GF/ST (Graphic Framework for Smalltalk)

GF/ST provides a rich Smalltalk framework for graphic objects. When applications need to go beyond text, tables, lists, and buttons GF/ST provides a great base to build on. With GF/ST, sophisticated graphical applications are created on a well-designed framework of reusable components, including graphic objects, tools, and visual handles.

If you have VA Smalltalk 7 or above, you already have this functionality. It has been incorporated into the product, and this page documents that functionality.

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Use GF/ST for:

  • Workflow Diagrams
  • PERT Charts
  • Business Graphics
  • Technical Drawings
  • Program Diagrams
  • Network Diagrams
  • and more

GF/ST has so many applications that is difficult to list or describe them. In general though, you need GF/ST if:

  • A graphical display of objects, their state, and their relationships would be more effective than lists and tables.
  • You want to enhance and supplement your standard displays with graphics.
  • Visual construction and editing techniques would simplify end-user tasks.
  • You want to visualize and manipulate "domain" objects graphically, without modifying your underlying code. With GF/ST, user actions — like clicking and dragging — translate directly into modification of underlying domain objects.
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Visual Inspector

As an added bonus, GF/ST includes a powerful Visual Inspector as an example application (with full source code!).What is the Visual Inspector? It is a learning tool, a productivity tool, and a better inspector, and we believe it will be a valuable addition to your VisualAge Smalltalk environment. It provides a graphical presentation of any objects in Smalltalk, showing the relationships between them and allowing you to modify them directly.

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Major Features of GF/ST

GF/ST is more than graphic objects — it is a framework based on years of experience. The framework provides the basis for building applications quickly now that can be extended and grown to meet tomorrows needs.

Graphic Object — Graphic Objects are the heart of GF/ST. GF/ST uses an event model for the basis of communication and updating. Graphics Objects use events to notify interested parties about things that happen to it. Events are used to enforce constraints and to provide loose coupling between a GO and a domain model object that it displays.

Closed Path Figures

Path Figures

Other Figures

Rectangle
RoundedRectangle
Ellipse
Closed Polyline

Line
Polyline
Line end styles, including arrowheads

Text
Image
Group
Composite

Tools — Tools define the mode of interaction with graphic objects. GF/ST comes with a set of tools used for drawing, selecting, and ordering. The base tools that come with GF/ST are probably sufficient for all new figures you might add; if not, you can easily add to or customize the ones we provide.

Composite GOs — Collections of arbitrary graphic objects grouped to behave as one graphic object

Coordinate system control — For scaling, zooming, and automatic mapping from world units to pixels.

Display list management — For controlling large complex collections of graphic objects.

Handles — Handles are visual cues that provide the mechanism to translate user input into actions, using an event model. You can use the default handles, specify your own, and display a handle using any GF/ST graphic object. An example of handles are the three small rectangles in this figure.

Other Uses of GF/ST

One problem in describing GF/ST is that it has so many uses. Here is a longer list of uses that may help inspire ideas.

  • organizational charts
  • engineering graphics
  • business graphics

  • specialized drawing editors
  • network diagrams
  • workflow diagrams
  • PERT charts
  • virtual reality
  • animation

 

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