FF_PDFium

DEPENDENCIES

1. PDFium Precompiled Binaries for various platforms (we use non-v8)
   https://github.com/bblanchon/pdfium-binaries

2. In order to view online PDF files, you have to use a HTTP Client plugin. You can use ours or get one from Github/Unreal Marketplace or write your own.
   https://github.com/FF-Projects-UE/HTTP_Client

3. Extended Variables for x64 bytes, external fonts and image adding
   https://github.com/FF-Projects-UE/ExtendedVars

TARGET PLATFORM

This is a runtime plugin. It won’t work on editor. It supports Windows and Android platforms as target.

HELPER FUNCTIONS

Unreal blueprints doesn’t support TArray64<uint8> and TArray<uint8> doesn’t support more than 2 GB file size. So, if you want to bigger PDF files than 2 GB, you have to use BytesObject_x64 from our Extended Variables plugin.</br> Add image function expects images as bytes array. You can use our Extended Variables plugin to get texture buffers, you can use another plugins from marketplace or you can write your own logic. Target texture shouldn’t be DXTvariations. For detailed information, you can look at Extended Variables’s README file.

PDFIUM SYSTEM FUNCTIONS

• Create Document
• Open PDF from file
• Open PDF from Memory

PDFIUM READ FUNCTIONS

• PDFium - PDFium Get Pages: It will give a Map of (Key: Texture2D, Value: Width and Height) pages as textures.
• PDFium - PDFium Get All Texts: It will get all texts of all pages.
• PDFium - PDFium Get Texts: It will get all texts of target page with their styles.
  • Transform (Location, size): Some editors use “1” point for font size and change text object’s size with transform matrixes. So, if you want to re-create that PDF file with only font size, you will get very small textures.
  • Font Size
  • Font Name
  • Font Color
  • Runtime Font Object : It is a container of UFont pointer. Because we have to release it and UFontFace when we want to close game.
• PDFium - Select Text: You can think this as a somekind of text selection. It will get text/strings in a rectangle area.
  • You have to define that rectangle’s size and location according with PDF’s size and location.
  • Don’t use your cursor location directly.
  • Sample math: (Cursor Location - PDF Location at screen) * Sampling (value which you used on Get Pages)
• PDFium - Get Links: It will give all weblinks in specified page. It won’t give internal bridges. It will give weblinks. This is limitation of PDFium.
• PDFium - Get Images: It will extract all images as a TMap<UTexture2D, FVector2D> (FVector2D is images location). But images of PDF have to be FPDF_PAGEOBJ_IMAGE
• PDFium - Get Page Count and Sizes: It will give an array of FVector2D. Lenght of array will be equal to page size, each elements contains size of its respective page.

PDFIUM WRITE FUNCTIONS

• PDFium - Add Pages: It adds pages to target PDF file with defined size. (Array count is page count and each vector element of array is its size)
• PDFium - Load Standart Font: There are 14 standart fonts embedded to PDF libraries according to PDF Spec 1.7 page 416. This function allows to select one them.
• PDFium - Load External Font: You have to use desktop fonts not web fonts. For example, some Google Fonts (such as Google Variant of Roboto) don’t work.< /br> You can download compatible fonts from these websites. < /br> https://all-free-download.com/font/ < /br> https://www.fontspace.com/category/truetype < /br> https://www.dafont.com/
• PDFium - Add Texts: It adds text objects to target page. PDFium doesn’t support line break at default but we integrated a basic auto wrap feature. Neverthless, you need to be careful about your layout. (When will you create a line break or not)
  • Text Color
  • Position X = Horizontal position.
  • Position Y = Vertical position but it starts from bottom. If your PDF page’s height is 800 pixel, top will be 800 and bottom will be 0.
  • Shear X and Y = It strecth your text object. Scaling won’t be vectoral. So we don’t suggest it.
  • Rotation X and Y = We don’t know how it works right now.
  • Border X and Y = It defines vertical and horizontal borders.
  • Use Charcodes: Frontend usage from blueprints are same but at backend it switches between ASCII Decimal based FPDFText_SetCharcodes() and FPDFText_SetText(). Charcodes has better character support.
• PDFium - Add Image: It expects byte array.
• PDFium - Draw Rectangle: It will draw a rectangle on PDF file with given location, size and color.
• PDFium - Save File
• PDFium - Save Bytes

INSTRUCTIONS

• Look at plugin’s content folder. There are example blueprints to show you how can you use this plugin.
• Spawn PDF_Manager actor class. All PDF related functions are its blueprint exposed member functions.
• Create or open a PDF file from actor class.
  • If you want to create one, you have to add a page to it.
• Do all your things.
• If you want to “view” changes on PDF file in UE5, you need to render it “again” and assign it to your widget or material.

ROADMAP

• Rotation inputs: Inputs are connected to internal functions but PDFium use a somekind of rotation matrix. So, use it if you know what you are doing. We will create a helper function about this.

LIMITATION

• Some external web fonts can cause crash. So, it will be good to test your fonts at development stage and give them to your customers.

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