thajohns
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webasm-dabble
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Got a basic image drawing program working

Thomas Johnson 1 year ago
commit
881dd4a55e
7 changed files with 119 additions and 0 deletions
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  1. 4
    0
      .cargo/config
  2. 2
    0
      .gitignore
  3. 14
    0
      Cargo.toml
  4. 8
    0
      index.html
  5. 38
    0
      index.js
  6. 52
    0
      src/lib.rs
  7. 1
    0
      wt.wasm

+ 4
- 0
.cargo/config View File 

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+
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+[build]
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+target = "wasm32-unknown-unknown"
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+

+ 2
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.gitignore View File 

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+/target
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+Cargo.lock

+ 14
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Cargo.toml View File 

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+[package]
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+name = "wt"
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+version = "0.1.0"
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+authors = ["thajohns <thajohns@clarkson.edu>"]
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+edition = "2018"
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+
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+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
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+
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+[dependencies]
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+wee_alloc = "0.4.5"
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+#wasm-bindgen = "0.2.59"
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+
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+[lib]
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+crate-type = ["cdylib"]

+ 8
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index.html View File 

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+<html>
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+  <head>
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+    <script defer src="index.js"></script>
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+  </head>
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+  <body id="body">
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+    <canvas id="canvas" height=1000 width=1500></canvas>
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+  </body>
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+</html>

+ 38
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index.js View File 

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+canvas = document.getElementById("canvas");
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+ctx = canvas.getContext("2d");
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+
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+function get_string(memory, pointer, size)
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+{
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+  var array = new Int8Array(memory.buffer, pointer, size);
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+  return (new TextDecoder()).decode(array);
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+}
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+
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+function paint(memory, pointer, width, height)
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+{
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+  array = new Uint8ClampedArray(memory.buffer, pointer, 4 * width * height);
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+  data = new ImageData(array, width, height);
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+  ctx.putImageData(data, 0, 0);
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+}
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+
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+fetch("wt.wasm").then(response => response.arrayBuffer()).then(bytes =>
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+  {
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+    var memory;
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+    WebAssembly.instantiate(bytes, { env:
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+      {
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+        console_log: function(str, len)
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+        {
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+          console.log(get_string(memory, str, len));
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+        },
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+        extern_paint: function(pointer, width, height)
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+        {
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+          paint(memory, pointer, width, height);
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+        }
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+      } }).then(mod =>
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+      {
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+        memory = mod.instance.exports.memory;
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+        mod.instance.exports.entrypoint();
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+        mod.instance.exports.paint_red(canvas.width, canvas.height);
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+      }
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+    )
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+  });
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+

+ 52
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src/lib.rs View File 

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+
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+extern crate wee_alloc;
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+
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+use core::mem::transmute;
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+
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+#[global_allocator]
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+pub static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
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+
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+extern "C"
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+{
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+  #[no_mangle]
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+  fn console_log(_: *const u8, _: usize);
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+  #[no_mangle]
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+  fn extern_paint(ptr: *const u8, w: usize, h: usize);
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+}
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+
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+fn log(string: &str)
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+{
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+  unsafe
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+  {
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+    let (ptr, size) = transmute::<_, (*const u8, usize)>(string);
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+    console_log(ptr, size);
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+  }
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+}
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+
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+fn paint(buffer: &[u8], w: usize, h: usize)
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+{
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+  unsafe { extern_paint(buffer.as_ptr(), w, h); }
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+}
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+
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+#[no_mangle]
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+pub extern "C" fn entrypoint()
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+{
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+  log("Test from Rust");
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+}
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+
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+#[no_mangle]
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+pub extern "C" fn paint_red(w: usize, h: usize)
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+{
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+  let mut buffer = vec![0; 4 * w * h];
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+  let mut c: (u8, u8, u8) = (0, 0, 0);
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+  for ii in 0 .. w * h
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+  {
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+    buffer[4 * ii] = c.0;
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+    buffer[4 * ii + 1] = c.1;
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+    buffer[4 * ii + 2] = c.2;
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+    buffer[4 * ii + 3] = 255;
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+    c = (c.0.wrapping_add(1), c.1.wrapping_add(254), c.2.wrapping_add(2));
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+  }
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+  paint(&buffer, w, h);
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+}
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+

+ 1
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wt.wasm View File 

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+/home/primary/rust/dabble/webasm/target/wasm32-unknown-unknown/debug/wt.wasm

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