Added support for reading comments from a GIF image.

Applied (modified) patch by troelsk. Changed comments (which are allowed per frame in an animated GIF) to be read using wxIMAGE_OPTION_GIF_COMMENT with wxImage.GetOption. Added unit tests for reading and writing GIF comments.

Closes #12843.



git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66828 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -424,6 +424,7 @@ All:
 - Added wxVersionInfo and various GetLibraryVersionInfo() functions (troelsk).
 - Added wxNumberFormatter for dealing with thousands separators.
 - Added wxIntegerValidator<> and wxFloatingPointValidator<> validators.
+- Added wxIMAGE_OPTION_GIF_COMMENT to read and write GIF comments (troelsk).
 
 Unix:
 

interface/wx/image.h

@@ -1136,6 +1136,12 @@ public:
             the resulting PNG file. Use this option if your application produces
             images with small size variation.
 
+        Options specific to wxGIFHandler:
+        @li @c wxIMAGE_OPTION_GIF_COMMENT: The comment text that is read from
+            or written to the GIF file. In an animated GIF each frame can have
+            its own comment. If there is only a comment in the first frame of
+            a GIF it will not be repeated in other frames.
+
         @param name
             The name of the option, case-insensitive.
         @return

src/common/gifdecod.cpp

@@ -40,6 +40,8 @@ enum
     GIF_MARKER_EXT_APP              = 0xFF
 };
 
+#define GetFrame(n)     ((GIFImage*)m_frames[n])
+
 //---------------------------------------------------------------------------
 // GIFImage
 //---------------------------------------------------------------------------
@@ -61,6 +63,7 @@ public:
     unsigned char *p;               // bitmap
     unsigned char *pal;             // palette
     unsigned int ncolours;          // number of colours
+    wxString comment;
 
     wxDECLARE_NO_COPY_CLASS(GIFImage);
 };
@@ -189,6 +192,12 @@ bool wxGIFDecoder::ConvertToImage(unsigned int frame, wxImage *image) const
         *(dst++) = pal[3 * (*src) + 2];
     }
 
+    wxString comment = GetFrame(frame)->comment;
+    if ( !comment.empty() )
+    {
+        image->SetOption(wxIMAGE_OPTION_GIF_COMMENT, comment);
+    }
+
     return true;
 }
 
@@ -197,9 +206,6 @@ bool wxGIFDecoder::ConvertToImage(unsigned int frame, wxImage *image) const
 // Data accessors
 //---------------------------------------------------------------------------
 
-#define GetFrame(n)     ((GIFImage*)m_frames[n])
-
-
 // Get data for current frame
 
 wxSize wxGIFDecoder::GetFrameSize(unsigned int frame) const
@@ -672,6 +678,7 @@ wxGIFErrorCode wxGIFDecoder::LoadGIF(wxInputStream& stream)
     int transparent = -1;
     disposal = wxANIM_UNSPECIFIED;
     delay = -1;
+    wxString comment;
 
     bool done = false;
     while (!done)
@@ -701,38 +708,68 @@ wxGIFErrorCode wxGIFDecoder::LoadGIF(wxInputStream& stream)
                 done = true;
                 break;
             case GIF_MARKER_EXT:
-                if (stream.GetC() == GIF_MARKER_EXT_GRAPHICS_CONTROL)
+                switch (stream.GetC())
-                // graphics control extension, parse it
                 {
-                    static const unsigned int gceSize = 6;
+                    case GIF_MARKER_EXT_GRAPHICS_CONTROL:
-                    stream.Read(buf, gceSize);
-                    if (stream.LastRead() != gceSize)
                     {
-                        Destroy();
+                        // graphics control extension, parse it
-                        return wxGIF_INVFORMAT;
-                    }
 
-                    // read delay and convert from 1/100 of a second to ms
+                        static const unsigned int gceSize = 6;
-                    delay = 10 * (buf[2] + 256 * buf[3]);
+                        stream.Read(buf, gceSize);
-
+                        if (stream.LastRead() != gceSize)
-                    // read transparent colour index, if used
-                    transparent = buf[1] & 0x01 ? buf[4] : -1;
-
-                    // read disposal method
-                    disposal = (wxAnimationDisposal)(((buf[1] & 0x1C) >> 2) - 1);
-                }
-                else
-                // other extension, skip
-                {
-                    while ((i = stream.GetC()) != 0)
-                    {
-                        if (stream.Eof() || (stream.LastRead() == 0) ||
-                            stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
                         {
-                            done = true;
+                            Destroy();
-                            break;
+                            return wxGIF_INVFORMAT;
                         }
+
+                        // read delay and convert from 1/100 of a second to ms
+                        delay = 10 * (buf[2] + 256 * buf[3]);
+
+                        // read transparent colour index, if used
+                        transparent = buf[1] & 0x01 ? buf[4] : -1;
+
+                        // read disposal method
+                        disposal = (wxAnimationDisposal)(((buf[1] & 0x1C) >> 2) - 1);
+                        break;
                     }
+                    case GIF_MARKER_EXT_COMMENT:
+                    {
+                        int len = stream.GetC();
+                        while (len)
+                        {
+                            if ( stream.Eof() )
+                            {
+                                done = true;
+                                break;
+                            }
+
+                            wxCharBuffer charbuf(len);
+                            stream.Read(charbuf.data(), len);
+                            if ( (int) stream.LastRead() != len )
+                            {
+                                done = true;
+                                break;
+                            }
+
+                            comment += wxConvertMB2WX(charbuf.data());
+
+                            len = stream.GetC();
+                        }
+
+                        break;
+                    }
+                    default:
+                        // other extension, skip
+                        while ((i = stream.GetC()) != 0)
+                        {
+                            if (stream.Eof() || (stream.LastRead() == 0) ||
+                                stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
+                            {
+                                done = true;
+                                break;
+                            }
+                        }
+                        break;
                 }
                 break;
             case GIF_MARKER_SEP:
@@ -751,6 +788,8 @@ wxGIFErrorCode wxGIFDecoder::LoadGIF(wxInputStream& stream)
                 if (stream.LastRead() != idbSize)
                     return wxGIF_INVFORMAT;
 
+                pimg->comment = comment;
+                comment.clear();
                 pimg->left = buf[0] + 256 * buf[1];
                 pimg->top = buf[2] + 256 * buf[3];
     /*

tests/image/image.cpp

@@ -73,6 +73,7 @@ private:
         CPPUNIT_TEST( CompareSavedImage );
         CPPUNIT_TEST( SaveAnimatedGIF );
         CPPUNIT_TEST( ReadCorruptedTGA );
+        CPPUNIT_TEST( GIFComment );
     CPPUNIT_TEST_SUITE_END();
 
     void LoadFromSocketStream();
@@ -83,6 +84,7 @@ private:
     void CompareSavedImage();
     void SaveAnimatedGIF();
     void ReadCorruptedTGA();
+    void GIFComment();
 
     DECLARE_NO_COPY_CLASS(ImageTestCase)
 };
@@ -1171,6 +1173,81 @@ void ImageTestCase::ReadCorruptedTGA()
     CPPUNIT_ASSERT( !tgaImage.LoadFile(memIn) );
 }
 
+static void TestGIFComment(const wxString& comment)
+{
+    wxImage image("horse.gif");
+
+    image.SetOption(wxIMAGE_OPTION_GIF_COMMENT, comment);
+    wxMemoryOutputStream memOut;
+    CPPUNIT_ASSERT(image.SaveFile(memOut, wxBITMAP_TYPE_GIF));
+
+    wxMemoryInputStream memIn(memOut);
+    CPPUNIT_ASSERT( image.LoadFile(memIn) );
+
+    CPPUNIT_ASSERT_EQUAL(comment,
+        image.GetOption(wxIMAGE_OPTION_GIF_COMMENT));
+}
+
+void ImageTestCase::GIFComment()
+{
+    // Test reading a comment.
+    wxImage image("horse.gif");
+    CPPUNIT_ASSERT_EQUAL("  Imported from GRADATION image: gray",
+        image.GetOption(wxIMAGE_OPTION_GIF_COMMENT));
+
+
+    // Test writing a comment and reading it back.
+    TestGIFComment("Giving the GIF a gifted giraffe as a gift");
+
+
+    // Test writing and reading a comment again but with a long comment.
+    TestGIFComment(wxString(wxT('a'), 256)
+        + wxString(wxT('b'), 256)
+        + wxString(wxT('c'), 256));
+
+
+    // Test writing comments in an animated GIF and reading them back.
+    CPPUNIT_ASSERT( image.LoadFile("horse.gif") );
+
+    wxImageArray images;
+    int i;
+    for (i = 0; i < 4; ++i)
+    {
+        if (i)
+        {
+            images.Add( images[i-1].Rotate90() );
+            images[i].SetPalette(images[0].GetPalette());
+        }
+        else
+        {
+            images.Add(image);
+        }
+
+        images[i].SetOption(wxIMAGE_OPTION_GIF_COMMENT,
+            wxString::Format("GIF comment for frame #%d", i+1));
+
+    }
+
+
+    wxMemoryOutputStream memOut;
+    CPPUNIT_ASSERT( wxGIFHandler().SaveAnimation(images, &memOut) );
+
+    wxGIFHandler handler;
+    wxMemoryInputStream memIn(memOut);
+    CPPUNIT_ASSERT(memIn.IsOk());
+    const int imageCount = handler.GetImageCount(memIn);
+    for (i = 0; i < imageCount; ++i)
+    {
+        wxFileOffset pos = memIn.TellI();
+        CPPUNIT_ASSERT( handler.LoadFile(&image, memIn, true /*verbose?*/, i) );
+
+        CPPUNIT_ASSERT_EQUAL(
+            wxString::Format("GIF comment for frame #%d", i+1),
+            image.GetOption(wxIMAGE_OPTION_GIF_COMMENT));
+        memIn.SeekI(pos);
+    }
+}
+
 #endif //wxUSE_IMAGE