2.17. Viewing Differences

If you have configured a third party diff tool, you can use Shift when selecting the Diff command to use the alternate tool resp. the build in tool. Read Section 2.36.4, “External Program Settings” to find out about configuring other diff tools.

Sometimes in the life of a project you might change the line endings from CRLF to LF, or you may change the indentation of a section. Unfortunately this will mark a large number of lines as changed, even though there is no change to the meaning of the code. The options here will help to manage these changes when it comes to comparing and applying differences. You will see these settings in the Comparing Version dialog (cf. Section 2.17.3, “Comparing Version”), as well as in the settings for TortoiseGitMerge.

Ignore line endings excludes changes which are due solely to difference in line-end style.

Compare whitespaces includes all changes in indentation and inline whitespace as added/removed lines.

Ignore whitespace changes excludes changes which are due solely to a change in the amount or type of whitespace, eg. changing the indentation or changing tabs to spaces. Adding whitespace where there was none before, or removing a whitespace completely is still shown as a change.

Ignore all whitespaces excludes all whitespace-only changes.

Naturally, any line with changed content is always included in the diff.

Figure 2.36. The Compare Revisions Dialog

In log dialog, when you select two commits Context menu → Compare revisions , or when you select a commit Context menu → Compare with previous version / Compare with working tree ; or in Windows Explorer, when you select no files or a folder TortoiseGit context menu → Diff with previous version , the Compare Revisions Dialog comes up.

This dialog shows a list of all files which have changed and allows you to compare them individually using context menu.

You can Revert selected files to version 1 or version 2. There are 2 menu items for this purpose. Context menu → Revert to revision xxxxxxx / Revert to revision yyyyyyy where xxxxxxx is revision 1 short hash and yyyyyyy revision is 2 short hash.

You can export a change tree, which is useful if you need to send someone else your project tree structure, but containing only the files which have changed. This operation works on the selected files only, so you need to select the files of interest - usually that means all of them - and then Context menu → Export selection to.... You will be prompted for a location to save the change tree.

You can also export the list of changed files to a text file using Context menu → Save list of selected files to....

If you want to export the list of files and the actions (modified, added, deleted) as well, you can do that using Context menu → Copy selection to clipboard.

The button at the top allows you to change the direction of comparison. You can show the changes need to get from A to B, or if you prefer, from B to A.

The buttons with the revision numbers on can be used to change to a different revision range. When you change the range, the list of items which differ between the two revisions will be updated automatically.

If the list of filenames is very long, you can use the search box to reduce the list to filenames containing specific text. Note that a simple text search is used, so if you want to restrict the list to C source files you should enter .c rather than *.c.

The built-in diff command of git is available for diffing submodules, but we often find ourselves wanting to see more details how a submodule has changed too. That's why we created Submodule Diff Dialog. The Submodule Diff Dialog is only accessible using the Section 2.5, “Committing Your Changes To The Repository” or Section 2.6, “Getting Status Information” dialogs using the COmpare with base entry in the context menu for a submodule.

Figure 2.37. The submodule difference dialog

The 'From' group box on the top displays the information of the original revision. Below it, there is a 'To' group box, which display the information of the changed revision. For each group box, the full commit hash is displayed, and can be highlighted and copied to clipboard; the subject (i.e. first line of commit message) is displayed and also copyable to clipboard; the Show Log button brings you to a new Log Dialog and jump to that revision.

To better draw the attention of the change of revision of submodule mounted, we added some indicators. In 'To' group box, there is a change type field. Here list out the types:

If current workspace of the submodule is dirty, the commit hash will be rendered in yellow background and red text.

In both group boxes, if the revision is not fetched, submodule not initialized or other errors, the commit hash will be rendered in red background.

There are many tools available for diffing text files, including our own TortoiseGitMerge, but we often find ourselves wanting to see how an image file has changed too. That's why we created TortoiseGitIDiff.

Figure 2.38. The image difference viewer

TortoiseGit → Diff for any of the common image file formats will start TortoiseGitIDiff to show image differences. By default the images are displayed side-by-side but you can use the View menu or toolbar to switch to a top-bottom view instead, or if you prefer, you can overlay the images and pretend you are using a lightbox.

Naturally you can also zoom in and out and pan around the image. You can also pan the image simply by left-dragging it. If you select the Link images together option, then the pan controls (scrollbars, mousewheel) on both images are linked.

An image info box shows details about the image file, such as the size in pixels, resolution and colour depth. If this box gets in the way, use View → Image Info to hide it. You can get the same information in a tooltip if you hover the mouse over the image title bar.

When the images are overlaid, the relative intensity of the images (alpha blend) is controlled by a slider control at the left side. You can click anywhere in the slider to set the blend directly, or you can drag the slider to change the blend interactively. Ctrl+Shift-Wheel to change the blend.

The button above the slider toggles between two preset blends, indicated by the markers on either side of the blend slider. By default one is at the top and the other at the bottom, so the toggle button just switches between one image and the other. You can move the markers to choose the two blend values that the toggle button will use.

Sometimes you want to see a difference rather than a blend. You might have the image files for two revisions of a printed circuit board and want to see which tracks have changed. If you disable alpha blend mode, the difference will be shown as an XOR of the pixel colour values. Unchanged areas will be plain white and changes will be coloured.

If the tools we provide don't do what you need, try one of the many open-source or commercial programs available. Everyone has their own favourites, and this list is by no means complete, but here are a few that you might consider:

Read Section 2.36.4, “External Program Settings” for information on how to set up TortoiseGit to use these tools.