Add badge printing capabilities (#868)

Add badge printing capabilities

src/pretix/plugins/badges/models.py

@@ -0,0 +1,51 @@
+import string
+
+from django.db import models
+from django.utils.crypto import get_random_string
+from django.utils.translation import ugettext_lazy as _
+
+from pretix.base.models import LoggedModel
+
+
+def bg_name(instance, filename: str) -> str:
+    secret = get_random_string(length=16, allowed_chars=string.ascii_letters + string.digits)
+    return 'pub/{org}/{ev}/badges/{id}-{secret}.pdf'.format(
+        org=instance.event.organizer.slug,
+        ev=instance.event.slug,
+        id=instance.pk,
+        secret=secret
+    )
+
+
+class BadgeLayout(LoggedModel):
+    event = models.ForeignKey(
+        'pretixbase.Event',
+        on_delete=models.CASCADE,
+        related_name='badge_layouts'
+    )
+    default = models.BooleanField(
+        verbose_name=_('Default'),
+        default=False,
+    )
+    name = models.CharField(
+        max_length=190,
+        verbose_name=_('Name')
+    )
+    layout = models.TextField(
+        default='[{"type":"textarea","left":"13.09","bottom":"49.73","fontsize":"23.6","color":[0,0,0,1],'
+                '"fontfamily":"Open Sans","bold":true,"italic":false,"width":"121.83","content":"attendee_name",'
+                '"text":"Max Mustermann","align":"center"}]'
+    )
+    background = models.FileField(null=True, blank=True, upload_to=bg_name, max_length=255)
+
+    class Meta:
+        ordering = ("name",)
+
+    def __str__(self):
+        return self.name
+
+
+class BadgeItem(models.Model):
+    item = models.OneToOneField('pretixbase.Item', null=True, blank=True, related_name='badge_assignment',
+                                on_delete=models.CASCADE)
+    layout = models.ForeignKey('BadgeLayout', on_delete=models.CASCADE, related_name='item_assignments')