Fix and improve Fl_GIF_Image (issue #271, #274)

- add error and EOF checks
- fix transparent pixel index outside ColorMap (#271)
- fix Fl_GIF_Image decoder bug (#274)
- add Fl_Image_Reader::skip(unsigned int)
- use new skip() method in GIF reader

1 files changed, 3 insertions, 0 deletions

diff --git a/src/Fl_Image_Reader.h b/src/Fl_Image_Reader.h
index 7d176acc1..2c62e4a27 100644
--- a/src/Fl_Image_Reader.h
+++ b/src/Fl_Image_Reader.h
@@ -82,6 +82,9 @@ public:
   // return the name or filename for this reader
   const char *name() { return pName; }
 
+  // skip a given number of bytes
+  void skip(unsigned int n) { seek(tell() + n); }
+
 private:
 
   // open() sets this if we read from a file