Introduction

Demarco5 is a diagram drawing application originally designed to produce data flow diagrams. In this version (1.4) four diagram types are supported

• Data Flow Diagram.
• State Transition Diagram.
• Free Format Flow Diagram.
• Bitmap Link Diagram.

The Demarco5 application enables the creation, editing, storage, printing and export of the diagrams to provide a complete diagramming resource for an EPOC hand-held device.

Data Flow Diagram

Data flow diagrams consist of the following elements.

• Processes – these represent a transformation of data and have at least one data input flow and one data output flow. A process has a name consisting of verb noun, an action taking place on data. A process may have a definition which may consist of a child diagram (another data flow diagram with terminators representing the input and output flows of its parent) or a text description.
• Terminators – these represent sources and destinations for data flow which fall outside the scope of the system under consideration. Terminators may only be connected to processes. A terminator may have a text definition.
• Stores – these represent items within a system where data is stored – a file a filing cabinet etc. Stores may only be connected to processes. A store may have a text definition.
• Nodes – these represent points at where data flows are merged with no transformation of the data. A note may have a text definition.
• Control Processes and Control Flows – these are not strictly part of a data flow diagram. They are used as part of a real-time modelling of systems. Control flows have only two states enable/disable, start stop trigger/reset. Control processes may only be connected to other (control or data) processes via control flows. A control process may have a text definition.

Free text may also be added to data flow diagrams.

State Transistion Diagram

State transition diagrams consist of the following elements.

• States – these represent individual states. They will have at least one incoming transition and one outgoing transistion. Each state may have a text definition.
• Transitions – these connect individual states and have an event and action associated with each of them. Each transition may also have a text definition.

Free Format Diagrams

The Free-format diagram option is intended to allow the construction of process flow diagrams, mind maps, org charts, family trees etc. A palette of symbols is provided as follows:

The symbols can mean anything you like, however they have been chosen to cover common shapes used in flow diagramming. For example the rhombus represents a decision or process branch point.

The T symbol represents free text that may be added to a diagram. Links may be added between any of the symbol types.

Links may be of the following types.

• Solid arrow direct from symbol to symbol (only available for simple shapes).
• Dotted arrow direct from symbol to symbol (only available for simple shapes).
• Horizontally cranked solid arrow.
• Vertically cranked solid arrow.
• Right angled arrow (vertical from source)
• Right angled arrow (horizontal from source)

Bitmap Link Diagrams

These are a variant of the Free Format Flow diagrams where the symbols are bitmap images (currently borrowed from the Sketch clip art). The palette of symbols is as follows:

The T symbol represents free text that may be added to a diagram. Links may be added between any of the symbol types. Link types are as the free format flow diagram.

It is possible to create your own palette of bitmap symbols. Contact me at adfhome[at]btinternet.com for details.

Creating, Opening and Saving

Diagram files are created, opened and saved in the normal way – either from the main menu or using ctl keys. The type of diagram is selected during creation. When opening an existing file a recent file list is displayed – select a recent file by selecting it and pressing enter – otherwise select “Other…”

Viewing

Once opened a diagram is rendered graphically on the Psion screen. The diagram may be larger than the screen so the viewing window may be panned across it using the cursor keys. In addition the diagram may be shown at different zoom levels (currently not for the bitmap link diagram). The smaller zoom levels are useful for navigating larger diagrams as although the text cannot be read directly tapping on an object causes a pop up to be displayed with its name.

The find function (button on the toolbar) can be used to find an object by its name. If an object is selected in this way the diagram will be automatically panned to ensure it is on screen.

Adding Symbols

To add a symbol to a diagram tap twice on a vacant space – a symbol type menu or palette will then be displayed.

Select a symbol type by tapping on it and you will be invited to add a name for the symbol. Once a name has been entered the symbol has been created and is shown on the diagram.

Adding Flows/Links

The arrows leading form one symbol to another are called flows in data flow diagrams and links in the other diagram types. The method of creation is the same for both.

To add a link the source and destination must already exist. Tap twice on the symbol from which the link is to originate and a pop-up menu will appear.

Select the “add data flow”, “add control flow” or “add link” option as appropriate. A message will appear inviting you to select the flow/link destination. This is achieved by tapping twice on a suitable destination object. For a data flow diagram you will then be invited to enter a name for the flow and once entered the flow/link will be created. For the other diagram types a link type selection palette will appear for you to tap on the desired link type.

Editing Symbols

A symbol editing pop up-menu is displayed by tapping twice on an existing symbol.

Editing Flows/Links

A link editing pop up-menu is displayed by tapping twice on an existing symbol.

Printing

Diagrams may be printed in the normal way. Only one page can be generated and the diagram is scaled to fit.

The EPOC printing system has a number of limitations of which you should be aware.

• Landscape printing is only available on some printer drivers – Fax, Laserjet, Print-via-PC and (optionally) PostScript.
• The EPOC printing system only uses the printer built-in fonts when printing directly. This limits the diagram scaling possibilities.
• Colour is not supported.

I recommend using the Print-via-PC option wherever possible. If you cant use this and you have access to a PostScript printer an excellent generic L1 PostScript driver has been produced by Andrew Johnson which is available for download on the internet.

Thanks to Andy Clarkson for making his vector printing gprinter.opx available as freeware.

Exporting

A diagram may be exported in either EPOC bitmap format or as a Windows metafile. The Windows metafile is a scalable format that can be directly inserted into Windows applications on a PC. The Windows metafile also supports colour on a colour EPOC device.