Change color of text in GTK 3.0

Question

I am using a Gtk.TextBuffer() inside a Gtk.TextView() to write some text on the screen. I wish to change colors of the text while writing often. eg.

In Green -- Printing Green color
In Red   -- Printing Red color
In Green -- Printing Green color
In Red   -- Printing Red color

Can you please suggest some function to do this.

Answer 1

To specify that some text in the buffer should have specific formatting, you must define a tag to hold that formatting information, and then apply that tag to the region of text using create_tag("tag name", property) and apply_tag(tag, start_iter, end_iter) as in, for instance:

tag = textbuffer.create_tag("orange_bg", background="orange")
textbuffer.apply_tag(tag, start_iter, end_iter)

The following are some of the common styles applied to text:

• Background colour ("background" property)
• Foreground colour ("foreground" property)
• Underline ("underline" property)
• Bold ("weight" property)
• Italics ("style" property)
• Strikethrough ("strikethrough" property)
• Justification ("justification" property)
• Size ("size" and "size-points" properties)
• Text wrapping ("wrap-mode" property)

You can also delete particular tags later using remove_tag() or delete all tags in a given region by calling remove_all_tags().

Answer 2

Since GTK3.16 you can use pango markup.

self.textbuffer.insert_markup(iter, markup);

.

self.textbuffer.insert_markup(self.textbuffer.get_end_iter(), "<b>and some bold text</b>", -1)

StackOverflow answer with example

GTK3+ doc: https://developer.gnome.org/gtk3/stable/GtkTextBuffer.html#gtk-text-buffer-insert-markup

Inserts the text in markup at position iter . markup will be inserted in its entirety and must be nul-terminated and valid UTF-8. Emits the “insert-text” signal, possibly multiple times; insertion actually occurs in the default handler for the signal. iter will point to the end of the inserted text on return.