ajrcarey
commented
2 years ago Hi @sunnyawake6, thank you for raising the issue.
Pdfium (and therefore pdfium-render) does not support extracting embedded fonts. There are two reasons for this. First, only the font glyphs actually required by the document are included in the document; this is a feature called font subsetting. For instance, if you use a custom font for a drop-cap, and thus use only a single letter from the font, only the glyph for that single letter will be embedded in the document; all other font information will be discarded. So even if you could extract font data from a document, it would probably be incomplete. The second reason you cannot directly extract embedded fonts is to do with licensing. If it was easy to extract complete font resources, it would be trivial to violate licensing agreements made with font creators.
Instead, you may wish to consider using one of the the methods suggested at https://stackoverflow.com/questions/3488042/how-can-i-extract-embedded-fonts-from-a-pdf-as-valid-font-files. Please be aware that this may violate the licenses of font creators. I cannot assist you further with this.
Extracting images is usually straight-forward, since (unlike fonts) images are stored intact in the PDF file. Unless the PDF's security settings have specifically been set to prevent image extraction, you can use a recipe like the following to extract images from a document:
Pdfium::new(
Pdfium::bind_to_library(Pdfium::pdfium_platform_library_name_at_path("./"))
.or_else(|_| Pdfium::bind_to_system_library())?,
)
.load_pdf_from_file("test/image-test.pdf", None)?
.pages()
.iter()
.enumerate()
.for_each(|(page_index, page)| {
// For each page in the document, output the images on the page to separate files.
page.objects()
.iter()
.enumerate()
.for_each(|(object_index, object)| {
if let Some(image) = object.as_image_object() {
// This page object contains an image. Attempt to extract the raw image data.
if let Ok(image) = image.get_raw_image() {
// Export the raw image data as a JPG.
assert!(image
.save_with_format(
format!(
"image-test-page-{}-image-{}.jpg",
page_index, object_index
),
ImageFormat::Jpeg,
)
.is_ok());
}
}
});
});You have two options when extracting images. You can extract the raw image data, exactly as it was embedded in the PDF file; this what the code above does. The extracted image will ignore any transforms (e.g. rotation, skew, etc.) and image filters that may have been applied to the page object containing the image data, so it may look different to how the image appears when viewed as part of the PDF document. Alternatively you can extract the processed image data, with any transforms and image filters applied during rendering; an image extracted in this way will look exactly the same as it does when viewed as part of the PDF document. The two functions you want are PdfPageImageObject::get_raw_image() and PdfPageImageObject::get_processed_image().
The code above is available as a new example in examples/image_extract.rs.
richcanvas
hi, can you add examples on extracting embedded fonts and images?