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PDF Thumbnails

Create image previews from PDF files.

This Flow generates an image thumbnail from PDF using the command-line tool pdftoppm.

Important Note

As the Flow is using the "Shell Command" action, you must make sure to install the pdftoppm binary on the machine, and declare it manually in the Cells configuration to allow Cells Flows user to acces it. This is done using the configuration key "defaults/schedulerShellAllowedCommands", that must contains a {key:Label} object. It will look like : 

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{
/// config file
   "defaults":{
      // other existing keys
      "schedulerShellAllowedCommands":{
        "pdftoppm": "PDF Converter"
      }
   }
You can add here any other binary that you wish to use with Cells Flows.

How It Works

The Flow is composed of two branches to handle the complete files lifecycle:

  • The Create/Update event triggers a call to pdfppm to associate a preview image with the PDF. It is attached to the original file as "ImagePreview" metadata.
  • The Delete event will clean the associated thumbnail if it exists.

Parameters

No parameters defined

Trigger Type

Event-based

JSON Representation

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{
  "Label": "PDF Thumbnails",
  "Owner": "pydio.system.user",
  "Metadata": {
    "Description": "Create image previews from PDF files",
    "Icon": "mdi mdi-image-filter",
    "TplCategory": "content-processing",
    "Usage": "This Flow generates an image thumbnail from PDF using the command-line tool `pdftoppm`. \n\n### Important Note\n\nAs the Flow is using the \"Shell Command\" action, you must make sure to **install** the pdftoppm binary on the machine, **and declare** it manually in the Cells configuration to allow Cells Flows user to acces it. \nThis is done using the configuration key \"defaults/schedulerShellAllowedCommands\", that must contains a {key:Label} object. It will look like : \n```\n{\n/// config file\n   \"defaults\":{\n      // other existing keys\n      \"schedulerShellAllowedCommands\":{\n      \t\"pdftoppm\": \"PDF Converter\"\n      }\n   }\n```\nYou can add here any other binary that you wish to use with Cells Flows.\n\n### How It Works\n\nThe Flow is composed of two branches to handle the complete files lifecycle: \n\n - The Create/Update event triggers a call to pdfppm to associate a preview image with the PDF. It is attached to the original file as \"**ImagePreview**\" metadata.\n - The Delete event will clean the associated thumbnail if it exists."
  },
  "Custom": true,
  "EventNames": [
    "NODE_CHANGE:0",
    "NODE_CHANGE:3",
    "NODE_CHANGE:5"
  ],
  "Actions": [
    {
      "ID": "actions.cmd.shell",
      "Label": "PDF to Image",
      "TriggerFilter": {
        "Label": "Create/Update",
        "Query": {
          "SubQueries": [
            {
              "type_url": "type.googleapis.com/jobs.TriggerFilterQuery",
              "value": "Gg1OT0RFX0NIQU5HRTowGg1OT0RFX0NIQU5HRToz"
            }
          ]
        }
      },
      "Parameters": {
        "cmd": "pdftoppm",
        "inputStream": "true",
        "inputTempFile": "false",
        "outputBinary": "true",
        "outputStream": "true",
        "parameters": "- -jpeg -jpegopt quality=60 -f 1 -l 1 -r 72 -singlefile",
        "storeOutput": "thumbnails/{{.Node.Uuid}}.jpg"
      },
      "ChainedActions": [
        {
          "ID": "actions.tree.meta",
          "Parameters": {
            "fieldname": "{\"@value\":\"Paths\"}",
            "metaJSON": "{\"ImagePreview\":\"{{.Node.Uuid}}.jpg\"}"
          }
        }
      ]
    },
    {
      "ID": "actions.scheduler.log-input",
      "NodesSelector": {
        "Query": {
          "SubQueries": [
            {
              "type_url": "type.googleapis.com/tree.Query",
              "value": "ah10aHVtYm5haWxzL3t7Lk5vZGUuVXVpZH19LmpwZw=="
            }
          ],
          "Operation": 1
        },
        "Collect": true,
        "Label": "Find Thumbnail"
      },
      "TriggerFilter": {
        "Label": "Clean on Delete",
        "Query": {
          "SubQueries": [
            {
              "type_url": "type.googleapis.com/jobs.TriggerFilterQuery",
              "value": "Gg1OT0RFX0NIQU5HRTo1"
            }
          ]
        }
      },
      "Parameters": {
        "fieldname": "{\"@value\":\"Paths\"}",
        "message": "",
        "taskLogger": "true"
      },
      "ChainedActions": [
        {
          "ID": "actions.tree.delete",
          "NodesFilter": {
            "Query": {
              "SubQueries": [
                {
                  "type_url": "type.googleapis.com/tree.Query",
                  "value": "Cgp0aHVtYm5haWxz"
                }
              ]
            }
          }
        }
      ]
    }
  ],
  "MaxConcurrency": 10,
  "NodeEventFilter": {
    "Query": {
      "SubQueries": [
        {
          "type_url": "type.googleapis.com/service.Query",
          "value": "CicKHnR5cGUuZ29vZ2xlYXBpcy5jb20vdHJlZS5RdWVyeRIFUgNwZGY="
        },
        {
          "type_url": "type.googleapis.com/service.Query",
          "value": "CiQKHnR5cGUuZ29vZ2xlYXBpcy5jb20vdHJlZS5RdWVyeRICMAEQAQ=="
        }
      ],
      "Operation": 1
    }
  }
}