Metadata-Version: 2.4
Name: wagtail-thumbnails
Version: 0.2.0
Summary: A lightweight Wagtail StreamField block + DRF serializer that exposes responsive WebP thumbnails with dimensions and focal points.
Project-URL: Homepage, https://github.com/profilsoftware/wagtail-thumbnails
Project-URL: Repository, https://github.com/profilsoftware/wagtail-thumbnails
Project-URL: Issues, https://github.com/profilsoftware/wagtail-thumbnails/issues
Project-URL: Changelog, https://github.com/profilsoftware/wagtail-thumbnails/blob/main/CHANGELOG.md
Author-email: Profil Software <contact@profil-software.com>
License: MIT License
        
        Copyright (c) 2026 Profil Software
        
        Permission is hereby granted, free of charge, to any person obtaining a copy
        of this software and associated documentation files (the "Software"), to deal
        in the Software without restriction, including without limitation the rights
        to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
        copies of the Software, and to permit persons to whom the Software is
        furnished to do so, subject to the following conditions:
        
        The above copyright notice and this permission notice shall be included in all
        copies or substantial portions of the Software.
        
        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
        FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
        AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
        LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
        OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
        SOFTWARE.
License-File: LICENSE
Keywords: django,djangorestframework,headless,streamfield,thumbnails,wagtail,webp
Classifier: Development Status :: 4 - Beta
Classifier: Environment :: Web Environment
Classifier: Framework :: Django
Classifier: Framework :: Django :: 4.2
Classifier: Framework :: Django :: 5.1
Classifier: Framework :: Django :: 5.2
Classifier: Framework :: Wagtail
Classifier: Framework :: Wagtail :: 6
Classifier: Framework :: Wagtail :: 7
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.10
Classifier: Programming Language :: Python :: 3.11
Classifier: Programming Language :: Python :: 3.12
Classifier: Programming Language :: Python :: 3.13
Classifier: Topic :: Internet :: WWW/HTTP
Classifier: Topic :: Multimedia :: Graphics
Classifier: Typing :: Typed
Requires-Python: >=3.10
Requires-Dist: django>=4.2
Requires-Dist: djangorestframework>=3.14
Requires-Dist: pillow>=10
Requires-Dist: wagtail>=6.3
Provides-Extra: dev
Requires-Dist: build>=1.2; extra == 'dev'
Requires-Dist: django-stubs>=5.0; extra == 'dev'
Requires-Dist: djangorestframework-stubs>=3.15; extra == 'dev'
Requires-Dist: mypy>=1.11; extra == 'dev'
Requires-Dist: pytest-cov>=5; extra == 'dev'
Requires-Dist: pytest-django>=4.8; extra == 'dev'
Requires-Dist: pytest>=8; extra == 'dev'
Requires-Dist: ruff>=0.6; extra == 'dev'
Requires-Dist: twine>=5; extra == 'dev'
Description-Content-Type: text/markdown

# wagtail-thumbnails

[![PyPI](https://img.shields.io/pypi/v/wagtail-thumbnails)](https://pypi.org/project/wagtail-thumbnails/)
[![CI](https://github.com/profilsoftware/wagtail-thumbnails/actions/workflows/test.yml/badge.svg)](https://github.com/profilsoftware/wagtail-thumbnails/actions/workflows/test.yml)
[![Python](https://img.shields.io/pypi/pyversions/wagtail-thumbnails)](https://pypi.org/project/wagtail-thumbnails/)
[![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)

A drop-in Wagtail StreamField block + DRF serializer that turns any uploaded image into a multi-variant WebP payload with dimensions and focal points - ready for headless frontends.

## What you get

- A `ThumbnailBlock` - a thin extension of Wagtail's built-in `ImageBlock` that adds a pluggable validator pipeline and emits a `ThumbnailSerializer` payload
- A `ThumbnailSerializer` that emits:
  - Source URL
  - Resolved alt text (block override → image `description` → `null`; titles are intentionally not used)
  - Focal point (from Wagtail's built-in picker)
  - A configurable map of responsive variants (defaults: `full_hd`, `large`, `medium`, `small`) - each with `url`, `width`, `height`, `format`
- An `ImageResolutionValidator` you can configure globally (`WAGTAIL_THUMBNAILS` settings) or per-field
- Settings-driven variants - ship sensible defaults, override per project

You upload JPEG/PNG. Wagtail/Pillow generates and caches WebP renditions on first request. No user-side conversion required.

## Install

Requires Django 4.2+, Wagtail **6.3+** (the block subclasses Wagtail's built-in `ImageBlock`, added in 6.3), and DRF 3.14+.

```bash
pip install wagtail-thumbnails
```

Add to `INSTALLED_APPS`:

```python
INSTALLED_APPS = [
    # ...
    "wagtail_thumbnails",
]
```

## Quickstart

### StreamField block

```python
from wagtail.fields import StreamField
from wagtail_thumbnails.blocks import ThumbnailBlock

class ArticlePage(Page):
    body = StreamField([
        ("thumbnail", ThumbnailBlock()),
        # ... your other blocks
    ])
```

`ThumbnailBlock` is a subclass of Wagtail's [`ImageBlock`](https://docs.wagtail.org/en/stable/reference/streamfield/blocks.html#wagtail.images.blocks.ImageBlock), so editors get the same `image` / `alt_text` / `decorative` UI and behaviours - including the alt-text-required check (a value must have alt text *or* be marked decorative). The block adds:

1. A configurable validator pipeline (see [Validation](#validation)).
2. A multi-variant API payload via `ThumbnailSerializer.get_api_representation`.

### Nested serializer

```python
from rest_framework import serializers
from wagtail_thumbnails.serializers import ThumbnailSerializer

class ProductSerializer(serializers.ModelSerializer):
    hero_image = ThumbnailSerializer()

    class Meta:
        model = Product
        fields = ["hero_image"]
```

## Example output

```json
{
  "src": "https://cdn.example.com/media/images/hero.jpg",
  "alt_text": "A sunset over the bay",
  "focal_point": { "x": 400, "y": 300, "width": 100, "height": 100 },
  "variants": {
    "full_hd": { "url": "https://.../hero.fill-1920x1280.format-webp.webp", "width": 1920, "height": 1280, "format": "webp" },
    "large":   { "url": "https://.../hero.fill-800x533.format-webp.webp",   "width": 800,  "height": 533,  "format": "webp" },
    "medium":  { "url": "https://.../hero.fill-450x300.format-webp.webp",   "width": 450,  "height": 300,  "format": "webp" },
    "small":   { "url": "https://.../hero.fill-125x83.format-webp.webp",    "width": 125,  "height": 83,   "format": "webp" }
  }
}
```

Notes on the shape:

- `focal_point` is `null` when no focal point is set. Its `width` / `height` are `null` when only a centre point was picked (no focal *area*).
- `alt_text` is `null` when nothing is available. Wagtail titles are intentionally **not** used as alt text - they're typically filenames, which makes for a poor screen-reader experience.
- The block emits `alt_text: ""` (empty string, *not* null) when the editor ticks the **Decorative** checkbox. Mark purely visual imagery this way so assistive tech can skip it.
- Variants never upscale: if the source is narrower than a variant's target width, the variant is generated at the source's native dimensions.

## Configuration

All settings live under a single dict. User-supplied keys override defaults (variant maps fully replace, not merge).

```python
WAGTAIL_THUMBNAILS = {
    "VARIANTS": {
        "full_hd": {"width": 1920, "format": "webp", "quality": 80},
        "large":   {"width": 800,  "format": "webp", "quality": 80},
        "medium":  {"width": 450,  "format": "webp", "quality": 80},
        "small":   {"width": 125,  "format": "webp", "quality": 40},
    },
    "MIN_IMAGE_WIDTH": 1920,   # optional
    "MIN_IMAGE_HEIGHT": 1080,  # optional
}
```

| Key | Default | Description |
| --- | --- | --- |
| `VARIANTS` | see above | Mapping of variant name → `{width, format, quality}`. Variant names become keys in the API output's `variants` dict. |
| `MIN_IMAGE_WIDTH` | `None` | Minimum source-image width enforced by `image_resolution_validator`. Omit (or set to `None`) to skip the width check. |
| `MIN_IMAGE_HEIGHT` | `None` | Minimum source-image height. Omit (or set to `None`) to skip the height check. |

Supported `format` values: `webp` (default), `jpeg`, `png`. `quality` is honoured for `webp` and `jpeg`.

Misconfigurations (unknown keys, bad variant shapes, unsupported formats, out-of-range quality) raise `ImproperlyConfigured` at first access - not at request time.

## Validation

`ThumbnailBlock` accepts a `validators=` keyword argument: an iterable of callables of the shape `f(image) -> None` that raise `django.core.exceptions.ValidationError` on failure. The default is the module-level `image_resolution_validator`, which itself silently passes any image until you configure `MIN_IMAGE_WIDTH` / `MIN_IMAGE_HEIGHT` (globally or per-instance) - so adding the block to a project without any settings is safe and side-effect-free.

```python
from wagtail_thumbnails.blocks import ThumbnailBlock
from wagtail_thumbnails.validators import ImageResolutionValidator, image_resolution_validator

# 1. Defaults - reads MIN_IMAGE_* from WAGTAIL_THUMBNAILS, or skips if unset.
ThumbnailBlock()

# 2. Per-field threshold, ignoring whatever is in settings.
ThumbnailBlock(validators=[ImageResolutionValidator(min_width=1920, min_height=1080)])

# 3. Disable validation entirely on this field.
ThumbnailBlock(validators=[])

# 4. Add extra checks on top of the default.
def must_be_landscape(image):
    if image.width <= image.height:
        raise ValidationError("Landscape orientation required.")

ThumbnailBlock(validators=[image_resolution_validator, must_be_landscape])

# 5. Project-wide override via subclass.
class HeroImageBlock(ThumbnailBlock):
    default_validators = (ImageResolutionValidator(min_width=1920, min_height=1080),)
```

`ImageResolutionValidator` resolves each axis independently: setting only `min_width` (per-instance *or* in settings) leaves the height check disabled, and vice versa. Per-instance values take precedence over the global setting; pass `None` to fall back to the setting.

The validator pipeline runs from `ThumbnailBlock.clean()`, on top of Wagtail's built-in `ImageBlock` checks (a value must have alt text or be marked decorative). Validators run for non-empty values only - an empty optional block is not run through the pipeline.

## Migrating from `ImageChooserBlock`

`ThumbnailBlock` subclasses Wagtail's `ImageBlock`, whose on-disk JSON shape inside a StreamField is `{"image": <id>, "alt_text": "...", "decorative": false}` - different from a bare `ImageChooserBlock` (whose value is just an image ID). Existing rows need a one-shot data migration:

```python
# yourapp/migrations/00XX_migrate_image_chooser_to_thumbnail.py
from django.db import migrations

OLD_TYPE = "image_block"
NEW_TYPE = "thumbnail"


def forwards(apps, schema_editor):
    YourPage = apps.get_model("yourapp", "YourPage")
    for page in YourPage.objects.all():
        changed = False
        for block in page.body.raw_data:
            if block["type"] == OLD_TYPE:
                block["type"] = NEW_TYPE
                block["value"] = {"image": block["value"], "alt_text": "", "decorative": False}
                changed = True
        if changed:
            page.save()


class Migration(migrations.Migration):
    dependencies = [("yourapp", "00XX_previous")]
    operations = [migrations.RunPython(forwards, migrations.RunPython.noop)]
```

For revisions (`PageRevision`), apply the same transform to `revision.content`.

If you're already on Wagtail's own `ImageBlock`, no data migration is needed - the StructBlock shape matches and `ThumbnailBlock` is a drop-in replacement.

## Development

```bash
git clone https://github.com/profilsoftware/wagtail-thumbnails
cd wagtail-thumbnails
uv sync --extra dev
uv run pytest
uv run ruff check .
uv run mypy src/
```
