Merge pull request thingsboard#783 from smatvienko-tb/image-preview-generator-doc-and-improve

[3.3.3] Preview generator documented. Generate-preview script usability improved

Author: ashvayka

README.md

@@ -3,6 +3,7 @@
 * [Fork this repository](https://help.github.com/articles/fork-a-repo/)
 * [Deploy the site locally](#deployment-of-the-site-locally)
 * Add your changes
+* [Generate image preview](#image-preview-generator)
 * [Create Pull Request](https://help.github.com/articles/creating-a-pull-request/)
 
 ## Deployment of the site locally
@@ -44,3 +45,22 @@ or execute the below script from the project root directory:
 
 Your copy of the site will then be viewable at: [http://localhost:4000](http://localhost:4000)
 (or wherever Jekyll tells you).
+
+## Image preview generator
+
+For new *.png images preview is required along with original images.
+
+To create a previews use the script
+````bash
+#run once
+#install mogrify utility to perform resize 
+sudo apt install graphicsmagick-imagemagick-compat
+````
+Usage:
+```bash
+./generate-previews.sh path file_mask*.png
+```
+Example:
+```bash
+./generate-previews.sh images/solution-templates *.png
+```

generate-previews.sh

@@ -7,7 +7,17 @@ YELLOW='\033[1;33m'
 BROWN='\033[0;33m'
 NC='\033[0m'
 [ $# -eq 0 ] && { echo "Usage: $0 path_to_folder filter"; exit 1; }
- 
+[ -z "$2" ] && { echo "Filter not provided and was set to default *.png"; filter="*.png"; }
+
+# Check if mogrify installed
+if ! command -v mogrify &> /dev/null
+then
+    echo "'mogrify' not found"
+    echo "To install it use the command:"
+    echo "sudo apt install graphicsmagick-imagemagick-compat"
+    exit 1
+fi
+
 if [ -d "$dir" -a ! -h "$dir" ]
 then
    echo -e "${YELLOW}$dir${GREEN} found. Processing...${NC}"