The Independent JPEG Group's JPEG software v6b

1 files changed, 25 insertions, 1 deletions

diff --git a/jerror.c b/jerror.c
index 8b89e39..3da7be8 100644
--- a/jerror.c
+++ b/jerror.c
@@ -1,7 +1,7 @@
 /*
  * jerror.c
  *
- * Copyright (C) 1991-1996, Thomas G. Lane.
+ * Copyright (C) 1991-1998, Thomas G. Lane.
  * This file is part of the Independent JPEG Group's software.
  * For conditions of distribution and use, see the accompanying README file.
  *
@@ -10,6 +10,11 @@
  * stderr is the right thing to do.  Many applications will want to replace
  * some or all of these routines.
  *
+ * If you define USE_WINDOWS_MESSAGEBOX in jconfig.h or in the makefile,
+ * you get a Windows-specific hack to display error messages in a dialog box.
+ * It ain't much, but it beats dropping error messages into the bit bucket,
+ * which is what happens to output to stderr under most Windows C compilers.
+ *
  * These routines are used by both the compression and decompression code.
  */
 
@@ -19,6 +24,10 @@
 #include "jversion.h"
 #include "jerror.h"
 
+#ifdef USE_WINDOWS_MESSAGEBOX
+#include <windows.h>
+#endif
+
 #ifndef EXIT_FAILURE		/* define exit() codes if not provided */
 #define EXIT_FAILURE  1
 #endif
@@ -74,6 +83,15 @@ error_exit (j_common_ptr cinfo)
  * Actual output of an error or trace message.
  * Applications may override this method to send JPEG messages somewhere
  * other than stderr.
+ *
+ * On Windows, printing to stderr is generally completely useless,
+ * so we provide optional code to produce an error-dialog popup.
+ * Most Windows applications will still prefer to override this routine,
+ * but if they don't, it'll do something at least marginally useful.
+ *
+ * NOTE: to use the library in an environment that doesn't support the
+ * C stdio library, you may have to delete the call to fprintf() entirely,
+ * not just not use this routine.
  */
 
 METHODDEF(void)
@@ -84,8 +102,14 @@ output_message (j_common_ptr cinfo)
   /* Create the message */
   (*cinfo->err->format_message) (cinfo, buffer);
 
+#ifdef USE_WINDOWS_MESSAGEBOX
+  /* Display it in a message dialog box */
+  MessageBox(GetActiveWindow(), buffer, "JPEG Library Error",
+	     MB_OK | MB_ICONERROR);
+#else
   /* Send it to stderr, adding a newline */
   fprintf(stderr, "%s\n", buffer);
+#endif
 }