Direct analysis of internal binary structures based on the **ISO 32000-1** standard
In the ISO 32000-1 standard that defines the basis of Portable Document Format, a file entity is constructed as a collection of objects.
This mechanism complies with this specification and grasps the entire file structure by starting reading from the Trailer placed at the end of the file.
By referencing the pointer to the root node recorded in the Trailer and then parsing the Cross-Reference Table, we determine exactly in which byte position each object resides in the file.
This allows random access to the required objects without having to read the entire file sequentially.
In particular, in the Page Tree structure that manages pages, it searches the hierarchical dictionary objects and extracts indirect references to each page stored in the Kids array.
In this process, we identify all page-specific dependencies such as content streams, resource dictionaries, and font information, and logically extract binary objects to be combined and split.
Because it performs object analysis at the binary level rather than simple text processing, it is possible to accurately understand the page structure even for documents with complex nested structures.
Non-destructive page extraction and reordering algorithm
When working with PDF documents, non-destructive processing that does not degrade the original image quality or vector information is an absolute requirement.
In this environment, we apply technology infrastructure such as pdf-lib, and instead of directly modifying existing objects, we construct a new document shell and relocate only the necessary objects.
During the splitting process, references to resources and content streams associated with the target page are extracted from the original document and accurately ported to the newly generated Page Tree.
In the merging process, pages extracted from different documents are integrated into a single file, so numbers are dynamically reassigned and references are rewritten to avoid conflicts between the unique object identification numbers of each document.
Additionally, when reordering or rotating a page, update the angle parameter of the Rotate entry in the page dictionary, or logically redefine the MediaBox's coordinate system using a transform matrix.
This allows the physical appearance to be changed simply by updating metadata without re-rendering images or text, reducing processing time and completely preserving the original data.
Browser heap memory shortage protection and stream control
When dealing with large documents (hundreds of pages) or files with many embedded high-resolution images, the web browser's garbage collection and limited heap memory exhaustion can become a serious issue.
To deal with this problem, we have implemented a chunk-by-chunk reading mechanism using ArrayBuffer, instead of expanding the file to the main storage area all at once.
By dividing the binary data obtained from the file system into smaller pieces and retaining only the block currently being processed in memory, Out of Memory is prevented.
In addition, we strictly manage the lifecycle of Blob URLs when returning the results of merging or splitting to the user interface for download.
Blob URLs for large generated files temporarily occupy browser memory space, so monitor triggers such as download completion or view component destruction, and immediately issue the URL.revokeObjectURL method to release space when it is no longer needed.
Such careful stream control and memory management ensure stable operation even in terminal environments with severe hardware resource constraints.
Principles of protection of confidential information in a completely local environment
Eliminating the risk of information leakage is a top priority when working with documents that require high security requirements, such as confidential contracts, undisclosed financial statements, or various application documents containing personal information.
This system employs an architecture that completes all file operations using only the JavaScript engine running within the browser's sandbox environment.
As a result, no data is sent to an external server in the name of uploading, and the entire process from parsing to merging, splitting, and exporting is performed entirely within the local client's memory space.
A design that does not involve network communication not only physically blocks the threat of eavesdropping and man-in-the-middle attacks on the communication path, but also eliminates the risk of temporary files remaining on the server side and the possibility of unexpected data viewing by service operators.
In compliance with corporate compliance standards and strict laws and regulations such as the Personal Information Protection Act, users can safely process highly confidential documents in the closed and safe environment of their own devices.
Rendering speed optimization and preview generation mechanism
Visual feedback is essential for intuitive operations such as merging and splitting pages, but fully rendering pages with complex vector graphics and heavy fonts is computationally expensive.
Therefore, it is equipped with a preview thumbnail generation mechanism that optimizes rendering speed so as not to impair operability on the user interface.
When parsing a document, we focus on the fact that high resolution is not required when drawing previews, and use the Canvas API to perform rasterization processing at a reduced scale.
At this time, only the thumbnails of pages that are within the visible area of the screen are drawn with priority, and by performing lazy loading in response to scrolling, we dramatically shorten the initial load time and avoid blocking the main thread.
Generated thumbnail images are temporarily stored in an in-memory cache hierarchy, providing a smooth visual response with no lag during interactive operations such as drag-and-drop reordering or deleting individual pages.
Practical application guide for organizing contracts, extracting paper pages, etc.
In actual business flows, this binary manipulation technology is effective in a wide variety of situations. When organizing contracts in the legal department, it is possible to safely and quickly extract only specific pages with signature fields from a large number of scanned documents and integrate them into a separate confirmation file.
In sales and planning sites, when selecting only the slides of successful cases from multiple past presentation materials and centralizing them as proposal materials for new customers, it is possible to combine them non-destructively without destroying the original layout or embedded fonts.
In addition, in the fields of academic research and education, users can precisely divide a PDF of a journal containing hundreds of pages into pages that contain the chapters they have written and the reference list, and reconstruct them into lightweight files suitable for registration in repositories and sharing with reviewers.
In this way, by combining analysis capabilities that penetrate the depths of standards with optimization technology that brings out the limits of browsers, we are providing a platform for highly automating complex daily document management tasks and dramatically improving productivity in practice.