vectorcraft/docs/dimensions.md

Dimensions

The Dimension Tool is in the Modify section of the toolbar. Its strip offers Linear, Angular, Radial and Tool Options… (double-clicking the tool opens Tool Options too).

• Linear: hover a path segment and drag outwards: releasing places the dimension. Or click two points (anchors snap, Shift constrains to 45°), then click to place. A click within 8 pixels of an anchor of any path, in groups and compound paths too, takes that anchor, and the dimension stays linked to it. A point on a segment stays at its place along the segment, also when the segment's anchors or handles are edited. Any other point is linked to the path under it, or, with no path under it, to the path at the other end, and moves, scales, turns and reflects with that path. Beside a path whose anchors and handles all lie on one line, such as a straight line, the point keeps its distance along and across the path: a reflection moves it as a half turn does, and a scale that is not uniform changes its distance across the path in proportion to the path's length. A press on an anchor picks it when the pointer moves less than 8 pixels before the release; a longer drag drags out the dimension of the segment under the pointer. A curved segment is measured from end to end. With Smart Guides on, both points also snap into line with other objects' anchors and centres, and the second onto the construction guides through the first; the guides show while hovering, before each click. A linear dimension is aligned, horizontal or vertical, as the linear dimensions help describes: after the second click, clicking again places an aligned dimension, and moving the pointer away gives a horizontal or vertical one. Which one a pointer position gives is VectorCraft's own rule. When the pointer is beside the two points (the nearest point of the line through them lies between them) or on that line, the dimension is aligned. When the pointer is past either point, the line through the points and the perpendicular through that point divide the area beyond it into two quarters, one on each side of the line. The quarter that contains the direction straight up or down from the point gives the horizontal distance, and the quarter that contains the direction straight left or right gives the vertical distance. A click within 8 pixels of the second point, or of where the pointer was for the second click, places an aligned dimension. Two points on one horizontal or vertical line always give an aligned dimension. A dragged segment uses the same rule with its two ends. A horizontal or vertical dimension keeps its orientation when it or the art it measures turns, and shows the new horizontal or vertical distance, as the help describes for rotated objects. It shows 0 when its points lie on one line across its axis. When the line of a linked dimension lies outside its points, the line stays on the same side of the art, as far past the outermost point as before. An unlinked dimension that turns has its line where the turn puts it, or, when that would put it between the points, as far past the outermost point as before.
• Angular: hover a corner where two straight segments meet and drag outwards. Or click two straight lines that meet (or would, extended), then click to place.
• Radial: hover a circle, or a segment that is a perfect arc, and drag: outwards gives its radius, inwards its diameter. Clicking it gives its radius. Ellipses have no single radius.
• Escape or switching tools cancels a dimension being placed.

Tool Options set the style of new dimensions: units (inches, millimetres, points, picas, pixels, centimetres, metres, feet, yards), precision (0–6 decimals), scale, the dimension and extension lines (weight, type, colour, arrows), and the text (font, size, colour, position and alignment). Position is Away from the Line (the label on the far side of the dimension line from the object) or Between Line and Object; Alignment is Left, Center or Right along the line. Save keeps them for new dimensions; existing ones don't change.

Scale means drawing : real size, independent of zoom. At 1:10 a 1 in line on the page is labelled 10 in; at 10:1, 0.1 in. It scales lengths, not angles or the size of text and arrows.

Properties shows a selected dimension's units, precision, line, arrows, text size, colour, position and alignment; changing one changes that dimension. Apply to All gives every dimension in the document its style; Set as Default makes it the style of new dimensions.

Measurements follow the art they measure through moves, scaling and anchor and handle edits, undo and redo included. When the art is reflected, the line of a linked linear dimension goes to the reflected side, as far past the outermost point as before. This does not happen for art whose anchors and handles all lie on one line, such as a straight line, which a half turn puts in the same place as a reflection. Deleting the art, changing its number of anchors or whether it is closed, turning an angle's arm into a curve, or making a measured circle or arc no longer circular leaves its dimensions where they were, no longer linked, in the same undo step, rather than attaching them to a different edge. Undo links them again. A linked dimension moved on its own stays where it was dropped (its distance from the art changes); moved together with its art, it keeps its distance.

Native .vectorcraft files keep the recipes and links. SVG, PDF and bitmap output contain ordinary paths and text, so exported dimensions look the same. Ungrouping a dimension leaves its paths and text as ordinary art. Object › Expand, Object › Expand Appearance, Type › Create Outlines and Object › Path › Outline Stroke turn a dimension whose art they change into a plain group of that art, also when they reach only a part of it: moving or scaling the group does not redraw it, it does not follow the art it measured, and undoing the command gives the live dimension back. The menus dim Object › Expand… while a whole dimension is selected, because its label has appearance items; Object › Expand Appearance and the object.expand command still reach it. A dimension selected with the art it measures also becomes a plain group when Object › Expand, Object › Expand Appearance or Object › Path › Outline Stroke changes only that art and the art no longer fits the dimension's link, for example because its number of anchors changed. When the art keeps its id and anchor count and the dimension's own art does not change, the dimension stays live and its label shows the new length. Pasted dimensions keep their geometry and drop their links, so they never bind to unrelated art in another document.

Commands

• dimension.create: two points, or a source (segment, angle, circle, arc, points), the mode, the orientation of a linear dimension (aligned, the default, horizontal or vertical), offset and style; returns the group id and label. offset is the distance of the dimension line from the first point: along the left normal of a → b for an aligned dimension, downward for a horizontal one and leftward for a vertical one. A negative offset goes the other way.
• dimension.update: restyle or move existing dimensions, or change the orientation of linear ones. A new orientation keeps the line on the side of the points it was on. An update that changes nothing records no undo step.
• dimension.applyToAll: every dimension takes one dimension's style, in one undo step.
• tool.select {"tool":"dimension"} and tool.setOption {"tool":"dimension","values":{"mode":"linear","style":{"units":"mm","scale":"1:10"}}} (mode: linear, angular or radial).
• tool.options {"tool":"dimension"} opens the dimensionOptions dialog.

Recipes live on ordinary groups (the node's dimension field); rendering and export use their generated children. Commands check options and bounds before changing anything. Linked dimensions refresh inside Session::edit, sharing the source edit's undo step; documents without any (Document::dimensions unset) skip that refresh.