Add Stamps to PDF Documents Online Add stamps to PDF.

The tool works by utilizing client-side JavaScript with React to handle file uploads and stamp additions. When a PDF file is dropped into the FileDropzone component, the handleFile function is triggered, which loads the PDF document using the pdf-lib library. This library allows for the creation and manipulation of PDF documents in the browser, without requiring any server-side processing. The tool then extracts the page count from the loaded PDF document and stores it in the pageCount state variable.

The stamp settings are stored in various state variables, such as preset, customText, fontSize, opacity, rotation, color, and position, which are updated when the user interacts with the corresponding input fields. When the process function is called, it uses the pdf-lib library to embed a font, specifically StandardFonts.HelveticaBold, into the PDF document. The tool then calculates the text width and height using the font's widthOfTextAtSize and heightAtSize methods, and computes the position of the stamp on each page based on the selected placement option.

The computePosition function uses a switch statement to determine the x and y coordinates of the stamp based on the chosen position, taking into account the page width, height, text width, and text height. The tool then draws the stamp text onto each page using the drawText method, applying the specified font size, color, opacity, and rotation. The resulting PDF document is saved as a blob and stored in the result state variable, which can be downloaded by the user.

The tool's responsive UI is built using React components, such as FileDropzone, InputWithHelp, and SelectWithHelp, which are designed to work seamlessly on various devices and screen sizes. The use of memoized functions, such as useCallback, helps optimize performance by reducing unnecessary re-renders and computations. Additionally, the tool uses the Clipboard API to enable users to download the stamped PDF document by creating a temporary link and simulating a click event on it.