═══ 1. Contrast ═══

Contrast compares two files on disk and notes lines that are common to both. A 
bar chart is drawn, giving an overall view of which lines match, and the text 
of either file, or a composite file, is displayed. The default view is the 
composite file. 


═══ 2. Open Dialog ═══

The Open dialog supplies lists of files and directories from which the source 
files can be selected. The full path of the file is made by concatenating the 
file name to the directory, so you can type subdirectories in the name field if 
you want. '..' means the parent directory. If the name of File B is null, the 
name from File A is used. 


═══ 3. Problem Message Box ═══

The Problem message box informs the user of a problem in the program. This may 
or may not be fatal. The user is required to acknowledge the message; the 
program will take appropriate action. 


═══ 4. File Menu ═══

The File menu contains the following items: 

 Open 
     Allows new source files to be opened. 
 Exit 
     Closes the Contrast program. 


═══ 5. Help Menu ═══

The Help menu contains the following items: 

 Help for help 
     Explains the use of the help functions. 
 Extended help 
     Displays general help on the Contrast program. 
 Keys help 
     Displays help on the keys that can be used in the Contrast program. 
 Help index 
     Displays a list of selectable help topics. 
 About 
     Displays the application logo. 


═══ 6. Keys for Contrast ═══

The Contrast program assigns the following special functions to keys: 

 Alt+O 
     Bring up the Open dialog. 
 F3 
     Exit the Contrast program. 
 Alt+A 
 Alt+B 
     Display file A or B 
 Alt+C 
     Display the composite file 
 Alt+L 
 Alt+T 
 Alt+I 
     Ignore leading, trailing, or all blanks for line comparison. Use the 
     Options menu to see the current status. 
 Alt+U 
     Display lines unique to either source file interleaved, as opposed to 
     alternately. 
 Alt+D 
     Bring up the Define Colours dialog. 
 Alt+F 
     Bring up the Fonts dialog. 
 Arrow keys 
     Scroll the displayed file by one character. 
 Page Up 
 Page Down 
     Scroll the file by the height of the text window. 


═══ 7. View Menu ═══

The View menu changes the text displayed. This can be either of the source 
files, or the composite file. 


═══ 8. Options Menu ═══

The Options menu contains the following items: 

 Ignore leading blanks 
     Re-contrasts the files, with white space (i.e. spaces, tabs or nulls) at 
     the beginning of lines ignored. Any formatting of programs will thus be 
     irrelevent. 
 Ignore trailing blanks 
     Ignores white space at the end of lines. Some editors can be inconsistent 
     about leaving this in files. 
 Ignore all blanks 
     Disregards all white space, wherever it is in the files. This is useful 
     for comparing programs in free-format languages, especially if differing 
     editors have been used. 
 Interleave unique lines 
     Orders unmatching blocks in the composite file so that lines from files A 
     and B alternate. If this option is off, unmatching blocks will displayed 
     as whole blocks from file A or B. 
 Define colours used 
     Allows user definition of the colours used by Contrast. 
 Set font used 
     Changes the font and style used for the text display. 


═══ 9. Bar Chart ═══

The bar chart is a graphical representation of the two source files. Blocks of 
common lines are assigned a colour different from those around them, and drawn 
on the bars representing the files; a line links the matched blocks. The 
matched colours in the bar chart are used as the text colour for the file 
display; the default text colour for unmatched lines is black (red or yellow on 
the chart). Black marks by the bar chart show where the current text display is 
in the files. 


═══ 10. Composite ═══

The composite file is made from the two source files, using the common lines 
where possible. 

This is the default colour scheme: 

Common lines have a white background. 

Lines unique to File A are shown in black on yellow. 

Lines unique to File B are shown in black on red. 

Where a block of lines in File B has been moved from where it was in File A the 
program has to guess whether block 1 was moved up past block 2 or block 2 moved 
down past block 1. It shows the larger block as common and the other as moved 
in each file. The text shown as moved is drawn in a dark colour (not black) on 
yellow or red. The bar chart shows the connections. 


═══ 11. Colours ═══

Default colours are: 

Text Background 

 Yellow 
     Lines unique to File A (or moved in File A) Used in bar chart and as text 
     background. 
 Red 
     Lines unique to File B (or moved in File B) Used in bar chart and as text 
     background. 
 White 
     Lines common to File A and File B Text background only. 

 See Composite for how moved blocks are coloured. 

 Text Foreground 

 Blue 
 Dark pink 
 Dark green 
 Dark cyan 
     Text that has been matched in both files. The same colour is used for the 
     identical text in each file; the choice of colour is such that surrounding 
     blocks of matched lines use different ones. The same colour is used in the 
     bar chart to show the lines. 
 Black 
     Unmatched text. 

  The actual colours are defined by the user in the Define colours dialog. 


═══ 12. Colours dialog ═══

The Colours dialog allows the colours used by Contrast to be set to any of 16 
colours provided by Presentation Manager. Five text and three background 
colours need to be defined. They do not have to be all different, but the 
display may be confusing if they are not. 

The default button resets all the colours to the program-supplied settings. 


═══ 13. Font Dialog ═══

The Font dialog allows any fixed-width font present on the system to be used to 
display the file. If there is no suitable font, the program will use the System 
Proportional font, but text alignment will suffer as a result. The numbers 
given after the font names are point sizes. 

The italic and bold checkboxes allow the font to be displayed in different 
styles.