fix icc warnings about shadowed variables and mismatching printf format

[wxWidgets.git] / src / common / imagjpeg.cpp

diff --git a/src/common/imagjpeg.cpp b/src/common/imagjpeg.cpp
index f36b632c7f08fb4904d7afbc72b201d491a9197d..d045596065270a56b7da4401918e00eb83abd49c 100644 (file)
--- a/src/common/imagjpeg.cpp
+++ b/src/common/imagjpeg.cpp
@@ -1,180 +1,349 @@
 /////////////////////////////////////////////////////////////////////////////
 /////////////////////////////////////////////////////////////////////////////

-// Name:        imagjpeg.cpp
+// Name:        src/common/imagjpeg.cpp

 // Purpose:     wxImage JPEG handler
 // Purpose:     wxImage JPEG handler

-// Author:      Robert Roebling
+// Author:      Vaclav Slavik

 // RCS-ID:      $Id$
 // RCS-ID:      $Id$

-// Copyright:   (c) Robert Roebling
+// Copyright:   (c) Vaclav Slavik

 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 

-#ifdef __GNUG__
-#pragma implementation "image.h"
-#endif
-

 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
 #ifdef __BORLANDC__
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
 #ifdef __BORLANDC__

-#pragma hdrstop
+    #pragma hdrstop
+#endif
+
+#if wxUSE_IMAGE && wxUSE_LIBJPEG
+
+#include "wx/imagjpeg.h"
+
+#ifndef WX_PRECOMP
+    #include "wx/log.h"
+    #include "wx/app.h"
+    #include "wx/intl.h"
+    #include "wx/bitmap.h"
+    #include "wx/module.h"

 #endif
 
 #endif
 

-#include "wx/image.h"
-#include "wx/bitmap.h"
-#include "wx/debug.h"
-#include "wx/log.h"
-#include "wx/app.h"
-#if wxUSE_LIBJPEG
-extern "C" {
-#include <jpeglib.h>
+// A hack based on one from tif_jpeg.c to overcome the problem on Windows
+// of rpcndr.h defining boolean with a different type to the jpeg headers.
+// 
+// This hack is only necessary for an external jpeg library, the builtin one
+// usually used on Windows doesn't use the type boolean, so always works.
+//
+#ifdef wxHACK_BOOLEAN
+    #define HAVE_BOOLEAN
+    #define boolean wxHACK_BOOLEAN
+#endif
+
+extern "C"
+{
+    #if defined(__WXMSW__)
+        #define XMD_H
+    #endif
+    #include "jpeglib.h"

 }
 }

+
+#ifndef HAVE_WXJPEG_BOOLEAN
+typedef boolean wxjpeg_boolean;

 #endif
 #endif

+

 #include "wx/filefn.h"
 #include "wx/wfstream.h"
 #include "wx/filefn.h"
 #include "wx/wfstream.h"

-#include "wx/intl.h"
-#include "wx/module.h"

 
 // For memcpy
 #include <string.h>
 
 // For memcpy
 #include <string.h>

+// For JPEG library error handling
+#include <setjmp.h>

 
 #ifdef __SALFORDC__
 
 #ifdef __SALFORDC__

-#ifdef FAR

 #undef FAR
 #endif
 #undef FAR
 #endif

-#endif

 
 

-#ifdef __WXMSW__
-#include <windows.h>
+// ----------------------------------------------------------------------------
+// types
+// ----------------------------------------------------------------------------
+
+// the standard definition of METHODDEF(type) from jmorecfg.h is "static type"
+// which means that we can't declare the method functions as extern "C" - the
+// compiler (rightfully) complains about the multiple storage classes in
+// declaration
+//
+// so we only add extern "C" when using our own, modified, jmorecfg.h - and use
+// whatever we have in the system headers if this is what we use hoping that it
+// should be ok (can't do anything else)
+#ifdef JPEG_METHOD_LINKAGE
+    #define CPP_METHODDEF(type) extern "C" METHODDEF(type)
+#else // not using our jmorecfg.h header
+    #define CPP_METHODDEF(type) METHODDEF(type)

 #endif
 
 //-----------------------------------------------------------------------------
 // wxJPEGHandler
 //-----------------------------------------------------------------------------
 
 #endif
 
 //-----------------------------------------------------------------------------
 // wxJPEGHandler
 //-----------------------------------------------------------------------------
 

-#if wxUSE_LIBJPEG
-
-#if !USE_SHARED_LIBRARIES

 IMPLEMENT_DYNAMIC_CLASS(wxJPEGHandler,wxImageHandler)
 IMPLEMENT_DYNAMIC_CLASS(wxJPEGHandler,wxImageHandler)

-#endif

 
 #if wxUSE_STREAMS
 
 
 #if wxUSE_STREAMS
 

-

 //------------- JPEG Data Source Manager
 
 //------------- JPEG Data Source Manager
 

+#define JPEG_IO_BUFFER_SIZE   2048
+

 typedef struct {
     struct jpeg_source_mgr pub;   /* public fields */
 typedef struct {
     struct jpeg_source_mgr pub;   /* public fields */

-    
+

     JOCTET* buffer;               /* start of buffer */
     JOCTET* buffer;               /* start of buffer */

-} my_source_mgr;
+    wxInputStream *stream;
+} wx_source_mgr;

 
 

-typedef my_source_mgr * my_src_ptr;
+typedef wx_source_mgr * wx_src_ptr;

 
 

-METHODDEF(void) my_init_source ( j_decompress_ptr cinfo )
+extern "C"
+{
+
+CPP_METHODDEF(void) wx_init_source ( j_decompress_ptr WXUNUSED(cinfo) )

 {
 }
 
 {
 }
 

-METHODDEF(boolean) my_fill_input_buffer ( j_decompress_ptr cinfo )
+CPP_METHODDEF(wxjpeg_boolean) wx_fill_input_buffer ( j_decompress_ptr cinfo )

 {
 {

+    wx_src_ptr src = (wx_src_ptr) cinfo->src;
+
+    src->pub.next_input_byte = src->buffer;
+    src->pub.bytes_in_buffer = src->stream->Read(src->buffer, JPEG_IO_BUFFER_SIZE).LastRead();
+
+    if (src->pub.bytes_in_buffer == 0) // check for end-of-stream
+    {
+        // Insert a fake EOI marker
+        src->buffer[0] = 0xFF;
+        src->buffer[1] = JPEG_EOI;
+        src->pub.bytes_in_buffer = 2;
+    }

     return TRUE;
 }
 
     return TRUE;
 }
 

-METHODDEF(void) my_skip_input_data ( j_decompress_ptr cinfo, long num_bytes )
+CPP_METHODDEF(void) wx_skip_input_data ( j_decompress_ptr cinfo, long num_bytes )

 {
 {

-    my_src_ptr src = (my_src_ptr) cinfo->src;
-    
-    src->pub.next_input_byte += (size_t) num_bytes;
-    src->pub.bytes_in_buffer -= (size_t) num_bytes;
+    if (num_bytes > 0)
+    {
+        wx_src_ptr src = (wx_src_ptr) cinfo->src;
+
+        while (num_bytes > (long)src->pub.bytes_in_buffer)
+        {
+            num_bytes -= (long) src->pub.bytes_in_buffer;
+            src->pub.fill_input_buffer(cinfo);
+        }
+        src->pub.next_input_byte += (size_t) num_bytes;
+        src->pub.bytes_in_buffer -= (size_t) num_bytes;
+    }
+}
+
+CPP_METHODDEF(void) wx_term_source ( j_decompress_ptr cinfo )
+{
+    wx_src_ptr src = (wx_src_ptr) cinfo->src;
+
+    if (src->pub.bytes_in_buffer > 0)
+        src->stream->SeekI(-(long)src->pub.bytes_in_buffer, wxFromCurrent);
+    delete[] src->buffer;
+}
+
+
+// JPEG error manager:
+
+struct wx_error_mgr {
+  struct jpeg_error_mgr pub;    /* "public" fields */
+
+  jmp_buf setjmp_buffer;    /* for return to caller */
+};
+
+typedef struct wx_error_mgr * wx_error_ptr;
+
+/*
+ * Here's the routine that will replace the standard error_exit method:
+ */
+
+CPP_METHODDEF(void) wx_error_exit (j_common_ptr cinfo)
+{
+  /* cinfo->err really points to a wx_error_mgr struct, so coerce pointer */
+  wx_error_ptr myerr = (wx_error_ptr) cinfo->err;
+
+  /* Always display the message. */
+  /* We could postpone this until after returning, if we chose. */
+  (*cinfo->err->output_message) (cinfo);
+
+  /* Return control to the setjmp point */
+  longjmp(myerr->setjmp_buffer, 1);

 }
 
 }
 

-METHODDEF(void) my_term_source ( j_decompress_ptr cinfo )
+/*
+ * This will replace the standard output_message method when the user
+ * wants us to be silent (verbose==false). We must have such method instead of
+ * simply using NULL for cinfo->err->output_message because it's called
+ * unconditionally from within libjpeg when there's "garbage input".
+ */
+CPP_METHODDEF(void) wx_ignore_message (j_common_ptr WXUNUSED(cinfo))

 {
 {

-    my_src_ptr src = (my_src_ptr) cinfo->src;
-    
-    free (src->buffer);

 }
 
 }
 

-void jpeg_wxio_src( j_decompress_ptr cinfo, wxInputStream& infile )
+void wx_jpeg_io_src( j_decompress_ptr cinfo, wxInputStream& infile )

 {
 {

-    my_src_ptr src;
-    
-    if (cinfo->src == NULL) {  /* first time for this JPEG object? */
+    wx_src_ptr src;
+
+    if (cinfo->src == NULL) {    /* first time for this JPEG object? */

         cinfo->src = (struct jpeg_source_mgr *)
             (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
         cinfo->src = (struct jpeg_source_mgr *)
             (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,

-            sizeof(my_source_mgr));
-        src = (my_src_ptr) cinfo->src;
+            sizeof(wx_source_mgr));

     }
     }

-    src = (my_src_ptr) cinfo->src;
-    src->pub.bytes_in_buffer = infile.StreamSize(); /* forces fill_input_buffer on first read */
-    src->buffer = (JOCTET *) malloc (infile.StreamSize());
-    src->pub.next_input_byte = src->buffer; /* until buffer loaded */
-    infile.Read(src->buffer, infile.StreamSize());
-    
-    src->pub.init_source = my_init_source;
-    src->pub.fill_input_buffer = my_fill_input_buffer;
-    src->pub.skip_input_data = my_skip_input_data;
+    src = (wx_src_ptr) cinfo->src;
+    src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
+    src->buffer = new JOCTET[JPEG_IO_BUFFER_SIZE];
+    src->pub.next_input_byte = NULL; /* until buffer loaded */
+    src->stream = &infile;
+
+    src->pub.init_source = wx_init_source;
+    src->pub.fill_input_buffer = wx_fill_input_buffer;
+    src->pub.skip_input_data = wx_skip_input_data;

     src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
     src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */

-    src->pub.term_source = my_term_source;
+    src->pub.term_source = wx_term_source;

 }
 
 }
 

+} // extern "C"

 
 

+static inline void wx_cmyk_to_rgb(unsigned char* rgb, const unsigned char* cmyk)
+{
+    register int k = 255 - cmyk[3];
+    register int k2 = cmyk[3];
+    register int c;
+
+    c = k + k2 * (255 - cmyk[0]) / 255;
+    rgb[0] = (unsigned char)((c > 255) ? 0 : (255 - c));
+
+    c = k + k2 * (255 - cmyk[1]) / 255;
+    rgb[1] = (unsigned char)((c > 255) ? 0 : (255 - c));
+
+    c = k + k2 * (255 - cmyk[2]) / 255;
+    rgb[2] = (unsigned char)((c > 255) ? 0 : (255 - c));
+}

 
 

-bool wxJPEGHandler::LoadFile( wxImage *image, wxInputStream& stream )
+// temporarily disable the warning C4611 (interaction between '_setjmp' and
+// C++ object destruction is non-portable) - I don't see any dtors here
+#ifdef __VISUALC__
+    #pragma warning(disable:4611)
+#endif /* VC++ */
+
+bool wxJPEGHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbose, int WXUNUSED(index) )

 {
     struct jpeg_decompress_struct cinfo;
 {
     struct jpeg_decompress_struct cinfo;

-    struct jpeg_error_mgr jerr;
-    JSAMPARRAY tempbuf;
+    struct wx_error_mgr jerr;

     unsigned char *ptr;
     unsigned char *ptr;

-    unsigned stride;
-    
+

     image->Destroy();
     image->Destroy();

-    cinfo.err = jpeg_std_error( &jerr );
+    cinfo.err = jpeg_std_error( &jerr.pub );
+    jerr.pub.error_exit = wx_error_exit;
+
+    if (!verbose)
+        cinfo.err->output_message = wx_ignore_message;
+
+    /* Establish the setjmp return context for wx_error_exit to use. */
+    if (setjmp(jerr.setjmp_buffer)) {
+      /* If we get here, the JPEG code has signaled an error.
+       * We need to clean up the JPEG object, close the input file, and return.
+       */
+      if (verbose)
+        wxLogError(_("JPEG: Couldn't load - file is probably corrupted."));
+      (cinfo.src->term_source)(&cinfo);
+      jpeg_destroy_decompress(&cinfo);
+      if (image->Ok()) image->Destroy();
+      return false;
+    }
+

     jpeg_create_decompress( &cinfo );
     jpeg_create_decompress( &cinfo );

-    jpeg_wxio_src( &cinfo, stream );
+    wx_jpeg_io_src( &cinfo, stream );

     jpeg_read_header( &cinfo, TRUE );
     jpeg_read_header( &cinfo, TRUE );

-    cinfo.out_color_space = JCS_RGB;
+
+    int bytesPerPixel;
+    if ((cinfo.out_color_space == JCS_CMYK) || (cinfo.out_color_space == JCS_YCCK))
+    {
+        cinfo.out_color_space = JCS_CMYK;
+        bytesPerPixel = 4;
+    }
+    else // all the rest is treated as RGB
+    {
+        cinfo.out_color_space = JCS_RGB;
+        bytesPerPixel = 3;
+    }
+

     jpeg_start_decompress( &cinfo );
     jpeg_start_decompress( &cinfo );

-    
+

     image->Create( cinfo.image_width, cinfo.image_height );
     if (!image->Ok()) {
         jpeg_finish_decompress( &cinfo );
         jpeg_destroy_decompress( &cinfo );
     image->Create( cinfo.image_width, cinfo.image_height );
     if (!image->Ok()) {
         jpeg_finish_decompress( &cinfo );
         jpeg_destroy_decompress( &cinfo );

-        return FALSE;
+        return false;

     }
     }

-    image->SetMask( FALSE );
+    image->SetMask( false );

     ptr = image->GetData();
     ptr = image->GetData();

-    stride = cinfo.output_width * 3;
-    tempbuf = (*cinfo.mem->alloc_sarray)
-        ((j_common_ptr) &cinfo, JPOOL_IMAGE, stride, 1 );
-    
-    while ( cinfo.output_scanline < cinfo.output_height ) {
+
+    unsigned stride = cinfo.output_width * bytesPerPixel;
+    JSAMPARRAY tempbuf = (*cinfo.mem->alloc_sarray)
+                            ((j_common_ptr) &cinfo, JPOOL_IMAGE, stride, 1 );
+
+    while ( cinfo.output_scanline < cinfo.output_height )
+    {

         jpeg_read_scanlines( &cinfo, tempbuf, 1 );
         jpeg_read_scanlines( &cinfo, tempbuf, 1 );

-        memcpy( ptr, tempbuf[0], stride );
-        ptr += stride;
+        if (cinfo.out_color_space == JCS_RGB)
+        {
+            memcpy( ptr, tempbuf[0], stride );
+            ptr += stride;
+        }
+        else // CMYK
+        {
+            const unsigned char* inptr = (const unsigned char*) tempbuf[0];
+            for (size_t i = 0; i < cinfo.output_width; i++)
+            {
+                wx_cmyk_to_rgb(ptr, inptr);
+                ptr += 3;
+                inptr += 4;
+            }
+        }

     }
     }

-    jpeg_finish_decompress( &cinfo );
-    jpeg_destroy_decompress( &cinfo );
-    return TRUE;
-}
-

 
 

+    // set up resolution if available: it's part of optional JFIF APP0 chunk
+    if ( cinfo.saw_JFIF_marker )
+    {
+        image->SetOption(wxIMAGE_OPTION_RESOLUTIONX, cinfo.X_density);
+        image->SetOption(wxIMAGE_OPTION_RESOLUTIONY, cinfo.Y_density);

 
 

+        // we use the same values for this option as libjpeg so we don't need
+        // any conversion here
+        image->SetOption(wxIMAGE_OPTION_RESOLUTIONUNIT, cinfo.density_unit);
+    }

 
 

+    jpeg_finish_decompress( &cinfo );
+    jpeg_destroy_decompress( &cinfo );
+    return true;
+}

 
 typedef struct {
     struct jpeg_destination_mgr pub;
 
 typedef struct {
     struct jpeg_destination_mgr pub;

-    
+

     wxOutputStream *stream;
     JOCTET * buffer;
     wxOutputStream *stream;
     JOCTET * buffer;

-} my_destination_mgr;
+} wx_destination_mgr;

 
 

-typedef my_destination_mgr * my_dest_ptr;
+typedef wx_destination_mgr * wx_dest_ptr;

 
 

-#define OUTPUT_BUF_SIZE  4096  /* choose an efficiently fwrite'able size */
+#define OUTPUT_BUF_SIZE  4096    /* choose an efficiently fwrite'able size */

 
 

-METHODDEF(void) init_destination (j_compress_ptr cinfo)
+extern "C"

 {
 {

-    my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
-    
+
+CPP_METHODDEF(void) wx_init_destination (j_compress_ptr cinfo)
+{
+    wx_dest_ptr dest = (wx_dest_ptr) cinfo->dest;
+

     /* Allocate the output buffer --- it will be released when done with image */
     dest->buffer = (JOCTET *)
         (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
     /* Allocate the output buffer --- it will be released when done with image */
     dest->buffer = (JOCTET *)
         (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,


@@ -183,62 +352,104 @@ METHODDEF(void) init_destination (j_compress_ptr cinfo)
     dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
 }
 
     dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
 }
 

-METHODDEF(boolean) empty_output_buffer (j_compress_ptr cinfo)
+CPP_METHODDEF(wxjpeg_boolean) wx_empty_output_buffer (j_compress_ptr cinfo)

 {
 {

-    my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
-    
+    wx_dest_ptr dest = (wx_dest_ptr) cinfo->dest;
+

     dest->stream->Write(dest->buffer, OUTPUT_BUF_SIZE);
     dest->pub.next_output_byte = dest->buffer;
     dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
     return TRUE;
 }
 
     dest->stream->Write(dest->buffer, OUTPUT_BUF_SIZE);
     dest->pub.next_output_byte = dest->buffer;
     dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
     return TRUE;
 }
 

-METHODDEF(void) term_destination (j_compress_ptr cinfo)
+CPP_METHODDEF(void) wx_term_destination (j_compress_ptr cinfo)

 {
 {

-    my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
+    wx_dest_ptr dest = (wx_dest_ptr) cinfo->dest;

     size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
     /* Write any data remaining in the buffer */
     if (datacount > 0)
         dest->stream->Write(dest->buffer, datacount);
 }
 
     size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
     /* Write any data remaining in the buffer */
     if (datacount > 0)
         dest->stream->Write(dest->buffer, datacount);
 }
 

-GLOBAL(void) jpeg_wxio_dest (j_compress_ptr cinfo, wxOutputStream& outfile)
+GLOBAL(void) wx_jpeg_io_dest (j_compress_ptr cinfo, wxOutputStream& outfile)

 {
 {

-    my_dest_ptr dest;
-    
-    if (cinfo->dest == NULL) { /* first time for this JPEG object? */
+    wx_dest_ptr dest;
+
+    if (cinfo->dest == NULL) {    /* first time for this JPEG object? */

         cinfo->dest = (struct jpeg_destination_mgr *)
             (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
         cinfo->dest = (struct jpeg_destination_mgr *)
             (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,

-            sizeof(my_destination_mgr));
+            sizeof(wx_destination_mgr));

     }
     }

-    
-    dest = (my_dest_ptr) cinfo->dest;
-    dest->pub.init_destination = init_destination;
-    dest->pub.empty_output_buffer = empty_output_buffer;
-    dest->pub.term_destination = term_destination;
+
+    dest = (wx_dest_ptr) cinfo->dest;
+    dest->pub.init_destination = wx_init_destination;
+    dest->pub.empty_output_buffer = wx_empty_output_buffer;
+    dest->pub.term_destination = wx_term_destination;

     dest->stream = &outfile;
 }
 
     dest->stream = &outfile;
 }
 

-bool wxJPEGHandler::SaveFile( wxImage *image, wxOutputStream& stream )
+} // extern "C"
+
+bool wxJPEGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbose )

 {
     struct jpeg_compress_struct cinfo;
 {
     struct jpeg_compress_struct cinfo;

-    struct jpeg_error_mgr jerr;
-    JSAMPROW row_pointer[1];   /* pointer to JSAMPLE row[s] */
+    struct wx_error_mgr jerr;
+    JSAMPROW row_pointer[1];    /* pointer to JSAMPLE row[s] */

     JSAMPLE *image_buffer;
     JSAMPLE *image_buffer;

-    int stride;                        /* physical row width in image buffer */
-    
-    cinfo.err = jpeg_std_error(&jerr);
+    int stride;                /* physical row width in image buffer */
+
+    cinfo.err = jpeg_std_error(&jerr.pub);
+    jerr.pub.error_exit = wx_error_exit;
+
+    if (!verbose)
+        cinfo.err->output_message = wx_ignore_message;
+
+    /* Establish the setjmp return context for wx_error_exit to use. */
+    if (setjmp(jerr.setjmp_buffer))
+    {
+        /* If we get here, the JPEG code has signaled an error.
+         * We need to clean up the JPEG object, close the input file, and return.
+         */
+         if (verbose)
+            wxLogError(_("JPEG: Couldn't save image."));
+         jpeg_destroy_compress(&cinfo);
+         return false;
+    }
+

     jpeg_create_compress(&cinfo);
     jpeg_create_compress(&cinfo);

-    jpeg_wxio_dest(&cinfo, stream);
-    
+    wx_jpeg_io_dest(&cinfo, stream);
+

     cinfo.image_width = image->GetWidth();
     cinfo.image_height = image->GetHeight();
     cinfo.input_components = 3;
     cinfo.in_color_space = JCS_RGB;
     jpeg_set_defaults(&cinfo);
     cinfo.image_width = image->GetWidth();
     cinfo.image_height = image->GetHeight();
     cinfo.input_components = 3;
     cinfo.in_color_space = JCS_RGB;
     jpeg_set_defaults(&cinfo);

+
+    // TODO: 3rd parameter is force_baseline, what value should this be?
+    // Code says: "If force_baseline is TRUE, the computed quantization table entries
+    // are limited to 1..255 for JPEG baseline compatibility."
+    // 'Quality' is a number between 0 (terrible) and 100 (very good).
+    // The default (in jcparam.c, jpeg_set_defaults) is 75,
+    // and force_baseline is TRUE.
+    if (image->HasOption(wxIMAGE_OPTION_QUALITY))
+        jpeg_set_quality(&cinfo, image->GetOptionInt(wxIMAGE_OPTION_QUALITY), TRUE);
+
+    // set the resolution fields in the output file
+    int resX, resY;
+    wxImageResolution res = GetResolutionFromOptions(*image, &resX, &resY);
+    if ( res != wxIMAGE_RESOLUTION_NONE )
+    {
+        cinfo.X_density = resX;
+        cinfo.Y_density = resY;
+
+        // it so happens that wxIMAGE_RESOLUTION_INCHES/CM values are the same
+        // ones as used by libjpeg, so we can assign them directly
+        cinfo.density_unit = res;
+    }
+

     jpeg_start_compress(&cinfo, TRUE);
     jpeg_start_compress(&cinfo, TRUE);

-    
-    stride = cinfo.image_width * 3;    /* JSAMPLEs per row in image_buffer */
+
+    stride = cinfo.image_width * 3;    /* JSAMPLEs per row in image_buffer */

     image_buffer = image->GetData();
     while (cinfo.next_scanline < cinfo.image_height) {
         row_pointer[0] = &image_buffer[cinfo.next_scanline * stride];
     image_buffer = image->GetData();
     while (cinfo.next_scanline < cinfo.image_height) {
         row_pointer[0] = &image_buffer[cinfo.next_scanline * stride];


@@ -246,12 +457,24 @@ bool wxJPEGHandler::SaveFile( wxImage *image, wxOutputStream& stream )
     }
     jpeg_finish_compress(&cinfo);
     jpeg_destroy_compress(&cinfo);
     }
     jpeg_finish_compress(&cinfo);
     jpeg_destroy_compress(&cinfo);

-    
-    return TRUE;
+
+    return true;

 }
 }

-#endif // wxUSE_STREAMS

 
 

-#endif
+#ifdef __VISUALC__
+    #pragma warning(default:4611)
+#endif /* VC++ */
+
+bool wxJPEGHandler::DoCanRead( wxInputStream& stream )
+{
+    unsigned char hdr[2];
+
+    if ( !stream.Read(hdr, WXSIZEOF(hdr)) )
+        return false;
+
+    return hdr[0] == 0xFF && hdr[1] == 0xD8;
+}

 
 

-// wxUSE_LIBJPEG
+#endif   // wxUSE_STREAMS

 
 

+#endif   // wxUSE_LIBJPEG