Window Transitions

A window transition is the method by which graphic window contents are dispalyed on a change of view (i.e. a full repaint of the window). Transition is closely associated with window double buffering.

A transition is a numeric value. 0 implies the default transition (no double buffering) where entity graphics are displayed immediately as they are processed during rendering.

Non-zero transition styles invoke double buffering, where the new window image is computed off-screen and then displayed when complete. The transition style then defines how this new image replaces the existing image. The commonest transition value (style 1) is a simple replacement of the old image with the new.

The transition for a window repaint is set by the -dbt switch (short for double buffer transition) on various commands, e.g. wpaint, plan, blow, pan, suppress, etc., or it can be associated with a window (via the window.double_buffering element) so that every repaint of the window uses it as the transition.

The following table describes the various transition styles:

Style

Name

Description

0 None No double buffering. Graphic primitives are drawn as they are processed in the appropriate window layer/group/entity draw order.

1 Normal The new image replaces the old in one operation.

2 Staged Partial new images are drawn over the old as entity groups are processed by any window.populate callbacks during the redraw process.

3 Fade from black The new image replaces the old by fading from black to full color.

4 Fade from white The new image replaces the old by fading from white to full color.

5* Horizontal wipe The new image is wiped over the old from left to right.

6* Vertical wipe The new image is wiped over the old from top to bottom.

7* Spiral out The new image replaces the old by a series of centered rectangles from the middle to the outer edges.

8* Spiral in The new image replaces the old by a series of centered rectangles from the outer edges to the middle.

9* Vertical strips The new image replaces the old by a series of vertical strips.

10* Horizontal strips The new image replaces the old by a series of horizontal strips.

* Add 32 to the style number to draw accentuating edge lines during the transition.

Style	Name	Description
0	None	No double buffering. Graphic primitives are drawn as they are processed in the appropriate window layer/group/entity draw order.
1	Normal	The new image replaces the old in one operation.
2	Staged	Partial new images are drawn over the old as entity groups are processed by any window.populate callbacks during the redraw process.
3	Fade from black	The new image replaces the old by fading from black to full color.
4	Fade from white	The new image replaces the old by fading from white to full color.
5*	Horizontal wipe	The new image is wiped over the old from left to right.
6*	Vertical wipe	The new image is wiped over the old from top to bottom.
7*	Spiral out	The new image replaces the old by a series of centered rectangles from the middle to the outer edges.
8*	Spiral in	The new image replaces the old by a series of centered rectangles from the outer edges to the middle.
9*	Vertical strips	The new image replaces the old by a series of vertical strips.
10*	Horizontal strips	The new image replaces the old by a series of horizontal strips.