graphical output in code blocks

content/programming/blog/tairu.tree

@@ -40,7 +40,7 @@ styles = ["tairu.css"]
     </canvas>
 
     % id = "01HPJ8GHDEC0Z334M04MTNADV9"
-    - for each tile, we can assign a bitset of cardinal directions like so:
+    - for each tile we can assign a bitset of cardinal directions, based on which tiles it should connect to - like so:
 
     <canvas
         is="tairu-editor-cardinal-directions"
@@ -372,22 +372,29 @@ styles = ["tairu.css"]
             - and it's even possible to autogenerate most of them given just a few smaller 4x4 pieces - but for now, let's not go down that path.\
             maybe another time.
 
+        % id = "01HPWJB4Y047YGYAP6XQXJ3576"
         - so we only need to draw 47 tiles, but to actually display them in a game we still need to pack them into an image.
 
+        % id = "01HPWJB4Y0QX6YR6TQKZ7T1C2E"
         - we *could* use a similar approach to the 16 tile version, but that would leave us with lots of wasted space!
 
+            % id = "01HPWJB4Y0HKGSDABB56CNFP9H"
             - think that with this redundancy elimination approach most of the tiles will never even be looked up by the renderer, because the bit combinations will be collapsed into a more canonical form before the lookup.
 
+        % id = "01HPWJB4Y0705RWPFB89V23M1P"
         - we could also use the approach I mentioned briefly [here][branch:01HPQCCV4RB65D5Q4RANJKGC0D], which involves introducing a lookup table - which sounds reasonable, so let's do it!
 
+        % id = "01HPWJB4Y0F9JGXQDAAVC3ERG1"
         - I don't want to write the lookup table by hand, so let's generate it! I'll reuse the redundancy elimination code from before to make this easier.
 
+            % id = "01HPWJB4Y0HTV32T4WMKCKWTVA"
             - we'll start by obtaining our ordinal directions array again:
 
             ```javascript ordinal-directions
             export let xToConnectionBitSet = ordinalDirections();
             ```
 
+            % id = "01HPWJB4Y03WYYZ3VTW27GP7Z3"
             - then we'll turn that array upside down... in other words, invert the index-value relationship, so that we can look up which X position in the tile strip to use for a specific connection combination.
 
             remember that our array has only 256 values, so it should be pretty cheap to represent using a `Uint8Array`:
@@ -399,6 +406,7 @@ styles = ["tairu.css"]
             }
             ```
 
+            % id = "01HPWJB4Y0CWQB9EZG6C91A0H0"
             - and there we go! we now have a mapping from our bitset to positions within the tile strip. try to play around with the code example to see which bitsets correspond to which position!
 
             ```javascript ordinal-directions
@@ -408,8 +416,10 @@ styles = ["tairu.css"]
             4
             ```
 
+            % id = "01HPWJB4Y09P9Q3NGN59XWX2X9"
             + for my own (and your) convenience, here's a complete list of *all* the possible combinations in order.
 
+                % id = "01HPWJB4Y01VJFMHYEC1WZ353W"
                 - ```javascript ordinal-directions
                 function toString(bitset) {
                     if (bitset == 0) return "0";
@@ -480,15 +490,18 @@ styles = ["tairu.css"]
                 46 => E | SE | S | SW | W | NW | N | NE
                 ```
 
+        % id = "01HPWJB4Y0NMP35M9138DV3P8W"
         - with the lookup table generated, we are now able to prepare a tile strip like before - except now it's even more tedious work arranging the pieces together :ralsei_dead:
 
         anyways I spent like 20 minutes doing that by hand, and now we have a neat tile strip just like before, except way longer:
 
         ![horizontal tile strip of 47 8x8 pixel metal tiles][pic:01HPW47SHMSVAH7C0JR9HWXWCM]
 
+        % id = "01HPWJB4Y0J3DHQV5F9GD3VNQ8"
         - now let's hook it up to our tileset renderer! TODO literate program.
 
         % template = true
+          id = "01HPWJB4Y00ARHBGDF2HTQQ4SD"
         - with the capability to render with 47-tile tilesets, our examples suddenly look a whole lot better!
 
         <canvas

content/treehouse/sandbox.tree

@@ -0,0 +1,133 @@
+%% title = "the treehouse sandbox"
+scripts = ["components/literate-programming.js"]
+
+% id = "01HPWJB4Y5ST6AEK9VDYNS865P"
+- the sandbox is a framework for playing around with code
+
+    % id = "01HPWJB4Y5HSDMEHNJXVET212V"
+    - one might call it "literate programming" and indeed that's the name used inside the code
+
+    % id = "01HPWJB4Y583X6RXD060RZJ7WA"
+    - it's based on JavaScript; basically, you write scripts in JavaScript that may embed output into the parent page
+
+    % id = "01HPWJB4Y56KH9MVC7Y5DDJ0CH"
+    - this is a bit of documentation on how to use its features
+
+% id = "01HPWJB4Y5G4XXDE4ZPY3SWPXP"
++ ### basic usage
+
+    % id = "01HPWJB4Y5JG6SGV3A5SS6V0JY"
+    - the smallest building block is a module. each code block is a separate ES module, and therefore it has separate imports and exports.
+
+    % id = "01HPWJB4Y5HDEGNVRE307ND6H3"
+    - for example, in the example below, the two code blocks cannot access each other's variables:
+
+    ```javascript module-separation-broken
+    let myVariable = 1;
+    ```
+
+    ```javascript module-separation-broken
+    console.log(myVariable);
+    ```
+
+    ```output module-separation-broken
+    ReferenceError: myVariable is not defined
+    ```
+
+    % id = "01HPWJB4Y574NADEWXYWZR8C6C"
+    - to fix this, export the variable:
+
+    ```javascript module-separation-works
+    export let myVariable = 1;
+    ```
+
+    ```javascript module-separation-works
+    console.log(myVariable);
+    ```
+
+    ```output module-separation-works
+    1
+    ```
+
+% id = "01HPWJB4Y5GDMQTG6F6K4TDYWA"
++ ### outputting text
+
+    % id = "01HPWJB4Y55S28PVMBD4FKK98C"
+    - for code blocks which are followed by an `Output` block, such as [this one], it is possible to use `console.log` to output text to the console:
+
+    ```javascript text-output
+    console.log("Hello, world!");
+    ```
+
+    ```output text-output
+    Hello, world!
+    ```
+
+    % id = "01HPWJB4Y5CMHY36HW8EPTBSYG"
+    - `console.warn`, `console.error`, etc. are not supported right now. sorry.
+
+    % id = "01HPWJB4Y5CXAMYHGWSG72FP4J"
+    - code blocks are generally tied together when I say so. for example, you can access variables `export`ed from the above code blocks here; try making this example compile without touching this code block:
+
+    ```javascript text-output
+    console.log(x + 1);
+    ```
+
+    ```output text-output
+    3
+    ```
+
+        % id = "01HPWJB4Y54R6ZB0GHCXRF674M"
+        - you'll notice that if you edit the first code block in this section, both the code blocks' outputs get updated automatically. neat, huh?
+
+% id = "01HPWJB4Y57BVC7H5N94FREGRK"
++ ### outputting graphics
+
+    % id = "01HPWJB4Y5CB5MSBWMG58VMR2G"
+    - some code blocks allow for graphical output. such as this one:
+
+    ```javascript graphical-output
+    import { Sketch } from "treehouse/sandbox.js";
+
+    let sketch = new Sketch(200, 200);
+    sketch.ctx.fillStyle = "white";
+    sketch.ctx.fillRect(0, 0, sketch.canvas.width, sketch.canvas.height);
+    sketch.ctx.strokeStyle = "black";
+    sketch.ctx.strokeRect(32, 32, 32, 32);
+    ```
+
+    <th-literate-program data-mode="graphics" data-program="graphical-output"></th-literate-program>
+
+    % id = "01HPWJB4Y5ER6SAQZ17ZFH8RK7"
+    - `Sketch` is an API for drawing things using HTML `<canvas>`.
+
+        % id = "01HPWJB4Y5MRKCXRNSRFG7PVP5"
+        - the act of creating a `Sketch` using `new` causes a new `<canvas>` to be created.
+
+            % id = "01HPWJB4Y5HZG6QH5N6N2Q9Z99"
+            - this `<canvas>` can be accessed using the sketch's `canvas` field, and the canvas's 2D drawing context is accessible using the `ctx` field.
+
+        % id = "01HPWJB4Y5ANS55R32X7GJP1N7"
+        - this API wraps a lower-level message-passing API which is used to communicate with the main page, to let it set things like the sandbox `<iframe>`'s size (as well as make it visible).
+        see the source code for details.
+
+% id = "01HPWJB4Y5H9DKZT2ZA8PWNV99"
++ ### known issues
+
+    % id = "01HPWJB4Y56FPNHJNVGJQ57DWH"
+    - the code editors are very janky on Firefox right now.
+
+        % id = "01HPWJB4Y5T2GA42SJ80JNY2FK"
+        - the sandbox uses CodeJar to facilitate code editing, and to do this it uses `contenteditable` attributes.
+
+        % id = "01HPWJB4Y5H9M4W0ZYYPVWQ6MY"
+        - I love CodeJar for its simplicity. it brings you text editing, and you bring your own everything else. so I'd love to
+
+        % id = "01HPWJB4Y5WWPJXSWQDCMG6J32"
+        - however, for non-janky text editing, CodeJar uses `contenteditable="plaintext-only"`, which is only supported on Chromium-based browsers.
+
+            % id = "01HPWJB4Y5ZJC1P0M6D3VNM0SF"
+            - I may patch it at some point to support regular `contenteditable` better at some point, but it's not a priority right now.
+
+            % id = "01HPWJB4Y52XZJRRZ41F1XK0ZT"
+            - the sandbox is only used for small, editable, interactive code examples and is not intended to be a fully fledged IDE.

crates/treehouse/src/cli/generate.rs

@@ -1,4 +1,5 @@
 use std::{
+    collections::HashMap,
     ffi::OsStr,
     path::{Path, PathBuf},
     time::Instant,
@@ -174,12 +175,49 @@ impl Generator {
         parsed_trees: impl IntoIterator<Item = ParsedTree>,
     ) -> anyhow::Result<()> {
         let mut handlebars = Handlebars::new();
-        let tree_template = Self::register_template(
+
-            &mut handlebars,
+        let mut template_file_ids = HashMap::new();
+        for entry in WalkDir::new(paths.template_dir) {
+            let entry = entry?;
+            let path = entry.path();
+            if !entry.file_type().is_dir() && path.extension() == Some(OsStr::new("hbs")) {
+                let relative_path = path
+                    .strip_prefix(paths.template_dir)?
+                    .to_string_lossy()
+                    .into_owned();
+                let file_id =
+                    Self::register_template(&mut handlebars, treehouse, &relative_path, path)?;
+                template_file_ids.insert(relative_path, file_id);
+            }
+        }
+
+        std::fs::create_dir_all(paths.template_target_dir)?;
+        for (name, &file_id) in &template_file_ids {
+            if !name.starts_with('_') {
+                #[derive(Serialize)]
+                struct StaticTemplateData<'a> {
+                    config: &'a Config,
+                }
+
+                let templated_html = match handlebars.render(name, &StaticTemplateData { config }) {
+                    Ok(html) => html,
+                    Err(error) => {
+                        Self::wrangle_handlebars_error_into_diagnostic(
                             treehouse,
-            "tree",
+                            file_id,
-            &paths.template_dir.join("tree.hbs"),
+                            error.line_no,
+                            error.column_no,
+                            error.desc,
                         )?;
+                        continue;
+                    }
+                };
+                std::fs::write(
+                    paths.template_target_dir.join(name).with_extension("html"),
+                    templated_html,
+                )?;
+            }
+        }
 
         for parsed_tree in parsed_trees {
             let breadcrumbs = breadcrumbs_to_html(config, navigation_map, &parsed_tree.tree_path);
@@ -216,11 +254,11 @@ impl Generator {
             }
 
             #[derive(Serialize)]
-            pub struct TemplateData<'a> {
+            pub struct PageTemplateData<'a> {
                 pub config: &'a Config,
                 pub page: Page,
             }
-            let template_data = TemplateData {
+            let template_data = PageTemplateData {
                 config,
                 page: Page {
                     title: roots.attributes.title.clone(),
@@ -244,12 +282,12 @@ impl Generator {
 
             treehouse.roots.insert(parsed_tree.tree_path, roots);
 
-            let templated_html = match handlebars.render("tree", &template_data) {
+            let templated_html = match handlebars.render("_tree.hbs", &template_data) {
                 Ok(html) => html,
                 Err(error) => {
                     Self::wrangle_handlebars_error_into_diagnostic(
                         treehouse,
-                        tree_template,
+                        template_file_ids["_tree.hbs"],
                         error.line_no,
                         error.column_no,
                         error.desc,

crates/treehouse/src/cli/mod.rs

@@ -78,6 +78,8 @@ pub struct ServeArgs {
 #[derive(Debug, Clone, Copy)]
 pub struct Paths<'a> {
     pub target_dir: &'a Path,
+    pub template_target_dir: &'a Path,
+
     pub static_dir: &'a Path,
     pub template_dir: &'a Path,
     pub content_dir: &'a Path,

crates/treehouse/src/main.rs

@@ -21,6 +21,8 @@ async fn fallible_main() -> anyhow::Result<()> {
 
     let paths = Paths {
         target_dir: Path::new("target/site"),
+        template_target_dir: Path::new("target/site/static/html"),
+
         config_file: Path::new("treehouse.toml"),
 
         // NOTE: These are intentionally left unconfigurable from within treehouse.toml

static/css/main.css

@@ -567,6 +567,21 @@ th-literate-program[data-mode="output"] {
     }
 }
 
+th-literate-program[data-mode="graphics"] {
+    padding: 0;
+    background: none;
+
+    & iframe {
+        border-style: none;
+        border-radius: 4px;
+    }
+
+    /* The inner iframe is hidden until something requests display. */
+    & iframe.hidden {
+        display: none;
+    }
+}
+
 /* Syntax highlighting */
 
 :root {

static/js/components/literate-programming.js

@@ -202,6 +202,42 @@ class OutputMode {
     }
 }
 
+class GraphicsMode {
+    constructor(frame) {
+        this.frame = frame;
+
+        this.iframe = document.createElement("iframe");
+        this.iframe.classList.add("hidden");
+        this.iframe.src = import.meta.resolve("../../html/sandbox.html");
+        this.frame.appendChild(this.iframe);
+
+        this.iframe.contentWindow.addEventListener("message", event => {
+            let message = event.data;
+            if (message.kind == "resize") {
+                this.resize(message);
+            }
+        });
+
+        this.iframe.contentWindow.addEventListener("DOMContentLoaded", () => this.evaluate());
+        this.frame.program.onChanged.push(_ => this.evaluate());
+
+        this.evaluate();
+    }
+
+    evaluate() {
+        this.iframe.contentWindow.postMessage({
+            action: "eval",
+            input: getLiterateProgramWorkerCommands(this.frame.programName),
+        });
+    }
+
+    resize(message) {
+        this.iframe.width = message.width;
+        this.iframe.height = message.height;
+        this.iframe.classList.remove("hidden");
+    }
+}
+
 class LiterateProgram extends HTMLElement {
     connectedCallback() {
         this.programName = this.getAttribute("data-program");
@@ -212,6 +248,8 @@ class LiterateProgram extends HTMLElement {
             this.modeImpl = new InputMode(this);
         } else if (this.mode == "output") {
             this.modeImpl = new OutputMode(this);
+        } else if (this.mode == "graphics") {
+            this.modeImpl = new GraphicsMode(this);
         }
     }
 

static/js/components/literate-programming/eval.js

@@ -0,0 +1,48 @@
+let outputIndex = 0;
+
+export function getOutputIndex() {
+    return outputIndex;
+}
+
+async function withTemporaryGlobalScope(callback) {
+    let state = {
+        oldValues: {},
+        set(key, value) {
+            this.oldValues[key] = globalThis[key];
+            globalThis[key] = value;
+        }
+    };
+    await callback(state);
+    for (let key in state.oldValues) {
+        globalThis[key] = state.oldValues[key];
+    }
+}
+
+export async function evaluate(commands) {
+    outputIndex = 0;
+    try {
+        await withTemporaryGlobalScope(async scope => {
+            for (let command of commands) {
+                if (command.kind == "module") {
+                    let blobUrl = URL.createObjectURL(new Blob([command.source], { type: "text/javascript" }));
+                    let module = await import(blobUrl);
+                    for (let exportedKey in module) {
+                        scope.set(exportedKey, module[exportedKey]);
+                    }
+                } else if (command.kind == "output") {
+                    ++outputIndex;
+                }
+            }
+        });
+    } catch (error) {
+        postMessage({
+            kind: "output",
+            output: {
+                kind: "error",
+                message: [error.toString()],
+            },
+            outputIndex,
+        });
+    }
+}
+

static/js/components/literate-programming/worker.js

@@ -1,4 +1,4 @@
-let outputIndex = 0;
+import { evaluate, getOutputIndex } from "./eval.js";
 
 let debugLog = console.log;
 
@@ -10,56 +10,14 @@ globalThis.console = {
                 kind: "log",
                 message: [...message],
             },
-            outputIndex,
+            outputIndex: getOutputIndex(),
         });
     }
 };
 
-async function withTemporaryGlobalScope(callback) {
-    let state = {
-        oldValues: {},
-        set(key, value) {
-            this.oldValues[key] = globalThis[key];
-            globalThis[key] = value;
-        }
-    };
-    await callback(state);
-    for (let key in state.oldValues) {
-        globalThis[key] = state.oldValues[key];
-    }
-}
-
 addEventListener("message", async event => {
     let message = event.data;
     if (message.action == "eval") {
-        outputIndex = 0;
+        evaluate(message.input);
-        try {
-            await withTemporaryGlobalScope(async scope => {
-                for (let command of message.input) {
-                    if (command.kind == "module") {
-                        let blobUrl = URL.createObjectURL(new Blob([command.source], { type: "text/javascript" }));
-                        let module = await import(blobUrl);
-                        for (let exportedKey in module) {
-                            scope.set(exportedKey, module[exportedKey]);
-                        }
-                    } else if (command.kind == "output") {
-                        ++outputIndex;
-                    }
-                }
-            });
-        } catch (error) {
-            postMessage({
-                kind: "output",
-                output: {
-                    kind: "error",
-                    message: [error.toString()],
-                },
-                outputIndex,
-            });
-        }
-
-        postMessage({
-            kind: "evalComplete",
-        });
     }
 });

static/js/sandbox.js

@@ -0,0 +1,16 @@
+export class Sketch {
+    constructor(width, height) {
+        this.canvas = document.createElement("canvas");
+        this.canvas.width = width;
+        this.canvas.height = height;
+        this.ctx = this.canvas.getContext("2d");
+
+        document.body.appendChild(this.canvas);
+
+        postMessage({
+            kind: "resize",
+            width,
+            height,
+        });
+    }
+}

template/_tree.hbs

@@ -26,7 +26,6 @@
     <link rel="stylesheet" href="{{ config.site }}/static/css/main.css">
     <link rel="stylesheet" href="{{ config.site }}/static/css/tree.css">
 
-
     <script>const TREEHOUSE_SITE = `{{ config.site }}`;</script>
     <script type="module" src="{{ config.site }}/navmap.js"></script>
     <script type="module" src="{{ config.site }}/static/js/ulid.js"></script>

template/sandbox.hbs

@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+
+<html>
+
+<head>
+    <title>treehouse iframe sandbox</title>
+
+    <style>
+        body {
+            margin: 0;
+            overflow: hidden;
+        }
+    </style>
+
+    <script type="importmap">{ "imports": { "treehouse/": "{{ config.site }}/static/js/" } }</script>
+
+    <script type="module">
+        import { evaluate } from "treehouse/components/literate-programming/eval.js";
+        console.log("yo");
+        addEventListener("message", async event => {
+            let message = event.data;
+            if (message.action == "eval") {
+                document.body.replaceChildren();
+                evaluate(message.input);
+            }
+        });
+    </script>
+</head>
+
+<body></body>
+
+</html>