tech.html
150
152 Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
153 license file included in the distribution for a complete license
154 statement.
155
157 Generated automatically from the source code.
158
160 If you find a bug in Qt, please report it as described in
161 http://doc.trolltech.com/bughowto.html. Good bug reports help us to
162 help you. Thank you.
163 The definitive Qt documentation is provided in HTML format; it is
165 located at $QTDIR/doc/html and can be read using Qt Assistant or with a
166 web browser. This man page is provided as a convenience for those users
167 who prefer man pages, although this format is not officially supported
168 by Trolltech.
169 If you find errors in this manual page, please report them to qt-
171 bugs@trolltech.com. Please include the name of the manual page
172 (qdirectpainter.3qt) and the Qt version (3.3.8).
173Trolltech AS 2 February 2007 QDirectPainter(3qt)