PDF Positioning, hands on

1. Vertical anchors: what y means

Libraries disagree about the vertical meaning of y: a raw PDF text matrix anchors the baseline, the legacy engine's fixed-position layout lays text down from the top of its layout box, legacy PDF libraries hangs it from a rectangle edge. rust-pdf makes the choice explicit. Pick an anchor and watch the text move while the anchor point ● stays put.

2. Rotation pivots at the anchor

rotationDeg rotates counter-clockwise about the anchor. Offsets from alignment or vertical anchors rotate together with the text, so the anchor remains the same physical point of the text box at every angle. Spin it.

3. Rotated scans: StampSpace

Scanned documents usually carry /Rotate 90. There are two honest ways to interpret your coordinates on such a page, and rust-pdf lets you pick per document instead of guessing.

4. Paragraphs: wrapping, bottom-pinning and the ceiling

PlaceParagraph wraps by word inside a width. With the Bottom anchors the block is bottom-pinned: its bottom rests on y and it grows upward by the real content height. maxHeight is a ceiling, not a box to fill: overflowing lines are cut from the top and the last lines stay pinned. The call reports the consumed height.

5. MaskedText: a box, a mask, aligned text

MaskedText paints an opaque box and writes a value over it, the classic "cover the placeholder" move. The vertical alignment and the horizontal inset are explicit.

6. Images: corner pivot or bounding box

A rotated image can be anchored two ways: Corner (default) keeps (x, y) as the image's own lower-left corner and the image sweeps around it; BoundingBox lands the rotated image's bounding box at (x, y), which is how legacy layout engines lays out rotated images.

The same contract in every language

One Rust core, ten bindings, identical semantics. A signature block stamped at the bottom of a scanned page looks like this:

# pip install rustpdf
import rustpdf
from rustpdf import EditableDoc, StampSpace, VerticalAnchor, Align

doc = EditableDoc.load(open("scan.pdf", "rb").read())
doc.set_stamp_space(StampSpace.MEDIA)      # legacy-style raw coordinates
times = doc.add_font_file("Times New Roman.ttf")

# Bottom-pinned signature block: the block bottom rests on y = 96.
doc.place_paragraph(0, 72, 96, 220,
    "Digitally signed by Maria Silva\nReason: Approval\n2026-07-02 14:31 UTC",
    size=10, font_id=times, max_height=64,
    anchor=VerticalAnchor.LINE_BOTTOM)
open("signed-stamped.pdf", "wb").write(doc.to_bytes())

// dotnet add package RustPdf
using RustPdf;

using var doc = EditableDoc.Load(File.ReadAllBytes("scan.pdf"));
doc.StampSpace = StampSpace.Media;         // legacy-style raw coordinates
int times = doc.AddFontFile("Times New Roman.ttf");

// Bottom-pinned signature block: the block bottom rests on y = 96.
doc.PlaceParagraph(0, 72, 96, 220,
    "Digitally signed by Maria Silva\nReason: Approval\n2026-07-02 14:31 UTC",
    size: 10, fontId: times, maxHeight: 64,
    anchor: VerticalAnchor.LineBottom);
File.WriteAllBytes("signed-stamped.pdf", doc.ToBytes());

// go get github.com/rustpdf/rustpdf-go@latest
doc, _ := rustpdf.Load(data)
defer doc.Close()
doc.SetStampSpace(rustpdf.StampMedia)      // legacy-style raw coordinates
times, _ := doc.AddFontFile("Times New Roman.ttf")

// Bottom-pinned signature block: the block bottom rests on y = 96.
doc.PlaceParagraph(0, 72, 96, 220,
    "Digitally signed by Maria Silva\nReason: Approval\n2026-07-02 14:31 UTC",
    10, 0, 0, 0, rustpdf.AlignLeft, times,
    64, 1.0, rustpdf.AnchorLineBottom, 0)
out, _ := doc.Bytes()

// npm install rustpdf
const { EditableDoc, StampSpace, VerticalAnchor } = require("rustpdf");

const doc = EditableDoc.load(fs.readFileSync("scan.pdf"));
doc.setStampSpace(StampSpace.Media);       // legacy-style raw coordinates
const times = doc.addFontFile("Times New Roman.ttf");

// Bottom-pinned signature block: the block bottom rests on y = 96.
doc.placeParagraph(0, 72, 96, 220,
  "Digitally signed by Maria Silva\nReason: Approval\n2026-07-02 14:31 UTC",
  { size: 10, fontId: times, maxHeight: 64,
    anchor: VerticalAnchor.LineBottom });
fs.writeFileSync("signed-stamped.pdf", doc.toBytes());

Full API reference per language: Python, C#, Go, Node, Java, PHP, Ruby, Swift, Delphi.

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