With a little help from a friend... size of the image

[LordAdef]

Any good soul could help me out here. I need to get the width and height of an image, but I can reach the bitmap structure with what I got from searching the forum. Yep, very nooby.. but I really need to get this done quickly:

   inv CreateCompatibleDC,hdc
   mov hCpDC, eax   
   inv   LoadBitmap, hInstance,  IDB_CP
      
   inv SelectObject, hCpDC, eax

   lea edi, [ ???? +sizeof(BITMAPFILEHEADER)]
   mov ebx, BITMAPINFOHEADER.biWidth[edi]
   mov edx, BITMAPINFOHEADER.biHeight[edi]


I really thank any help
Cheers

[jj2007]

Try this:

Code Select Expand

  invoke GetCurrentObject, hDC, OBJ_BITMAP
  invoke GetObject, eax, BITMAP, addr bitmap
  print str$(bitmap.bmWidth), " is the width"

[mabdelouahab]

Code Select Expand

.data
bm BITMAP <>
.code
invoke GetObject, rv(LoadBitmap,rv(GetModuleHandle,0),IDB_CP),sizeof BITMAP, addr bm
printf("\n Width=%d,Height=%d ",bm.bmWidth,bm.bmHeight)



[dedndave]

similar to what Jochen suggested  :P

Code Select Expand

    LOCAL   hbmpCp      :HBITMAP
    LOCAL   bmpCp       :BITMAP

;------------------------------------------------

    INVOKE  LoadBitmap,hInstance,IDB_CP
    mov     hbmpCp,eax
    INVOKE  SelectObject,hCpDC,eax
    INVOKE  GetObject,hbmpCp,sizeof BITMAP,addr bmpCp

    mov     ecx,bmpCp.bmWidth               ;ECX = image width
    mov     edx,bmpCp.bmHeight              ;EDX = image height

GetObject function
https://msdn.microsoft.com/en-us/library/dd144904(v=vs.85).aspx

BITMAP structure
https://msdn.microsoft.com/en-us/library/dd183371(v=vs.85).aspx

GetObject returns information based on the type of handle that is passed
if you don't have the correct information size for that handle type, it will return error

[aw27]

That information is part of the file header.
So, you can use the Microsoft abstract and C++-inspired way or handling graphic files, SelectObject  GetObject, etc, or or can roll your sleeves and look directly learning something in the process.
There is an essay here:
http://masm32.com/board/index.php?topic=6733.0

[LordAdef]

Thanks guys, I really mean it!

It's working!


Hey aw27, I'm a rolling sleeves kind of guy! Sometimes, you learn a lot when you ask a question and people teach you the way, and you go from there.

Unfortunately I've got a son that needs extra care, along with my day job. Without such a help from you guys, I could never evolve in assembly (maybe I wouldn't even be coding).

[aw27]

Unfortunately I've got a son that needs extra care, along with my day job.

I have a large experience with that and my son related dramas are far from over.
What I meant with rolling the sleeves is "not be afraid of plunging in the dirty waters" as opposed to "not be afraid of working like a horse".

[LordAdef]

Unfortunately I've got a son that needs extra care, along with my day job.

I have a large experience with that and my son related dramas are far from over.
What I meant with rolling the sleeves is "not be afraid of plunging in the dirty waters" as opposed to "not be afraid of working like a horse".

Ok! Thanks

[daydreamer]

does it also work if you want to use a .jpg,.gif etc?
its easier to make something small with help of .jpgs, so I dont break the forum limit
I wonder if its possible to emulate old games that uses palette tricks, by Reading in a 8bit bitmap and change its palette data and use bitblt to output it?

[dedndave]

it can be done with a regular bitmap image
however, it is much easier to change the palette if you load the image as a DIB section
i have done this using 256-color images (not as effective with other types)

to load the image as a DIB section, use LoadImage with the LR_CREATEDIBSECTION flag

LoadImage
https://msdn.microsoft.com/en-us/library/ms648045(v=vs.85).aspx

then, in addition to using GetObject as mentioned before, you can use...

GetDIBColorTable
https://msdn.microsoft.com/en-us/library/dd144878(v=vs.85).aspx

SetDIBColorTable
https://msdn.microsoft.com/en-us/library/dd162972(v=vs.85).aspx

notice, that with a DIB section, GetObject may be used to fill either a BITMAP or a DIBSECTION structure

GetObject
https://msdn.microsoft.com/en-us/library/dd144904(v=vs.85).aspx

DIBSECTION
https://msdn.microsoft.com/en-us/library/dd183567%28v=vs.85%29.aspx

BITMAP
https://msdn.microsoft.com/en-us/library/dd183371%28v=vs.85%29.aspx

[dedndave]

by the way, JPG and GIF files are very different from BMP's
i don't know, LoadImage might support one or both (i doubt it)
if so, it will load the image as a bitmap, though
it always returns a handle to a bitmap

[jj2007]

by the way, JPG and GIF files are very different from BMP's
i don't know, LoadImage might support one or both (i doubt it)
if so, it will load the image as a bitmap, though
it always returns a handle to a bitmap

Right. I normally use GdipCreateBitmapFromStream, and it doesn't care what format the buffer provides. So GetObject works fine with JPG, PNG & friends.

[daydreamer]

by the way, JPG and GIF files are very different from BMP's
i don't know, LoadImage might support one or both (i doubt it)
if so, it will load the image as a bitmap, though
it always returns a handle to a bitmap

Right. I normally use GdipCreateBitmapFromStream, and it doesn't care what format the buffer provides. So GetObject works fine with JPG, PNG & friends.

thanks, thats what I was looking for, so I can start to port some java and load small jpgs
and after I get it working improve speed

[LordAdef]

AW27, so agora descobri que voce e Portugues! Maravilha saber.

[hutch--]

I confess to being very rusty with bitmaps but I am getting a weird result.

    invoke GetObject,hBitmap,SIZEOF BITMAP, ADDR bmp
    invoke MessageBox,hWnd,LastError$(),"LastError",MB_OK

    mov ecx, bmp.bmWidth
    mov edx, bmp.bmHeight

    invoke MessageBox,hWnd,str$(rcx),"Width",MB_OK
    invoke MessageBox,hWnd,str$(rdx),"Height",MB_OK


The width is correct but the height is wrong. The bitmap is 384 wide and 32 high but the results I am getting are respectively 384 and 100.

LATER : It helped not to overwrite EDX with the 1st messagebox call.  :P