Back to UWaterloo
Summary
- batch, conversational, graphical are interface types
Express intention ot controller, translates to change model, view presents to person to perceive
-
interface is what's presented to the user
-
interactions are the sequence of actions a person expresses
- batch interfaces are like punch cards
- conversational interfaces get feedback during execution, CLI
- GUI
- Recognition over Recall enables discovery of new options
Handles I/O, where output is drawing graphically. Provides "low level" input, output and window management capabilities to the OS
-
X Windows is the standard system for
*nix
- essentially a protocol
Design Criteria
- display independent
- device independent
- network transparent
- support multiple displays
- overlapping, resizable windows
- extensible
X Client-server architecture
- separate the UI from the application
- typiclaly runs on an event loop
0,0 is top left
3 Drawing primatives: pixel, stroke and ergion
Graphics Context(GC) holds all options in a structure and is passed to the draw routine
- in X, GC is on the X Server
- fast to switch between contexts since reduced network request size between client and server
- modern systems (OpenGL) have GC, called attribute state
-
XGCValues in Xlib
Painter's Algorithm is a really primitve algorithm to draw more complex shapes (combine, layers)
- to paint, a program needs low level primatives, or high level things like game sprites, buttons, etc..
- bunch of
Displayable base class objects, where derived classes are for things you wnat to paiunt
- ordered display list for layers
- other displayables are polylines, text, shapes, clipRectangle
Makes it easier to maintain code by allowing the interface (view or controller) to be easily changed. Makes for better unit testing.