[lcd4linux] CrystalFontz 635 Cancel button plus some extra functions.

[Michael D. <mi...@mi...>]

Hi,

Now that I've got lcd4linux to output some text on my CrystalFontz 635 I've
had some time to play with the system. I've come across a couple of issues.

The first was that whenever I press the Cancel button on the keypad it did
nothing. Down, left, right and Confirm all did fine. However when I pressed
Up I got an Up event and a Cancel event raised. After some investigating I
discovered the offending line to be in the drv_CF_keypad function. The code
had Cancel Key Pressed as being 7 when page 14 of CrystalFontz data sheet
says its 6. Having looked a bit more in depth at this it look like the
released events were never converted correctly either as they were 1 out.
The patch attached fixes this issue.

The second was some missing functionality. I gather from the wiki there is
currently no way of switching layouts from a key press. Unfortunately I
don't have time to implement that so I've made lcd4linux read from a text
file for the output to display and another program handles updating the
display. To aid in this I added some extra functions to the file plugin...

file::writeline(string file, string text, int mode)

This writes the line of text to the specified file. If mode is 0 it appends
the text, if it is 1 it overwrites the file with the text. It returns a
blank string so is only really useful in key handlers.

file::exec(string command)

This function runs the command. Unlike exec it runs the command only once
and doesn't return any output text. This makes it useful for controlling the
system from a key handler.

I've attached a diff that contains these additions and I give you full
permission to incorporate the code in lcd4linux.

Mike