mirror of https://github.com/GNOME/gimp.git
65 lines
2.6 KiB
Plaintext
65 lines
2.6 KiB
Plaintext
|
contexts.txt
|
||
|
|
============
|
||
|
|
|
||
|
|
Introduction
|
||
|
|
------------
|
||
|
|
|
||
|
|
This file describes how the GimpContext's in GIMP are used.
|
||
|
|
|
||
|
|
|
||
|
|
Overview
|
||
|
|
--------
|
||
|
|
|
||
|
|
One imporant context is the so called "user context",
|
||
|
|
gimp_get_user_context(). This context keeps track on what image the
|
||
|
|
user currently has active, for example. Dock windows have their own
|
||
|
|
context which does not necessarily mirror the user context. A dock
|
||
|
|
window can be set to show information for a specific image. Plug-ins
|
||
|
|
also have their own context.
|
||
|
|
|
||
|
|
|
||
|
|
Communication between contexts
|
||
|
|
------------------------------
|
||
|
|
|
||
|
|
So how does the various contexts synchronize and propagate changes?
|
||
|
|
This is most easily explained by a sequence diagram. Let's say there
|
||
|
|
are two image windows with different images opened in GIMP. Call them
|
||
|
|
A and B. Let's say A is currently active. When the user activates B,
|
||
|
|
this is the sequence of events from the focus event to the layers
|
||
|
|
dockable have been updated with the new image. To understand the
|
||
|
|
diagram, you have to know that the dock window has connected signal
|
||
|
|
handlers to image changes in the user context (through a dialog
|
||
|
|
factory getter), and the layer dockable have connected a signal
|
||
|
|
handler to image changes in the dock window context. The sequence of
|
||
|
|
events is as follows:
|
||
|
|
|
||
|
|
|
||
|
|
GimpContext GimpContext GimpItemTreeView,
|
||
|
|
GimpDisplayShell user GimpDockWindow dock window GimpLayerTreeView
|
||
|
|
|
||
|
|
| | | | |
|
||
|
|
focus event | | | |
|
||
|
|
------->| | | | |
|
||
|
|
| gimp_context_set_display() | | |
|
||
|
|
|--------------->|----------+ | | |
|
||
|
|
| | | | | |
|
||
|
|
| gimp_context_set_image() | | | |
|
||
|
|
| |<---------+ | | |
|
||
|
|
| | | | |
|
||
|
|
| | "image-changed" | |
|
||
|
|
| |------------->| | |
|
||
|
|
| | | gimp_context_set_image() |
|
||
|
|
| | |------------->| |
|
||
|
|
| | | | "image-changed" /
|
||
|
|
| | | | set_image()
|
||
|
|
| | | |------------>|
|
||
|
|
| | | | |
|
||
|
|
|
||
|
|
|
||
|
|
Parent/child relationships
|
||
|
|
--------------------------
|
||
|
|
|
||
|
|
TODO
|
||
|
|
|
||
|
|
|