win32: Show TIFF warnings on console

Showing them in a window (default) is not acceptable for a console
application like Tesseract which must be able to work in batch mode.

Signed-off-by: Stefan Weil <sw@weilnetz.de>

api/tesseractmain.cpp

@@ -33,6 +33,23 @@
 #include "openclwrapper.h"
 #include "osdetect.h"
 
+#if defined(_WIN32)
+
+#include <tiffio.h>
+#include <windows.h>
+
+static void Win32WarningHandler(const char* module, const char* fmt,
+                                va_list ap) {
+    if (module != NULL) {
+        fprintf(stderr, "%s: ", module);
+    }
+    fprintf(stderr, "Warning, ");
+    vfprintf(stderr, fmt, ap);
+    fprintf(stderr, ".\n");
+}
+
+#endif /* _WIN32 */
+
 void PrintVersionInfo() {
     char *versionStrP;
 
@@ -352,6 +369,11 @@ int main(int argc, char **argv) {
   int arg_i = 1;
   tesseract::PageSegMode pagesegmode = tesseract::PSM_AUTO;
 
+#if defined(_WIN32)
+  /* Show libtiff warnings on console (not in GUI). */
+  TIFFSetWarningHandler(Win32WarningHandler);
+#endif /* _WIN32 */
+
   ParseArgs(argc, argv,
           &lang, &image, &outputbase, &datapath,
           &list_langs, &print_parameters,