MyraTexturePacker is console utility for making a texture atlas.
Download the binary release(MyraTexturePacker.v.v.v.zip from the latest release at Releases). The executable(MyraTexturePacker.exe) should be runnable under Windows natively. And runnable under Linux and MacOSX too with the help of Mono.
MyraTexturePacker.exe <input_folder> <output_file>
I.e.
MyraTexturePacker.exe "C:\Temp" "C:\Temp\my_atlas.png"
That command will make MyraTexturePacker go over all images in the folder "C:\Temp" and create the texture atlas from it.
The texture atlas will consist of two files: my_atlas.png(atlas image) and my_atlas.xmat(atlas definition in XML format).
MyraTexturePacker supports nine patch images. In order to use that feature, the input image name must have ".9" before the extension(i.e. image.9.png). Also such image must have 1px border with black lines marking strechable areas.
See this link for thorough explanation of this feature: https://github.com/libgdx/libgdx/wiki/Ninepatches
Example set of input images(both ordinary and nine-patch): https://github.com/rds1983/Myra/tree/master/assets-raw