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GroupDocs.Signature provides PreviewOptions class to specify different options to manage signature preview generation process.
Here are the steps to generate signature preview with GroupDocs.Signature:
- Create new instance of Signature class and pass source document path as a constructor parameter.
- Instantiate the PreviewOptions object with:
- delegate for each signature stream creation (see event handler CreatePageStream);
- image preview format - PNG / JPG / BMP,
- signature numbers to process;
- custom size of preview images (if needed).NoteStream that were created by CreatePageStreamdelegate will be disposed automatically once after generation of preview image. If you need to implement custom image preview stream disposing you have to pass additional argument ReleaseStream to clean up resources.
- Call GeneratePreview method of Signature class instance and pass PreviewOptions to it.
GroupDocs.Signature expects CreatePageStreamdelegate to obtain each signature stream for image preview generation process
def create_page_stream(page_data):
image_name = f"signature-{page_data.page_number}.jpg"
image_file_path = os.path.join("GeneratePreviewFolder", image_name)
folder = os.path.dirname(image_file_path)
if not os.path.exists(folder):
os.makedirs(folder)
return open(image_file_path, "wb")
def release_page_stream(page_data, page_stream):
page_stream.close()
image_name = f"signature-{page_data.page_number}.jpg"
image_file_path = os.path.join("GeneratePreviewFolder", image_name)
print(f"Image file {image_file_path} is ready for preview")
import os
import groupdocs.signature as signature
def get_preview():
with signature.Signature("sample.pdf") as sign:
# create preview options object
preview_option = signature.PreviewOptions(create_page_stream)
preview_option.preview_format = signature.PreviewOptions.PreviewFormats.JPEG
# generate preview
sign.generate_preview(preview_option)
def create_page_stream(page_data):
image_name = f"signature-{page_data.page_number}.jpg"
image_file_path = os.path.join("GeneratePreviewFolder", image_name)
folder = os.path.dirname(image_file_path)
if not os.path.exists(folder):
os.makedirs(folder)
return open(image_file_path, "wb")
import os
import groupdocs.signature as signature
def get_preview():
with open("sample.pdf", "rb") as stream:
with signature.Signature(stream) as sign:
# create preview options object
preview_option = signature.PreviewOptions(create_page_stream, release_page_stream)
preview_option.preview_format = signature.PreviewOptions.PreviewFormats.JPEG
# generate preview
sign.generate_preview(preview_option)
def create_page_stream(page_data):
image_name = f"signature-{page_data.page_number}.jpg"
image_file_path = os.path.join("GeneratePreviewFolder", image_name)
folder = os.path.dirname(image_file_path)
if not os.path.exists(folder):
os.makedirs(folder)
return open(image_file_path, "wb")
def release_page_stream(page_data, page_stream):
page_stream.close()
image_name = f"signature-{page_data.page_number}.jpg"
image_file_path = os.path.join("GeneratePreviewFolder", image_name)
print(f"Image file {image_file_path} is ready for preview")
import os
import groupdocs.signature as signature
# The path to the documents
file_path = "sample.pdf"
with signature.Signature(file_path) as sign:
resolution = 96
# create preview options object
# You can reuse create_page_stream and release_page_stream methods from the previous example
preview_option = signature.PreviewOptions(create_page_stream, release_page_stream, resolution)
preview_option.preview_format = signature.PreviewOptions.PreviewFormats.JPEG
# generate preview
sign.generate_preview(preview_option)
You may easily run the code above and see the feature in action in our GitHub examples:
Along with the full-featured Python library, we provide simple but powerful free online apps.
To sign PDF, Word, Excel, PowerPoint, and other documents you can use the online apps from the GroupDocs.Signature App Product Family.
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