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Take screenshots of webpages or uploaded HTML files

The /html/convert Robot takes screenshots of web pages or uploaded HTML pages.

A URL can be provided instead of an input HTML file, to capture a screenshot from the website referenced by the URL.

Use the /image/resize Robot to resize or crop the screenshot as needed.

Warning: A validation error will occur if neither an HTML file is uploaded nor a URL parameter is given.

Parameters

  • use

    String / Array of Strings / Object required

    Specifies which Step(s) to use as input.

    • You can pick any names for Steps except ":original" (reserved for user uploads handled by Transloadit)

    • You can provide several Steps as input with arrays:

      "use": [
        ":original",
        "encoded",
        "resized"
      ]
      

    :bulb: That’s likely all you need to know about use, but you can view advanced use cases:

    › Advanced use cases
    • Step bundling. Some Robots can gather several Step results for a single invocation. For example, the /file/compress Robot would normally create one archive for each file passed to it. If you'd set bundle_steps to true, however, it will create one archive containing all the result files from all Steps you give it. To enable bundling, provide an object like the one below to the use parameter:

      "use": {
        "steps": [
          ":original",
          "encoded",
          "resized"
        ],
        "bundle_steps": true
      }
      

      This is also a crucial parameter for the /video/adaptive Robot, otherwise you'll generate 1 playlist for each viewing quality.
      Keep in mind that all input Steps must be present in your Template. If one of them is missing (for instance it is rejected by a filter), no result is generated because the Robot waits indefinitely for all input Steps to be finished.

      Here’s a demo that showcases Step bundling.

    • Group by original. Sticking with the /file/compress Robot example, you can set group_by_original to true, in order to create a separate archive for each of your uploaded or imported files, instead of creating one archive containing all originals (or one per resulting file). This is important for for the /media/playlist Robot where you'd typically set:

      "use": {
        "steps": [
          "segmented"
        ],
        "bundle_steps": true,
        "group_by_original": true
      }
      
    • Fields. You can be more discriminatory by only using files that match a field name by setting the fields property. When this array is specified, the corresponding Step will only be executed for files submitted through one of the given field names, which correspond with the strings in the name attribute of the HTML file input field tag for instance. When using a back-end SDK, it corresponds with myFieldName1 in e.g.: $transloadit->addFile('myFieldName1', './chameleon.jpg').

      This parameter is set to true by default, meaning all fields are accepted.

      Example:

      "use": {
        "steps": [ ":original" ],
        "fields": [ "myFieldName1" ]
      }
      
    • Use as. Sometimes Robots take several inputs. For instance, the /video/merge Robot can create a slideshow from audio and images. You can map different Steps to the appropriate inputs.

      Example:

      "use": {
        "steps": [
          { "name": "audio_encoded", "as": "audio" },
          { "name": "images_resized", "as": "image" }
        ]
      }
      

      Sometimes the ordering is important, for instance, with our concat Robots. In these cases, you can add an index that starts at 1. You can also optionally filter by the multipart field name. Like in this example, where all files are coming from the same source (end-user uploads), but with different <input> names:

      Example:

      "use": {
        "steps": [
          { "name": ":original", "fields": "myFirstVideo", "as": "video_1" },
          { "name": ":original", "fields": "mySecondVideo", "as": "video_2" },
          { "name": ":original", "fields": "myThirdVideo", "as": "video_3" }
        ]
      }
      

      For times when it is not apparent where we should put the file, you can use Assembly Variables to be specific. For instance, you may want to pass a text file to the /image/resize Robot to burn the text in an image, but you are burning multiple texts, so where do we put the text file? We specify it via ${use.text_1}, to indicate the first text file that was passed.

      Example:

      "watermarked": {
        "robot": "/image/resize",
        "use"  : {
          "steps": [
            { "name": "resized", "as": "base" },
            { "name": "transcribed", "as": "text" },
          ],
        },
        "text": [
          {
            "text"  : "Hi there",
            "valign": "top",
            "align" : "left",
          },
          {
            "text"    : "From the 'transcribed' Step: ${use.text_1}",
            "valign"  : "bottom",
            "align"   : "right",
            "x_offset": 16,
            "y_offset": -10,
          }
        ]
      }
      
  • url

    String / Null ⋅ default: null

    The URL of the web page to be converted. Optional, as you can also upload/import HTML files and pass it to this Robot.

  • format

    String ⋅ default: "png"

    The format of the resulting image. The supported values are "pdf", "jpg", "jpeg" and "png".

  • fullpage

    Boolean ⋅ default: true

    Determines if a screenshot of the full page should be taken or not.

    If set to true, the height parameter will not have any effect, as heights of websites vary. You can control the size of the resulting image somewhat, though, by setting the width parameter.

    If set to false, an image will be cropped from the top of the webpage according to your width and height parameters.

  • omit_background

    Boolean ⋅ default: false

    Determines whether to preserve a transparent background in HTML pages. Useful if you're generating artwork in HTML that you want to overlay on e.g. a video.

    The default of false fills transparent areas with a white background, for easier reading/printing.

    This parameter is only used when format is not pdf.

  • width

    Integer ⋅ default: 1024

    The screen width that will be used, in pixels. Change this to change the dimensions of the resulting image.

  • height

    Integer ⋅ default: 768

    The screen height that will be used, in pixels. By default this equals the length of the web page in pixels if fullpage is set to true. If fullpage is set to false, the height parameter takes effect and defaults to the value 768.

  • delay

    Integer ⋅ default: 0

    The delay (in milliseconds) applied to allow the page and all of its JavaScript to render before taking the screenshot.

Demos

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