gflLoadBitmapFromMemory problem under linux ??

[tiboy08]

Hi,

I have a problem when loading a gflBitmap (from a standard unsigned char * buffer) using the gflLoadBitmapFromMemory function. The function call returns the error code 6 ("Unknown format") only under linux, under windows there is no problem ... I post the tested code below :

#include <iostream>
#include <libgfl.h>

void PgmRead(int & sx, int & sy, unsigned char ** buffer, const char * filename){

FILE * fic = fopen(filename, "rb");
fscanf(fic, "P5\n");
fscanf(fic, "%d %d\n", &sx, &sy);
fscanf(fic, "255\n");
(*buffer) = new unsigned char[sx*sy];
fread((*buffer), sizeof(unsigned char), sx*sy, fic);
fclose(fic);

}

int main(int argc, char ** argv){

gflLibraryInit();

unsigned char * image = 0;
int sx, sy;
PgmRead(sx, sy, &image, "test.pgm");

GFL_LOAD_PARAMS load_params;
gflGetDefaultLoadParams(&load_params);
load_params.FormatIndex = gflGetFormatIndexByName("raw");
load_params.Origin = GFL_TOP_LEFT;
load_params.Width = sx;
load_params.Height = sy;
load_params.Offset = 0;
load_params.ChannelOrder = GFL_CORDER_INTERLEAVED;
load_params.ChannelType = GFL_CTYPE_GREYSCALE;

GFL_BITMAP * bitmap = 0;
bitmap = gflAllockBitmap(GFL_GREY, sx, sy, 1, NULL);

std::cout << gflGetErrorString(gflLoadBitmapFromMemory(image, sx*sy, &bitmap, &load_params, NULL)) << std::endl;

gflLibraryExit();

return 0;

}

returns "Unknown format". Can you please give me some information about this problem ??

[xnview]

Why you don't load ppm data and use gflGetFormatIndexByName("ppm")?

[tiboy08]

Because, in my program (not in this little test code), the greyscale buffer is computed during by a previous step and is already in memory ....

[xnview]

Because, in my program (not in this little test code), the greyscale buffer is computed during by a previous step and is already in memory ....

So perhaps the better way is to create GFL_BITMAP structure, and to copy data only

[tiboy08]

Ok, so i create an GFL_BITMAP instance using the gflAllockBitmap function, then operate a memcpy on the GFL_BITMAP::Data ??

[xnview]

Ok, so i create an GFL_BITMAP instance using the gflAllockBitmap function, then operate a memcpy on the GFL_BITMAP::Data ??

yes, more simple

[tiboy08]

ok thank you, i will try this now ....

[tiboy08]

Ok, seems to work correctly now. Thank you !! I will contact you in case of further issues.

[tiboy08]

Ok, so the first problem is solved. But it remains one, i work on a image compression program so this is what I need to do :

1) compress an unsigned char * buffer in PNG format into a memory buffer (using GFL_BITMAP & gflSaveBitmapIntoMemory) (seems to work)
2) From the PNG bitstream, retrieve the original unsigned char * buffer using (gflLoadBitmapFromMemory) (produces segfault)

This is the resulting C++ code :

int main(int argc, char * argv[]){

gflLibraryInit();

unsigned char * image = 0;
unsigned char * imagePNG = 0;
unsigned int imagePNGSize = 0;
unsigned char * image_decomp = 0;

int sx, sy;
PgmRead(sx, sy, &image, "test.pgm");

GFL_SAVE_PARAMS save_params;
gflGetDefaultSaveParams(&save_params);
save_params.FormatIndex = gflGetFormatIndexByName("png");
save_params.Compression = GFL_NO_COMPRESSION;
save_params.CompressionLevel = 7;

GFL_LOAD_PARAMS load_params2;
gflGetDefaultLoadParams(&load_params2);
load_params2.FormatIndex = gflGetFormatIndexByName("png");
load_params2.Origin = GFL_TOP_LEFT;
load_params2.Width = sx;
load_params2.Height = sy;
load_params2.Offset = 0;
load_params2.ChannelOrder = GFL_CORDER_INTERLEAVED;
load_params2.ChannelType = GFL_CTYPE_GREYSCALE;


//Creating a bitmap for PNG compression into memory
GFL_BITMAP * bitmap = 0;
bitmap = gflAllockBitmap(GFL_GREY, sx, sy, 1, NULL);
bitmap->Data = new GFL_UINT8[sx*sy];
memcpy(bitmap->Data, image, sx*sy*sizeof(unsigned char));
gflSaveBitmapIntoMemory(&imagePNG, &imagePNGSize, bitmap, &save_params);

//Retrieve an unsigned char * buffer from the PNG bitstream
GFL_BITMAP * bitmap2 = 0;
bitmap2 = gflAllockBitmap(GFL_GREY, sx, sy, 1, NULL);
gflLoadBitmapFromMemory(imagePNG, imagePNGSize, &bitmap2, &load_params2, NULL); // ---> produces segfault

image_decomp = new unsigned char[sx*sy];
memcpy(image_decomp, bitmap2->Data, sx*sy*sizeof(unsigned char));

gflLibraryExit();

return 0;

}

[xnview]

No need to allocate bitmap before to load it

Code: Select all

bitmap2 = gflAllockBitmap(GFL_GREY, sx, sy, 1, NULL);

Do you use the last version?

[tiboy08]

Ok for the allocation, still resulting in seg fault. I use the version 3.40 of the library, is there a newer ?? Or is this bug not present in older versions ??

[tiboy08]

any clue ??

[xnview]

I've tried, but no crash

One thing

Code: Select all

bitmap = gflAllockBitmap(GFL_GREY, sx, sy, 1, NULL);
bitmap->Data = new GFL_UINT8[sx*sy];
memcpy(bitmap->Data, image, sx*sy*sizeof(unsigned char));
gflSaveBitmapIntoMemory(&imagePNG, &imagePNGSize, bitmap, &save_params);

No need to make a new, gflAllockBitmap allocate data

Could you send me PgmRead & test.pgm?

[tiboy08]

Here is my code for the test program with the .pgm test file ... Have you made the test under windows or linux ?? I'm using ubuntu 10.04 32bits ...

test_GFL.tar.gz

(219.02 KiB) Downloaded 140 times

[tiboy08]

Here is the stack trace from my debugger ...

stack-trace.jpeg (46.21 KiB) Viewed 2756 times