Ensure window stays on screen after external monitor removed.

src/main/util/ensureWindowOnScreen.ts

@@ -0,0 +1,109 @@
+import { screen } from "electron";
+
+function ensureWindowOnScreen(
+  x: number | undefined,
+  y: number | undefined,
+  windowWidth: number,
+  windowHeight: number,
+): { validX: number | undefined; validY: number | undefined } {
+  // If no coordinates stored, let Electron position window automatically
+  if (x === undefined || y === undefined) {
+    return { validX: undefined, validY: undefined };
+  }
+
+  const displays = screen.getAllDisplays();
+
+  // Minimum visible pixels required on each edge to be considered "visible enough"
+  const MIN_VISIBLE = 50; // Ensure at least 50px from each edge is visible
+
+  // Try to find a display where the window would be almost fully visible
+  for (const display of displays) {
+    const { bounds } = display;
+
+    // Check if window is mostly within this display
+    if (
+      x + MIN_VISIBLE >= bounds.x &&
+      x + windowWidth - MIN_VISIBLE <= bounds.x + bounds.width &&
+      y + MIN_VISIBLE >= bounds.y &&
+      y + windowHeight - MIN_VISIBLE <= bounds.y + bounds.height
+    ) {
+      // Window is adequately visible on this display
+      return { validX: x, validY: y };
+    }
+  }
+
+  // If window isn't adequately visible on any display, try to adjust it to fit the closest display
+  const closestDisplay = findClosestDisplay(displays, x, y);
+  const { bounds } = closestDisplay;
+
+  // Adjust position to ensure window is fully on screen
+  let adjustedX = x;
+  let adjustedY = y;
+
+  // Adjust horizontal position if needed
+  if (x < bounds.x) {
+    adjustedX = bounds.x;
+  } else if (x + windowWidth > bounds.x + bounds.width) {
+    adjustedX = bounds.x + bounds.width - windowWidth;
+  }
+
+  // Adjust vertical position if needed
+  if (y < bounds.y) {
+    adjustedY = bounds.y;
+  } else if (y + windowHeight > bounds.y + bounds.height) {
+    adjustedY = bounds.y + bounds.height - windowHeight;
+  }
+
+  // If adjustments keep window on screen, use adjusted position
+  if (
+    adjustedX >= bounds.x &&
+    adjustedX + windowWidth <= bounds.x + bounds.width &&
+    adjustedY >= bounds.y &&
+    adjustedY + windowHeight <= bounds.y + bounds.height
+  ) {
+    return { validX: adjustedX, validY: adjustedY };
+  }
+
+  // If all else fails, center on primary display
+  const primaryDisplay = screen.getPrimaryDisplay();
+  const primaryBounds = primaryDisplay.bounds;
+
+  return {
+    validX: Math.floor(
+      primaryBounds.x + (primaryBounds.width - windowWidth) / 2,
+    ),
+    validY: Math.floor(
+      primaryBounds.y + (primaryBounds.height - windowHeight) / 2,
+    ),
+  };
+}
+
+// Helper function to find the closest display to a point
+function findClosestDisplay(
+  displays: Electron.Display[],
+  x: number,
+  y: number,
+): Electron.Display {
+  let closestDisplay = displays[0];
+  let shortestDistance = Number.MAX_VALUE;
+
+  for (const display of displays) {
+    const { bounds } = display;
+    // Calculate distance to center of display
+    const displayCenterX = bounds.x + bounds.width / 2;
+    const displayCenterY = bounds.y + bounds.height / 2;
+
+    const distance = Math.sqrt(
+      Math.pow(x - displayCenterX, 2) + Math.pow(y - displayCenterY, 2),
+    );
+
+    if (distance < shortestDistance) {
+      shortestDistance = distance;
+      closestDisplay = display;
+    }
+  }
+
+  return closestDisplay;
+}
+
+export default ensureWindowOnScreen;