Image from a buffer
Blitz3D Forums/Blitz3D Programming/Image from a buffer
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| Hi Guys, I'm trying to load an image from a bitmap buffer instead of a file. The basic idea is that I will link to a DLL (this I know how to do already) and the dll function read the bitmap from a file and then return it. In the Blitz env I take the buffer and create an image from this buffer. The question is how do I take the buffer and create the image from it's data? Any code snippest would be great! Thanks in advance Yiftah |
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| ok, you don't have to use a dll to do this, i would only use a dll if i really had to personally.... but onto the task. ok, this is from something i just wrote a few days ago actually, i got the information from the read/writepixelfast examples i think, the docs can cover this stuff if you can pay attention for long enough that is! heh this is how to load a bmp and read the pixels into a pixel array for writing to later, comments below. xdim=256 : ydim=256 ;the image dimension vars Dim Imagedata(xdim,ydim) ;size pixel array mypic=LoadImage(filename$) ;load a bmp DrawImage mypic,0,0 ;draw image to screen LockBuffer ;must have for ReadPixelFast For y=0 To ydim ;x/y loop For x=0 To xdim Imagedata(x,y)=ReadPixelFast(x,y) ;read to array Next Next UnlockBuffer Cls ;clear image from screen now you've got all pixels in the array, you want to, ehh... create the image from the data now. ok, this writes the pixel array to a new image. mynewpic=CreateImage(xdim,ydim) ;size new image SetBuffer ImageBuffer(mynewpic) ;put image in buffer LockBuffer ;must have for WritePixelFast For y=0 To ydim ;draw new image For x=0 To xdim WritePixelFast x,y,Imagedata(x,y) ;write to image Next Next UnlockBuffer SetBuffer BackBuffer() ;reset to screen buffer I cant garantee this code is 100% perfect, as i havent tested, but it should be. One thing id like to mention is that i found writepixelfast doesn't work in fullscreen 16bit!? but plot does, its a little slower and more complex but at least it works, i guess. Hope that helps some anyway. |
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| It really depends on the way you want to fill the buffer with image data. If blitz will fill the buffer (read the data from somewhere, eg. using RTLMemoryMove with a Pointer given by the DLL) then it's pretty simple, all you need to do is writing them to the image, as muk suggested. If the DLL will fill the buffer using a pointer sent by Blitz, you need to send a banks physical adress to the dll. you may send the bank handle to the DLL, as usual, but there's something faster that will let the DLL draw directly to a blitz image. See here: http://www.blitzbasic.com/codearcs/codearcs.php?code=1518 |
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| i just want to add this bit of information. in my post above i was saying that writepixelfast doesn't work in fullscreen 16-bit. this is wrong as i checked, well, spotted what the reason is. in the Blitz3d version.txt file it says that a pixel by default has its alpha as full by default, which is why in 16-bit it wasn't working for me. the solution is to mask out the alpha channel with $FFFFFF. So the above code for reading pixels should be: xdim=256 : ydim=256 ;image dimension vars Dim Imagedata(xdim,ydim) ;size pixel array mypic=LoadImage(filename$) ;load a bmp DrawImage mypic,0,0 ;draw image LockBuffer For y=0 To ydim ;read x/y loop For x=0 To xdim Imagedata(x,y)=ReadPixelFast(x,y) And $FFFFFF ;<- mask out alpha value Next Next UnlockBuffer Cls ;clear image from screen |
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| I think he might be reading the image using a .dll for speed reasons. |
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| Thanks for your help. I managed through the posts on userlibs forum. |
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| Coppercircle was searching for a similar solution, could you show use how you did it? |
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| I used the method described in this thread : http://www.blitzbasic.com/Community/posts.php?topic=44333 I blit the Image buffer onto the DD surface using StrechDib or DrawDibDraw GDI functions. |
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