fix: prevent segmentation fault if mesuring empty text

Close #426
Brooooooklyn · Mar 10, 2022 · 2117ddb · 2117ddb
1 parent 4c9ac1e
commit 2117ddb
Show file tree

Hide file tree

Showing 2 changed files with 28 additions and 2 deletions.
diff --git a/__test__/draw.spec.ts b/__test__/draw.spec.ts
@@ -578,6 +578,20 @@ test('measureText', (t) => {
   t.true(Math.abs(metrics.actualBoundingBoxRight - 372) < 0.001)
 })
 
+test('measureText with empty string should not throw', (t) => {
+  const { ctx } = t.context
+  ctx.font = '50px Iosevka Slab'
+  t.deepEqual(ctx.measureText(''), {
+    actualBoundingBoxAscent: 0,
+    actualBoundingBoxDescent: 0,
+    actualBoundingBoxLeft: 0,
+    actualBoundingBoxRight: 0,
+    fontBoundingBoxAscent: 0,
+    fontBoundingBoxDescent: 0,
+    width: 0,
+  })
+})
+
 test('moveTo', async (t) => {
   const { ctx } = t.context
   ctx.beginPath()

diff --git a/src/ctx.rs b/src/ctx.rs
@@ -1338,11 +1338,23 @@ fn line_to(ctx: CallContext) -> Result<JsUndefined> {
 fn measure_text(ctx: CallContext) -> Result<JsObject> {
   let text = ctx.get::<JsString>(0)?.into_utf8()?;
   let this = ctx.this_unchecked::<JsObject>();
+  let mut metrics = ctx.env.create_object()?;
+  let text_str = text.as_str()?;
+  if text_str.is_empty() {
+    metrics.set_named_property("actualBoundingBoxAscent", ctx.env.create_double(0.0f64)?)?;
+    metrics.set_named_property("actualBoundingBoxDescent", ctx.env.create_double(0.0f64)?)?;
+    metrics.set_named_property("actualBoundingBoxLeft", ctx.env.create_double(0.0f64)?)?;
+    metrics.set_named_property("actualBoundingBoxRight", ctx.env.create_double(0.0f64)?)?;
+    metrics.set_named_property("fontBoundingBoxAscent", ctx.env.create_double(0.0f64)?)?;
+    metrics.set_named_property("fontBoundingBoxDescent", ctx.env.create_double(0.0f64)?)?;
+    metrics.set_named_property("width", ctx.env.create_double(0.0f64)?)?;
+    return Ok(metrics);
+  }
+
   let context_2d = ctx.env.unwrap::<Context>(&this)?;
 
-  let m = context_2d.get_line_metrics(text.as_str()?)?.0;
+  let m = context_2d.get_line_metrics(text_str)?.0;
 
-  let mut metrics = ctx.env.create_object()?;
   metrics.set_named_property(
     "actualBoundingBoxAscent",
     ctx.env.create_double(m.ascent as f64)?,