- Getting Started with Qt/Embedded Linux
- Customizing Qt/Embedded Linux
- Integrating Qt Applications with Qtopia
- Using Qtopia APIs
This chapter is from the book
This chapter is from the book
This chapter is from the book
Customizing Qt/Embedded Linux
When installing Qt/Embedded Linux, we can specify features we want to leave out to reduce its memory footprint. Qt/Embedded Linux includes more than one hundred configurable features, each of which is associated with a preprocessor symbol. For example, QT_NO_FILEDIALOG excludes QFileDialog from the QtGui library, and QT_NO_I18N leaves out all support for internationalization. The features are listed in src/corelib/global/qfeatures.txt.
Qt/Embedded Linux provides five example configurations (minimum, small, medium, large, and dist) that are stored in src/corelib/global/qconfig- xxx .h files. These configurations can be specified using the configure script's -qconfig xxx option, for example:
./configure -qconfig small
To create custom configurations, we can manually provide a qconfig- xxx .h file and use it as though it were a standard configuration. Alternatively, we can use the qconfig graphical tool, located in Qt's tools subdirectory.
Qt/Embedded Linux provides the following classes for interfacing with input and output devices and for customizing the look and feel of the window system:
|
Class |
Base Class for |
|
QScreen |
Screen drivers |
|
QScreenDriverPlugin |
Screen driver plugins |
|
QWSMouseHandler |
Mouse drivers |
|
QMouseDriverPlugin |
Mouse driver plugins |
|
QWSKeyboardHandler |
Keyboard drivers |
|
QKbdDriverPlugin |
Keyboard driver plugins |
|
QWSInputMethod |
Input methods |
|
QDecoration |
Window decoration styles |
|
QDecorationPlugin |
Window decoration style plugins |
To obtain the list of predefined drivers, input methods, and window decoration styles, run the configure script with the -help option.
The screen driver can be specified using the -display command-line option when starting the Qt/Embedded Linux server, as seen in the previous section, or by setting the QWS_DISPLAY environment variable. The mouse driver and the associated device can be specified using the QWS_MOUSE_PROTO environment variable, whose value must have the syntax type : device , where type is one of the supported drivers and device is the path to the device (e.g., QWS_MOUSE_PROTO=IntelliMouse:/dev/mouse). Keyboards are handled similarly through the QWS_KEYBOARD environment variable. Input methods and window decorations are set programmatically in the server using QWSServer::setCurrentInputMethod() and QApplication::qwsSetDecoration().
Window decoration styles can be set independently of the widget style, which is encapsulated by a QStyle subclass. For example, it is entirely possible to set Windows as the window decoration style and Plastique as the widget style. If desired, decorations can be set on a per-window basis.
The QWSServer class provides various functions for customizing the window system. Applications that run as Qt/Embedded Linux servers can access the unique QWSServer instance through the QWSServer::instance() static function.
Qt/Embedded Linux supports the following font formats: TrueType (TTF), PostScript Type 1, Bitmap Distribution Format (BDF), and Qt Pre-rendered Fonts (QPF).
Because QPF is a raster format, it is designed to be faster and more compact than vector formats such as TTF and Type 1 if we need it only at one or two different sizes. The makeqpf tool can be used to pre-render a TTF or a Type 1 file and save the result in QPF format. An alternative is to run our applications with the -savefonts command-line option.