Optimize the usage of windows from Screen

QNX SDP8.0Boot Optimization GuideDeveloper

We recommend that you use a single, static window buffer (SCREEN_PROPERTY_STATIC) whenever possible, and that you try to load the image directly into the window buffer.

When your application tries to show content from multiple, visible windows, Screen likely needs to create a framebuffer. When Screen creates a framebuffer, additional drivers may need to start as well, which can increase the time required to show content on the display. For this reason, to get content shown quickly, we recommend that you minimize the number of visible windows you use in your application.

Note:
If your board supports more than one pipeline, you can use the pipelines to avoid the requirement to use a framebuffer to do composition.
To improve the time it takes to show content on the display, avoid using these unnecessary operations on the splash screen content when possible. The following operations require extra processing time and aren't usually required for a splash screen application:
  • rotation
  • transparency
  • scaling

Since the contents of the window buffer shouldn't change, set the window's property type to SCREEN_PROPERTY_STATIC.

If you use clipped regions in the source rectangle of the window buffer, ensure that the source rectangle (or source view port) is contained within the clipped region. Your clip region should be at least the same size so the source rectangle can be contained within it. So avoid what's shown in the following illustration from occurring:
Figure 1Avoid - Source rectangle isn't contained within the clipped region.


For more information about source clipped regions, see the Using a source clip rectangle section in the Windowing chapter of the Screen Developer's Guide.
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