[Qt-interest] Hardware Acceleration in QT

[Chetan Murthy]

Hi All,

I am looking at QT for embedded Linux for the first time as one of the
options for the display framework. After studying the architecture, class
documentation and sources for a bit, I have a few questions that will help
me clear my understanding & proceed further.

1) Is it possible to display YUV data through out of the box QT (assuming
display layers are configured that way). As I see it, all the currently
supported format are based on RGB. Please note I am not talking of
converting RGB data into YUV before rendering. The scenario is where I
already have YUV image data available.

2) I have gone through the documentation on how to integrate hardware
accelerators. I understand that we need to implement our own screen class
and provide hardware acceleration for blitting etc. Also, a custom
implementation of the QWSWindowSurface may be needed to provide access to
contiguous physical memory (mmaped access) for the purpose of hardware
blitting. The client would then draw using this surface, and then the
hardware blitter can be used by the server to copy the pixels over to the
destination. Is this understanding accurate?

Please note that I am not trying to accelerate any of the painting
operations. The main purpose is to get access to dma'able memory.

3) Is MultiScreen or sub screen paradigm the way to go when it comes to
handling multiple display layers (OSD's) ? The way I see it, is a displayID
can be used to open the appropriate framebuffer (/dev/fb0, /dev/fb1) etc.
for the desired layers and operations can be done on it. I know one way to
do this is to specify a QT environment variable to pick up the correct fb to
connect to at start up, and handle this in the connect call. Is it also
possible for the user application to chose a layer or a sub-screen
dynamically at run time? For example, render the image on layer 1 and menu
on layer 2.

Please let me know what you think? Thank you!

Regards,
Chetan
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