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2.9 KiB
ReStructuredText
109 lines
2.9 KiB
ReStructuredText
======================
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Previews configuration
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======================
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The Nextcloud thumbnail system generates previews of files for all
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Nextcloud apps that display files, such as Files and Gallery.
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The following image shows some examples of previews of various file types.
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.. figure:: ../images/preview_images.png
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:alt: Thumbnails of various image and audio/video files.
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By default, Nextcloud can generate previews for the following filetypes:
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* Images files
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* Cover of MP3 files
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* Text documents
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.. note:: Technically Nextcloud can also generate the previews
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of other file types such as PDF, SVG or various office documents.
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Due to security concerns those providers have been disabled by
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default and are considered unsupported.
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While those providers are still available, we discourage enabling
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them, and they are not documented.
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Parameters
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----------
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Please notice that the Nextcloud preview system comes already with sensible
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defaults, and therefore it is usually unnecessary to adjust those configuration
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values.
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But deemed necessary, following changes have to be made in ``config/config.php`` file. As a best practice, take a backup of this config file before making a lot of changes.
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Disabling previews:
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^^^^^^^^^^^^^^^^^^^
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Under certain circumstances, for example if the server has limited
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resources, you might want to consider disabling the generation of previews.
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Note that if you do this all previews in all apps are disabled, including
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the Gallery app, and will display generic icons instead of
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thumbnails.
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Set the configuration option ``enable_previews`` to ``false``:
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::
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<?php
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'enable_previews' => false,
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Maximum preview size:
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^^^^^^^^^^^^^^^^^^^^^
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There are two configuration options to set the maximum size of a preview.
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::
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<?php
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'preview_max_x' => null,
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'preview_max_y' => null,
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By default, both options are set to null. 'Null' is equal to no limit.
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Numeric values represent the size in pixels. The following code limits previews
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to a maximum size of 100×100px:
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::
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<?php
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'preview_max_x' => 100,
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'preview_max_y' => 100,
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'preview_max_x' represents the x-axis and 'preview_max_y' represents the y-axis.
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Maximum scale factor:
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^^^^^^^^^^^^^^^^^^^^^
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If a lot of small pictures are stored on the Nextcloud instance and the preview
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system generates blurry previews, you might want to consider setting a maximum
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scale factor. By default, pictures are upscaled to 10 times the original size:
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::
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<?php
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'preview_max_scale_factor' => 10,
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If you want to disable scaling at all, you can set the config value to '1':
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::
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<?php
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'preview_max_scale_factor' => 1,
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If you want to disable the maximum scaling factor, you can set the config value
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to 'null':
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::
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<?php
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'preview_max_scale_factor' => null,
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JPEG quality setting:
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^^^^^^^^^^^^^^^^^^^^^
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Default JPEG quality setting for preview images is '80'. Change this with:
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::
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occ config:app:set preview jpeg_quality --value="60"
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