View source for The "Compare with" dialog

== Abstract ==

The goal of this project is to provide a more flexible and user-friendly way to compare files inside the Eclipse environment. Currently, the Eclipse's "Compare With" feature has a few problems: 
*There is no easy way to compare files located outside the workspace with ones located inside (see {{bug|73923}} for details).
*To compare two or three files in the current workspace the user has to select them (using a ctrl-click) and choose the "Compare With"->"Each Other" option from a pop-up menu.
Both these issues can be solved by providing an UI element (possibly a dialog or a view) to which user can add two or three files and than invoke a compare editor from it.

This project is part of [[Google Summer of Code 2008|2008 Google Summer of Code]].

'''Participants:'''
*Student: Aleksandra Woźniak
*Mentor: Tomasz Zarna

== Features (by priority) ==

=== Must have ===
*adding files for comparison by drag'n'dropping them from the Package Explorer
*adding files for comparison by "Open Resource"/"Open Type" dialogs 
*adding files for comparison by "Open file" dialog (for choosing files located outside the current workspace): [https://bugs.eclipse.org/bugs/show_bug.cgi?id=73923 73923 (ASSIGNED)] 
*adding clipboard content for comparison

=== Should have ===
*invoking folder compares from the dialog
*clipboard content preview
*basic info about files selected for comparison, eg. filename, modification date, icon
*moving files/content between left, right and ancestor (either d'n'd or buttons)
*extension mechanism to support other "Items selection dialogs" like "Open Type"
*compare two opened files: [https://bugs.eclipse.org/bugs/show_bug.cgi?id=39126 39125 (ASSIGNED)]

=== Nice to have === 
*invoking a compare editor by drag'n'dropping one file to another in the Package Manager
*ancestor is an optional part of comparison so this section of the dialog could be expandable (should be hidden when no needed, and expanded/shown when the user would like to use ancestor in the comparison)
*don't make the dialog too busy, limit number of widgets to minimum

== Features (related are grouped together) ==

"One bug to block them all": [https://bugs.eclipse.org/bugs/show_bug.cgi?id=224562 224562 (ASSIGNED)]

=== Invoking the dialog ===
*from context menu in Package Manager
*from context menu in editors
*by drag&dropping one file to another in Package Manager

=== Adding content to the dialog === 
*drag&dropping from Package Manager 
*by "Items selection dialog" 
*from clipboard (+ clipboard content preview) 
*external files and folders 
'''Tasks:'''
*d'n'd support: [https://bugs.eclipse.org/bugs/show_bug.cgi?id=239959 bug 239959 (FIXED)]
*history for each "file:" [https://bugs.eclipse.org/bugs/show_bug.cgi?id=240298 bug 240298]
*handling selection of 4 or more resources: [https://bugs.eclipse.org/bugs/show_bug.cgi?id=241077 bug 241077]
*"Open resource" dialog: [https://bugs.eclipse.org/bugs/show_bug.cgi?id=243744 bug 243744]
*clipboard content + preview: [https://bugs.eclipse.org/bugs/show_bug.cgi?id=241088 bug 241088]
*external files and folders: [https://bugs.eclipse.org/bugs/show_bug.cgi?id=73923 bug 73923]

=== Layout and navigation within the dialog ===
*extendable ancestor section
*displaying basic info about files chosen for comparison (name, modification date, icon)
*moving files between left, right and ancestor section
'''Tasks:'''
*resizing of the dialog, when the dialog should and should not be resized? [https://bugs.eclipse.org/bugs/show_bug.cgi?id=241649 bug 241649]

=== Other tasks ===
*help and documentation [https://bugs.eclipse.org/bugs/show_bug.cgi?id=241643 bug 241643]
*key binding for the dialog [https://bugs.eclipse.org/bugs/show_bug.cgi?id=241539 bug 241539 (FIXED)]

== Community proposals ==
Feel free to add your comments and ideas.

* Please also have a look at the "AnyEdit tools" plugin: http://andrei.gmxhome.de/anyedit/index.html <br/>It also adds several enhancement to the selection of to be compared artifacts (like clipboard, opened editor...), so maybe you can benefit from the ideas or work over there.

* (copied from [https://bugs.eclipse.org/bugs/show_bug.cgi?id=73923#c10 73923])
** I'd really like to drag and drop files from Konqueror or another filesystem-browser.
** The dialog could be invoked via a rightclick on the editor tab (but as of bug #216710 the normal rightclickmenue will do)
** I second the request, to paste clipboard contents in a temp-file as another source. It should be possible, to first pass one portion of text, select the next text and create a second temp file before invoking the compare. Therefore the dialog should not be modal (but may or may not hover in front?).
** It might be worthwhile to rearrange the order of the files. If several files are dragged, it would be nice to sort them for last modification. But a manual reorder without the tedious copying of filenames around should be possible.
** Last, if there is too much time :-) I envision a feature like the formula-editor in spreadsheet-applications offer. A button to click, that reduces the whole dialog to a single line of textinput, that stays in front, to monitor, where the user clicked / which editor-.tab got the focus last / which entry of the package explorer was clicked.

* an idea of a dynamic context menu is mentioned in [https://bugs.eclipse.org/bugs/show_bug.cgi?id=198701#c7 198701 (ASSIGNED)]

* it would be great if it was possible to compare not only whole files, but also separate methods (or internal classes)

== Getting the source ==

Part of the project was recently released to HEAD. For further modifications see patches submitted to the following bugs:
*[https://bugs.eclipse.org/bugs/show_bug.cgi?id=243744 bug 243744]
*[https://bugs.eclipse.org/bugs/show_bug.cgi?id=73923 bug 73923]
*[https://bugs.eclipse.org/bugs/show_bug.cgi?id=241088 bug 241088]
*[https://bugs.eclipse.org/bugs/show_bug.cgi?id=240298 bug 240298]