ui/src/test/diff_viewer/README.md - third_party/perfetto - Git at Google

 # CI screenshot diff viewer

 This directory contains the source of screenshots diff viewer used on Perfetto
 CI. The way it works as follows:

 When a screenshot test is failing, the testing code will write a line of the
 form

 ```
 failed-screenshot.png;failed-screenshot-diff.png
 ```

 To a file called `report.txt`. Diff viewer is just a static page that uses Fetch
 API to download this file, parse it, and display images in a list of rows.

 The page assumes `report.txt` to be present in the same directory, same goes for
 screenshot files. To simplify deployment, the viewer is developed without a
 framework and constructs DOM using `document.createElement` API.
	# CI screenshot diff viewer

	This directory contains the source of screenshots diff viewer used on Perfetto
	CI. The way it works as follows:

	When a screenshot test is failing, the testing code will write a line of the
	form

	```
	failed-screenshot.png;failed-screenshot-diff.png
	```

	To a file called `report.txt`. Diff viewer is just a static page that uses Fetch
	API to download this file, parse it, and display images in a list of rows.

	The page assumes `report.txt` to be present in the same directory, same goes for
	screenshot files. To simplify deployment, the viewer is developed without a
	framework and constructs DOM using `document.createElement` API.