gdi32.dll and ".jpg" dimensions

[honky]

Hello,
With gdi32.dll we can transform a: ".jpg" into: ".bmp"? good.
When I pass the mouse over a: ".jpg", Windows shows me its dimensions.
Does anyone know how to extract the dimensions of a: ".jpg" with gdi32.dll or other dll?

Another question:
If I put the: "gdi32.dll" in the ".bas" folder.
Will the "call" take the dll from the folder or will it take the one from: "system32"
Thank you for.

[Walt Decker]

gdi32.dll will NOT translate a jpg to a bmp. For that you need gdiplus.

Do not move windows dlls to different directories. You will confuse the search engine.

[honky]

Is it possible to have the dimensions of a: ".jpg" with: "gdiplus"
And if yes, how ?
I conclude that it is useless to put the ".dll" in the ".bas" folder
It's not a deplacment it's a copy

[Walt Decker]

Is it possible to have the dimensions of a: ".jpg" with: "gdiplus"
And if yes, how ?

Yes, but for what purpose? Windows does not work with image formats other than BMP so you might as well translate the other format to bmp and get the size from that, then you can work with the result.

[tsh73]

There probably an API way of getting JPG dimensions
but I found non-API way on stackOverflow
and translated it to native LB.
Here it is (put in DATA section some real Jpegs, I just saved some from Paint):
1000x10.jpg   1000 x 10 pixels
10x1000.jpg   10 x 1000 pixels
10x20.bmp     Likely not a Jpeg file!
10x20.jpg     10 x 20 pixels
40000x10.jpg  40000 x 10 pixels
photo355x474.jpg            355 x 474 pixels
photo355x474bw.jpg          355 x 474 pixels, greyscale


'reading jpeg size from jpeg file, without library
'translation of C code from
' https://stackoverflow.com/questions/2517854/getting-image-size-of-jpeg-from-its-binary

data "1000x10.jpg"
data "10x1000.jpg"
data "10x20.bmp"
data "10x20.jpg"
data "40000x10.jpg"
data "photo355x474.jpg"
data "photo355x474bw.jpg"
data "XYZZY"

read fileName$
do
print fileName$,
res$=getJpegProps$(fileName$)
'print res$
if word$(res$, 4)="0" then
print "Likely not a Jpeg file!"
else
print word$(res$, 1) ;" x "; word$(res$, 2) ; " pixels";
if word$(res$, 4) ="1" then print ", grayscale";
print 'finally break that line
end if
read fileName$
loop until fileName$="XYZZY"

'----------------------------------------------------
function getJpegProps$(fileName$)
' ret$= w;" "; h;" "; bpc;" ";cps
' so word$(getJpegProps$(fileName$),1) , width in pixels, (,2) height, (,3) is bits per channel,
' (,4) is color components (3 is color, 1 is grayscale)

open fileName$ for binary as #1
dataLength = lof(#1)
data$=input$(#1, dataLength)
close #1
getJpegProps$ ="0 0 0 0"
if mid$(data$,7,4)<>"JFIF" then exit function 'likely not a Jpeg file!

off = 1 'BASIC numbers characters from 1
'some constants
Oxff=hexdec("ff")
Oxd0=hexdec("d0")
Oxd7=hexdec("d7")
Oxd8=hexdec("d8")
Oxd9=hexdec("d9")
Ox01=hexdec("01")
Oxc0=hexdec("c0")

while (off<=dataLength)
while(asc(mid$(data$,off,1))=Oxff)
off=off+1
wend
mrkr = asc(mid$(data$,off,1)):off=off+1
if(mrkr=Oxd8) then [continue]    '// SOI
if(mrkr=Oxd9) then exit while     '// EOI
if(Oxd0<=mrkr AND mrkr<=Oxd7) then [continue]
if(mrkr=Ox01) then [continue]   '// TEM

secLen = asc(mid$(data$,off,1))*256 + asc(mid$(data$,off+1,1))  
off=off+2
if(mrkr=Oxc0) then
bpc = asc(mid$(data$,off,1))  '// precission (bits per channel)
h = asc(mid$(data$,off+1,1))*256 + asc(mid$(data$,off+2,1))  
w = asc(mid$(data$,off+3,1))*256 + asc(mid$(data$,off+4,1))  
cps = asc(mid$(data$,off+5,1)) '// number of color components
'ret$=bpc;" "; h;" "; w;" "; cps
ret$= w;" "; h;" "; bpc;" ";cps
'print ret$
getJpegProps$ = ret$
'end
exit function
end if
off=off+secLen-2

[continue]
wend

end function

'sorce C code
' https://stackoverflow.com/questions/2517854/getting-image-size-of-jpeg-from-its-binary

' function jpegProps(data$) {          // data$ is an array of bytes
   ' var off = 0;
   ' while(off<data$.length) {
       ' while(data$[off]==0xff) off++;
       ' var mrkr = data$[off];  off++;
       
       ' if(mrkr==0xd8) continue;    // SOI
       ' if(mrkr==0xd9) break;       // EOI
       ' if(0xd0<=mrkr && mrkr<=0xd7) continue;
       ' if(mrkr==0x01) continue;    // TEM
       
       ' var len = (data$[off]<<8) | data$[off+1];  off+=2;  
       
       ' if(mrkr==0xc0) return {
           ' bpc : data$[off],     // precission (bits per channel)
           ' h   : (data$[off+1]<<8) | data$[off+2],
           ' w   : (data$[off+3]<<8) | data$[off+4],
           ' cps : data$[off+5]    // number of color components
       ' }
       ' off+=len-2;
   ' }
' }


[honky]

Oh yess it'work !

[Rod]

It is actually all in the LBPE. Janet's code will load any image then get its dimensions and other info.

alycesrestaurant.com/lbpe/APIGettingImageInformation.html

[honky]

@ tsh73: Thank you for your code
@ Rod: Thank you for the link
I have everything I need to transform from: ".jpg" to: ".bmp", on the fly.
This will make to considerably lighten the image files.
And opens up great prospects for games.

[Rod]

Unfortunately .jpg are pretty useless for games. Especially if you have to mask an image. The .jpg never leaves your graphics alone it always reduces color or recolors pixels to help reduce storage. You will find that for sprites and for transparent blitting that there is nothing better than pixel perfect .bmps that hold their color. Transparency and sprite masking relies on perfect black or masking color placement.

The LBPE has a short tutorial on blitting, alycesrestaurant.com/lbpe/Fun%20with%20the%20blitter.html

You will need this .bmp gamebin.webs.com/Ocean.bmp

[honky]

I did a test with a ".jpg" transformed into: ".bmp", and from: ".bmp" I made a sprite.
And it works great for all sizes.
The goal is to be able to integrate a lot of images or large images in a game, without the whole thing weighing megatons.