Príprava generovaných obrázkov pre fb

image_renderer/__init__.py

@@ -0,0 +1,2 @@
+# -*- coding: utf-8 -*-
+default_app_config = 'image_renderer.apps.AppConfig'

image_renderer/apps.py

@@ -0,0 +1,7 @@
+# -*- coding: utf-8 -*-
+from django.apps import AppConfig as BaseAppConfig
+
+
+class AppConfig(BaseAppConfig):
+	name = 'image_renderer'
+	verbose_name = "Image renderer"

image_renderer/urls.py

@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+from django.urls import path
+
+from . import views
+
+
+app_name = 'image_renderer'
+
+urlpatterns = [
+	path('<slug:image_type>/<int:content_type>/<path:object_id>.png', views.RenderImageView.as_view(), name='render'),
+]

image_renderer/views.py

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+# -*- coding: utf-8 -*-
+import os
+
+from PIL import Image, ImageFont
+from django.contrib.contenttypes.models import ContentType
+from django.http.response import HttpResponseNotFound, HttpResponse
+from django.shortcuts import get_object_or_404
+from django.views.generic import View
+from pil_text_block import Block
+
+
+STATIC_DIR = os.path.join(os.path.dirname(__file__), '..', 'static')
+
+
+def get_fallback_response():
+	if get_fallback_response.image_cache is None:
+		with open(os.path.join(STATIC_DIR, 'images', 'share_text_fallback.png'), 'rb') as fallback_fp:
+			get_fallback_response.image_cache = fallback_fp.read()
+	return HttpResponse(get_fallback_response.image_cache, content_type='image/png')
+get_fallback_response.image_cache = None
+
+
+class BaseRenderer(object):
+	_backgrund_image = None
+
+	def __init__(self, image_type, content_type, content_object):
+		self.image_type = image_type
+		self.content_type = content_type
+		self.content_object = content_object
+
+	def get_background_image(self):
+		if self._backgrund_image is None:
+			path = os.path.join(STATIC_DIR, 'images', 'share_text_background.png')
+			self._backgrund_image = Image.open(path)
+		return self._backgrund_image.convert('RGBA')
+
+	def render_layout(self, bg, layout):
+		return self.render_node(bg, (0, 0) + bg.size, layout)
+
+	def render_node(self, bg, window, node):
+		node = node.copy()
+		node_type = node.pop('type')
+		return getattr(self, f'render_{node_type}')(bg, window, **node)
+
+	def render_row(self, bg, window, children=None):
+		children = [] if children is None else children
+		for child in children:
+			child_window = self.render_node(bg, window, child)
+			window = (window[0], window[1] + child_window[3], window[2], window[3] - child_window[3])
+		return window
+
+	def render_text(self, bg, window, text, width=None, height=None):
+		width = window[2] if width is None else width
+		height = window[3] if height is None else height
+		font = ImageFont.truetype(os.path.join(STATIC_DIR, 'fonts', 'OpenSans', 'OpenSans-ExtraBold.ttf'), size=75)
+		block = Block(text, (width, height), color='#ffffff', font=font, ellipsis='…')
+		result = block.render()
+		bg.alpha_composite(result.image, dest=(window[0], window[1]))
+		window = (window[0], window[1], result.size[0], result.size[1])
+		return window
+
+	def render_canvas(self, bg, window, width=None, height=None): # pylint: disable=unused-argument
+		width = window[2] if width is None else width
+		height = window[3] if height is None else height
+		window = (window[0], window[1], width, height)
+		return window
+
+	def render(self):
+		raise NotImplementedError()
+
+
+class TextRenderer(BaseRenderer):
+	def __init__(self, image_type, content_type, content_object, content_field, title_field):
+		self.content = getattr(content_object, content_field)
+		self.title = getattr(content_object, title_field)
+		super().__init__(image_type, content_type, content_object)
+
+	def render(self):
+		bg = self.get_background_image()
+		layout = {
+			'type': 'row',
+			'children': [
+				{
+					'type': 'canvas',
+					'height': 20,
+				},
+				{
+					'type': 'text',
+					'height': 103,
+					'text': self.title,
+				},
+				{
+					'type': 'canvas',
+					'height': 20,
+				},
+				{
+					'type': 'text',
+					'text': 'World'
+				},
+				{
+					'type': 'canvas',
+					'height': 20,
+				},
+			]
+		}
+		self.render_layout(bg, layout)
+		response = HttpResponse(content_type='image/png')
+		bg.convert('RGB').save(response, format='PNG')
+		return response
+
+
+RENDERERS = {
+	('opengraph', 'news', 'news'): (TextRenderer, {'title_field': 'title', 'content_field': 'short_text'}),
+}
+
+
+class RendererFactory():
+	@staticmethod
+	def get_renderer(image_type, content_type, content_object):
+		try:
+			renderer_class, kwargs = RENDERERS[(image_type, content_type.app_label, content_type.model)]
+		except KeyError:
+			return None
+		return renderer_class(image_type, content_type, content_object, **kwargs)
+
+
+class RenderImageView(View):
+	def get(self, request, image_type, content_type, object_id):
+		content_type = get_object_or_404(ContentType, pk=content_type)
+		try:
+			content_object = get_object_or_404(content_type.model_class(), pk=object_id)
+		except ValueError:
+			return HttpResponseNotFound()
+		renderer = RendererFactory.get_renderer(image_type, content_type, content_object)
+		if renderer is None:
+			return get_fallback_response()
+		else:
+			return renderer.render()

web/urls.py

@@ -47,6 +47,7 @@
 	url(r'^api/editor/', include('rich_editor.urls')),
 	url(r'^hijack/', include('hijack.urls')),
 	url(r'^django-email-log/', include('django_email_log.urls')),
+	url(r'^image/', include('image_renderer.urls')),
 	url(r'^favicon.ico$', RedirectView.as_view(url=staticfiles_storage.url('images/favicon/favicon.ico'), permanent=True)),
 ]