From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <14ec7b180706080837o29f4436fh76ea771ad5a4524f@mail.gmail.com>
Date: Fri,  8 Jun 2007 09:37:25 -0600
From: "andrey mirtchovski" <mirtchovski@gmail.com>
To: "Fans of the OS Plan 9 from Bell Labs" <9fans@cse.psu.edu>
Subject: Re: [9fans] Some libdraw help
In-Reply-To: <46697374.1020507@kix.in>
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References: <46697374.1020507@kix.in>
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see "loadimage" for the function that creates an Image * from a
bitstream. if you look at the xscreensaves hacks (xscr.tgz in
/contrib/andrey on sources) you'll find a couple that use that hack,
most notably "eruption".

you can fullscreen an application in two ways: use that app instead of
rio (then it'll use the entire screen but you won't be able to resize
it, or run any other draw app); or use a helper function (thanks to
Russ):

    % fullscr=`{echo $vgasize | awk -Fx '{print "0 0 " $1 " " $2}'}
    % window -r $fullscr myapp

cheers!

On 6/8/07, Anant Narayanan <anant@kix.in> wrote:
> Hi All,
>
> I'm a little new to libdraw and need some advice on drawing bitmap data
>  onto a window.
>
> I have with me some bitmap data on memory, the address of the first byte
> is known. I also know the width of the bitmap data and the total number
> of scanlines in it. The number of pixels in each scanline is rounded up
> so that each scanline is word-aligned.
>
> I also know the depth, i.e. the number of bits in a pixel. The color
> arrangement per pixel depends on the depth. In the case of a 32-bit
> depth, the 8 most significant bits are to be ignored, the next 8 bits
> represent the red, the next 8 green and the next 8 blue. For a 16 bit
> depth, the most significant bit is ignored and the next 15 bits are for
> red, green and blue respectively. So on for 8, 4, 2 and 1-bit depths.
>
> The byte order of the data is the same as that of the host CPU.
>
> Finally, I have with me the co-ordinates of a "mask rectangle", i.e. the
> portion of the bitmap that needs to updated on the screen. Consequently,
> the first time my function is called, the mask rectangle will be the
> entire window size; but later calls will contain mask rectangle
> co-ordinates for portions of the screen that need updating.
>
> Now for the questions :)
>
> 1) What is the best way to draw this bitmap data onto the screen? Note
> that the bitmap data on memory will not stick around, I have to copy it.
>  I had a look at the Memimage set of methods, but am not sure that it's
> the best way to go about it.
>
> 2) Do I have to worry about endianness?
>
> 3) A general question (un-related to the description above): How can I
> create a "full-screen" window? "full-screen" means the application has
> the undivided attention of the user, like many games run in other
> operating systems. This is different from just resizing the window to
> the size of the screen because the window border would still be visible
> in this case :)
>
> Help would be most appreciated!
>
> Thank you,
>
> Regards,
> --
> Anant
>