Visustin - Large flow charts

Large charts are best viewed on the screen either in Visustin itself or as PDF. A large monitor gives you the best view into complex flow charts. Visustin has no built-in size limitation, but various technical reasons may limit what you can do with huge charts. Even when Visustin can produce very large charts, such as 50x50 sheets or 50000x50000 pixels, printing or saving may turn impractical. Saving as PDF usually works out best.

Good news to veteran users! Visustin v6 is significantly more robust than previous versions. Earlier versions were limited to some 100 kB or 3000 lines at a time. This limitation has been lifted.

Ways to handle large charts

Quick tip #1. Work large files in parts. Use the Structure tab to create partial flow charts of a file.

Quick tip #2. Press Birdseye instead of Draw.

Quick tip #3. Save as PDF.

Quick tip #4. Use options to create smaller charts: Shorten code (or Minimal code), Hide comments, Black & White, Font size 7pt, Zoom 100%.

Viewing large charts

Navigating in large charts is easier with the navigation features Visustin provides.

Zoom out. Right-click the chart for zoom options or just press Ctrl+2 to fit the code in the view.
Overview. Press F9 to display the overview panel.
Hold Shift down and move the mouse over the chart to scroll fast.
Use the keyboard shortcuts to navigate.

Keeping charts smaller

A smaller physical chart size means increased performance. You have several ways to keep the chart area down.

Birdseye. Press F6 to display a "bird's eye" view of the flow chart. In this mode, Visustin shortens the code, hides the comments and squeezes the chart to fit in a small area.
Use a smaller font, not just zoom out. Hit Ctrl+< to decrease the font size (and Ctrl+> to increase it back). A smaller font results in a smaller chart and also in smaller files – but no less information.
Hide comments. Hiding the comments via the Options menu can make charts considerably smaller.
Compress continuous blocks or shorten the code via the Options menu.
Less is more. Delete unimportant code and redraw.
Use the checkboxes of the Structure tab to flowchart a part of your code at a time.
Alternatively, select the important code lines and press Draw. Visustin works on the currently selected code lines.
For saving files, PDF is a robust format. Of bitmap formats, PNG is a proper choice with a good quality to size ratio.

Memory considerations

A large flow chart can consume 500 MB RAM or more. If Visustin appears to work slowly because of the chart size, you may be running low on memory. Try the following tricks:

Zoom to 100%. Zoom levels 50%-99% consume a lot of memory (2x-3x the original image).
Create a Black & White chart. Less colors, less bytes.
Press Editor to work in vector format.

The Statistics command in the View menu tells you the chart size and the current memory requirements. You can also use the Windows Task Manager to determine the overall memory usage of Visustin. In the Task Manager, enable columns Mem Usage and Peak Mem Usage (in the View menu in Windows XP).

Extremely large charts

The table below shows the results of a stress test with very large input files. The test was run with the default options: Flow chart, Zoom level 100%, 9pt Arial font, Color chart, Comments as detached labels.

Source kB	Source lines	Language	Memory	Pixels	Sheets
161 kB	5000 lines	Fortran	200 MB	29,000x10,000	40x9
263 kB	7300 lines	VB6	200 MB	110,000x12,000	140x10
557 kB	12000 lines	VB6	650 MB	112,000x46,000	147x39
546 kB	18000 lines	T-SQL	500 MB	52,000x56,000	65x48
1.2 MB	31000 lines	Visual FoxPro	1600 MB	340,000x32,000	353x27

Memory = Peak Mem Usage after pressing Draw. Sheets = Print-out size on regular paper (A4 portrait).

While these charts display well, it is not practical to print or save them in their entirety.

Do not expect miracles from Windows or your printer. Printing the 65x48 sheet chart failed with a Windows error message about a result exceeding the limits of a 32-bit integer. Saving as PDF worked fine.

On a separate note, it's good programming practice to keep source files at a reasonable size. Besides making flowcharting easier, smaller files are easier to understand and maintain as well.

Troubleshooting large charts

Chart does not show up: Press Birdseye instead of Draw.
Chart shows up but saving fails: 1) The file format does not support large images. Save as PDF instead.; 2) The complete bitmap is too large for Windows. Save in parts via the Structure tab.; 3) You are running low on memory. Close other applications and try again.
Printing fails: Print in parts. Use the Structure tab to print parts of the code at a time.
Zooming displays rasterized picture or strange colors: You are running low on memory. Visustin has switched to low-color mode to preserve RAM. Close other programs to free some memory or add RAM into your system. You can also try zooming again as the operating system may have freed up some memory meanwhile. Visustin requires physical RAM, not just virtual memory.
Zooming stops working: The image is too large to zoom. Try zooming out to a lower level (below 50%).
Bulk charting fails: Check Split files by Structure to process the files in parts.

Increasing system performance

Add RAM up to 2 GB.
Increase the operating system's virtual memory size.
Get a faster processor.
Get a large monitor.
Run Visustin on the fastest disk drive.
See also: System requirements