AreaVi Marks

Marks are strings that corresponds to positions of the AreaVi instance. The marks can change its position according to text being deleted or inserted.

Consider the following example:

from vyapp.areavi import *
area = AreaVi('None')
area.pack(expand=True, fill=BOTH)
area.insert('1.0', 'cool\n')

# Set a mark named 'm' at the position '1.2'.
area.mark_set('m', '1.2')
area.insert('1.0', 'that ')

# It will print 1.7. It means that the mark position
# has changed when the text 'that' was inserted.
# The area.index method returns the index of a given mark.
print area.index('m')

The most basic marks are the 'insert' one which corresponds to the position in which the cursor is in, and 'end' mark that is used to insert text at the end of the text.

There are other important marks as 'insert lineend' that maps the end of the cursor line, the 'insert linestart' that maps the beginning of the cursor line.

Example:

# It would insert the string 'alpha' to the end of the cursor line.
area.insert('insert lineend', 'alpha')

# It would delete the entire line that is under the cursor.

area.delete('insert linestart, 'insert lineend')

# It gives the index 'Line.Col' for the end of the cursor line.
area.index('insert lineend')

There are other kind of possible marks used line. 'insert +1c' that corresponds to 1 character after the cursor position. The example below shows better:

# It deletes the char at the cursor position.
area.delete('insert', 'insert +1c')

# It deletes the second character ahead the cursor position.
area.delete('insert +1c', 'insert +2c')

You could use a negative index like 'insert -1c' that means one char back the cursor position. Other possible marks are 'insert linestart +1c' that means one char after the beginning of the cursor line.

Example:

# It deletes the first char of the cursor line.
area.delete('insert linestart', 'insert linestart +1c')

Try playing with 'insert lineend -1c' as well. It is possible to have marks relative to lines, this is very useful. You could try the following marks 'insert +1l' and 'insert -1l' these means one line down the cursor position and one line up the cursor position. You could even have stuff like 'insert +1l linestart +1c' that means one line down the cursor position and one char ahead the beginning of the line down the cursor position :P

Try:

area.delete('insert +1l linestart', 'insert +1l linestart +1c')

You could use an index instead of a mark like '4.3 +1l' as well.:

# It would insert the char '#' at the position 3.3'.
area.insert('2.3 +1l', '#')

These examples should be played interactively. Make sure to change the cursor position along the examples to check what happens when the statements are executed.