diagram

diagram is a tool for manipulating PNG images using imagemagick and the Go image library

Dependencies

Go
ImageMagick with Pango support
- on Arch Pango is an optional dependency of ImageMagick, so make sure you also have that installed for creating labels
elm

Usage

Basic usage

To load a list of captions from capfile and place them on input.png run:

$ diagram -cap capfile input.png

Captions

Caption files are of the form

Text Size Xpos,Ypos

Text is arbitrary text, not including spaces. HTML codes like <sub> and <sup> are passed directly to Pango, but you can also use a LaTeX-style _X, where X is one or more digits (\d+).
Size is the size in pixels of the text for the label
Xpos,Ypos is the x (y) or horizontal (vertical) position of the label in pixels

Flags

For pure commandline usage, the -grid flag is very helpful for aligning your captions manually, and the -o flag allows you to save the resulting image directly. For interactive use, see the Web interface section below.

-grid h,v : draw a grid with h horizontal and v vertical divisions of the image
-o outfile : write the resulting image to outfile
-cap capfile : take the list of captions from capfile
-web : use the web interface
-crop lx,uy,rx,by : crop the image to the dimensions specified by lx, uy, rx, and by, which are the left-x, upper-y, right-x, and bottom-y coordinates, respectively
-port port : specify the port to use for the web server, defaults to :8080

Web interface

Since it can be unwieldy to write the captions from scratch, there is a web interface available via the -web flag. This starts a server on localhost:8080 by default, but you can adjust the port with the -port flag. After you finish editing the captions, you can save them to a file for later commandline use. Save the image by right-clicking and saving the image using your typical browser facilities.