From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 21 Mar 2021 23:36:39 +0000 (+0000)
Subject: shapelib: Provide sensible default for centre
X-Git-Tag: otter-0.5.0~538
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=8a1e49c4239679f13253bc8fd7178b54a6aca625;p=otter.git

shapelib: Provide sensible default for centre

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/src/shapelib-toml.rs b/src/shapelib-toml.rs
index 8ae0f8d3..796b91c7 100644
--- a/src/shapelib-toml.rs
+++ b/src/shapelib-toml.rs
@@ -110,7 +110,9 @@ pub struct GroupDetails {
   /// scale by different amounts in x and y.
   pub orig_size: Vec<f64>,
 
-  pub centre: [f64; 2],
+  #[serde(default)]
+  /// Default if not supplied is the centre according to the size.
+  pub centre: Option<[f64; 2]>,
 
   #[serde(default)]
   /// Default is `false`
diff --git a/src/shapelib.rs b/src/shapelib.rs
index 02a55645..13090a46 100644
--- a/src/shapelib.rs
+++ b/src/shapelib.rs
@@ -196,9 +196,23 @@ impl OutlineTrait for Item { delegate! { to self.outline {
 impl FaceTransform {
   #[throws(LLE)]
   fn from_group(d: &GroupDetails) -> Self {
-    let centre = d.centre;
+    // by this point d.size has already been scaled by scale
+    let centre = d.centre.map(Ok).unwrap_or_else(|| Ok::<_,LLE>({
+      match d.size.as_slice() {
+        [a] => [a,a],
+        [a,b] => [a,b],
+        x => throw!(LLE::WrongNumberOfSizeDimensions {
+          got: x.len(),
+          expected: [1,2],
+        }),
+      }.iter().cloned().map(|size| {
+        size * 0.5 / d.scale
+      })
+        .collect::<ArrayVec<[_;2]>>()
+        .into_inner()
+        .unwrap()
+    }))?;
     let scale = if ! d.orig_size.is_empty() && ! d.size.is_empty() {
-      // by this point d.size has already been scaled by scale
       izip!(&d.orig_size, &d.size)
         .map(|(&orig_size, &target_size)| {
           target_size / orig_size