Extract scene functions to their respective modules (#208)

- Also, extract utilities into utils module -- capitalizeString, getDateTime, isInputLike

src/scene/scrollbars.ts

@@ -0,0 +1,115 @@
+import { ExcalidrawElement } from "../element/types";
+import {
+  getElementAbsoluteX1,
+  getElementAbsoluteX2,
+  getElementAbsoluteY1,
+  getElementAbsoluteY2
+} from "../element";
+
+const SCROLLBAR_MIN_SIZE = 15;
+const SCROLLBAR_MARGIN = 4;
+export const SCROLLBAR_WIDTH = 6;
+export const SCROLLBAR_COLOR = "rgba(0,0,0,0.3)";
+
+export function getScrollBars(
+  elements: ExcalidrawElement[],
+  canvasWidth: number,
+  canvasHeight: number,
+  scrollX: number,
+  scrollY: number
+) {
+  let minX = Infinity;
+  let maxX = 0;
+  let minY = Infinity;
+  let maxY = 0;
+
+  elements.forEach(element => {
+    minX = Math.min(minX, getElementAbsoluteX1(element));
+    maxX = Math.max(maxX, getElementAbsoluteX2(element));
+    minY = Math.min(minY, getElementAbsoluteY1(element));
+    maxY = Math.max(maxY, getElementAbsoluteY2(element));
+  });
+
+  minX += scrollX;
+  maxX += scrollX;
+  minY += scrollY;
+  maxY += scrollY;
+  const leftOverflow = Math.max(-minX, 0);
+  const rightOverflow = Math.max(-(canvasWidth - maxX), 0);
+  const topOverflow = Math.max(-minY, 0);
+  const bottomOverflow = Math.max(-(canvasHeight - maxY), 0);
+
+  // horizontal scrollbar
+  let horizontalScrollBar = null;
+  if (leftOverflow || rightOverflow) {
+    horizontalScrollBar = {
+      x: Math.min(
+        leftOverflow + SCROLLBAR_MARGIN,
+        canvasWidth - SCROLLBAR_MIN_SIZE - SCROLLBAR_MARGIN
+      ),
+      y: canvasHeight - SCROLLBAR_WIDTH - SCROLLBAR_MARGIN,
+      width: Math.max(
+        canvasWidth - rightOverflow - leftOverflow - SCROLLBAR_MARGIN * 2,
+        SCROLLBAR_MIN_SIZE
+      ),
+      height: SCROLLBAR_WIDTH
+    };
+  }
+
+  // vertical scrollbar
+  let verticalScrollBar = null;
+  if (topOverflow || bottomOverflow) {
+    verticalScrollBar = {
+      x: canvasWidth - SCROLLBAR_WIDTH - SCROLLBAR_MARGIN,
+      y: Math.min(
+        topOverflow + SCROLLBAR_MARGIN,
+        canvasHeight - SCROLLBAR_MIN_SIZE - SCROLLBAR_MARGIN
+      ),
+      width: SCROLLBAR_WIDTH,
+      height: Math.max(
+        canvasHeight - bottomOverflow - topOverflow - SCROLLBAR_WIDTH * 2,
+        SCROLLBAR_MIN_SIZE
+      )
+    };
+  }
+
+  return {
+    horizontal: horizontalScrollBar,
+    vertical: verticalScrollBar
+  };
+}
+
+export function isOverScrollBars(
+  elements: ExcalidrawElement[],
+  x: number,
+  y: number,
+  canvasWidth: number,
+  canvasHeight: number,
+  scrollX: number,
+  scrollY: number
+) {
+  const scrollBars = getScrollBars(
+    elements,
+    canvasWidth,
+    canvasHeight,
+    scrollX,
+    scrollY
+  );
+
+  const [isOverHorizontalScrollBar, isOverVerticalScrollBar] = [
+    scrollBars.horizontal,
+    scrollBars.vertical
+  ].map(
+    scrollBar =>
+      scrollBar &&
+      scrollBar.x <= x &&
+      x <= scrollBar.x + scrollBar.width &&
+      scrollBar.y <= y &&
+      y <= scrollBar.y + scrollBar.height
+  );
+
+  return {
+    isOverHorizontalScrollBar,
+    isOverVerticalScrollBar
+  };
+}