[GM-help] exception when write webp to blob

[卢永菁 <sy...@gm...>]

Hi, Bob
	I have used GraphicsMagick c++ api to change format to webp, then write it to blob, but I got errors like this: 
	'Magick: Unable to write blob (WEBP) reported by magick/blob.c:2004 (ImageToBlob)’

	My GraphicsMagick version is 1.3.19, I see the new features in 1.3.19 says support Googles’ WEBP, so could you help me?
	Here is my code:
 
	Magick::InitializeMagick(*argv); 
	Magick::Image image; 
	Magick::Blob blob;
	
	try
        {
		image.read("/home/luyongjing/1.jpg"); 
                image.magick("WEBP"); 
                image.write(&blob); 
        }
       catch( Magick::Exception &error_ )
       {
                std::cout << "Caught exception: " << error_.what() << std::endl;
                return 1;
       }
       return 0;

       But when I replace the image.write(&blob) to image.write(“path/to/pic”), it works well.