UPDATE: Adds cell and formula editing

webapp/src/App.css

@@ -1,6 +1,7 @@
 #root {
   position: absolute;
-  inset: 10px;
+  inset: 0px;
+  margin: 10px;
   border: 1px solid #aaa;
   border-radius: 4px;
 }

webapp/src/App.tsx

@@ -11,6 +11,7 @@ function App() {
   const [workbookState, setWorkbookState] = useState<WorkbookState | null>(
     null,
   );
+
   useEffect(() => {
     async function start() {
       await init();
@@ -42,6 +43,7 @@ function App() {
 
   // We could use context for model, but the problem is that it should initialized to null.
   // Passing the property down makes sure it is always defined.
+
   return <Workbook model={model} workbookState={workbookState} />;
 }
 

webapp/src/components/WorksheetCanvas/worksheetCanvas.ts

@@ -30,6 +30,7 @@ export interface CanvasSettings {
     columnGuide: HTMLDivElement;
     rowGuide: HTMLDivElement;
     columnHeaders: HTMLDivElement;
+    editor: HTMLDivElement;
   };
   onColumnWidthChanges: (sheet: number, column: number, width: number) => void;
   onRowHeightChanges: (sheet: number, row: number, height: number) => void;
@@ -48,6 +49,23 @@ export const defaultCellFontFamily = fonts.regular;
 export const headerFontFamily = fonts.regular;
 export const frozenSeparatorWidth = 3;
 
+// Get a 10% transparency of an hex color
+function hexToRGBA10Percent(colorHex: string): string {
+  // Remove the leading hash (#) if present
+  const hex = colorHex.replace(/^#/, "");
+
+  // Parse the hex color
+  const red = Number.parseInt(hex.substring(0, 2), 16);
+  const green = Number.parseInt(hex.substring(2, 4), 16);
+  const blue = Number.parseInt(hex.substring(4, 6), 16);
+
+  // Set the alpha (opacity) to 0.1 (10%)
+  const alpha = 0.1;
+
+  // Return the RGBA color string
+  return `rgba(${red}, ${green}, ${blue}, ${alpha})`;
+}
+
 export default class WorksheetCanvas {
   sheetWidth: number;
 
@@ -61,6 +79,8 @@ export default class WorksheetCanvas {
 
   canvas: HTMLCanvasElement;
 
+  editor: HTMLDivElement;
+
   areaOutline: HTMLDivElement;
 
   cellOutline: HTMLDivElement;
@@ -92,6 +112,7 @@ export default class WorksheetCanvas {
     this.height = options.height;
     this.ctx = this.setContext();
     this.workbookState = options.workbookState;
+    this.editor = options.elements.editor;
 
     this.cellOutline = options.elements.cellOutline;
     this.cellOutlineHandle = options.elements.cellOutlineHandle;
@@ -1092,7 +1113,7 @@ export default class WorksheetCanvas {
       this.getColumnWidth(selectedSheet, selectedColumn) + 2 * padding;
     const height = this.getRowHeight(selectedSheet, selectedRow) + 2 * padding;
 
-    const { cellOutline, areaOutline, cellOutlineHandle } = this;
+    const { cellOutline, editor, areaOutline, cellOutlineHandle } = this;
     const cellEditing = null;
 
     cellOutline.style.visibility = "visible";
@@ -1105,6 +1126,11 @@ export default class WorksheetCanvas {
       cellOutlineHandle.style.visibility = "hidden";
     }
 
+    editor.style.left = `${x + 3}px`;
+    editor.style.top = `${y + 3}px`;
+    editor.style.width = `${width - 1}px`;
+    editor.style.height = `${height - 1}px`;
+
     // Position the cell outline and clip it
     cellOutline.style.left = `${x - padding}px`;
     cellOutline.style.top = `${y - padding}px`;
@@ -1214,6 +1240,52 @@ export default class WorksheetCanvas {
     cellOutlineHandle.style.top = `${handleY - handleHeight / 2}px`;
   }
 
+  private drawActiveRanges(topLeftCell: Cell, bottomRightCell: Cell): void {
+    const activeRanges = this.workbookState.getActiveRanges();
+    const activeRangesCount = activeRanges.length;
+    const ctx = this.ctx;
+    ctx.setLineDash([2, 2]);
+    for (let rangeIndex = 0; rangeIndex < activeRangesCount; rangeIndex += 1) {
+      const range = activeRanges[rangeIndex];
+
+      const allowedOffset = 1; // to make borders look nicer
+      const minRow = topLeftCell.row - allowedOffset;
+      const maxRow = bottomRightCell.row + allowedOffset;
+      const minColumn = topLeftCell.column - allowedOffset;
+      const maxColumn = bottomRightCell.column + allowedOffset;
+
+      if (
+        minRow <= range.rowEnd &&
+        range.rowStart <= maxRow &&
+        minColumn <= range.columnEnd &&
+        range.columnStart < maxColumn
+      ) {
+        // Range in the viewport.
+        const displayRange: typeof range = {
+          ...range,
+          rowStart: Math.max(minRow, range.rowStart),
+          rowEnd: Math.min(maxRow, range.rowEnd),
+          columnStart: Math.max(minColumn, range.columnStart),
+          columnEnd: Math.min(maxColumn, range.columnEnd),
+        };
+        const [xStart, yStart] = this.getCoordinatesByCell(
+          displayRange.rowStart,
+          displayRange.columnStart,
+        );
+        const [xEnd, yEnd] = this.getCoordinatesByCell(
+          displayRange.rowEnd + 1,
+          displayRange.columnEnd + 1,
+        );
+        ctx.strokeStyle = range.color;
+        ctx.lineWidth = 1;
+        ctx.strokeRect(xStart, yStart, xEnd - xStart, yEnd - yStart);
+        ctx.fillStyle = hexToRGBA10Percent(range.color);
+        ctx.fillRect(xStart, yStart, xEnd - xStart, yEnd - yStart);
+      }
+    }
+
+    ctx.setLineDash([]);
+  }
   renderSheet(): void {
     console.time("renderSheet");
     this._renderSheet();
@@ -1352,5 +1424,6 @@ export default class WorksheetCanvas {
 
     this.drawCellOutline();
     this.drawExtendToArea();
+    this.drawActiveRanges(topLeftCell, bottomRightCell);
   }
 }

webapp/src/components/editor/editor.tsx

@@ -0,0 +1,243 @@
+// This is the cell editor for IronCalc
+// It is also the most difficult part of the UX. It is based on an idea of Mateusz Kopec.
+// There is a hidden texarea and we only show the caret. What we see is a div with the same text content
+// but in HTML so we can have different colors.
+// Some keystrokes have different behaviour than a raw HTML text area.
+// For those cases we capture the keydown event and stop its propagation.
+// As the editor changes content we need to propagate those changes so the spreadsheet can
+// mark with colors the active ranges or update the formula in the formula bar
+
+import type { Model } from "@ironcalc/wasm";
+import {
+  type CSSProperties,
+  type KeyboardEvent,
+  useCallback,
+  useEffect,
+  useRef,
+  useState,
+} from "react";
+import type { WorkbookState } from "../workbookState";
+import getFormulaHTML from "./util";
+
+const commonCSS: CSSProperties = {
+  fontWeight: "inherit",
+  fontFamily: "inherit",
+  fontSize: "inherit",
+  position: "absolute",
+  left: 0,
+  top: 0,
+  whiteSpace: "pre",
+  width: "100%",
+  padding: 0,
+  lineHeight: "22px",
+};
+
+const caretColor = "#FF8899";
+
+interface EditorOptions {
+  minimalWidth: number | string;
+  minimalHeight: number | string;
+  display: boolean;
+  expand: boolean;
+  originalText: string;
+  onEditEnd: () => void;
+  onTextUpdated: () => void;
+  model: Model;
+  workbookState: WorkbookState;
+  type: "cell" | "formula-bar";
+}
+
+const Editor = (options: EditorOptions) => {
+  const {
+    display,
+    expand,
+    minimalHeight,
+    minimalWidth,
+    model,
+    onEditEnd,
+    onTextUpdated,
+    originalText,
+    workbookState,
+    type,
+  } = options;
+
+  const [width, setWidth] = useState(minimalWidth);
+  const [height, setHeight] = useState(minimalHeight);
+  const [text, setText] = useState(originalText);
+  const [styledFormula, setStyledFormula] = useState(
+    getFormulaHTML(model, text).html,
+  );
+
+  const formulaRef = useRef<HTMLDivElement>(null);
+  const maskRef = useRef<HTMLDivElement>(null);
+  const textareaRef = useRef<HTMLTextAreaElement>(null);
+
+  useEffect(() => {
+    setText(originalText);
+    setStyledFormula(getFormulaHTML(model, originalText).html);
+    if (textareaRef.current) {
+      textareaRef.current.value = originalText;
+    }
+  }, [originalText, model]);
+
+  const onKeyDown = useCallback(
+    (event: KeyboardEvent) => {
+      const { key, shiftKey, altKey } = event;
+      const textarea = textareaRef.current;
+      if (!textarea) {
+        return;
+      }
+      switch (key) {
+        case "Enter": {
+          if (altKey) {
+            // new line
+            const start = textarea.selectionStart;
+            const end = textarea.selectionEnd;
+            const newText = `${text.slice(0, start)}\n${text.slice(end)}`;
+            setText(newText);
+            setTimeout(() => {
+              textarea.setSelectionRange(start + 1, start + 1);
+            }, 0);
+            event.stopPropagation();
+            event.preventDefault();
+            return;
+          }
+          // end edit and select cell bellow
+          setTimeout(() => {
+            const cell = workbookState.getEditingCell();
+            if (cell) {
+              workbookState.clearEditingCell();
+              model.setUserInput(cell.sheet, cell.row, cell.column, cell.text);
+              const sign = shiftKey ? -1 : 1;
+              model.setSelectedCell(cell.row + sign, cell.column);
+            }
+            onEditEnd();
+          }, 0);
+          // event bubbles up
+          return;
+        }
+        case "Tab": {
+          // end edit and select cell to the right
+          const cell = workbookState.getEditingCell();
+          if (cell) {
+            workbookState.clearEditingCell();
+            model.setUserInput(cell.sheet, cell.row, cell.column, cell.text);
+            const sign = shiftKey ? -1 : 1;
+            model.setSelectedCell(cell.row, cell.column + sign);
+            if (textareaRef.current) {
+              textareaRef.current.value = "";
+              setStyledFormula(getFormulaHTML(model, "").html);
+            }
+            event.stopPropagation();
+            event.preventDefault();
+          }
+          onEditEnd();
+          return;
+        }
+        case "Escape": {
+          // quit editing without modifying the cell
+          workbookState.clearEditingCell();
+          onEditEnd();
+          return;
+        }
+        // TODO: Arrow keys navigate in Excel
+        case "ArrowRight": {
+          return;
+        }
+        default: {
+          // We run this in a timeout because the value is not yet in the textarea
+          // since we are capturing the keydown event
+          setTimeout(() => {
+            const value = textarea.value;
+            const styledFormula = getFormulaHTML(model, value);
+            const cell = workbookState.getEditingCell();
+            if (cell) {
+              cell.text = value;
+              workbookState.setEditingCell(cell);
+
+              workbookState.setActiveRanges(styledFormula.activeRanges);
+              setStyledFormula(styledFormula.html);
+
+              onTextUpdated();
+            }
+          }, 0);
+        }
+      }
+    },
+    [model, text, onEditEnd, onTextUpdated, workbookState],
+  );
+
+  useEffect(() => {
+    if (display) {
+      textareaRef.current?.focus();
+    }
+  }, [display]);
+
+  const onChange = useCallback(() => {
+    if (textareaRef.current) {
+      textareaRef.current.value = "";
+      setStyledFormula(getFormulaHTML(model, "").html);
+    }
+
+    // This happens if the blur hasn't been taken care before by
+    // onclick or onpointerdown events
+    // If we are editing a cell finish that
+    const cell = workbookState.getEditingCell();
+    if (cell) {
+      workbookState.clearEditingCell();
+      model.setUserInput(cell.sheet, cell.row, cell.column, cell.text);
+    }
+    onEditEnd();
+  }, [model, workbookState, onEditEnd]);
+
+  const isCellEditing = workbookState.getEditingCell() !== null;
+
+  const showEditor =
+    isCellEditing && (display || type === "formula-bar") ? "block" : "none";
+
+  return (
+    <div
+      style={{
+        position: "relative",
+        width,
+        height,
+        overflow: "hidden",
+        display: showEditor,
+        background: "#FFF",
+      }}
+    >
+      <div
+        ref={maskRef}
+        style={{
+          ...commonCSS,
+          textAlign: "left",
+          pointerEvents: "none",
+          height,
+        }}
+      >
+        <div ref={formulaRef}>{styledFormula}</div>
+      </div>
+      <textarea
+        ref={textareaRef}
+        rows={1}
+        style={{
+          ...commonCSS,
+          color: "transparent",
+          backgroundColor: "transparent",
+          caretColor,
+          outline: "none",
+          resize: "none",
+          border: "none",
+          height,
+          display: display ? "block" : "none",
+          overflow: "hidden",
+        }}
+        defaultValue={text}
+        spellCheck="false"
+        onKeyDown={onKeyDown}
+        onBlur={onChange}
+      />
+    </div>
+  );
+};
+export default Editor;

webapp/src/components/editor/util.tsx

@@ -0,0 +1,189 @@
+import {
+  type Model,
+  type Range,
+  type Reference,
+  type TokenType,
+  getTokens,
+} from "@ironcalc/wasm";
+import type { ActiveRange } from "../workbookState";
+
+export function tokenIsReferenceType(token: TokenType): token is Reference {
+  return typeof token === "object" && "Reference" in token;
+}
+
+export function tokenIsRangeType(token: TokenType): token is Range {
+  return typeof token === "object" && "Range" in token;
+}
+
+function isInReferenceMode(text: string, cursor: number): boolean {
+  // FIXME
+  // This is a gross oversimplification
+  // Returns true if both are true:
+  // 1. Cursor is at the end
+  // 2. Last char is one of [',', '(', '+', '*', '-', '/', '<', '>', '=', '&']
+  // This has many false positives like '="1+' and also likely some false negatives
+  // The right way of doing this is to have a partial parse of the formula tree
+  // and check if the next token could be a reference
+  if (!text.startsWith("=")) {
+    return false;
+  }
+  if (text === "=") {
+    return true;
+  }
+  const l = text.length;
+  const chars = [",", "(", "+", "*", "-", "/", "<", ">", "=", "&"];
+  if (cursor === l && chars.includes(text[l - 1])) {
+    return true;
+  }
+  return false;
+}
+
+// IronCalc Color Palette
+export function getColor(index: number, alpha = 1): string {
+  const colors = [
+    {
+      name: "Cyan",
+      rgba: [89, 185, 188, 1],
+      hex: "#59B9BC",
+    },
+    {
+      name: "Flamingo",
+      rgba: [236, 87, 83, 1],
+      hex: "#EC5753",
+    },
+    {
+      hex: "#3358B7",
+      rgba: [51, 88, 183, 1],
+      name: "Blue",
+    },
+    {
+      hex: "#F8CD3C",
+      rgba: [248, 205, 60, 1],
+      name: "Yellow",
+    },
+    {
+      hex: "#3BB68A",
+      rgba: [59, 182, 138, 1],
+      name: "Emerald",
+    },
+    {
+      hex: "#523E93",
+      rgba: [82, 62, 147, 1],
+      name: "Violet",
+    },
+    {
+      hex: "#A23C52",
+      rgba: [162, 60, 82, 1],
+      name: "Burgundy",
+    },
+    {
+      hex: "#8CB354",
+      rgba: [162, 60, 82, 1],
+      name: "Wasabi",
+    },
+    {
+      hex: "#D03627",
+      rgba: [208, 54, 39, 1],
+      name: "Red",
+    },
+    {
+      hex: "#1B717E",
+      rgba: [27, 113, 126, 1],
+      name: "Teal",
+    },
+  ];
+  if (alpha === 1) {
+    return colors[index % 10].hex;
+  }
+  const { rgba } = colors[index % 10];
+  return `rgba(${rgba[0]}, ${rgba[1]}, ${rgba[2]}, ${alpha})`;
+}
+
+function getFormulaHTML(
+  model: Model,
+  text: string,
+): { html: JSX.Element[]; activeRanges: ActiveRange[] } {
+  let html: JSX.Element[] = [];
+  const activeRanges: ActiveRange[] = [];
+  let colorCount = 0;
+  if (text.startsWith("=")) {
+    const formula = text.slice(1);
+    const tokens = getTokens(formula);
+    const tokenCount = tokens.length;
+    const usedColors: Record<string, string> = {};
+    const sheet = model.getSelectedSheet();
+    const sheetList = model.getWorksheetsProperties().map((s) => s.name);
+    for (let index = 0; index < tokenCount; index += 1) {
+      const { token, start, end } = tokens[index];
+      if (tokenIsReferenceType(token)) {
+        const { sheet: refSheet, row, column } = token.Reference;
+        const sheetIndex = refSheet ? sheetList.indexOf(refSheet) : sheet;
+        const key = `${sheetIndex}-${row}-${column}`;
+        let color = usedColors[key];
+        if (!color) {
+          color = getColor(colorCount);
+          usedColors[key] = color;
+          colorCount += 1;
+        }
+        html.push(
+          <span key={index} style={{ color }}>
+            {formula.slice(start, end)}
+          </span>,
+        );
+        activeRanges.push({
+          sheet: sheetIndex,
+          rowStart: row,
+          columnStart: column,
+          rowEnd: row,
+          columnEnd: column,
+          color,
+        });
+      } else if (tokenIsRangeType(token)) {
+        let {
+          sheet: refSheet,
+          left: { row: rowStart, column: columnStart },
+          right: { row: rowEnd, column: columnEnd },
+        } = token.Range;
+        const sheetIndex = refSheet ? sheetList.indexOf(refSheet) : sheet;
+
+        const key = `${sheetIndex}-${rowStart}-${columnStart}:${rowEnd}-${columnEnd}`;
+        let color = usedColors[key];
+        if (!color) {
+          color = getColor(colorCount);
+          usedColors[key] = color;
+          colorCount += 1;
+        }
+
+        if (rowStart > rowEnd) {
+          [rowStart, rowEnd] = [rowEnd, rowStart];
+        }
+        if (columnStart > columnEnd) {
+          [columnStart, columnEnd] = [columnEnd, columnStart];
+        }
+        html.push(
+          <span key={index} style={{ color }}>
+            {formula.slice(start, end)}
+          </span>,
+        );
+        colorCount += 1;
+
+        activeRanges.push({
+          sheet: sheetIndex,
+          rowStart,
+          columnStart,
+          rowEnd,
+          columnEnd,
+          color,
+        });
+      } else {
+        html.push(<span key={index}>{formula.slice(start, end)}</span>);
+      }
+    }
+    html = [<span key="equals">=</span>].concat(html);
+  } else {
+    html = [<span key="single">{text}</span>];
+  }
+  return { html, activeRanges };
+}
+
+export default getFormulaHTML;

webapp/src/components/formulaDialog.tsx

@@ -1,50 +0,0 @@
-import {
-  Button,
-  Dialog,
-  DialogActions,
-  DialogContent,
-  DialogTitle,
-  TextField,
-} from "@mui/material";
-import { useState } from "react";
-import { useTranslation } from "react-i18next";
-
-interface FormulaDialogProps {
-  isOpen: boolean;
-  close: () => void;
-  onFormulaChanged: (name: string) => void;
-  defaultFormula: string;
-}
-
-export const FormulaDialog = (properties: FormulaDialogProps) => {
-  const { t } = useTranslation();
-  const [formula, setFormula] = useState(properties.defaultFormula);
-  return (
-    <Dialog open={properties.isOpen} onClose={properties.close}>
-      <DialogTitle>{t("formula_input.title")}</DialogTitle>
-      <DialogContent dividers>
-        <TextField
-          defaultValue={formula}
-          label={t("formula_input.label")}
-          onClick={(event) => event.stopPropagation()}
-          onKeyDown={(event) => {
-            event.stopPropagation();
-          }}
-          onChange={(event) => {
-            setFormula(event.target.value);
-          }}
-          spellCheck="false"
-        />
-      </DialogContent>
-      <DialogActions>
-        <Button
-          onClick={() => {
-            properties.onFormulaChanged(formula);
-          }}
-        >
-          {t("formula_input.update")}
-        </Button>
-      </DialogActions>
-    </Dialog>
-  );
-};

webapp/src/components/formulabar.tsx

@@ -1,28 +1,39 @@
+import type { Model } from "@ironcalc/wasm";
 import { Button, styled } from "@mui/material";
 import { ChevronDown } from "lucide-react";
 import { useState } from "react";
 import { Fx } from "../icons";
-import { FormulaDialog } from "./formulaDialog";
+import Editor from "./editor/editor";
+import type { WorkbookState } from "./workbookState";
 
 type FormulaBarProps = {
   cellAddress: string;
   formulaValue: string;
-  onChange: (value: string) => void;
+  model: Model;
+  workbookState: WorkbookState;
+  onChange: () => void;
+  onTextUpdated: () => void;
 };
 
 const formulaBarHeight = 30;
-const headerColumnWidth = 30;
+const headerColumnWidth = 35;
 
 function FormulaBar(properties: FormulaBarProps) {
-  const [formulaDialogOpen, setFormulaDialogOpen] = useState(false);
-  const handleCloseFormulaDialog = () => {
-    setFormulaDialogOpen(false);
-  };
+  const {
+    cellAddress,
+    formulaValue,
+    model,
+    onChange,
+    onTextUpdated,
+    workbookState,
+  } = properties;
+
+  const [display, setDisplay] = useState(false);
 
   return (
     <Container>
       <AddressContainer>
-        <CellBarAddress>{properties.cellAddress}</CellBarAddress>
+        <CellBarAddress>{cellAddress}</CellBarAddress>
         <StyledButton>
           <ChevronDown />
         </StyledButton>
@@ -32,23 +43,40 @@ function FormulaBar(properties: FormulaBarProps) {
         <FormulaSymbolButton>
           <Fx />
         </FormulaSymbolButton>
-        <Editor
-          onClick={() => {
-            setFormulaDialogOpen(true);
+        <EditorWrapper
+          onClick={(event) => {
+            const [sheet, row, column] = model.getSelectedCell();
+            workbookState.setEditingCell({
+              sheet,
+              row,
+              column,
+              text: formulaValue,
+              cursor: 0,
+              focus: "formula-bar",
+              activeRanges: [],
+            });
+            setDisplay(true);
+            event.stopPropagation();
+            event.preventDefault();
           }}
         >
-          {properties.formulaValue}
-        </Editor>
+          <Editor
+            minimalWidth={"100%"}
+            minimalHeight={"100%"}
+            display={display}
+            expand={false}
+            originalText={formulaValue}
+            model={model}
+            workbookState={workbookState}
+            onEditEnd={() => {
+              setDisplay(false);
+              onChange();
+            }}
+            onTextUpdated={onTextUpdated}
+            type="formula-bar"
+          />
+        </EditorWrapper>
       </FormulaContainer>
-      <FormulaDialog
-        isOpen={formulaDialogOpen}
-        close={handleCloseFormulaDialog}
-        defaultFormula={properties.formulaValue}
-        onFormulaChanged={(newName) => {
-          properties.onChange(newName);
-          setFormulaDialogOpen(false);
-        }}
-      />
     </Container>
   );
 }
@@ -113,7 +141,7 @@ const CellBarAddress = styled("div")`
   text-align: "center";
 `;
 
-const Editor = styled("div")`
+const EditorWrapper = styled("div")`
   position: relative;
   width: 100%;
   padding: 0px;
@@ -127,6 +155,7 @@ const Editor = styled("div")`
   span {
     min-width: 1px;
   }
+  font-family: monospace;
 `;
 
 export default FormulaBar;

webapp/src/components/workbook.tsx

@@ -143,11 +143,31 @@ const Workbook = (props: { model: Model; workbookState: WorkbookState }) => {
       setRedrawId((id) => id + 1);
     },
     onEditKeyPressStart: (initText: string): void => {
-      console.log(initText);
-      throw new Error("Function not implemented.");
+      const { sheet, row, column } = model.getSelectedView();
+      workbookState.setEditingCell({
+        sheet,
+        row,
+        column,
+        text: initText,
+        cursor: 0,
+        focus: "cell",
+        activeRanges: [],
+      });
+      setRedrawId((id) => id + 1);
     },
     onCellEditStart: (): void => {
-      throw new Error("Function not implemented.");
+      const { sheet, row, column } = model.getSelectedView();
+      const text = model.getCellContent(sheet, row, column);
+      workbookState.setEditingCell({
+        sheet,
+        row,
+        column,
+        text,
+        cursor: text.length,
+        focus: "cell",
+        activeRanges: [],
+      });
+      setRedrawId((id) => id + 1);
     },
     onBold: () => {
       const { sheet, row, column } = model.getSelectedView();
@@ -237,7 +257,9 @@ const Workbook = (props: { model: Model; workbookState: WorkbookState }) => {
     if (!rootRef.current) {
       return;
     }
-    rootRef.current.focus();
+    if (!workbookState.getEditingCell()) {
+      rootRef.current.focus();
+    }
   });
 
   const {
@@ -251,12 +273,25 @@ const Workbook = (props: { model: Model; workbookState: WorkbookState }) => {
     { rowStart, rowEnd, columnStart, columnEnd },
     { row, column },
   );
-  const formulaValue = model.getCellContent(sheet, row, column);
+  const formulaValue = (() => {
+    const cell = workbookState.getEditingCell();
+    if (cell) {
+      return cell.text;
+    }
+    return model.getCellContent(sheet, row, column);
+  })();
 
   const style = model.getCellStyle(sheet, row, column);
 
   return (
-    <Container ref={rootRef} onKeyDown={onKeyDown} tabIndex={0}>
+    <Container
+      ref={rootRef}
+      onKeyDown={onKeyDown}
+      tabIndex={0}
+      onClick={() => {
+        rootRef.current?.focus();
+      }}
+    >
       <Toolbar
         canUndo={model.canUndo()}
         canRedo={model.canRedo()}
@@ -313,10 +348,15 @@ const Workbook = (props: { model: Model; workbookState: WorkbookState }) => {
       <FormulaBar
         cellAddress={cellAddress}
         formulaValue={formulaValue}
-        onChange={(value) => {
-          model.setUserInput(sheet, row, column, value);
+        onChange={() => {
+          setRedrawId((id) => id + 1);
+          rootRef.current?.focus();
+        }}
+        onTextUpdated={() => {
           setRedrawId((id) => id + 1);
         }}
+        model={model}
+        workbookState={workbookState}
       />
       <Worksheet
         model={model}
@@ -325,6 +365,7 @@ const Workbook = (props: { model: Model; workbookState: WorkbookState }) => {
           setRedrawId((id) => id + 1);
         }}
       />
+
       <Navigation
         sheets={info}
         selectedIndex={model.getSelectedSheet()}

webapp/src/components/workbookState.ts

@@ -1,3 +1,18 @@
+// This are properties of the workbook that are not permanently stored
+// They only happen at 'runtime' while the workbook is being used:
+//
+// * What are we editing
+// * Are we copying styles?
+// * Are we extending a cell? (by pulling the cell outline handle down, for instance)
+//
+// Editing the cell is the most complex operation.
+//
+// * What cell are we editing?
+// * Are we doing that from the cell editor or the formula editor?
+// * What is the text content of the cell right now
+// * The active ranges can technically be computed from the text.
+//   Those are the ranges or cells that appear in the formula
+
 import type { CellStyle } from "@ironcalc/wasm";
 
 export enum AreaType {
@@ -15,15 +30,44 @@ export interface Area {
   columnEnd: number;
 }
 
+// Active ranges are ranges in the sheet that are highlighted when editing a formula
+export interface ActiveRange {
+  sheet: number;
+  rowStart: number;
+  rowEnd: number;
+  columnStart: number;
+  columnEnd: number;
+  color: string;
+}
+
+type Focus = "cell" | "formula-bar";
+
+// The cell that we are editing
+export interface EditingCell {
+  sheet: number;
+  row: number;
+  column: number;
+  // raw text in the editor
+  text: string;
+  // position of the cursor
+  cursor: number;
+  focus: Focus;
+  activeRanges: ActiveRange[];
+}
+
+// Those are styles that are copied
 type AreaStyles = CellStyle[][];
 
 export class WorkbookState {
   private extendToArea: Area | null;
   private copyStyles: AreaStyles | null;
+  private cell: EditingCell | null;
 
   constructor() {
+    // the extendTo area is the area we are covering
     this.extendToArea = null;
     this.copyStyles = null;
+    this.cell = null;
   }
 
   getExtendToArea(): Area | null {
@@ -45,4 +89,41 @@ export class WorkbookState {
   getCopyStyles(): AreaStyles | null {
     return this.copyStyles;
   }
+
+  setActiveRanges(activeRanges: ActiveRange[]) {
+    if (!this.cell) {
+      return;
+    }
+    this.cell.activeRanges = activeRanges;
+  }
+
+  getActiveRanges(): ActiveRange[] {
+    return this.cell?.activeRanges || [];
+  }
+
+  getEditingCell(): EditingCell | null {
+    return this.cell;
+  }
+
+  setEditingCell(cell: EditingCell) {
+    this.cell = cell;
+  }
+
+  clearEditingCell() {
+    this.cell = null;
+  }
+
+  isCellEditorActive(): boolean {
+    if (this.cell) {
+      return this.cell.focus === "cell";
+    }
+    return false;
+  }
+
+  isFormulaEditorActive(): boolean {
+    if (this.cell) {
+      return this.cell.focus === "formula-bar";
+    }
+    return false;
+  }
 }

webapp/src/components/worksheet.tsx

@@ -6,6 +6,7 @@ import {
   outlineColor,
 } from "./WorksheetCanvas/constants";
 import WorksheetCanvas from "./WorksheetCanvas/worksheetCanvas";
+import Editor from "./editor/editor";
 import type { Cell } from "./types";
 import usePointer from "./usePointer";
 import { AreaType, type WorkbookState } from "./workbookState";
@@ -32,7 +33,8 @@ function Worksheet(props: {
 
   const worksheetElement = useRef<HTMLDivElement>(null);
   const scrollElement = useRef<HTMLDivElement>(null);
-  // const rootElement = useRef<HTMLDivElement>(null);
+
+  const editorElement = useRef<HTMLDivElement>(null);
   const spacerElement = useRef<HTMLDivElement>(null);
   const cellOutline = useRef<HTMLDivElement>(null);
   const areaOutline = useRef<HTMLDivElement>(null);
@@ -45,8 +47,12 @@ function Worksheet(props: {
 
   const ignoreScrollEventRef = useRef(false);
 
+  const [display, setDisplay] = useState(false);
+  const [originalText, setOriginalText] = useState("");
+
   const { model, workbookState, refresh } = props;
   const [clientWidth, clientHeight] = useWindowSize();
+
   useEffect(() => {
     const canvasRef = canvasElement.current;
     const columnGuideRef = columnResizeGuide.current;
@@ -58,6 +64,7 @@ function Worksheet(props: {
     const handle = cellOutlineHandle.current;
     const area = areaOutline.current;
     const extendTo = extendToOutline.current;
+    const editor = editorElement.current;
 
     if (
       !canvasRef ||
@@ -69,7 +76,8 @@ function Worksheet(props: {
       !handle ||
       !area ||
       !extendTo ||
-      !scrollElement.current
+      !scrollElement.current ||
+      !editor
     )
       return;
     model.setWindowWidth(clientWidth - 37);
@@ -88,6 +96,7 @@ function Worksheet(props: {
         cellOutlineHandle: handle,
         areaOutline: area,
         extendToOutline: extendTo,
+        editor: editor,
       },
       onColumnWidthChanges(sheet, column, width) {
         model.setColumnWidth(sheet, column, width);
@@ -100,7 +109,7 @@ function Worksheet(props: {
     });
     const scrollX = model.getScrollX();
     const scrollY = model.getScrollY();
-    const [sheetWidth, sheetHeight] = [scrollX + 100_000, scrollY + 500_000]; //canvas.getSheetDimensions();
+    const [sheetWidth, sheetHeight] = [scrollX + 100_000, scrollY + 500_000];
     if (spacerElement.current) {
       spacerElement.current.style.height = `${sheetHeight}px`;
       spacerElement.current.style.width = `${sheetWidth}px`;
@@ -127,10 +136,6 @@ function Worksheet(props: {
     worksheetCanvas.current = canvas;
   });
 
-  const sheetNames = model
-    .getWorksheetsProperties()
-    .map((s: { name: string }) => s.name);
-
   const {
     onPointerMove,
     onPointerDown,
@@ -311,20 +316,55 @@ function Worksheet(props: {
         className="sheet-container"
         ref={worksheetElement}
         onPointerDown={(event) => {
+          // if we are editing a cell finish that
+          const cell = workbookState.getEditingCell();
+          if (cell) {
+            workbookState.clearEditingCell();
+            model.setUserInput(cell.sheet, cell.row, cell.column, cell.text);
+          }
           onPointerDown(event);
         }}
         onPointerMove={onPointerMove}
         onPointerUp={onPointerUp}
         onDoubleClick={(event) => {
           const { sheet, row, column } = model.getSelectedView();
-          const _text = model.getCellContent(sheet, row, column) || "";
-          // TODO
+          const text = model.getCellContent(sheet, row, column) || "";
+          workbookState.setEditingCell({
+            sheet,
+            row,
+            column,
+            text,
+            cursor: 0,
+            focus: "cell",
+            activeRanges: [],
+          });
+          setDisplay(true);
+          setOriginalText(text);
           event.stopPropagation();
           event.preventDefault();
         }}
       >
         <SheetCanvas ref={canvasElement} />
         <CellOutline ref={cellOutline} />
+        <EditorWrapper ref={editorElement}>
+          <Editor
+            minimalWidth={"100%"}
+            minimalHeight={"100%"}
+            display={workbookState.getEditingCell()?.focus === "cell"}
+            expand={true}
+            originalText={workbookState.getEditingCell()?.text || originalText}
+            onEditEnd={(): void => {
+              setDisplay(false);
+              props.refresh();
+            }}
+            onTextUpdated={(): void => {
+              props.refresh();
+            }}
+            model={model}
+            workbookState={workbookState}
+            type={"cell"}
+          />
+        </EditorWrapper>
         <AreaOutline ref={areaOutline} />
         <ExtendToOutline ref={extendToOutline} />
         <CellOutlineHandle
@@ -461,4 +501,21 @@ const ExtendToOutline = styled("div")`
   border-radius: 3px;
 `;
 
+const EditorWrapper = styled("div")`
+  position: absolute;
+  width: 100%;
+  padding: 0px;
+  border-width: 0px;
+  outline: none;
+  resize: none;
+  white-space: pre-wrap;
+  vertical-align: bottom;
+  overflow: hidden;
+  text-align: left;
+  span {
+    min-width: 1px;
+  }
+  font-family: monospace;
+`;
+
 export default Worksheet;

webapp/src/index.css

@@ -1,4 +1,5 @@
 body {
+  inset: 0px;
   margin: 0;
   padding: 0;
 }