Sixel support for plan9port devdraw

Sixeldraw is an implementation of plan9port's devdraw(1) that runs inside a terminal and uses sixel for drawing and DEC Locator for mouse inputs. To use it just point DEVDRAW to the sixeldraw binary and run some draw(3) program, e.g.

DEVDRAW=sixeldraw sam

If SIXELDBG= is set to a file then sixeldraw debug messages are sent there.

There is a known bug where sixeldraw will leave the terminal in a messy state after it exits. This is race condition between sixeldraw cleaning up and sh(1) reading the tty settings and is hard to fix. An easy workaround is to append sleep 0.1 to the command.

By default sixeldraw maintains its own snarf buffer. If SNARF=1 is set, it uses the xterm sequences to read and write the clipboard, which may need to be enabled in the terminal emulator configuration.

Draw(3) operations that change the current window's size, location etc. are currently ignored. Changing the cursor could be supported with a softcursor but isn't implemented yet.

Terminal support

• Recent (!) xterm compiled with --enable-sixel-graphics --enable-dec-locator and with Xresources settings along the lines of

    XTerm*decTerminalID: vt340
    XTerm*numColorRegisters: 256
    XTerm*maxGraphicSize: 2560x1440
  

  For snarf support the setting is something like

    XTerm*disallowedWindowOps: 20,21,SetXprop
  

• Mlterm needs QUIRKS=3 to work around two bugs: The "sixel scrolling" mode is inverted and the order of mouse buttons in the DEC locator response is wrong.