Hello all,I've got a RPi 1B rev1, onto which I've installed "bullseye lite", meaningno GUI of any kind.I ofcourse wanted to see if I could draw some graphics on it. :-)I've found that it supports a "Frame Buffer" onto which pixels can beplotted.I also found the "fb.h" include file, and was able to get FBIOCOPYAREA towork.Alas, thats as far as I got. Even though the file mentions hardwaresupport for a mouse cursor I've not been able to get that to work. :-(The file also contains "fb_fillrect" structure, but doesn't show anythingabout how / where its used.tl;dr:I could use an example which shows how to use "_iowr()" to get the build-in mouse cursor to work, and would not mind at all if someone knows how to draw a simple rectangle using the same "_iowr()" method.Regards,Rudy Wieser

RISC OS uses the GPU to draw its hardware pointer. Here's the code: appears to be using VCHIQ which is the service to send messages to theGPU: OS appears to be using the vc_dispman API to ask the GPU to draw thepointer._iowr() is a basic 32-bit I/O write (ie write 32 bits to I/O address0x....).The GPU is several levels above this in the stack: you need to craft amessage to ask the GPU to do it, using the appropriate API, and then asksomething (/dev/vchiq on Linux) to deliver the message.There may be some support for this stuff in the RPi userland libraries: it's not immediately clear where it might be.Having said all this, you're on Linux not baremetal so I think a better waywould be to use some existing library. I'd have a look at SDL as that mightbe easier to deal with (SDL 2 is '3D', SDL 1.2 is older and more 2D focused. You might be better starting with SDL 2 to begin with, even if you only want2D stuff). SDL is designed to be run either in a window or on a bareframebuffer style...

Does the RPi 1B rev1 Framebuffer have hardware support for a mouse cursor ?

Jun 25, 2023 Last reply: 3 years ago 43 Replies

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Computer Nerd Kev 3 years ago

At least now you're specifying which frame buffer you mean when you use that term in your posts. What irked me before was that you didn't do so even after the problems with understanding had arisen.

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R.Wieser 3 years ago

Kev,

Only after someone told me that that was the one I most likely ment with all my initialy given information (I'm still wondering how some, given that info, could have assumed I would be referring to another one, hardware or otherwise.).

At some point you understood which one I ment, but you still needed me to call it by its full name instead of the short one ? That sounds like your problem, not mine.

Regards, Rudy Wieser

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The Natural Philosopher 3 years ago

That depends on if it is you that wants help...

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mm0fmf 3 years ago

Typical Rudy behaviour.

He doesn't want help he wants a argument.

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