InvenTree/InvenTree/plugin/builtin/labels/label_sheet.py

283 lines
8.4 KiB
Python

"""Label printing plugin which supports printing multiple labels on a single page."""
import logging
import math
from django.core.exceptions import ValidationError
from django.core.files.base import ContentFile
from django.http import JsonResponse
from django.utils.translation import gettext_lazy as _
import weasyprint
from rest_framework import serializers
import report.helpers
from label.models import LabelOutput, LabelTemplate
from plugin import InvenTreePlugin
from plugin.mixins import LabelPrintingMixin, SettingsMixin
logger = logging.getLogger('inventree')
class LabelPrintingOptionsSerializer(serializers.Serializer):
"""Custom printing options for the label sheet plugin."""
page_size = serializers.ChoiceField(
choices=report.helpers.report_page_size_options(),
default='A4',
label=_('Page Size'),
help_text=_('Page size for the label sheet'),
)
skip = serializers.IntegerField(
default=0,
label=_('Skip Labels'),
help_text=_('Skip this number of labels when printing label sheets'),
min_value=0,
)
border = serializers.BooleanField(
default=False,
label=_('Border'),
help_text=_('Print a border around each label'),
)
landscape = serializers.BooleanField(
default=False,
label=_('Landscape'),
help_text=_('Print the label sheet in landscape mode'),
)
class InvenTreeLabelSheetPlugin(LabelPrintingMixin, SettingsMixin, InvenTreePlugin):
"""Builtin plugin for label printing.
This plugin arrays multiple labels onto a single larger sheet,
and returns the resulting PDF file.
"""
NAME = 'InvenTreeLabelSheet'
TITLE = _('InvenTree Label Sheet Printer')
DESCRIPTION = _('Arrays multiple labels onto a single sheet')
VERSION = '1.0.0'
AUTHOR = _('InvenTree contributors')
BLOCKING_PRINT = True
SETTINGS = {}
PrintingOptionsSerializer = LabelPrintingOptionsSerializer
def print_labels(self, label: LabelTemplate, items: list, request, **kwargs):
"""Handle printing of the provided labels."""
printing_options = kwargs['printing_options']
# Extract page size for the label sheet
page_size_code = printing_options.get('page_size', 'A4')
landscape = printing_options.get('landscape', False)
border = printing_options.get('border', False)
skip = int(printing_options.get('skip', 0))
# Extract size of page
page_size = report.helpers.page_size(page_size_code)
page_width, page_height = page_size
if landscape:
page_width, page_height = page_height, page_width
# Calculate number of rows and columns
n_cols = math.floor(page_width / label.width)
n_rows = math.floor(page_height / label.height)
n_cells = n_cols * n_rows
if n_cells == 0:
raise ValidationError(_('Label is too large for page size'))
# Prepend the required number of skipped null labels
items = [None] * skip + list(items)
n_labels = len(items)
# Data to pass through to each page
document_data = {
'border': border,
'landscape': landscape,
'page_width': page_width,
'page_height': page_height,
'label_width': label.width,
'label_height': label.height,
'n_labels': n_labels,
'n_pages': math.ceil(n_labels / n_cells),
'n_cols': n_cols,
'n_rows': n_rows,
}
pages = []
idx = 0
while idx < n_labels:
if page := self.print_page(
label, items[idx : idx + n_cells], request, **document_data
):
pages.append(page)
idx += n_cells
if len(pages) == 0:
raise ValidationError(_('No labels were generated'))
# Render to a single HTML document
html_data = self.wrap_pages(pages, **document_data)
# Render HTML to PDF
html = weasyprint.HTML(string=html_data)
document = html.render().write_pdf()
output_file = ContentFile(document, 'labels.pdf')
output = LabelOutput.objects.create(label=output_file, user=request.user)
return JsonResponse({
'file': output.label.url,
'success': True,
'message': f'{len(items)} labels generated',
})
def print_page(self, label: LabelTemplate, items: list, request, **kwargs):
"""Generate a single page of labels.
For a single page, generate a simple table grid of labels.
Styling of the table is handled by the higher level label template
Arguments:
label: The LabelTemplate object to use for printing
items: The list of database items to print (e.g. StockItem instances)
request: The HTTP request object which triggered this print job
Kwargs:
n_cols: Number of columns
n_rows: Number of rows
"""
n_cols = kwargs['n_cols']
n_rows = kwargs['n_rows']
# Generate a table of labels
html = """<table class='label-sheet-table'>"""
for row in range(n_rows):
html += "<tr class='label-sheet-row'>"
for col in range(n_cols):
# Cell index
idx = row * n_cols + col
if idx >= len(items):
break
html += f"<td class='label-sheet-cell label-sheet-row-{row} label-sheet-col-{col}'>"
# If the label is empty (skipped), render an empty cell
if items[idx] is None:
html += """<div class='label-sheet-cell-skip'></div>"""
else:
try:
# Render the individual label template
# Note that we disable @page styling for this
cell = label.render_as_string(
request, target_object=items[idx], insert_page_style=False
)
html += cell
except Exception as exc:
logger.exception('Error rendering label: %s', str(exc))
html += """
<div class='label-sheet-cell-error'></div>
"""
html += '</td>'
html += '</tr>'
html += '</table>'
return html
def wrap_pages(self, pages, **kwargs):
"""Wrap the generated pages into a single document."""
border = kwargs['border']
page_width = kwargs['page_width']
page_height = kwargs['page_height']
label_width = kwargs['label_width']
label_height = kwargs['label_height']
n_rows = kwargs['n_rows']
n_cols = kwargs['n_cols']
inner = ''.join(pages)
# Generate styles for individual cells (on each page)
cell_styles = []
for row in range(n_rows):
cell_styles.append(
f"""
.label-sheet-row-{row} {{
top: {row * label_height}mm;
}}
"""
)
for col in range(n_cols):
cell_styles.append(
f"""
.label-sheet-col-{col} {{
left: {col * label_width}mm;
}}
"""
)
cell_styles = '\n'.join(cell_styles)
return f"""
<head>
<style>
@page {{
size: {page_width}mm {page_height}mm;
margin: 0mm;
padding: 0mm;
}}
.label-sheet-table {{
page-break-after: always;
table-layout: fixed;
width: {page_width}mm;
border-spacing: 0mm 0mm;
}}
.label-sheet-cell-error {{
background-color: #F00;
}}
.label-sheet-cell {{
border: {'1px solid #000;' if border else '0mm;'}
width: {label_width}mm;
height: {label_height}mm;
padding: 0mm;
position: absolute;
}}
{cell_styles}
body {{
margin: 0mm !important;
}}
</style>
</head>
<body>
{inner}
</body>
</html>
"""