UPDATE: Adds web app (#79)

Things missing:

* Browse mode
* Front end tests
* Storybook

webapp/src/components/usePointer.ts

@@ -0,0 +1,169 @@
+import { type PointerEvent, type RefObject, useCallback, useRef } from "react";
+import type WorksheetCanvas from "./WorksheetCanvas/worksheetCanvas";
+import {
+  headerColumnWidth,
+  headerRowHeight,
+} from "./WorksheetCanvas/worksheetCanvas";
+import type { Cell } from "./types";
+
+interface PointerSettings {
+  canvasElement: RefObject<HTMLCanvasElement>;
+  worksheetCanvas: RefObject<WorksheetCanvas | null>;
+  worksheetElement: RefObject<HTMLDivElement>;
+  onCellSelected: (cell: Cell, event: React.MouseEvent) => void;
+  onAreaSelecting: (cell: Cell) => void;
+  onAreaSelected: () => void;
+  onExtendToCell: (cell: Cell) => void;
+  onExtendToEnd: () => void;
+}
+
+interface PointerEvents {
+  onPointerDown: (event: PointerEvent) => void;
+  onPointerMove: (event: PointerEvent) => void;
+  onPointerUp: (event: PointerEvent) => void;
+  onPointerHandleDown: (event: PointerEvent) => void;
+}
+
+const usePointer = (options: PointerSettings): PointerEvents => {
+  const isSelecting = useRef(false);
+  const isExtending = useRef(false);
+
+  const onPointerMove = useCallback(
+    (event: PointerEvent): void => {
+      // Range selections are disabled on non-mouse devices. Use touch move only
+      // to scroll for now.
+      if (event.pointerType !== "mouse") {
+        return;
+      }
+
+      if (isSelecting.current) {
+        const { canvasElement, worksheetCanvas } = options;
+        const canvas = canvasElement.current;
+        const worksheet = worksheetCanvas.current;
+        // Silence the linter
+        if (!worksheet || !canvas) {
+          return;
+        }
+        let x = event.clientX;
+        let y = event.clientY;
+        const canvasRect = canvas.getBoundingClientRect();
+        x -= canvasRect.x;
+        y -= canvasRect.y;
+        const cell = worksheet.getCellByCoordinates(x, y);
+        if (cell) {
+          options.onAreaSelecting(cell);
+        } else {
+          console.log("Failed");
+        }
+      } else if (isExtending.current) {
+        const { canvasElement, worksheetCanvas } = options;
+        const canvas = canvasElement.current;
+        const worksheet = worksheetCanvas.current;
+        // Silence the linter
+        if (!worksheet || !canvas) {
+          return;
+        }
+        let x = event.clientX;
+        let y = event.clientY;
+        const canvasRect = canvas.getBoundingClientRect();
+        x -= canvasRect.x;
+        y -= canvasRect.y;
+        const cell = worksheet.getCellByCoordinates(x, y);
+        if (!cell) {
+          return;
+        }
+        options.onExtendToCell(cell);
+      }
+    },
+    [options],
+  );
+
+  const onPointerUp = useCallback(
+    (event: PointerEvent): void => {
+      if (isSelecting.current) {
+        const { worksheetElement } = options;
+        isSelecting.current = false;
+        worksheetElement.current?.releasePointerCapture(event.pointerId);
+        options.onAreaSelected();
+      } else if (isExtending.current) {
+        const { worksheetElement } = options;
+        isExtending.current = false;
+        worksheetElement.current?.releasePointerCapture(event.pointerId);
+        options.onExtendToEnd();
+      }
+    },
+    [options],
+  );
+
+  const onPointerDown = useCallback(
+    (event: PointerEvent) => {
+      let x = event.clientX;
+      let y = event.clientY;
+      const { canvasElement, worksheetElement, worksheetCanvas } = options;
+      const worksheet = worksheetCanvas.current;
+      const canvas = canvasElement.current;
+      const worksheetWrapper = worksheetElement.current;
+      // Silence the linter
+      if (!canvas || !worksheet || !worksheetWrapper) {
+        return;
+      }
+      const canvasRect = canvas.getBoundingClientRect();
+      x -= canvasRect.x;
+      y -= canvasRect.y;
+      // Makes sure is in the sheet area
+      if (
+        x > canvasRect.width ||
+        x < headerColumnWidth ||
+        y < headerRowHeight ||
+        y > canvasRect.height
+      ) {
+        if (
+          x > 0 &&
+          x < headerColumnWidth &&
+          y > headerRowHeight &&
+          y < canvasRect.height
+        ) {
+          // Click on a row number
+          const cell = worksheet.getCellByCoordinates(headerColumnWidth, y);
+          if (cell) {
+            // TODO
+            // Row selected
+          }
+        }
+        return;
+      }
+      const cell = worksheet.getCellByCoordinates(x, y);
+      if (cell) {
+        options.onCellSelected(cell, event);
+        isSelecting.current = true;
+        worksheetWrapper.setPointerCapture(event.pointerId);
+      }
+    },
+    [options],
+  );
+
+  const onPointerHandleDown = useCallback(
+    (event: PointerEvent) => {
+      const worksheetWrapper = options.worksheetElement.current;
+      // Silence the linter
+      if (!worksheetWrapper) {
+        return;
+      }
+      isExtending.current = true;
+      worksheetWrapper.setPointerCapture(event.pointerId);
+      event.stopPropagation();
+      event.preventDefault();
+    },
+    [options],
+  );
+
+  return {
+    onPointerDown,
+    onPointerMove,
+    onPointerUp,
+    onPointerHandleDown,
+    // onContextMenu,
+  };
+};
+
+export default usePointer;