plot: Refine default style (#423)

Allow setting different grid style for major and minor grid lines.

Fixes #278

src/lib/axes.typ

@@ -15,23 +15,25 @@
   fill: none,
   stroke: black,
   label: (
-    offset: .2cm,
-    anchor: auto,
+    offset: .2cm,       // Axis label offset
+    anchor: auto,       // Axis label anchor
   ),
   tick: (
     fill: none,
     stroke: black,
-    length: .1cm,
-    minor-length: .08cm,
+    length: .1cm,       // Tick length: Number
+    minor-length: 80%,  // Minor tick length: Number, Ratio
     label: (
-      offset: .2cm,
-      angle: 0deg,
-      anchor: auto,
+      offset: .2cm,     // Tick label offset
+      angle: 0deg,      // Tick label angle
+      anchor: auto,     // Tick label anchor
     )
   ),
   grid: (
-    stroke: (paint: gray, dash: "dotted"),
-    fill: none
+    stroke: (paint: gray.lighten(50%), thickness: 1pt),
+  ),
+  minor-grid: (
+    stroke: (paint: gray.lighten(50%), thickness: .5pt),
   ),
 )
 
@@ -42,6 +44,9 @@
   style.label.offset = n(style.label.offset)
   style.tick.length = n(style.tick.length)
   style.tick.minor-length = n(style.tick.minor-length)
+  if type(style.tick.minor-length) == ratio {
+    style.tick.minor-length = style.tick.minor-length * style.tick.length / 100%
+  }
   style.tick.label.offset = n(style.tick.label.offset)
 
   if "padding" in style {
@@ -409,14 +414,20 @@
                         angle: style.tick.label.angle)
               }
 
-              if grid-mode.major and major or grid-mode.minor and not major {
+              let show-major-grid = grid-mode.major and major
+              if show-major-grid or grid-mode.minor and not major {
                 let (grid-begin, grid-end) = if name in ("top", "bottom") {
                   ((x, 0), (x, h))
                 } else {
                   ((0, y), (w, y))
                 }
 
-                line(grid-begin, grid-end, ..style.grid)
+                let grid-style = if show-major-grid {
+                  style.grid
+                } else {
+                  style.minor-grid
+                }
+                line(grid-begin, grid-end, ..grid-style)
               }
             }
 

src/lib/chart/barchart.typ

@@ -4,7 +4,7 @@
 #import "/src/styles.typ"
 
 #let barchart-default-style = (
-  axes: (tick: (length: 0)),
+  axes: (tick: (length: 0), grid: (stroke: (dash: "dotted"))),
   bar-width: .8,
   y-inset: 1,
 )

src/lib/chart/boxwhisker.typ

@@ -3,7 +3,7 @@
 #import "/src/styles.typ"
 
 #let boxwhisker-default-style = (
-  axes: (tick: (length: 0)),
+  axes: (tick: (length: 0), grid: (stroke: (dash: "dotted"))),
   box-width: 0.75,
   whisker-width: 0.5,
   mark-size: 0.15,

src/lib/chart/columnchart.typ

@@ -4,7 +4,7 @@
 #import "/src/styles.typ"
 
 #let columnchart-default-style = (
-  axes: (tick: (length: 0)),
+  axes: (tick: (length: 0), grid: (stroke: (dash: "dotted"))),
   bar-width: .8,
   x-inset: 1,
 )

tests/plot/grid/test.typ

@@ -0,0 +1,72 @@
+#set page(width: auto, height: auto)
+#import "/src/lib.typ": *
+
+/* X grid */
+#box(stroke: 2pt + red, canvas({
+  import draw: *
+
+  plot.plot(size: (3, 3),
+    x-grid: true,
+    x-tick-step: .5,
+    y-tick-step: .5,
+  {
+    plot.add(((0,0), (1,1)))
+  })
+}))
+
+/* X grid */
+#box(stroke: 2pt + red, canvas({
+  import draw: *
+
+  plot.plot(size: (3, 3),
+    x-grid: "both",
+    x-tick-step: .5,
+    x-minor-tick-step: .25,
+    y-tick-step: .5,
+  {
+    plot.add(((0,0), (1,1)))
+  })
+}))
+
+/* Y grid */
+#box(stroke: 2pt + red, canvas({
+  import draw: *
+
+  plot.plot(size: (3, 3),
+    y-grid: true,
+    x-tick-step: .5,
+    y-tick-step: .5,
+  {
+    plot.add(((0,0), (1,1)))
+  })
+}))
+
+/* Y grid */
+#box(stroke: 2pt + red, canvas({
+  import draw: *
+
+  plot.plot(size: (3, 3),
+    y-grid: "both",
+    x-tick-step: .5,
+    y-tick-step: .5,
+    y-minor-tick-step: .25,
+  {
+    plot.add(((0,0), (1,1)))
+  })
+}))
+
+/* X-Y grid */
+#box(stroke: 2pt + red, canvas({
+  import draw: *
+
+  plot.plot(size: (3, 3),
+    x-grid: "both",
+    y-grid: "both",
+    x-tick-step: .5,
+    x-minor-tick-step: .25,
+    y-tick-step: .5,
+    y-minor-tick-step: .25,
+  {
+    plot.add(((0,0), (1,1)))
+  })
+}))