Basic Organization

An editor or pasteboard is divided into three functional parts:

• The buffer stores the state of the editor or pasteboard and handles most events and edits. The wx:media-buffer% class implements the core buffer functionality, but buffers are created as instances of wx:media-edit% or wx:media-pasteboard%.
• A snip is a segment of information within the buffer. Each snip can contain a sequence of characters, a picture, or an interactive object (such as an embedded buffer). In an editor buffer, snips are constrained to fit on a single line and generally contain data of a single type. The wx:snip% class implements a basic snip. Other snip classes include wx:text-snip% for managing text, wx:image-snip% for managing pictures, and wx:media-snip% for managing embedded buffers.
• A view presents the buffer on the screen. The view lets the user scroll around a buffer or change buffers. Most views are instances of the wx:media-canvas% class, which is derived from wx:canvas%.

These three parts are illustrated by a simple text editor. The buffer in the editor corresponds to the text document itself. The buffer receives keyboard and mouse commands for editing the text, and manages the view of the text. The text itself is distributed among snips. Each character could be a separate snip, or multiple characters on a single line could be grouped together into a snip. The view roughly corresponds to the frame in which the text is displayed. While the buffer manages the arrangement of the text as it is displayed into a window, the view determines which window to draw into and which part of the buffer to display.

Each selectable thing in a buffer is an item. In a pasteboard, all selection and movements work on snips, so there is a one-to-one correspondence between snips and items. In an editor, one snip may own one or more consecutive items, and every item belongs to some snip. For example, in a simple text editor, each character is an item, although multiple characters may be grouped into a single snip.

The places where the insertion point can appear in an editor are the positions. If there are n items in a buffer, then there will be n + 1 positions in the buffer: one position before each item, and one position after the last item.

When a buffer is drawn into a view, then there are graphic locations associated with snips and positions. The location of a position or snip is specified in coordinates relative to the top-left corner of the buffer. Locations in an editor buffer are only meaningful if the buffer is being viewed.

• Administrators
• Styles