kidiff 2.3.0

KiCad PCB/SCH Diff

KiDiff (kicad-diff or kicad_pcb-diff)

This program generates a PDF file showing the changes between two KiCad PCB or SCH files.

PCBs are plotted into PDF files, one for each layer. Then ImageMagick is used to compare the layers and PNG files are generated. The PNGs are finally assembled into one PDF file and the default PDF reader is invoked.

All the intermediate files are generated in the system temporal directory and removed as soon as the job is finished. You can cache the layers PDFs specifying a cache directory and keep the resulting diff images specifying an output directory.

For SCHs the process is similar, but using KiAuto. Note that one schematic is compared at a time. The --all_pages option allows comparing multiple pages, but both documents must have the same ammount of pages.

The default resolution for the images is 150 DPI. It can be increased for better images, at the cost of (exponetially) longer execution times. You can provide a smaller resolution for faster processing. For high resolution you could need to configure the ImageMagick limits. Consult the 'identify -list resource' command.

Installation

Dependencies

In order to run the scripts you need:

• Python 3.5 or newer
• KiCad 5.1 or newer
• Python3 wxWidgets (i.e. python3-wxgtk4.0). This is usually installed with KiCad.
• ImageMagick tools (i.e. imagemagick Debian package). Used to manipulate images and create PDF files.
• pdftoppm tool (i.e. poppler-utils Debian package). Used to decode PDF files.
  • Alternative: Ghostscript (slower and worst results)
• xdg-open tool (i.e. xdg-utils Debian package). Used to open the PDF viewer.
• KiAuto. Used to print the schematic in PDF format.

In a Debian/Ubuntu system you'll first need to add this repo and then use:

$ sudo apt-get install python3 kicad imagemagick poppler-utils xdg-utils kiauto`

Note: if you are using Debian, or some derived distro like Ubuntu, you can find a Debian package in the releases section.

Standalone use

1. As root run:

# make install

The scripts will be copied to /usr/local/bin. If you want to install the scripts in /usr/bin run

# make prefix=/usr install

Note: if you are using Debian, or some derived distro like Ubuntu, you can find a Debian package in the releases section.

Git plug-in

1. Install the scripts
2. To initialize a repo just run the kicad_pcb-diff-init.py script from the root of the repo.
   This will configure the repo to read extra configuration from the .gitconfig file.
   It will also associate the kicad_pcb file extension with the kicad-git-diff.py script.
3. The initialization script will create a list of layers to be excluded in the .kicad-git-diff file.
   Review this file and adjust it to your needs. Lines starting with # will be ignored.

Once configured the tool will be used every time you do a diff using git.

Usage

The kicad-git-diff.py is a plug-in for git so you just need to configure git and then it becomes transparent. If you need to create a diff between two files outside git you can use the kicad-diff.py script.

You have to provide the name of the two PCB/SCHs to be compared. The first is the old one, the reference, and the second is the new, the one you want to compare. The additional command line options are:

--help

Shows a detailed list of the available options.

--all_pages

Compare all pages for a schematic. Note that the tool doesn't currently support adding or removing sheets, both documents must have the same ammount of pages.

--cache_dir

The PCB/SCH files are plotted to PDF files. One PDF file for layer. To avoid plotting them over and over you can specify a cache directory to store the PDFs.

--diff_mode

Selects the mechanism used to represent the differences:

• red_green this is the default mode. Here we try to mimic the colored text mode diff tools. Things added to the old file are reprsented in green and things removed in red.
• stats in this mode all difference are represented in red. We compute the ammount of pixels that are different, you can use this value to determine if the changes are significant. See the --fuzz and --threshold options.

--exclude

Specifies the name of a file containing a list of layers to be excluded. Each line of the file is interpreted as a layer name. An example for this file could be:

B.Adhes
F.Adhes
Cmts.User
Eco1.User
Eco2.User
Edge.Cuts
Margin

You can also use the KiCad internal layer ID number. Note that currently when using KiCad 6 the name of the layer is the default KiCad name, not the name defined by the user.

Note that when using the git plug-in the script looks for a file named .kicad-git-diff at the root of the repo.

Using this you can reduce the time wasted computing diffs for empty or useless layers.

See also --layers

--force_gs

KiDiff uses poppler utils if they are available. When they aren't KiDiff can use Ghostscript. The results using poppler are better and the process is faster, but you can choose to use Ghostscript using this option.

--fuzz

When comparing using the stats mode (see --diff_mode) this option controls how strict is the color comparison. The default is to tolerate 5 % of error in the colors. Enlarge it if you want to ignore bigger differences in the colors.

--keep_pngs

Don't remove the individual PNGs. Complements --output_dir. They are usually removed as soon as we get the output PDF.

--layers

Specifies the name of a file containing a list of layers to be included. This option works similar to --exclude but we process only the layers indicated here.

Important: when this list is only composed by layer numbers KiDiff skips any check and uses this list of layers, even if they aren't defined in any of the specified PCBs.

--layers and --exclude are mutually exclusive.

--new_file_hash

This is the equivalent of the --old_file_hash option used for the new PCB/SCH file.

--no_reader

Use it to avoid invoking the default PDF viewer. Note that you should also provide an output directory using --output_dir.

The default PDF reader is invoked using xdg-open

--old_file_hash

The plotted PDF files for each layer are stored in the cache directory using a SHA1 of the PCB/SCH file as name for the directory. You can specify another hash here to identify the old PCB/SCH file.

The git plug-in uses the hash provided by git instead of the SHA1 for the file.

--output_dir

Five seconds after invoking the PDF viewer the output files are removed. If you want to keep them for later review, or five seconds isn't enough for your system, you can specify a directory to store the generated files.

Note: individual PNGs are always removed, consult --keep_pngs

--output_name

Used to complement --output_dir. The default name is diff.pdf

--resolution

The PDF files are converted to bitmaps to be compared. The default resolution for these bitmaps is 150 DPIs. This is a compromise between speed and legibility. For faster compares you can use a smaller resolution. For detailed comparison you can use a higher resolution. Be careful because the time is increased exponentially. You can also run out of resources. In particular ImageMagick defines some limits to the disk used for operations. These limits can be very low for default installations. You can consult the limits using the following command:

identify -list resource

Consult ImageMagick documentation in order to increase them.

--threshold

In the stats mode this option can make KiDiff to return an error value if the difference is bigger than the specified threshold. Indicating 0 means that we don't look for errors, KiDiff always returns 0.

-v/--verbose

Increases the level of verbosity. The default is a quite mode, specifying one level (-v) you'll get information messages about what's going on. If you increase the level to two (-vv) you'll get very detailed information, most probably useful only to debug problems.

--version

Print the script version, copyright and license.

Credits and notes

• This script is strongly based on Jesse Vincent work.
• I borrowed the command to compare two images from Brecht Machiels. In particular from his diffpdf.sh tool.
• I'm not a Python programmer, stackoverflow helps me ...