72 lines
2.4 KiB
Markdown
72 lines
2.4 KiB
Markdown
title: Image Operations
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---
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summary: Shows how templates can work with images.
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---
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sort_key: 30
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---
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body:
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Images are separate files and as such just embedded into HTML files. However
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very often you want to perform modifications on these images that require
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interacting with those files directly. This can be conveniently done directly
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from the template code through the image APIs that Lektor provides.
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## Accessing Images
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To work with images one needs to get access to the image objects first. Images
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are returned from the attachments of a page. If you want to make sure you
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only operate with actual images the `.images` attribute can be used to filter
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the query. For instance this iterates over all attached images of a page:
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```html+jinja
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{% for image in this.attachments.images %}
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<div class="image"><img src="{{ image|url }}"></div>
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{% endfor %}
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```
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## Accessing Image Data
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One of the more common operations is to access the direct image data. This
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is resolution and file format. The `width`, `height` and `format` parameters
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are provided for this. In some cases this is very useful to generate CSS code
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that needs to know about the original resolution. For instance this achieves a
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retina rendered background:
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```html+jinja
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<div style="
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background: url({{ image|url }});
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background-size: {{ image.width / 2 }}px {{ image.height / 2 }}px
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"></div>
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```
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## Accessing EXIF Data
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Lektor can also give you access to a lot of the EXIF information that is stored
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in the images. Not all EXIF information is available but the most common
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values are. For the full list of attributes see [EXIF data
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:ref](../../api/db/record/exif/).
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Here an example that shows the camera information:
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```html+jinja
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<div class="image">
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<img src="{{ image|url }}" alt="">
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<p><strong>Camera:</strong> {{ image.exif.camera }}
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</div>
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```
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## Generating Thumbnails
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While browsers are reasonably good at downscaling images themselves, you
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still need to transmit the entire image. When you want smaller images it
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often makes sense to generate thumbnails automatically. In Lektor each
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image provides the [thumbnail :ref](../../api/db/record/thumbnail/) method.
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It accepts the width and height of the target image. If the height is not
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provided it will be scaled proportionally. The return value can be converted
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into a URL with the `|url` filter:
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```html+jinja
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<img src="{{ image.thumbnail(320)|url }}">
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```
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