Choosing the right layout method is a key challenge when converting PDF to Docx. The fundamental differences between fixed layout and reflowable layout often lead to issues such as text misalignment and table splitting during conversion.
Today, we will deeply discuss the core distinctions between these two layout modes, analyzing them from technical principles, application scenarios, implementation methods, and pros and cons. Then through real-world examples, we will explore the best strategies for adapting these layouts in document conversion.
Fixed Layout vs. Reflowable Layout: Absolute Positioning vs. Dynamic Layout
1. Fixed Layout (Absolute Coordinate Positioning)
The fixed (grid) layout is based on the "digital paper" model of PDF. It uses a coordinate system to precisely place all elements (text, images, and tables) on the page. For example, text can be precisely positioned "5 cm from the top of the page and 3 cm from the left edge of the page."
The main advantage of this layout is that it can reproduce content with high fidelity. It strictly adheres to the original design to ensure consistent rendering across platforms. In addition, the fixed layout is good at handling complex elements such as nested tables and vector graphics, which is very suitable for documents that need to be accurately reproduced, such as contracts, design drafts, and academic papers.
2. Flow Layout (Paragraph Properties And Style Control)
The reflow layout relies on the dynamic layout rules of Word, which adjusts the content locations by paragraph indentation, column, tab positioning, and so on. For example, the column layout is controlled by the Section object, while the paragraph width is defined by the Spacing Before/After properties.
Its key advantage is flexible editing, which the content to flow automatically by editing and supports different screen sizes of devices. What's more, the flow layout supports maintenance formatting, which can achieve global format consistency by style template(such as title and text). It is always used for frequently edited documents like reports, guides, and dynamic tables.
Technical Limitations of Fixed Layout and Reflowable Layout
1. Tech Limitations of Fixed Layout
- Page Fragmentation: When using a grid layout to convert PDF to Docx, a complete page will be divided into various text boxes. So, you need to adjust each block element one by one when advanced editing. For instance, converting the column layout of PDF to Word will produce multiple text boxes if parsing does not accurate logical structure.
- High Maintenance Cost: The AI model may introduce tiny absolute coordinates during recognition (for example, font replacement causes character width changes), which will cause chain dislocation and require subsequent coordinate adjustment
2. Tech Limitations of Reflowable Layout
- Insufficient Precision: Dynamic layout is difficult to replicate the accuracy alignment effect in PDF. As an example, when converting to Word, it may deviate from the original position because of the insertion of page breaks, or differ in layout from the PDF due to font size conversion.
- Difficulty in Parsing Complex Structure: For complex structures such as nested tables and multi-column layouts, streaming layout depends on the parsing tool's ability to handle complex layouts. Once there is a problem with the parsing, the layout of the entire document may become chaotic.
Compare PDF Conversion Tools of Grid Layout and Flow Layout
1. Fixed Layout Conversion Tools: PyMuPDF vs ComPDF
- PyMuPDF: This PDF conversion tool achieves fixed layout conversions by parsing the Textpage object in PDF, extracting the element coordinates and content, and utilizing python-docx's add_textbox() method to generate absolutely positioned text box.
- ComPDF: ComPDF parses PDF-pages-extraction data by using the PDFIUM library, and then input this data into the AI model, which then identifies and outputs the module data (including location and content) of each object on the page. In addition, read the document in text box mode by our self-developed comdocx library, thereby converting the box layout to ensure that the subsequent version is more accurate.
2. Reflowable Layout Conversion Tools: pdf2docx vs ComPDF
- pdf2docx: It parses PDF logic through the Converter class and rebuilds the dynamic layout using the add_paragraph() method and the style template.
- ComPDF: ComPDF also uses the PDFIUM library to parse PDF to extract page data, and input this data into the AI model. The AI model is responsible for outputting the style and properties of each object (such as before and after paragraphs, indents, etc.). The object is written through the comdocx library, and the style properties are filled in specifically. This method can roughly correspond to the layout of the original page, the overall layout is more natural, and subsequent adjustments are easier. At the same time, the document can be compatible with various title styles of Word software to avoid problems.
Final Words
In short, whether fixed (grid) layout or reflowable (flow) layout, has advantages and involves different technologies. When converting PDF to Docx, the difference between the two is always a core challenge that PDF solution providers need to overcome.
ComPDF Conversion SDK v3.0.0 is about to be released! Equipped with AI layout analysis technology and AI table recognition technology, combined with the self-developed natural reading order layout restoration algorithm, it realizes pixel-level layout restoration from PDF to Word, and completely says goodbye to format confusion!