The font is stored in the files called "SystemFont5x7.h" which is included with the program. Each entry in the table represents one column of the font and the binary bits in the number represent each LED in the row. You can easily create your own font by editing the file.
GLCD is for graphic LCD fonts, I'm not sure it will work for dot matrix LED.
The way to do it is to draw a 5x7 grid, fill in the cells you want to make the character shape, then for each empty cell write '0' and each filled cell write '1'. The result is a 7-bit binary number (leave bit 8 as '0' so there is a gap between characters) and it is that number you insert in the font table.
If you write the numbers in the existing font in binary you will see the '1's make the character shape at the end of the line.
I will try to explain. First, in the software in post #1, download the files and open the one called "SystemFont5x7.h" in a text editor.
Look for the line below, you can edit any line, I only chose this one because the character 'F' is easy to visualize and does not have symmetry.
Code:
0x7F, 0x09, 0x09, 0x01, 0x01,// F
The numbers are hexadecimal so you need to convert them to binary to see individual bits:
01111111 (0x7f)
00001001 (0x09)
00001001 (0x09)
00000001 (0x01)
00000001 (0x01)
You will see the '1's make the shape of the character, rotated through 90 degrees:
01111111
00001001
00001001
00000001
00000001
You need to do the reverse, start with the shape of the new character, convert the 'on' pixels to '1' in a new binary number then convert the result to hexadecimal and replace the line in the file with your new numbers. Note that there must be five numbers, each with eight bits on each line and the total number of lines must stay the same. Then recompile the program and the new character will be available.
RTL just means the order you display the characters, or parts of characters is the opposite way around. When you address the LED panel, start with the one on the right and move to the left. The character shapes as as you design them and you can span more than one line of numbers if necessary but remember that each line is the font for one LED display so if your character needs 3 shapes they have to be displayed across 3 displays, there is no way to avoid that as the resolution of the display is set by the number of LED pixels each has.
For example, your character would have to be displayed as: (1 = LED bright, 0 = LED off)
What do you mean? Searching for volunteers coding the Arabic font for you?
I presume this has been already done by others many times. There are standardized Arabic charsets, e.g. ISO 8859-6, that are used by computers in your country. Not sure if you need something like unicode to represent more than 256 codes.