This project allows users to read and extract text and other content from PDF files. In addition the library can be used to create simple PDF documents
Each font must be registered with the PdfDocumentBuilder prior to use enable pages to share the font resources. Only Standard 14 fonts and TrueType fonts (.ttf) are supported.
The ```PdfDocument``` class provides access to the contents of a document loaded either from file or passed in as bytes. To open from a file use the ```PdfDocument.Open``` static method:
Encrypted documents can be opened by PdfPig. To provide an owner or user password provide the optional `ParsingOptions` when calling `Open` with the `Password` property defined. For example:
using (PdfDocument document = PdfDocument.Open(@"C:\my-file.pdf", new ParsingOptions { Password = "password here" }))
For text content, a font must be registered with the builder. This library supports Standard 14 fonts provided by Adobe by default and TrueType format fonts.
Passing in the bytes of a TrueType file (.ttf). You can check the suitability of a TrueType file for embedding in a PDF document using:
bool CanUseTrueTypeFont(IReadOnlyList<byte> fontFileBytes, out IReadOnlyList<string> reasons)
Which provides a list of reasons why the font cannot be used if the check fails. You should check the license for a TrueType font prior to use, since the compressed font file is embedded in, and distributed with, the resultant document.
The ```AddedFont``` class represents a key to the font stored on the document builder. This must be provided when adding text content to pages. To add a page to a document use:
This creates a new ```PdfPageBuilder``` with the specified size. The first added page is page number 1, then 2, then 3, etc. The page builder supports adding text, drawing lines and rectangles and measuring the size of text prior to drawing.
To write text to the page you must have a reference to an ```AddedFont``` from the methods on ```PdfDocumentBuilder``` as described above. You can then draw the text to the page using:
Where ```position``` is the baseline of the text to draw. Currently **only ASCII text is supported**. You can also measure the resulting size of text prior to drawing using the method:
The ```PdfDocument``` provides access to the document metadata as ```DocumentInformation``` defined in the PDF file. These tend not to be provided therefore most of these entries will be ```null```:
The pages dictionary is the root of the pages tree within a PDF document. The structure also exposes a ```GetObject(IndirectReference reference)``` method which allows random access to any object in the PDF as long as its identifier number is known. This is an identifier of the form ```69 0 R``` where 69 is the object number and 0 is the generation.
Due to the way a PDF is structured internally the page text may not be a readable representation of the text as it appears in the document. Since PDF is a presentation format, text can be drawn in any order, not necessarily reading order. This means spaces may be missing or words may be in unexpected positions in the text.
To help users resolve actual text order on the page, the ```Page``` file provides access to a list of the letters:
IReadOnlyList<Letter> letters = page.Letters;
These letters contain:
+ The text of the letter: ```letter.Value```.
+ The location of the lower left of the letter: ```letter.Location```.
+ The width of the letter: ```letter.Width```.
+ The font size in unscaled relative text units (these sizes are internal to the PDF and do not correspond to sizes in pixels, points or other units): ```letter.FontSize```.
+ The name of the font used to render the letter if available: ```letter.FontName```.
+ The points at the start and end of the baseline `StartBaseLine` and `EndBaseLine` which indicate if the letter is rotated. The `TextDirection` indicates if this is a commonly used rotation or a custom rotation.
Letter position is measured in PDF coordinates where the origin is the lower left corner of the page. Therefore a higher Y value means closer to the top of the page.
This will return `false` if the document does not contain a form.
The fields can be accessed using the `AcroForm`'s `Fields` property. Since the form is defined at the document level this will return fields from all pages in the document. Fields are of the types defined by the enum `AcroFieldType`, for example `PushButton`, `Checkbox`, `Text`, etc.
*Why is class or property X internal?* Internal properties and classes are not stable enough for the end user yet. If you want to access them feel free to use reflection but be aware they may change or disappear between versions.
Most testing has taken place with Latin character sets. Due to the more complex way the PDF specification handles CJK (Chinese, Japanese and Korean) character sets these will probably not be handled correctly for now. Please raise an issue (or preferably a pull request) if you have problems trying to read these documents.
This project wouldn't be possible without the work done by the [PDFBox](https://pdfbox.apache.org/) team and the Apache Foundation. Any bugs in the code are entirely my fault.
