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fix: refactor to reduce cognitive complexity (#71)
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Refs: #69
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@grigoriev
grigoriev authored Sep 19, 2024
1 parent 58c8198 commit f4b733d
Showing 1 changed file with 89 additions and 76 deletions.
165 changes: 89 additions & 76 deletions app/SvgUtils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,29 +11,35 @@

# Process img tags, replacing base64 SVG images with PNGs
def process_svg(html):
pattern = re.compile(r'<img(?P<intermediate>[^>]+?src="data:)(?P<type>[^;>]*?);base64, (?P<base64>[^">]*?)"')
pattern = re.compile(r'<img(?P<intermediate>[^>]+?src="data:)(?P<type>[^;>]*?);base64,\s?(?P<base64>[^">]*?)"')
return re.sub(pattern, replace_img_base64, html)


# Decode and validate if the provided content is SVG.
def get_svg_content(content_type, content_base64):
# We do not require to have 'image/svg+xml' content type coz not all systems will properly set it

if content_type in NON_SVG_CONTENT_TYPES:
return False # Skip processing if content type set explicitly as not svg

decoded_content = base64.b64decode(content_base64)
if b'\0' in decoded_content:
return False # Skip processing if decoded content is binary (not text)
try:
decoded_content = base64.b64decode(content_base64)
if b'\0' in decoded_content:
return False # Skip processing if decoded content is binary (not text)

svg_content = decoded_content.decode('utf-8')
svg_content = decoded_content.decode('utf-8')

# Fast check that this is a svg
if '</svg>' not in svg_content:
return False
# Fast check that this is a svg
if '</svg>' not in svg_content:
return False

return svg_content
return svg_content
except Exception as e:
logging.error(f"Failed to decode base64 content: {e}")
return False


# Replace base64 SVG images with PNG equivalents in the HTML img tag.
def replace_img_base64(match):
entry = match.group(0)
content_type = match.group('type')
Expand All @@ -42,89 +48,107 @@ def replace_img_base64(match):
svg_content = get_svg_content(content_type, content_base64)
if svg_content is False:
return entry
else:
replaced_content_base64 = replace_svg_with_png(svg_content)
if replaced_content_base64 == content_base64:
return entry # For some reason content wasn't replaced
else:
return f'<img{match.group("intermediate")}image/svg+xml;base64, {replaced_content_base64}"'

replaced_content_base64 = replace_svg_with_png(svg_content)
if replaced_content_base64 == content_base64:
return entry # For some reason content wasn't replaced

return f'<img{match.group("intermediate")}image/svg+xml;base64,{replaced_content_base64}"'


# Checks that base64 encoded content is a svg image and replaces it with the png screenshot made by chromium
def replace_svg_with_png(svg_content):
chromium_executable = os.environ.get('CHROMIUM_EXECUTABLE_PATH')
if not chromium_executable:
logging.error('CHROMIUM_EXECUTABLE_PATH not set')
width, height = extract_svg_dimensions(svg_content)
if not width or not height:
return svg_content

# Fetch width & height from root svg tag
match = re.search(r'<svg[^>]+?width="(?P<width>[\d.]+)', svg_content)
if match:
width = match.group('width')
else:
logging.error('Cannot find svg width in ' + svg_content)
svg_filepath, png_filepath = prepare_temp_files(svg_content)
if not svg_filepath or not png_filepath:
return svg_content

match = re.search(r'<svg[^>]+?height="(?P<height>[\d.]+)', svg_content)
if match:
height = match.group('height')
else:
logging.error('Cannot find svg height in ' + svg_content)
if not convert_svg_to_png(width, height, png_filepath, svg_filepath):
return svg_content

# Log large svg content size
svg_content_length = len(svg_content)
if svg_content_length > 100_000:
logging.warning(f"SVG content length: {svg_content_length}")
png_base64 = read_and_cleanup_png(png_filepath)
return png_base64 if png_base64 else svg_content

# Will be used as a name for tmp files
uuid = str(uuid4())

temp_folder = tempfile.gettempdir()
# Extract the width and height from the SVG tag
def extract_svg_dimensions(svg_content):
width_match = re.search(r'<svg[^>]+?width="(?P<width>[\d.]+)', svg_content)
height_match = re.search(r'<svg[^>]+?height="(?P<height>[\d.]+)', svg_content)

# Put svg into tmp file
svg_filepath = os.path.join(temp_folder, uuid + '.svg')
f = open(svg_filepath, 'w', encoding='utf-8')
f.write(svg_content)
f.close()
width = width_match.group('width') if width_match else None
height = height_match.group('height') if height_match else None

# Feed svg file to chromium
png_filepath = os.path.join(temp_folder, uuid + '.png')
if not width or not height:
logging.error(f"Cannot find SVG dimensions. Width: {width}, Height: {height}")
return width, height

chromium_command = create_chromium_command(
chromium_executable,
height,
width,
png_filepath,
svg_filepath,
)

result = subprocess.run(chromium_command)
# Save the SVG content to a temporary file and return the file paths for the SVG and PNG.
def prepare_temp_files(svg_content):
try:
temp_folder = tempfile.gettempdir()
uuid = str(uuid4())

# Remove tmp svg file
os.remove(svg_filepath)
svg_filepath = os.path.join(temp_folder, f'{uuid}.svg')
png_filepath = os.path.join(temp_folder, f'{uuid}.png')

with open(svg_filepath, 'w', encoding='utf-8') as f:
f.write(svg_content)

return svg_filepath, png_filepath
except Exception as e:
logging.error(f"Failed to save SVG to temp file: {e}")
return None, None


# Convert the SVG file to PNG using Chromium and return success status
def convert_svg_to_png(width, height, png_filepath, svg_filepath):
command = create_chromium_command(width, height, png_filepath, svg_filepath)
result = subprocess.run(command)

if result.returncode != 0:
logging.error(f'Error converting to png, returncode = {result.returncode}')
return svg_content
logging.error(f"Error converting SVG to PNG, return code = {result.returncode}")
return False

# Get resulting screenshot content
with open(png_filepath, 'rb') as img_file:
img_data = img_file.read()
png_base64 = base64.b64encode(img_data).decode('utf-8')
return True


# Read the PNG file, encode it in base64, and clean up the temporary file.
def read_and_cleanup_png(png_filepath):
try:
with open(png_filepath, 'rb') as img_file:
img_data = img_file.read()

# Remove tmp png file
os.remove(png_filepath)
png_base64 = base64.b64encode(img_data).decode('utf-8')
os.remove(png_filepath)
return png_base64
except Exception as e:
logging.error(f"Failed to read or clean up PNG file: {e}")
return None

return png_base64

# Create the Chromium command for converting SVG to PNG
def create_chromium_command(width, height, png_filepath, svg_filepath):
chromium_executable = os.environ.get('CHROMIUM_EXECUTABLE_PATH')
if not chromium_executable:
logging.error('CHROMIUM_EXECUTABLE_PATH is not set.')
return None

def create_chromium_command(chromium_executable, height, width, png_filepath, svg_filepath):
# Check if the ENABLE_HARDWARE_ACCELERATION environment variable is set to true
enable_hardware_acceleration = os.getenv('ENABLE_HARDWARE_ACCELERATION', 'false').lower() == 'true'

command = [
f'{chromium_executable}',
chromium_executable,
'--headless=old',
'--no-sandbox',
'--default-background-color=00000000',
'--hide-scrollbars',
'--enable-features=ConversionMeasurement,AttributionReportingCrossAppWeb',
f'--screenshot={png_filepath}',
f'--window-size={width},{height}',
svg_filepath,
]

if not enable_hardware_acceleration:
Expand All @@ -134,15 +158,4 @@ def create_chromium_command(chromium_executable, height, width, png_filepath, sv
'--disable-dev-shm-usage',
])

command.extend([
'--headless=old', # because of issue in new with SVG conversion
'--no-sandbox',
'--default-background-color=00000000',
'--hide-scrollbars',
'--enable-features=ConversionMeasurement,AttributionReportingCrossAppWeb',
f'--screenshot={png_filepath}',
f'--window-size={width},{height}',
f'{svg_filepath}',
])

return command

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