hide: Add hide function for hiding elements

CHANGES.md

@@ -20,6 +20,7 @@ CeTZ 0.2.0 requires Typst 0.10.0
 - Added element `arc-through` to draw an arc through three points
 - Added Hobby curves (`hobby`) in addition to catmull (thanks to @Enivex)
 - Added `radius` style to `rect` for drawing rounded rects
+- Added `hide` function for hiding elements
 
 ### Plot
 - Added `plot.add-contour(..)` for plotting contour plots

src/canvas.typ

@@ -61,6 +61,9 @@
  return []
  }
 
+ // Filter hidden drawables
+ drawables = drawables.filter(d => not d.hidden)
+
  // Order draw commands by z-index
  drawables = drawables.sorted(key: (cmd) => {
  return cmd.at("z-index", default: 0)

src/draw.typ

@@ -1,4 +1,4 @@
-#import "draw/grouping.typ": intersections, group, anchor, copy-anchors, place-anchors, set-ctx, get-ctx, for-each-anchor, on-layer, place-marks
+#import "draw/grouping.typ": intersections, group, anchor, copy-anchors, place-anchors, set-ctx, get-ctx, for-each-anchor, on-layer, place-marks, hide
 #import "draw/transformations.typ": set-transform, rotate, translate, scale, set-origin, move-to, set-viewport
 #import "draw/styling.typ": set-style, fill, stroke
 #import "draw/shapes.typ": circle, circle-through, arc, arc-through, mark, line, grid, content, rect, bezier, bezier-through, catmull, hobby, merge-path

src/draw/grouping.typ

@@ -13,6 +13,42 @@
 
 #import "transformations.typ": move-to
 
+/// Hides an element.
+///
+/// Hidden elements are not drawn to the canvas,
+/// are ignored when calculating bounding boxes and discarded by `merge-path`. All
+/// other behaviours remain the same as a non-hidden element.
+///
+/// #example(```
+/// set-style(radius: .5)
+/// intersections("i", {
+/// circle((0,0), name: "a")
+/// circle((1,2), name: "b")
+/// // Use a hidden line to find the border intersections
+/// hide(line("a.center", "b.center"))
+/// })
+/// line("i.0", "i.1")
+/// ```)
+///
+/// - body (element): One or more elements to hide
+#let hide(body) = {
+ if type(body) == array {
+ return body.map(f => {
+ (ctx) => {
+ let element = f(ctx)
+ if "drawables" in element {
+ element.drawables = element.drawables.map(d => {
+ d.hidden = true
+ return d
+ })
+ }
+ return element
+ }
+ })
+ }
+ return body
+}
+
 /// Calculates the intersections between multiple paths and creates one anchor
 /// per intersection point.
 ///
@@ -44,6 +80,8 @@
 /// })
 /// ```)
 ///
+/// You can calculate intersections with hidden elements by using @@hide().
+///
 /// - name (string): Name to prepend to the generated anchors.
 /// - ..elements (elements,string): Elements and/or element names to calculate intersections with.
 /// Elements referred to by name are (unlike elements passed) not drawn by the intersections function!

src/draw/shapes.typ

@@ -1564,6 +1564,7 @@
  }
  }
  for drawable in r.drawables {
+ if drawable.hidden { continue }
  assert.eq(drawable.type, "path")
  segments += drawable.segments
  }

src/drawable.typ

@@ -41,7 +41,8 @@
  close: close,
  segments: segments,
  fill: fill,
- stroke: stroke
+ stroke: stroke,
+ hidden: false
  )
 }
 
@@ -52,6 +53,7 @@
  width: width,
  height: height,
  body: body,
+ hidden: false,
  )
 }
 

src/process.typ

@@ -15,15 +15,17 @@
  element.drawables = (element.drawables,)
  }
  for drawable in element.drawables {
- bounds = aabb.aabb(
- if drawable.type == "path" {
- path-util.bounds(drawable.segments)
- } else if drawable.type == "content" {
- let (x, y, _, w, h,) = drawable.pos + (drawable.width, drawable.height)
- ((x + w / 2, y - h / 2, 0), (x - w / 2, y + h / 2, 0))
- },
- init: bounds
- )
+ if not drawable.hidden {
+ bounds = aabb.aabb(
+ if drawable.type == "path" {
+ path-util.bounds(drawable.segments)
+ } else if drawable.type == "content" {
+ let (x, y, _, w, h,) = drawable.pos + (drawable.width, drawable.height)
+ ((x + w / 2, y - h / 2, 0), (x - w / 2, y + h / 2, 0))
+ },
+ init: bounds
+ )
+ }
  }
  }
  if "name" in element and type(element.name) == "string" and "anchors" in element {

tests/hide/test.typ

@@ -0,0 +1,37 @@
+#set page(width: auto, height: auto)
+#import "/src/lib.typ": *
+
+#box(stroke: 2pt + red, canvas({
+ import draw: *
+ rect((0,0), (5,5))
+
+ // Hide a circle
+ hide(circle((6,6)))
+
+ // Hide content
+ hide(content((-6,-6), [Hidden]))
+
+ // Hide multiple elements
+ hide({
+ rect((0,0), (1,1))
+ rect((1,1), (2,2))
+ rect((2,2), (3,3))
+ })
+
+ // Use hidden anchor
+ hide(line((0,0), (2.5, 2.5), name: "line"))
+ content("line.end", [Hidden anchor])
+}))
+
+#box(stroke: 2pt + red, canvas({
+ import draw: *
+
+ merge-path({
+ arc((0,0), start: 0deg, stop: 180deg)
+ hide({
+ // This gets ignored
+ line((), (rel: (-5,0), update: false))
+ })
+ line((), (rel: (1, -1)))
+ }, close: true)
+}))