Adding Stack and TextInput to the UI

src/main.ts

@@ -7,6 +7,7 @@ import { builtins } from './builtins';
 
 import counterApp from './counter.cg?raw';
 import stdlibCode from './stdlib.cg?raw';
+import textInputCode from './textinput-test.cg?raw';
 import testCode from './test.cg?raw';
 
 const canvas = document.createElement('canvas');
@@ -14,7 +15,7 @@ canvas.width = 800;
 canvas.height = 600;
 document.body.appendChild(canvas);
 
-const cgCode = stdlibCode + '\n' + testCode;
+const cgCode = stdlibCode + '\n' + textInputCode;
 
 const tokens = tokenize(cgCode);
 const parser = new Parser(tokens);
@@ -22,10 +23,9 @@ const ast = parser.parse();
 console.log(ast);
 
 const env: Env = new Map(Object.entries(builtins));
-const res = evaluate(ast, env);
-console.log(res);
+// const res = evaluate(ast, env);
+// console.log(res);
 
-/*
 const appRecord = evaluate(ast, env);
 
 console.log(appRecord);
@@ -38,4 +38,3 @@ const update = appRecord.fields.update;
 const view = appRecord.fields.view;
 
 runApp({ init, update, view }, canvas);
-*/

src/runtime.ts

@@ -1,6 +1,6 @@
 import type { Value } from './types';
 import { valueToUI } from './valueToUI';
-import { render, hitTest } from './ui';
+import { render, hitTest, hitTestTextInput, handleKeyboard } from './ui';
 import { evaluate } from './interpreter';
 
 export type App = {
@@ -24,14 +24,13 @@ export function runApp(app: App, canvas: HTMLCanvasElement) {
         render(ui, canvas);
     }
 
-    function handleEvent(eventName: string) {
+    function handleEvent(event: Value) {
         if (app.update.kind !== 'closure')
             throw new Error('update must be a function');
 
         if (app.update.params.length !== 2)
             throw new Error('update must have 2 parameters');
 
-        const event: Value = { kind: 'string', value: eventName };
         const callEnv = new Map(app.update.env);
         callEnv.set(app.update.params[0], state);
         callEnv.set(app.update.params[1], event);
@@ -46,11 +45,39 @@ export function runApp(app: App, canvas: HTMLCanvasElement) {
         const x = e.clientX - rect.left;
         const y = e.clientY - rect.top;
 
+        // Text Inputs
+        const hitTextInput = hitTestTextInput(x, y);
+        if (hitTextInput) {
+            rerender();
+            return;
+        }
+
         const eventName = hitTest(x, y);
         if (eventName) {
-            handleEvent(eventName);
+            const event: Value = {
+                kind: 'constructor',
+                name: eventName,
+                args: []
+            }
+            handleEvent(event);
         }
     });
 
+    window.addEventListener('keydown', (e) => {
+        const result = handleKeyboard(e.key);
+
+        if (result) {
+            const event: Value = {
+                kind: 'constructor',
+                name: result.event,
+                args: [{ kind: 'string', value: result.value }]
+            }
+
+            handleEvent(event);
+
+            e.preventDefault();
+        }
+    })
+
     rerender();
 }

src/textinput-test.cg

@@ -0,0 +1,31 @@
+init = { text = "" };
+
+update = state event \ event
+  | UpdateText newText \ state { text = newText }
+  | Submit _ \ state { text = "" };
+
+view = state \
+  Column {
+    gap = 20,
+    children = [
+      Text { content = "You typed: " & state.text, x = 0, y = 20 },
+      Stack {
+        children = [
+          Rect { w = 300, h = 40, color = "white" },
+          TextInput {
+            value = state.text,
+            placeholder = "Type something...",
+            x = 5,
+            y = 5,
+            w = 290,
+            h = 30,
+            focused = True,
+            onInput = "UpdateText",
+            onSubmit = "Submit"
+          }
+        ]
+      }
+    ]
+  };
+
+{ init = init, update = update, view = view }

src/types.ts

@@ -44,7 +44,6 @@ export type NativeFunction = {
     name: string
     arity: number
     fn: (...args: Value[]) => Value
-
 }
 
 export type UIValue =
@@ -54,5 +53,7 @@ export type UIValue =
     | { kind: 'column', children: UIValue[], gap: number }
     | { kind: 'clickable', child: UIValue, event: string }
     | { kind: 'padding', child: UIValue, amount: number }
+    | { kind: 'stack', children: UIValue[] }
+    | { kind: 'text-input', value: string, placeholder: string, x: number, y: number, w: number, h: number, focused: boolean, onInput: string, onSubmit: string }
 
 export type Value = IntValue | FloatValue | StringValue | Closure | ListValue | RecordValue | ConstructorValue | NativeFunction;

src/ui.ts

@@ -8,13 +8,26 @@ type ClickRegion = {
     event: string;
 };
 
+type TextInputRegion = {
+    x: number;
+    y: number;
+    width: number;
+    height: number;
+    inputId: string;
+    submitId: string;
+}
+
 let clickRegions: ClickRegion[] = [];
+let textInputRegions: TextInputRegion[] = [];
+let focusedInput: string | null = null;
+let focusedInputSubmit: string | null = null;
 
 export function render(ui: UIValue, canvas: HTMLCanvasElement) {
     const ctx = canvas.getContext('2d');
     if (ctx) {
         ctx.clearRect(0, 0, canvas.width, canvas.height);
         clickRegions = [];
+        textInputRegions = [];
         renderUI(ui, ctx, 0, 0);
     }
 }
@@ -56,16 +69,58 @@ function renderUI(ui: UIValue, ctx: CanvasRenderingContext2D, x: number, y: numb
             renderUI(ui.child, ctx, x, y);
             break;
         }
+
         case 'padding':
             renderUI(ui.child, ctx, x + ui.amount, y + ui.amount);
             break;
+
+        case 'stack': {
+            for (const child of ui.children) {
+                renderUI(child, ctx, x, y);
+            }
+            break;
+        }
+
+        case 'text-input': {
+            ctx.fillStyle = ui.value ? '#000000' : '#999999';
+            ctx.font = '16px monospace';
+            ctx.fillText(
+                ui.value || ui.placeholder,
+                x + ui.x + 8,
+                y + ui.y + ui.h / 2 + 6
+            );
+
+            // Draw cursor
+            if (ui.focused) {
+                const textWidth = ctx.measureText(ui.value).width;
+                ctx.fillStyle = '#000000';
+                ctx.fillRect(x + ui.x + 8 + textWidth, y + ui.y + 8, 2, ui.h - 16);
+            }
+
+            textInputRegions.push({
+                x: x + ui.x,
+                y: y + ui.y,
+                width: ui.w,
+                height: ui.h,
+                inputId: ui.onInput,
+                submitId: ui.onSubmit
+            });
+
+            if (ui.focused && ui.onInput === focusedInput) {
+                currentInputValue = ui.value;
+            }
+
+            break;
+        }
     }
 }
 
 function measure(ui: UIValue): { width: number, height: number } {
     switch (ui.kind) {
         case 'rect': return { width: ui.w, height: ui.h };
+
         case 'text': return { width: ui.content.length * 10, height: 20 }; // TODO
+
         case 'row': {
             let totalWidth = 0;
             let maxHeight = 0;
@@ -77,6 +132,7 @@ function measure(ui: UIValue): { width: number, height: number } {
             totalWidth += ui.gap * (ui.children.length - 1);
             return { width: totalWidth, height: maxHeight };
         }
+
         case 'column': {
             let totalHeight = 0;
             let maxWidth = 0;
@@ -88,8 +144,10 @@ function measure(ui: UIValue): { width: number, height: number } {
             totalHeight += ui.gap * (ui.children.length - 1);
             return { width: maxWidth, height: totalHeight };
         }
+
         case 'clickable':
             return measure(ui.child);
+
         case 'padding': {
             const childSize = measure(ui.child);
             return {
@@ -97,6 +155,21 @@ function measure(ui: UIValue): { width: number, height: number } {
                 height: childSize.height + ui.amount * 2,
             }
         }
+
+        case 'stack': {
+            let maxWidth = 0;
+            let maxHeight = 0;
+            for (const child of ui.children) {
+                const size = measure(child);
+                maxWidth = Math.max(maxWidth, size.width);
+                maxHeight = Math.max(maxHeight, size.height);
+            }
+
+            return { width: maxWidth, height: maxHeight };
+        }
+
+        case 'text-input':
+            return { width: ui.w, height: ui.h };
     }
 
     // return { width: 0, height: 0 };
@@ -111,3 +184,55 @@ export function hitTest(x: number, y: number): string | null {
     }
     return null;
 }
+
+let currentInputValue: string = '';
+
+export function hitTestTextInput(x: number, y: number): boolean {
+    for (const region of textInputRegions) {
+        if (x >= region.x && x < region.x + region.width &&
+           y >= region.y && y < region.y + region.height) {
+            focusedInput = region.inputId;
+            focusedInputSubmit = region.submitId;
+            return true;
+        }
+    }
+
+    focusedInput = null;
+    focusedInputSubmit = null;
+    return false;
+}
+
+export function getFocusedInput(): string | null {
+    return focusedInput;
+}
+
+export function storeInputValue(inputId: string, value: string) {
+    if (inputId === focusedInput) {
+        currentInputValue = value;
+    }
+}
+
+export function handleKeyboard(key: string): { event: string, value: string } | null {
+    if (!focusedInput) return null;
+
+    if (key === 'Enter') {
+        return focusedInputSubmit
+            ? { event: focusedInputSubmit, value: currentInputValue }
+            : null;
+    }
+
+    if (key === 'Backspace') {
+        const newValue = currentInputValue.slice(0, -1);
+        currentInputValue = newValue;
+        return { event: focusedInput, value: newValue };
+    }
+
+    // Character
+    if (key.length === 1) {
+        const newValue = currentInputValue + key;
+        currentInputValue = newValue;
+        return { event: focusedInput, value: newValue };
+    }
+
+    return null;
+}

src/valueToUI.ts

@@ -1,7 +1,6 @@
 import type { Value, UIValue } from './types';
 
 export function valueToUI(value: Value): UIValue {
-    console.log("valueToUI", value);
     if (value.kind !== 'constructor') {
         throw new Error('UI value must be a constructor');
     }
@@ -74,6 +73,39 @@ export function valueToUI(value: Value): UIValue {
             return { kind: 'padding', amount: amount.value, child: valueToUI(child) };
         }
 
+        case 'Stack': {
+            const children = fields.children;
+
+            if (children.kind !== 'list')
+                throw new Error('Invalid Stack fields');
+
+            return { kind: 'stack', children: children.elements.map(valueToUI) };
+        }
+
+        case 'TextInput': {
+            const { value, placeholder, x, y, w, h, focused, onInput, onSubmit } = fields;
+
+            if (value.kind !== 'string' || placeholder.kind !== 'string' ||
+               x.kind !== 'int' || y.kind !== 'int' || w.kind !== 'int' || h.kind !== 'int' ||
+               onInput.kind !== 'string' || onSubmit.kind !== 'string')
+                throw new Error('Invalid TextInput fields');
+
+            const isFocused = focused.kind === 'constructor' && focused.name === 'True';
+
+            return {
+                kind: 'text-input',
+                value: value.value,
+                placeholder: placeholder.value,
+                x: x.value,
+                y: y.value,
+                w: w.value,
+                h: h.value,
+                focused: isFocused,
+                onInput: onInput.value,
+                onSubmit: onSubmit.value
+            };
+        }
+
         default:
             throw new Error(`Unknown UI constructor: ${value.name}`);
     }