The boot is small and has FAT32 file system partition and system partition with ext4 filesystem on it. It will be mounted as two partitions: boot and system. We insert the flash drive into the computer again. What’s next? The device doesn’t know our WiFi credentials, we don’t know its IP-address, and it will not allow us to access it via ssh even with a cable connection. The device victoriously blinks with LEDs. Insert the flash drive and turn the RPi on. Copy the image using the dd utility to the USB flash drive.
Download the Raspbian image archive from the official site and unpack it. repaint() provides immediate painting.Everything is simple here. Typically, the update() or repaint() functions push QPaintEvent to the message loop. This event can be triggered by a window manager whenever the window is raised, or by the program itself in the response to some menu events. The chart class overrides paintEvent(), which is called whenever a chart window needs to be repainted or redrawn. Working with the Chart Class FeaturesĬhart is subclassed from QWidget and becomes a central widget to mainwindow (subclassed from QMainWindow).
QPaintEvent is triggered by the update() or repaint() function call or by a window manager when the window requires repainting. QPainter generally is instantiated within the paintEvent() function, which is a callback function for the QPaintEvent event. It implements painting functions like drawLine(), drawArc(), and so forth. The user needs to set the Pen (for line), Brush (for background), and Font (for text) attributes of the QPainter object. QPainter is a class which actually does the painting on the window (QWidget). QMainWindow is custom widget sub-classed from QWidget and adds Menus, Toolbar, Statusbar, Dockable widget, and a Central widget to a window.
Instantiating QWidget pushes a window which can take user input through a keyboard or mouse. Qt windowing support is available through the QWidget class. Working with the QWidget, QMainWindow, and QPainter Classes
Using Qt version 5.3.2 in /usr/lib/arm-linux-gnueabihf The Qt version can be checked with the following command: :~ $ qmake -version
Do the following command: :~ $ sudo apt-get install qtcreator If Qt creator (IDE) and Qt documentation (help page) are required, the qtcreator can be installed. You’ll want to start the Qt install with the following command: :~ $ sudo apt-get install qt5-default For higher versions of Qt (>5.3), Qt source code can be natively built on rPI3 or for eglfs, cross compilation can be done on the desktop (such as Ubuntu). It is currently used on the Raspibian PIXEL window manager with the X11 display server concept. It does not support embedded eglfs or wayland window manager, available for eglfs display. You should note that the Qt installed in this article works as a desktop application with the X11 protocol on the back end. Qt5.3 is among these apps that can be installed through the ‘apt-get install’ utility.
Raspibian is a Debian flavored version of Linux that has good support for third-party software available through an apt-get software management utility. The Raspberry PI3 (model b) is mostly used with the proprietary OS Raspbian, which is available at /downloads. The library can be integrated with any real time data collection software to display its run time data.
In this article, you will see how Qt is installed on a Raspberry PI3 and learn how to develop a 2D charts library.