Comparing 2 files.

BlitzMax Forums/BlitzMax Beginners Area/Comparing 2 files.

Thareh

(Posted 2010) [#1]

Hi,
I've loaded alot of small tile images into the memory and I want to compare them to each other to remove any duplicates.
I'm looping through them, but I have no idea on how to compare these 2 memory blocks to each other so to speak :P
Any idea on how I'd do this? :O
Thanks! :D

Zeke	(Posted 2010) [#2]

SuperStrict

Extern "C"
	Function memcmp:Int(First:Byte Ptr, second:Byte Ptr, bytecount:Int)
End extern

Local img1:TImage = LoadImage("test1.png")
Local img2:TImage = LoadImage("test2.png")

Local pix1:TPixmap = LockImage(img1)
Local pix2:TPixmap = LockImage(img2)

If memcmp(pix1.Pixels, pix2.Pixels, Max(pix1.Capacity, pix2.Capacity)) = 0 Then
	Print "pixels match!"
Else
	Print "No match!"
End If

UnlockImage(img1)
UnlockImage(img2)

Thareh

(Posted 2010) [#3]

Thanks Zeke! :)
This is Win only or?
I'd prefer a non-extern way of doing this aswell if there is one :O

Zeke	(Posted 2010) [#4]

memcmp is standard c-command so this is not windows only.
and using extern i think this is the easiest way to compare memory blocks.. this command should be added to bmax, because bmax have MemAlloc,MemCopy etc commands.

Thareh

(Posted 2010) [#5]

Okey, Great! :)
It works like a charm, Thanks alot Zeke!

chimaera

(Posted 2010) [#6]

Hmmm...I know I kinda missed the train here but I am using a different approach when using lots of tiles using the same image to save memory.

The image is probably connected to a type which contains an image like this:


type Ttile
   field image:Timage
   field posX:int
   field posY:int

   function create:Ttile(image:Ttimage,X:int,Y:int)
      local tile:TTile = new Ttile
      tile.image=image
      posX=x
      posY=y
      return tile
  end function
end type

If you know that you will have many tiles that uses the same image, instead of loading the image again, which will allocate more memory, it's better to use a templateimage that you only load once.

Global templateImage:Timage = loadimage(myimage)

tile1:TType = Ttype.create(templateImage,0,0)
tile2:TType = Ttype.create(templateImage,64,0)
tile3:TType = Ttype.create(templateImage,128,0)
tile4:TType = Ttype.create(templateImage,192,0)

Just remember that if you delete templateimage the game/app will crash since the other instances is pointing towards templateimage.