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Drawing an image from a byte array

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Natenstein

Post subject: Drawing an image from a byte array

Posted: Fri Mar 11, 2011 2:11 pm

Joined: Mon Mar 19, 2007 8:56 am
Posts: 21

I would like to take a byte array (received via UDP) and use this to draw a graphic on a G75. The format of my data array is bit-masked, where each bit of each byte represents an on/off of a pixel. My received data does not have any color information, just on/off's.

For example ...

Bit0 Bit1 Bit2 Bit3 ...
Byte[0] Row1xCol1 Row1xCol2 Row1xCol3 Row1xCol4 ...
Byte[1] Row2xCol1 Row2xCol2 Row2xCol3 Row2xCol4 ...

Is there any way to to turn this into something useful? Unfortunately I have no control over how this data has been formatted.

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Ron L.

Post subject: Re: Drawing an image from a byte array

Posted: Fri Mar 11, 2011 2:33 pm

Joined: Thu Mar 02, 2006 2:12 pm
Posts: 487
Location: Salt Lake City, Utah

The only way I know to do that in Qlarity is by comparing the bits in the array and creating a pixmap. Here is some sample code. 8x8 pixmap created from 8 bytes.

Code:

func Draw (pass as boolean)
    handles MSG_DRAW
    dim b[] as byte
    dim pixmap[] as byte
    dim i, j, idx, c, n as integer

    b := "abcdefgh"
    Redim(pixmap, Len(b) * 8)

    for i = 0 to Len(b) - 1
        n := 1
        for j = 0 to 7
            if (byte(n) and b[i]) <> 0 then
                c := 0
            else
                c := 255
            endif
            idx := i * j
            pixmap[idx] := c
            n := n * 2
        next
    next

    DrawPixmap(30, 30, pixmap, 8, 8)

    return
endfunc

_________________
Ron L.

http://www.beijerelectronicsinc.com/

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Natenstein

Post subject: Re: Drawing an image from a byte array

Posted: Sun Mar 13, 2011 8:37 pm

Joined: Mon Mar 19, 2007 8:56 am
Posts: 21

Thanks Ron. Very helpful. The pixmap is just a byte array that "wraps" to the next line based on the mapwidth and map height, and each byte is the color of the pixel? Now how do I call this function explicitly? It seems to only run at startup. Under what conditions (or not) can I call "DrawPixmap"?

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Ron L.

Post subject: Re: Drawing an image from a byte array

Posted: Mon Mar 14, 2011 8:02 am

Joined: Thu Mar 02, 2006 2:12 pm
Posts: 487
Location: Salt Lake City, Utah

You can call DrawPixmap inside any function that handles the MSG_DRAW message. If you would like an object to re-draw you can use the function "Rerender".

Code:

Rerender(obj_name_here)

If you need to create an object to do customer drawing in, go to Edit->Add Edit/Tempates to create a new template.

_________________
Ron L.

http://www.beijerelectronicsinc.com/

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