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FAQ

This topic lists the frequently asked questions concerning Qt Safe Renderer:

Can Qt Safe Renderer render parametrized information?

Qt Safe Renderer renders only texts and bitmaps. For example, you may have an LCD (liquid-crystal display) display where you need to show some numeric information. You need to create a bitmap for each number that must be displayed on the LCD display. So, for numbers from one to ten, you need ten different bitmaps. Qt Safe Renderer will render those on basis of your UI design.

What happens if Qt Safe Renderer crashes?

Qt Safe Renderer is designed to be stable in all conditions. However, if it should crash, the main UI functionality is not disturbed as the main UI does not depend on Qt Safe Renderer. You can have a watchdog that monitors Qt Safe Renderer and if needed, restarts it. The watchdog can assume that if the Qt Safe Renderer process is up and running, it renders the safety-critical content properly.

Can Qt Safe Renderer render the safety-critical UI even if the main UI fails?

Yes, Qt Safe Renderer continues to render the safety-critical UI elements even if an error occurs in the main UI.

How does Qt Safe Renderer ensure that the bitmaps are not broken or invalid?

Qt Safe Renderer validates the bitmap checksum information before it renders the bitmap.

How many safety-critical bitmaps can Qt Safe Renderer render inside one layout?

Qt Safe Renderer is able to render 128 bitmaps included in a layout file.

What kind of tests are included in the Qt Safe Renderer installation?

The Qt Safe Renderer installation includes the unit tests and their documentation. You find the tests under <Qt Safe Renderer installation directory>/Src/Qt-SafeRenderer-<version>/tests. The unit tests are documented in <Qt Safe Renderer installation directory>Docs/QtSafeRenderer-<version>/qtsaferenderer/qtsr-unit-tests.html.

How does Qt Safe Renderer support safety-critical touch input?

Qt Safe Renderer can be adapted to receive and handle events from the touch event controller. You should note that before you can handle touch events safely, the touch event controller must be certified. So, even if Qt Safe Renderer does not have a Safe Button QML type, you can use it as a part of system that supports safe touch functionality.

Available under certain Qt licenses.
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