Thread: How to fix pointer?

This is my function:

Code:

int JPEG_read_file_rgb2hsv( unsigned char ** image_buffer, struct jpeg_decompress_struct * cDecompresInfo)
{
  JSAMPARRAY rows_buffer;  // Output row rows_buffer
  int row_stride_len;

  // @TODO: row_stride_len
  row_stride_len = 512;//*cDecompresInfo.output_width * cDecompresInfo.output_components;
  rows_buffer = (*(*cDecompresInfo).mem->alloc_sarray)
                ((j_common_ptr) &*cDecompresInfo, JPOOL_IMAGE, row_stride_len, 1);

  // 6) Initiate image_buffer
  size_t counter=0;
  size_t raw_size = row_stride_len;
  printf("raw size:%d\n",row_stride_len*
            ((*cDecompresInfo).output_height));
  *image_buffer = (unsigned char*) malloc( row_stride_len*
                                            ((*cDecompresInfo).output_height) );

  /******************************
            RGB 2 HSV
  ******************************/

  float R, G, B, H, S, V,min, max, delta;
  H=S=V=0;
  int t;

  while ((*cDecompresInfo).output_scanline < (*cDecompresInfo).output_height) {
    (void) jpeg_read_scanlines(&*cDecompresInfo, rows_buffer, 1);
    for( t=0; t<row_stride_len ; t=t+3)
        {
           R=(float) rows_buffer[0][t];
           G=(float) rows_buffer[0][t+1];
           B=(float) rows_buffer[0][t+2];
           min = (B < G) ? ((R < B) ? R : B) : (R < G ? R : G);
           max = (B > G) ? ((R > B) ? R : B) : (R > G ? R : G);
           V = max;
           delta = max - min;
           if( max != 0 )
                S = delta / max;
           else {
                S = 0;
                H = -1;
                continue;
            }

            if( R == max )
                H = ( G - B ) / delta;        // between yellow & magenta
            else if( G == max )
                H = 2 + ( B - R ) / delta;    // between cyan & yellow
            else
                H = 4 + ( R - G ) / delta;    // between magenta & cyan

            H *= 60;                // degrees
            if( H < 0 )
                H += 360;
// Must perform the conversion to 3 bytes data
// Is it exact?
            (*image_buffer)[counter+t]=(unsigned char)((H*100)/255);
            (*image_buffer)[counter+t+1]=(unsigned char)(S*100);
            (*image_buffer)[counter+t+2]=(unsigned char)V;
            }
    // memcpy(image_buffer+counter, rows_buffer[0], raw_size);
    counter += row_stride_len;
    // copyScanlineToBuffer(image_buffer, rows_buffer[0], row_stride_len); // args: & pointer & sample count
  }
  image_buffer -=row_stride_len;

  // Save global values for later use
  image_width=(*cDecompresInfo).image_width;
  image_height=(*cDecompresInfo).image_height;

  (void) jpeg_finish_decompress(&cDecompresInfo); // Finish decompression, no errors possible
  jpeg_destroy_decompress(&cDecompresInfo); // 8) Release JPEG decompression object
  // @TODO: infile
  // fclose(infile);
  return 1;
}

I am completing this function. Originally it used global variables, but I remade it to use a pointer to struct: struct jpeg_decompress_struct * cDecompresInfo;

Code:

(void) jpeg_finish_decompress(&cDecompresInfo);

now it crashes on the line, where the pointer is not fixed yet:

Code:

(void) jpeg_finish_decompress(&cDecompresInfo);

It's not clear how to correct. I tried &*cDecompresInfo or &(*cDecompresInfo) none of them works.
jpeg_finish_decompress want the struct to be dereferenced, but I have it via pointer. How to correct?

I also tried jpeg_finish_decompress(cDecompresInfo); but this crashes permanently.


Edit:
I added

Code:

fclose(infile);

But the problem with crashing

Code:

(void) jpeg_finish_decompress(cDecompresInfo);

stays

Note:
Original working code had:

Code:

 jpeg_finish_decompress(&cInfo)

OMG I got luck! I have found this:

https://github.com/freebasic/fbc/blo...inc/jpeglib.bi
See it for definitions of the types.

Code:

type j_common_ptr as jpeg_common_struct ptr
type j_compress_ptr as jpeg_compress_struct ptr
type j_decompress_ptr as jpeg_decompress_struct ptr

Now I changed the function headers like that:

Code:

int JPEG_read_file_rgb2hsv( FILE ** infile, unsigned char ** image_buffer, j_decompress_ptr cDecompresInfo)

I don't know why, now it crashes also here:

Code:

(void) jpeg_read_header(&*cDecompresInfo, TRUE);

in

Code:

bool JPEG_prepareInfo(char * filename, FILE ** infile, j_decompress_ptr cDecompresInfo)

I don't know how to fix it. The declaration with j_decompress_ptr did not work at all. I am returning back to

Code:

int  JPEG_read_file_rgb2hsv( FILE ** infile, unsigned char ** image_buffer,  struct jpeg_decompress_struct * cDecompresInfo)

Yarin,
why it does not work with pointer?
(void) jpeg_start_decompress(&*cDecompresInfo);
When I would remove it, so the object would stay in memory.

I call the function like so:

Code:

JPEG_prepareInfo(filename1, &fsource, &cinfo);
JPEG_read_file_rgb2hsv(&image_buffer, &fsource, &cinfo);
JPEG_write_file(filename2, 95, &image_buffer, &cinfo);

Main thing is to read data from file and then write data to file. In read the cinfo is filled with header data. I need the cinfo data in write function. That's why I have the cinfo in scope of main(). If I would move the code from JPEG_prepareInfo to JPEG_read_file_rgb2hsv so I would need to use global cinfo. That looks odd. I wanted to write code without global.

nonpuz:
this is alternative to the original code

Code:

struct jpeg_decompress_struct cinfo;
...
buffer = (*cinfo.mem->alloc_sarray)

But I changed
struct jpeg_decompress_struct

for
struct jpeg_decompress_struct *

Note:
*image_buffer contains something what I did not see there before:
(unsigned char *) 0x7c949564 <ntdll!LdrFindEntryForAddress+11013> "é\201ýü\377d\241\030"
it looks like bad address? This is just three lines before I try to destroy cDecompresInfo

I have fixed some mistakes
Paste ofCode
but the problem with

Code:

jpeg_destroy_decompress(cDecompresInfo);

remains unsolved

So verdict is that it is not possible to do that for any reason. I will do as you said. Wait.. Now I realized that I could destroy the object out of the scope of reading function. I can destroy it in main!

So I fixed some errors, move some function calls to main:
Paste ofCode
but it crashes again on the
jpeg_finish_decompress()
or
jpeg_finish_compress()

This is current version:
Paste ofCode

I really don't understand why it crashes when it is in the same scope. Do you have some final solution?

Sharp eye. Sp I move it after JPEG_write_file(). But it still crashes here. I'm clueless.

Code:

if (isOpen){
        JPEG_write_file(filename2, 95, &image_buffer, &cinfo);
        jpeg_finish_compress(&cinfo);
        jpeg_destroy_compress(&cinfo);
}

I clear cinfo (finish compress) in main (failed) and local cinfo in JPEG_write_file() (success).