pdfcraft/crates/create

pdfcraft-create

Layer L4. Create a PDF (Acrobat's Create a PDF tool), execution plan M10.2:

• blank(width, height, pages): an empty document;
• from_images(&[(name, bytes)]): one page per image, sized from the image's resolution (PNG pHYs, JPEG JFIF density; 72 dpi when absent). JPEG data is embedded as is (/DCTDecode, grey, RGB or Adobe-inverted CMYK); PNG is decoded and stored with Flate, with transparency as a soft mask. A picture of only pure black and white (a 1-bit PNG or TIFF, eight-bit grey, a two-colour palette, RGB without a profile) is stored at one bit per pixel, as CCITT Group 4 or Flate, whichever is smaller as stored (pdfcraft_filters::encode_g4). An ICC profile in the file (JPEG APP2 ICC_PROFILE, PNG iCCP) that matches the image's colour space is kept as an /ICCBased colour space with the device space as /Alternate; images with the same profile share one profile object. JPEG metadata scanning skips marker fill bytes and reads application segments after the frame header, stopping at the first scan or end marker. Broken or mismatched ICC profiles still fall back to the device colour space;
• from_images_with_resolution(images, ImageResolution::Dpi(dpi)): override the page resolution (1–1200 dpi), without resampling or recompressing image pixels. Use 72 dpi for one point per pixel, or ImageResolution::Embedded for the same behavior as from_images. The largest page side is still capped at 14,400 points;
• from_text(text, …): plain text set in Helvetica, wrapped and paginated. Text Helvetica can't draw is refused, naming the line and the character, never set as ?.
• from_text_escaped(text, …): the same for reports PdfCraft generates from documents (comment summaries, compare reports): such characters are written as [U+XXXX] and the first line says so (ESCAPED_NOTE).

Every function returns a pdfcraft_cos::Document; the caller writes it.

Image export and Save Image As apply each lossless image's Decode pair before converting its color components. JBIG2 images and masks are decoded through pdfcraft_cos::ImageBudget (pdfcraft_filters::decode_jbig2_within), behind other filters too, with the /JBIG2Globals of their own /DecodeParms entry, as JBIG2Decode gives them: black as 0. An image whose JBIG2 page isn't its size (PdfCraft's renderer draws the whole page into the image; the page is refused before it is decoded), or whose globals can't be read or decode to more than 32 MiB (they are decoded before the page's size is known, so they have a limit of their own), is skipped, and such a mask is left out and the image exported opaque, as JPX and CCITT masks are. Past what one export may decode, which its images share, filters, decoders and pixels alike (ImageBudget; a JPEG when it has to be decoded, as a mask or to apply one, and not when it is written as it is), an image is skipped, and so is one whose mask is past it, which would otherwise come out showing what the mask hides. An export also stops at 2 GiB of files held, or twice the document if that is more, since they stay in memory until it ends. Indexed Decode values select palette entries after rounding and clipping. Color-key masks compare the original samples. Missing, null or malformed Decode arrays keep the default mapping. Soft-mask Decode intervals map samples to opacity before the mask is resized, including reversed ranges and indirect entries. The existing 16-bit path still uses each sample's high byte. JPEG image Decode handling remains limited. ICC transforms and calibrated color conversion remain outside this export path. CCITT fax images (Group 3 and 4) are decoded for export through pdfcraft_cos::Document::decoded_image with their /DecodeParms (/Columns has to be the image's width; up to /Height rows, whatever /Rows says), behind other filters such as ASCII85Decode too. Byte-aligned Group 3 rows are read by their end-of-line codes, whether the fill starts each code on a byte or ends it on one, when the data starts with one (T.4 sends one before the first row), and on bytes otherwise, whatever /EndOfLine says; data that comes up short is reported. Data with codes but none before the first row is read on bytes, and is reported or, at /K 0, may come out wrong. JPEG 2000 images are still reported, not exported.