mgdiff - Motif-based graphical file difference browser

Acknowledgements

       To Andrew C. Myers for writing gdiff.MGDIFF(1x)

Authors

       Daniel Williams (dan@sass.com)
       Erik  de  Castro Lopo (erikd AT mega-nerd DOT com) added "SaveasLeft/Right" and saving both and neither
       sides.

Command Line Options

-toolkitoption
These are the standard options accepted by all applications that use the X Toolkit Intrinsics.
See the OPTIONS section in the X(1) manual page.

-quit This option sets the resource Mgdiff.quitIfSame to "true". This will cause the program to exit
immediately without bringing up a window if the two files have no differences (as determined by
the diff command).

-argsdiffargs
This option sets the resource Mgdiff.diffArgs to the value of the diffargs argument. These flags
are passed to the diff command that actually computes the differences between the two files.
Since any argument can be passed, it is possible to specify flags that cause the diff command to
fail or to generate output in a different format that will cause mgdiff to fail. For most
versions of diff, only three flags make any sense. The first is '-b'; this causes diff to ignore
trailing blanks (spaces and tabs) and to treat all other strings of blanks as equivalent. The
second flag is '-w'; this ignores blanks and treats strings of blanks as equivalent. The last
flag is '-i'; this ignores case when comparing letters.

-filename
This command sets the resource Mgdiff.filename to the value of the name argument. mgdiff uses
this string to display over a file read from standard input.

Copyright

       Copyright (c) 1994, Daniel Williams
       Copyright (c) 2003, Erik de Castro Lopo
       See X(1) for a full statement of rights and permissions.

Description

Mgdiff is a graphical front end to the diff command. It permits the user to view the differences between
two ASCII files in context and, optionally, to write out a third file which is the user-defined merging
of those two files. It is inspired by a similar program, called gdiff, which runs only on Silicon
Graphics workstations and for which source code is not provided.

The program takes as arguments various flags (described in the next section) and the names of two files
to compare. Either filename (but not both) may be given as '-' to use standard input instead.

The resulting display consists mostly of two panes of text; the one on the left is the first file
specified and the one on the right is the second file specified. Between and below the text panes are
scrollbars that permit changing the visible portions of the two files being compared. In addition, the
program implements the Scrolled Region recommendations of Section 2.3.4 of the OSF/Motif Style Guide
(release 1.1), meaning that the arrow and paging keys will work to scroll as well. Above each text pane
is the name of the file in that text pane and the line number in the file which is being displayed.

The text in each of the text panes is divided into blocks of lines which are color-coded with one of five
different colors. This indicates that the block:

differs between the two files

is identical between the two files

has been inserted in one file or the other

is for display purposes (to match an inserted block in the other file)

has been selected by the user (for writing to a merged file)

These colors can be modified by the user via X resources; see the RESOURCES section of this manual page.
A legend display of the colors and their meanings is available using the Help menu.

On the right-hand side of the display is an overview area; this shows the files in their entirety. The
sliders in the overview area track the lines being displayed in the text panes.

At the top of the display is a Motif menu bar; those functions are discussed in the MENUS section of this
manual page.

Earlier versions of this program (pre 2003) only allowed the selection of the left hand side difference
or the right hand side difference. It also would not allow a file to be saved with unselected blocks.
The current version allows the user to select both sides of a difference by selecting blocks using the
middle mouse button. When both sides of a difference are selected both blocks will be saved to the
merged file and marked in a similar manner to the way CVS marks merges that require manual resolution of
conflicting changes. In addition, the current version also allows saving of a merged file with
unselected blocks. In this case, the merged file will contain neither the left hand side nor the right
hand side of the unselected blocks.

Diagnostics

       Returns  the exit status generated by the diff command.  This is usually 0 for no differences, 1 for some
       differences and 2 for errors.

Menus

The menubar contains the following menu topics as CascadeButtons: File, View, Select, Options and Help.
The rest of this section discusses each menu entry, showing it's name and accelerator, if any.

File

This pulldown menu controls file access:

Open...Ctrl+O

Brings up the "Open Files" FileSelectionDialog to allow the user to open two files for comparison.

OpenLeft...Ctrl+L

Brings up the "Open File" FileSelectionDialog to allow the user to specify a file to open and
compare with the already opened right-hand file.

OpenRight...Ctrl+R

Brings up the "Open File" FileSelectionDialog to allow the user to specify a file to open and
compare with the already opened left-hand file.

ReloadBothMeta+R

Re-runs diff on both the currently opened files.

SaveAs...Ctrl+S

Brings up the "Save File" FileSelectionDialog to allow the user to specify an output file for
writing the merged file; this is an application modal dialog. The program will allow the user to
overwrite an existing file but pops up a QuestionDialog to allow the user to cancel the operation
if desired. If there are any unselected areas of difference between the two files the user is
asked whether they want to continue or cancel the operation. If the user continues, the output
file will contain none of the unselected blocks.

SaveAsLeft...

Saves the merged file to the location given by the left hand side file location. The user will be
asked if they are sure they wish the existing file to be overwritten. As with the "Save As", if
there are any unselected areas of difference between the two files the user asked whether they
want to continue or cancel the operation. If the user continues, the output file will contain
none of the data in the unselected blocks.

SaveAsRight...

Saves the merged file to the location given by the right hand side file location. The user will be
asked if they are sure they wish the existing file to be overwritten. As with the "Save As", if
there are any unselected areas of difference between the two files the user asked whether they
want to continue or cancel the operation. If the user continues, the output file will contain
none of the data in the unselected blocks.

ExitCtrl+C

Exits the program immediately.

View

This pulldown menu contains commands for moving through the files.

PreviousCtrl+P

Scrolls both file views so that the previous area of difference is Mgdiff.linesOfContext lines
from the top of the application window.

NextCtrl+N

Scrolls both file views so that the next area of difference is Mgdiff.linesOfContext lines from
the top of the application window.

NextUnselectedCtrl+U

Scrolls both file views so that the next unselected area of difference is Mgdiff.linesOfContext
lines from the top of the application window.

Select

The two files being compared can be optionally merged into one file. To do this, the user must select
for each area of difference between the two files which version should be written to the merged file.
The menu entries in this pulldown menu allow the user to select or unselect differences in groups rather
than individually.

LeftAll

For all areas of difference between the two files select the left-hand file version.

RightAll

For all areas of difference between the two files select the right-hand file version.

UnselectAll

Unselects all areas of difference in both files.

Options

This pulldown menu controls miscellaneous appearance and/or behavior options.

OverviewCtrl+W

This menu entry toggles the presence of the overview area on the right-hand side of the
application window. The default value for this toggle is controlled by a resource,
Mgdiff.overview, which is described in the RESOURCES section.

HorizontalScrollbarCtrl+H

This menu entry toggles the presence of the horizontal scrollbar at the bottom of the application
window. The default value for this toggle is controlled by a resource, Mgdiff.horzScrollbar,
which is described in the RESOURCES section.

DragScrollCtrl+D

This menu entry toggles the behaviour of the scrollbars in the application window. When set,
dragging the slider of a scrollbar results in a immediate change in the view of the text being
compared. When unset, the view is only changed at the end of a slider drag (when the mouse button
is released.) This setting might be preferred on a slower X server. The default value for this
toggle is controlled by a resource, Mgdiff.dragScroll, which is described in the RESOURCES
section.

Help

This pulldown menu displays commands for obtaining help on or information about mgdiff.

Version...Ctrl+V

Brings up an InformationDialog with author and version information.

ManualPage...Ctrl+M

Brings up a DialogShell with a ScrolledText widget containing this manual page. The command for
generating this is customizable via a resource, Mgdiff.manCommand, which is described in the
RESOURCES section.

ColorLegend...Ctrl+G

Brings up a DialogShell which summarizes the use of color in encoding the types of differences
between the two files being compared.

Name

       mgdiff - Motif-based graphical file difference browser

Other Displays/Controls

       You can move directly to a particular spot in the two files by using BDrag in the overview area.

       The  program  uses  what the OSF/Motif Style Guide calls "multiple selection" to select individual blocks
       for writing to a merged file.  Clicking BSelect on an unselected block adds it to the  list  of  selected
       blocks.   Clicking BSelect on a selected block removes it from the list of selected blocks.  In addition,
       Clicking BSelect on an unselected block which is opposite a selected block  (in  the  other  text  panes)
       removes the selected block from the list of selected blocks.

       The numbers in the small boxes next to the file names are the line numbers of the lines at the top of the
       text panes.

Restrictions

       Using BDrag in the overview area doesn't work well when drag scrolling is turned off.

       Doesn't support monochrome displays.

       Input lines longer than BUFSIZ (see /usr/include/stdio.h) are silently truncated.

       The code for parsing and passing arguments to the diff command assumes arguments are delimited  by  white
       space and does not do any quote processing.

Synopsis

       mgdiff [-toolkitoption ...] [-quit] [-file name] [-args diffargs] [file1 file2]

Widgets

       What  follows  is the hierarchy of Motif widgets, as generated by editres(1).  The hierarchical structure
       of the widget tree is reflected in the indentation.  Each line consists of the widget class name followed
       by the widget instance name.  This information might be useful if you wish to customize the appearance of
       the program via resource settings.

       Mgdiff  mgdiff
            XmMainWindow  mainw
                 XmSeparatorGadget  MainWinSep1
                 XmSeparatorGadget  MainWinSep2
                 XmSeparatorGadget  MainWinSep3
                 XmRowColumn  menubar
                      XmCascadeButtonGadget  button_0
                      XmCascadeButtonGadget  button_1
                      XmCascadeButtonGadget  button_2
                      XmCascadeButtonGadget  button_3
                      XmCascadeButtonGadget  button_4
                      XmMenuShell  popup_file_menu
                           XmRowColumn  select_menu
                                XmPushButtonGadget  button_0
                                XmPushButtonGadget  button_1
                                XmSeparatorGadget  separator_0
                                XmPushButtonGadget  button_2
                           XmRowColumn  file_menu
                                XmPushButtonGadget  button_0
                                XmPushButtonGadget  button_1
                                XmPushButtonGadget  button_2
                                XmPushButtonGadget  button_3
                                XmPushButtonGadget  button_4
                                XmSeparatorGadget  separator_0
                                XmPushButtonGadget  button_5
                                XmPushButtonGadget  button_6
                                XmSeparatorGadget  separator_1
                                XmPushButtonGadget  button_7
                           XmRowColumn  options_menu
                                XmToggleButtonGadget  button_0
                                XmToggleButtonGadget  button_1
                                XmToggleButtonGadget  button_2
                           XmRowColumn  help_menu
                                XmPushButtonGadget  button_0
                                XmPushButtonGadget  button_1
                                XmPushButtonGadget  button_2
                           XmRowColumn  view_menu
                                XmPushButtonGadget  button_0
                                XmPushButtonGadget  button_1
                                XmPushButtonGadget  button_2
                 XmForm  form1
                      XmFrame  frame1
                           XmForm  form3
                                XmScrollBar  sbl
                                XmDrawingArea  dam
                                XmScrollBar  sbr
                      XmFrame  frame2
                           XmForm  form4
                                XmForm  form2
                                     XmScrollBar  sb
                                     XmForm  form21
                                          XmFrame  frame3
                                               XmLabel  fnamel
                                          XmFrame  frame31
                                               XmTextField  linenuml
                                     XmForm  form22
                                          XmFrame  frame4
                                               XmLabel  fnamer
                                          XmFrame  frame41
                                               XmTextField  linenumr
                                     XmDrawingArea  textl
                                     XmDrawingArea  textr
                                XmScrollBar  sbh
            XmDialogShell  version_popup
                 XmMessageBox  version
                      XmLabelGadget  symbol
                      XmLabelGadget
                      XmSeparatorGadget  separator
                      XmPushButtonGadget  OK
                      XmPushButtonGadget  Cancel
                      XmPushButtonGadget  Help
            XmDialogShell  manualpage_popup
                 XmForm  manualpage
                      XmPanedWindow  pane
                           XmScrolledWindow  help_textSW
                                XmScrollBar  vbar
                                XmText  help_text
                           XmForm  form2a
                                XmPushButton  OK
                           XmSash  sash
                           XmSeparatorGadget  separator
                           XmSash  sash
                           XmSeparatorGadget  separator
            XmDialogShell  legend_popup
                 XmForm  legend
                      XmPanedWindow  pane
                           XmRowColumn  rc
                                XmLabel  label1
                                XmLabel  label2
                                XmLabel  label3
                                XmLabel  label4
                                XmLabel  label5
                           XmForm  form2a
                                XmPushButton  OK
                           XmSash  sash
                           XmSeparatorGadget  separator
                           XmSash  sash
                           XmSeparatorGadget  separator
            XmDialogShell  werror_popup
                 XmMessageBox  werror
                      XmLabelGadget  symbol
                      XmLabelGadget
                      XmSeparatorGadget  separator
                      XmPushButtonGadget  OK
                      XmPushButtonGadget  Cancel
                      XmPushButtonGadget  Help

X Resources

Mgdiff.diffForeground:blackMgdiff.diffBackground:yellow

These colors are for blocks which differ between files.

Mgdiff.sameForeground:blackMgdiff.sameBackground:grey

These colors are for blocks which are identical between files.

Mgdiff.insertForeground:blackMgdiff.insertBackground:orange

These colors are for blocks which have been inserted in one file.

Mgdiff.blankForeground:blackMgdiff.blankBackground:grey66

These colors are for blocks which are for display purposes.

Mgdiff.selectForeground:blackMgdiff.selectBackground:lightslateblue

These colors are for blocks which have been selected by the user.

Mgdiff.font:7x13bold

Font for displaying text blocks.

Mgdiff.dragScroll:true

Set to true if scrollbar dragging should cause immediate changes in the viewed text, and false if the
view should only change after the scrollbar has been moved.

Mgdiff.overview:true

Set to true if the file overview section should appear.

Mgdiff.horzScrollbar:true

Set to true if the horizontal scrollbar should appear.

Mgdiff.linesOfContext:3

Number of lines that should appear above a difference block gotten to using the Previous or Next
commands. Should be greater or equal to zero.

Mgdiff.manCommand:(manmgdiff|col-b)2>&1

The command (or pipeline) used to produce a formatted manual page without escape codes.

Mgdiff.diffCommand:diff

The diff(1) compatible command to use for calculating differences between text files.

Mgdiff.diffArgs:

The arguments to be provided to the diff command. This resource can also be set via the -args command
line option.

Mgdiff.quitIfSame:false

If the two files have no differences (as determined by the diff command) then exit immediately without
bringing up a window. This resource can also be set to "true" via the -quit command line option.

Mgdiff.filename:(stdin)mgdiff uses this string to display over a file read from standard input. This resource can also be set
via the -file command line option.