Need help c++ builder OpenPictureDialog error

Nielszz · 04-19-2005, 04:25 AM

Hello,

I have a problem i have builded some thing that can open pictures and load them into a TImage...

i can open *.bmp's and some more standards *.jpg and *.jpeg are in my filter list too but if i want to open them it crashes and say: "Project blablabla.exe raised an exception class EInvalidGraphic with message 'unknown file extension' (.jpg) process stopped....."

what can i do to load a jpg

thx already

redhead · 04-19-2005, 04:36 AM

I moved the thread, since this sounds like a API specific thing..
Are you sure your jpg decompression algorithm is correct ?
You do know that .bmp/.tif arent compressed, but .jpg are ?

Nielszz · 04-19-2005, 04:38 AM

Yes i did know that jpg is a compressed type of picture, i am still a noob in c++ sow i would not know what this means: "Are you sure your jpg decompression algorithm is correct"

but thx for the reply

redhead · 04-19-2005, 05:04 AM

When reading .bmp/.tiff you basicaly read a header, defining image size/color palete and the like, the rest of the image you just read in a steady stream, not much conversion/decompression of any kind, virtualy any imagelibrary provide buildin support for those kind.

With .jpg you read a header, telling image size, color palete, compression rate, and from that moment on you read a compressed image, here is a small representation:

Code:

    0 represents black
    1 represents white

Orriginal image:
     11111111000011111011111000000111
Compressed image:
     8x1;4x0;5x1;1x0;5x1;6x0;3x1

Thus when reading the image you won't read the lines of 1 and 0 and display as read, which you would with .bmp/.tiff, but instead you read the compressed portion, which is declared by the compression rate from the header.
If at some point the read algorithm isn't supporting the compresssion which the header tells it to use, you'd end up with an error like the one you describe.

Nielszz · 04-19-2005, 05:27 AM

Oke wait a sec i having some difficulties to read it, i dont understand it completly

Nielszz · 04-19-2005, 05:32 AM

Ok untill so far i understand but what can i do exactly to solve this problem...? i am very new in using borland c++ builder i tried to find some info in the help files but i didn't come up with anything...

DJMaze · 04-19-2005, 08:26 AM

You need to include/load the Borland vcljpgxx.lib file (where xx is your BCB version like vcljpg40 or vcljpg50)

Nielszz · 04-19-2005, 08:29 AM

Thx i will try....

Nielszz · 04-19-2005, 12:12 PM

how do i add something like that in c++ builder whats the line?

DJMaze · 04-19-2005, 04:03 PM

There are several ways.

1) Project -> Options -> Packages (tab) -> Build with runtime packages

2) Project -> Add to project

3) Open the .cpp

PHP Code:


			
#pragma link "C:/Program Files/Borland/CBuilder4/Lib/vcljpg40.lib"

Nielszz · 04-20-2005, 02:16 AM

I have tried but i noticed that i dont have a vcljpg60.lib on my hard disk and if i try to add a package ( vlcjpg60.bpl) it says that i already have the package because its standard in c++ builder the file (vlcjpg60.bpl is located at c:\windows\system32) but why cant i use ist???

it is realy getting enoying

Nielszz · 04-23-2005, 01:29 AM

Help anyone?

redhead · 04-23-2005, 11:19 AM

Sorry, I wanted to help if I could, but since I've never used Borland C++ builder I have no idear where this specific file might orriginate, or how to include it in your project.
Now if this had paned out in a matter of fixing a ANSI/ISO C++ reading algorithm then I'm here.. But with this API specific library routine, I'm out of options.

DJMaze · 04-23-2005, 12:44 PM

Try vcljpg60.bpl instead of .lib atleast one of them must exist