Canvas

canvas provides absolute positioning within a section. Use it for watermarks, stamps, page headers/footers, decorative borders, and any element that must sit at an exact position independent of the flow layout.

Structure

All canvas primitives must be inside a layer. Bare primitives directly in canvas are not valid.

XML

<section>
  <layout>
    <text>Main content</text>
  </layout>
  <canvas>
    <layer page="each">
      <text x="0pt" y="756pt" font-size="9pt" color="#aaaaaa">Page footer</text>
    </layer>
  </canvas>
</section>

Node.js

L.section(NoAttr, [
    L.layout(NoAttr, [
        L.text(NoAttr, ['Main content']),
    ]),
    L.canvas(NoAttr, [
        L.layer({ page: 'each' }, [
            L.textAt({ x: '0pt', y: '756pt', fontSize: '9pt', color: '#aaaaaa' }, ['Page footer']),
        ]),
    ]),
])

Python

L.section(NoAttr, [
    L.layout(NoAttr, [
        L.text(NoAttr, ['Main content'])
    ]),
    L.canvas(NoAttr, [
        L.layer(LayerAttr(page='each'), [
            L.text_at(CanvasTextAttr(x='0pt', y='756pt', font_size='9pt', color='#aaaaaa'), ['Page footer'])
        ])
    ])
])

PHP

L::section(NoAttr, [
    L::layout(NoAttr, [
        L::text(NoAttr, ['Main content']),
    ]),
    L::canvas(NoAttr, [
        L::layer(new LayerAttr(page: 'each'), [
            L::textAt(new CanvasTextAttr(x: '0pt', y: '756pt', fontSize: '9pt', color: '#aaaaaa'), ['Page footer']),
        ]),
    ]),
])

.NET

L.Section(NoAttr, [
    L.Layout(NoAttr, [
        L.Text(NoAttr, ["Main content"]),
    ]),
    L.Canvas(NoAttr, [
        L.Layer(new() { Page = "each" }, [
            L.TextAt(new() { X = "0pt", Y = "756pt", FontSize = "9pt", Color = "#aaaaaa" }, ["Page footer"]),
        ]),
    ]),
])

Paint order (overlay vs underlay)

The element listed first in section is painted first:

<!-- canvas as underlay (behind layout) -->
<section>
  <canvas>…</canvas>
  <layout>…</layout>
</section>

<!-- canvas as overlay (in front of layout) -->
<section>
  <layout>…</layout>
  <canvas>…</canvas>
</section>

layer attributes

Attribute	Type	Default	Description
page	string	each	Which pages to render on: each first last odd even, or numbers and ranges such as 1, 2-last or 1,3-5
opacity	0–1	1	Layer-wide opacity
transform	string	—	Transform applied to everything in the layer; see below
clip	string	—	Reserved. It is accepted but has no effect yet

A layer cannot contain another layer. To combine opacity and a transform, put both on one layer.

Transforms

Form	Effect
translate(x, y)	Move by x and y
scale(s) or scale(sx, sy)	Scale by s, or by sx across and sy down
rotate(deg, cx, cy)	Rotate by deg degrees around the point cx, cy
matrix(a, b, c, d, e, f)	A full transform matrix

The numbers are plain numbers in points, separated by commas or spaces. A number with a unit, such as translate(10pt 20pt), is not read, and the transform does nothing.

Coordinate system

• Origin: top-left of the full page (ignores margin)
• Y axis: downward (y=0 is top of page)
• Units: pt, mm, in (negative values allowed for offsets from anchors)

Positioning with anchor

Instead of x/y coordinates, use anchor to reference one of nine points on the page. x and y become signed offsets from that point. The element is placed so its own matching point lands there: anchor="bottom-right" puts the element’s bottom-right corner on the page’s bottom-right corner, before the offset.

Anchor values
top-left top-center top-right
center-left center center-right
bottom-left bottom-center bottom-right

XML

<!-- Footer text anchored to bottom-left, offset 10pt from edge -->
<canvas>
  <layer page="each">
    <text anchor="bottom-left" x="10pt" y="-10pt" font-size="9pt">Footer</text>
  </layer>
</canvas>

Node.js

L.canvas(NoAttr, [
    L.layer({ page: 'each' }, [
        L.textAt({ anchor: 'bottom-left', x: '10pt', y: '-10pt', fontSize: '9pt' }, ['Footer']),
    ]),
])

Python

L.canvas(NoAttr, [
    L.layer(LayerAttr(page='each'), [
        L.text_at(CanvasTextAttr(anchor='bottom-left', x='10pt', y='-10pt', font_size='9pt'), ['Footer'])
    ])
])

PHP

L::canvas(NoAttr, [
    L::layer(new LayerAttr(page: 'each'), [
        L::textAt(new CanvasTextAttr(anchor: 'bottom-left', x: '10pt', y: '-10pt', fontSize: '9pt'), ['Footer']),
    ]),
])

.NET

L.Canvas(NoAttr, [
    L.Layer(new() { Page = "each" }, [
        L.TextAt(new() { Anchor = "bottom-left", X = "10pt", Y = "-10pt", FontSize = "9pt" }, ["Footer"]),
    ]),
])

Primitives

Element	Description
rect	Filled or stroked rectangle
circle	Circle
ellipse	Ellipse, with separate x and y radii
line	Straight line between two points
path	SVG path data
text	Absolutely positioned text
img	Absolutely positioned image

Canvas elements are not data-bound: data-* attributes have no effect on them. For text that changes per document, use the layout, or a region for page furniture.

DRAFT watermark example

XML

<canvas>
  <layer page="each" opacity="0.12" transform="rotate(45, 306, 396)">
    <text x="100pt" y="420pt" font-size="72pt" color="#cc0000">DRAFT</text>
  </layer>
</canvas>

Node.js

L.canvas(NoAttr, [
    L.layer({ page: 'each', opacity: '0.12', transform: 'rotate(45, 306, 396)' }, [
        L.textAt({ x: '100pt', y: '420pt', fontSize: '72pt', color: '#cc0000' }, ['DRAFT']),
    ]),
])

Python

L.canvas(NoAttr, [
    L.layer(LayerAttr(page='each', opacity='0.12', transform='rotate(45, 306, 396)'), [
        L.text_at(CanvasTextAttr(x='100pt', y='420pt', font_size='72pt', color='#cc0000'), ['DRAFT'])
    ])
])

PHP

L::canvas(NoAttr, [
    L::layer(new LayerAttr(page: 'each', opacity: '0.12', transform: 'rotate(45, 306, 396)'), [
        L::textAt(new CanvasTextAttr(x: '100pt', y: '420pt', fontSize: '72pt', color: '#cc0000'), ['DRAFT']),
    ]),
])

.NET

L.Canvas(NoAttr, [
    L.Layer(new() { Page = "each", Opacity = "0.12", Transform = "rotate(45, 306, 396)" }, [
        L.TextAt(new() { X = "100pt", Y = "420pt", FontSize = "72pt", Color = "#cc0000" }, ["DRAFT"]),
    ]),
])