[doc] Update pmd-demo.gif

README.md

@@ -39,7 +39,7 @@ See also [Getting Started](https://docs.pmd-code.org/latest/pmd_userdocs_install
 
 **Demo:**
 
-This shows how PMD can detect for loops, that can be replaced by for-each loops.
+This shows how PMD analyses [openjdk](https://github.com/openjdk/jdk):
 
 ![Demo](docs/images/userdocs/pmd-demo.gif)
 

docs/images/userdocs/README.md

@@ -0,0 +1,30 @@
+## How to create pmd-demo.gif
+
+### Prepare
+
+```shell
+mkdir $HOME/pmd-demo
+cd $HOME/pmd-demo
+curl -L -o jdk-master.zip https://github.com/openjdk/jdk/archive/refs/heads/master.zip
+unzip jdk-master.zip
+alias pmd=$HOME/PMD/source/pmd/pmd-dist/target/pmd-bin-7.0.0-SNAPSHOT/bin
+clear
+pmd check -R rulesets/java/quickstart.xml -d jdk-master/src/java.base -f text --cache pmd.cache --report-file jdk-report.txt
+```
+
+Second terminal window: `cd $HOME/pmd-demo; tail -f jdk-report.txt`
+
+### Recording
+
+Record screencast with https://github.com/EasyScreenCast/EasyScreenCast (a gnome3 extension)
+
+The recorded screencast can be found in `$HOME/Videos`.
+
+### Converting
+
+Convert webm to gif: https://engineering.giphy.com/how-to-make-gifs-with-ffmpeg/
+
+```shell
+cd $HOME/Videos
+ffmpeg -i pmd7-demo.webm -filter_complex "[0:v] fps=12,scale=960:-1,split [a][b];[a] palettegen [p];[b][p] paletteuse" pmd7-demo.gif
+```