Creating New Items

Creating New Items — how to create new canvas items.

How to Create New Canvas Items

There are 3 ways to create new canvas items, listed here in increasing order of complexity:

These will be discussed in turn below. (It is also possible to create new container items by subclassing GooCanvasGroup, but that is not covered here.)

The final part of this section covers creating item models.

Creating a Simple Subclass of GooCanvasItemSimple

For items that consist of a simple graphic element such as a line, rectangle or circle, it is possible to create a subclass of GooCanvasItemSimple and override just one method, simple_create_path(). (This method is used for the GooCanvasEllipse and GooCanvasPath items.)

The simple_create_path() method should create a path using the given cairo context. The path will be drawn using the stroke, fill and other painting properties from GooCanvasItemSimple.

This example shows the simple_create_path() method for a simple rectangular item, MyItem:

1
2
3
4
5
6
7
8
9
10
11