feat: add image class poc

example/image.js

@@ -0,0 +1,21 @@
+const { promises } = require('fs')
+const { join } = require('path')
+
+const { createCanvas, Image } = require('../index')
+
+const canvas = createCanvas(1024, 768)
+
+const ctx = canvas.getContext('2d')
+
+async function main() {
+  const file = await promises.readFile(join(__dirname, 'tiger.png'))
+  const image = new Image()
+  image.src = file
+  // console.log(image, image.width, image.height)
+  // ctx.drawImage(image, 0, 0)
+
+  const output = await canvas.png()
+  await promises.writeFile(join(__dirname, 'tiger-tmp.png'), output)
+}
+
+main()

index.d.ts

@@ -31,6 +31,12 @@ export class ImageData {
   constructor(data: Uint8ClampedArray, sw: number, sh?: number)
 }
 
+export class Image {
+  readonly width: number
+  readonly height: number
+  src: Buffer
+}
+
 export class Path2D {
   constructor(path?: Path2D | string)
 

index.js

@@ -8,7 +8,11 @@ const { loadBinding } = require('@node-rs/helper')
  * loadBinding helper will load `skia.[PLATFORM].node` from `__dirname` first
  * If failed to load addon, it will fallback to load from `@napi-rs/skia-[PLATFORM]`
  */
-const { CanvasRenderingContext2D, CanvasElement, Path2D, ImageData } = loadBinding(__dirname, 'skia', '@napi-rs/skia')
+const { CanvasRenderingContext2D, CanvasElement, Path2D, ImageData, Image } = loadBinding(
+  __dirname,
+  'skia',
+  '@napi-rs/skia',
+)
 
 CanvasRenderingContext2D.prototype.getImageData = function getImageData(x, y, w, h) {
   const data = this._getImageData(x, y, w, h)
@@ -61,4 +65,5 @@ module.exports = {
   createCanvas,
   Path2D,
   ImageData,
+  Image,
 }

src/image.rs

@@ -117,3 +117,97 @@ fn image_data_constructor(ctx: CallContext) -> Result<JsUndefined> {
   ])?;
   ctx.env.get_undefined()
 }
+
+#[derive(Debug, Clone)]
+pub struct Image {
+  pub(crate) width: u32,
+  pub(crate) height: u32,
+  bitmap: *mut u8,
+}
+
+impl Drop for Image {
+  fn drop(&mut self) {
+    let len = (self.width * self.height * 4) as usize;
+    unsafe { Vec::from_raw_parts(self.bitmap, len, len) };
+  }
+}
+
+impl Image {
+  pub fn create_js_class(env: &Env) -> Result<JsFunction> {
+    env.define_class(
+      "Image",
+      image_constructor,
+      &vec![
+        Property::new(&env, "width")?
+          .with_setter(set_noop)
+          .with_getter(get_width),
+        Property::new(&env, "height")?
+          .with_setter(set_noop)
+          .with_getter(get_height),
+        Property::new(&env, "src")?
+          .with_setter(set_src)
+          .with_getter(get_src),
+      ],
+    )
+  }
+}
+
+#[js_function]
+fn image_constructor(ctx: CallContext) -> Result<JsUndefined> {
+  let mut initial_data = ManuallyDrop::new(vec![0u8; 0]);
+  let data_ptr = initial_data.as_mut_ptr();
+  let image = Image {
+    width: 0u32,
+    height: 0u32,
+    bitmap: data_ptr,
+  };
+  let mut this = ctx.this_unchecked::<JsObject>();
+  ctx.env.wrap(&mut this, image)?;
+  ctx.env.get_undefined()
+}
+
+#[js_function]
+fn get_width(ctx: CallContext) -> Result<JsNumber> {
+  let this = ctx.this_unchecked::<JsObject>();
+  let image = ctx.env.unwrap::<Image>(&this)?;
+
+  ctx.env.create_double(image.width as f64)
+}
+
+#[js_function]
+fn get_height(ctx: CallContext) -> Result<JsNumber> {
+  let this = ctx.this_unchecked::<JsObject>();
+  let image = ctx.env.unwrap::<Image>(&this)?;
+
+  ctx.env.create_double(image.height as f64)
+}
+
+#[js_function(1)]
+fn set_noop(ctx: CallContext) -> Result<JsUndefined> {
+  ctx.env.get_undefined()
+}
+
+#[js_function]
+fn get_src(ctx: CallContext) -> Result<JsUndefined> {
+  ctx.env.get_undefined() // TODO
+}
+
+#[js_function(1)]
+fn set_src(ctx: CallContext) -> Result<JsUndefined> {
+  let this = ctx.this_unchecked::<JsObject>();
+  let mut image = ctx.env.unwrap::<Image>(&this)?;
+
+  let src_arg = ctx.get::<JsUnknown>(0)?;
+  let src_data_ab = unsafe { src_arg.cast::<JsTypedArray>() }.into_value()?;
+  if src_data_ab.typedarray_type != TypedArrayType::Uint8 {
+    return Err(Error::new(
+      Status::InvalidArg,
+      "Image src setter: Argument 1 does not implement interface Buffer."
+        .to_owned(),
+    ));
+  }
+  let arraybuffer_length = src_data_ab.len();
+  println!("buffer length {}", arraybuffer_length);
+
+  ctx.env.get_undefined()
+}

src/lib.rs

@@ -44,13 +44,17 @@ fn init(mut exports: JsObject, env: Env) -> Result<()> {
 
   let image_data_class = image::ImageData::create_js_class(&env)?;
 
+  let image_class = image::Image::create_js_class(&env)?;
+
   exports.set_named_property("CanvasRenderingContext2D", canvas_rendering_context2d)?;
 
   exports.set_named_property("CanvasElement", canvas_element)?;
 
   exports.set_named_property("Path2D", path_class)?;
 
   exports.set_named_property("ImageData", image_data_class)?;
+
+  exports.set_named_property("Image", image_class)?;
   Ok(())
 }