How to implement custom icons for my script/addon?

Question

Is it possible to use different icons other than the default set and how?

Answer 1

Since 2.75 the python API allows for custom icons.

You store custom icons and load them with bpy.utils.previews.ImagePreviewCollection class, which works like a dictionary.

So first let's create such icon dictionary:

import bpy.utils.previews
icons_dict = bpy.utils.previews.new()

Next we need to find path to our icons. Its best to put them inside folder named 'icons' next to the script file:

import os
# this will work for addons 
icons_dir = os.path.join(os.path.dirname(__file__), "icons")
# but it won't give you usefull path when you opened a file in text editor and hit run.
# this will work in that case:
script_path = bpy.context.space_data.text.filepath
icons_dir = os.path.join(os.path.dirname(script_path), "icons")

Finally load icon.png into the dictionary, Blender uses 32x32 icons in UI:

icons_dict.load("custom_icon", os.path.join(icons_dir, "icon.png"), 'IMAGE')

Reference the icon by it's ID, use like this inside UI elements:

icon_value=icons_dict["custom_icon"].icon_id

---

It's best to handle loading of icons in the register function, clearing the icons in unregister function and storing them in a global variable. Save this script, create 'icons' directory next to it and put icon.png inside. Load into Text Editor and hit Run:

import os
import bpy
import bpy.utils.previews

class Panel(bpy.types.Panel):
    """Creates a Panel in the 3D view Tools panel"""
    bl_label = "Custom Icon Preview Panel"
    bl_space_type = "VIEW_3D"
    bl_region_type = "TOOLS"

    def draw(self, context):
        global custom_icons
        self.layout.label(text="Blender SE", icon_value=custom_icons["custom_icon"].icon_id)

# global variable to store icons in
custom_icons = None

def register():
    global custom_icons
    custom_icons = bpy.utils.previews.new()
    script_path = bpy.context.space_data.text.filepath
    icons_dir = os.path.join(os.path.dirname(script_path), "icons")
    custom_icons.load("custom_icon", os.path.join(icons_dir, "icon.png"), 'IMAGE')
    bpy.utils.register_module(__name__)

def unregister():
    global custom_icons
    bpy.utils.previews.remove(custom_icons)
    bpy.utils.unregister_module(__name__)

if __name__ == "__main__":
    register()

Result: