Fix Generated TypeScript Types (#888)

Apparently `Uint8Array` is ambiguous in the latest TypeScript versions,
as it can be backed by either an `ArrayBuffer` or a `SharedArrayBuffer`
now. If you are working with an ambiguous `Uint8Array`, you can't
necessarily use it everywhere, such as when creating a `Blob` out of it.
We should be precise about which ones we are returning out of our C API
functions.

Additionally, this implements a slight improvement in the web renderer
around empty strings. Previously, there were various places where we had
to create an empty string. Now, we create it once and reuse it.

Author: CryZe

capi/bind_gen/src/wasm_bindgen.rs

@@ -1,4 +1,4 @@
-use crate::{typescript, Class, Function, Type, TypeKind};
+use crate::{Class, Function, Type, TypeKind, typescript};
 use heck::ToLowerCamelCase;
 use std::{
     collections::BTreeMap,
@@ -420,13 +420,13 @@ function allocString(str: string): Slice {
     return { ptr, len: stats.written, cap };
 }
 
-function decodeSlice(ptr: number): Uint8Array {
+function decodeSlice(ptr: number): Uint8Array<ArrayBuffer> {
     const memory = new Uint8Array(wasm.memory.buffer);
     const len = wasm.get_buf_len();
     return memory.slice(ptr, ptr + len);
 }
 
-function decodePtrLen(ptr: number, len: number): Uint8Array {
+function decodePtrLen(ptr: number, len: number): Uint8Array<ArrayBuffer> {
     const memory = new Uint8Array(wasm.memory.buffer);
     return memory.slice(ptr, ptr + len);
 }
@@ -574,7 +574,7 @@ export class {class_name_ref} {{"#,
                     writer,
                     "{}",
                     r#"
-    saveAsLssBytes(): Uint8Array {
+    saveAsLssBytes(): Uint8Array<ArrayBuffer> {
         if (this.ptr == 0) {
             throw "this is disposed";
         }
@@ -588,7 +588,7 @@ export class {class_name_ref} {{"#,
                     "{}",
                     r#"
     /**
-     * @return {Uint8Array}
+     * @return {Uint8Array<ArrayBuffer>}
      */
     saveAsLssBytes() {
         if (this.ptr == 0) {
@@ -605,7 +605,7 @@ export class {class_name_ref} {{"#,
                     writer,
                     "{}",
                     r#"
-    saveAsLssBytes(): Uint8Array {
+    saveAsLssBytes(): Uint8Array<ArrayBuffer> {
         if (this.ptr == 0) {
             throw "this is disposed";
         }
@@ -619,7 +619,7 @@ export class {class_name_ref} {{"#,
                     "{}",
                     r#"
     /**
-     * @return {Uint8Array}
+     * @return {Uint8Array<ArrayBuffer>}
      */
     saveAsLssBytes() {
         if (this.ptr == 0) {
@@ -642,7 +642,7 @@ export class {class_name_ref} {{"#,
      * data may not even represent a valid image at all. If the image is not in the
      * cache, null is returned. This does not mark the image as visited.
      */
-    lookupData(key: string): Uint8Array | undefined {
+    lookupData(key: string): Uint8Array<ArrayBuffer> | undefined {
         if (this.ptr == 0) {
             throw "this is disposed";
         }
@@ -668,7 +668,7 @@ export class {class_name_ref} {{"#,
      * cache, null is returned. This does not mark the image as visited.
      *
      * @param {string} key
-     * @return {Uint8Array | undefined}
+     * @return {Uint8Array<ArrayBuffer> | undefined}
      */
     lookupData(key) {
         if (this.ptr == 0) {

src/rendering/web/mod.rs

@@ -165,26 +165,25 @@ struct CanvasLabelInner {
     width_without_max_width: f32,
 }
 
-impl Default for CanvasLabelInner {
-    fn default() -> Self {
-        Self {
+struct CanvasLabel(Rc<RefCell<CanvasLabelInner>>);
+
+impl CanvasLabel {
+    fn new(empty_string: &JsString) -> Self {
+        Self(Rc::new(RefCell::new(CanvasLabelInner {
             font: Rc::new(CanvasFont {
-                descriptor: "".into(),
+                descriptor: empty_string.clone(),
                 font_handling: FontHandling::Normal,
-                font_kerning: "".into(),
+                font_kerning: empty_string.clone(),
                 top: 0.0,
                 bottom: 0.0,
             }),
-            shape: LabelShape::Normal("".into()),
+            shape: LabelShape::Normal(empty_string.clone()),
             width: 0.0,
             width_without_max_width: 0.0,
-        }
+        })))
     }
 }
 
-#[derive(Default)]
-struct CanvasLabel(Rc<RefCell<CanvasLabelInner>>);
-
 impl SharedOwnership for CanvasLabel {
     fn share(&self) -> Self {
         Self(self.0.share())
@@ -310,7 +309,7 @@ impl ResourceAllocator for CanvasAllocator {
         // FIXME: We query this to position a gradient from the top to the
         // bottom of the font. Is the ascent and descent what we want here?
         // That's not what we do in our default text engine.
-        let metrics = self.ctx_top.measure_text(&JsString::from("")).unwrap();
+        let metrics = self.ctx_top.measure_text(&self.cache.empty_string).unwrap();
         let top = -metrics.font_bounding_box_ascent() as f32;
         let bottom = metrics.font_bounding_box_descent() as f32;
 
@@ -362,7 +361,7 @@ impl ResourceAllocator for CanvasAllocator {
         font: &mut Self::Font,
         max_width: Option<f32>,
     ) -> Self::Label {
-        let mut label = CanvasLabel::default();
+        let mut label = CanvasLabel::new(&self.cache.empty_string);
         self.update_label(&mut label, text, font, max_width);
         label
     }
@@ -491,6 +490,7 @@ struct JsValueCache {
     colors: HashMap<[u8; 16], JsString>,
     filters: HashMap<HashFilter, JsString>,
     digits: [JsString; 10],
+    empty_string: JsString,
     transparent: JsString,
     none: JsString,
     auto: JsString,
@@ -673,6 +673,7 @@ impl Renderer {
                 colors: HashMap::new(),
                 filters: HashMap::new(),
                 digits: array::from_fn(|digit| JsString::from((digit as u8 + b'0') as char)),
+                empty_string: JsString::from(""),
                 transparent: JsString::from("transparent"),
                 none: JsString::from("none"),
                 auto: JsString::from("auto"),