1 files changed, 160 insertions, 0 deletions
diff --git a/app/window-controller.js b/app/window-controller.js
new file mode 100644
index 0000000000..849da007cf
--- /dev/null
+++ b/app/window-controller.js
@@ -0,0 +1,160 @@
+// @flow
+
+import electron, { screen } from 'electron';
+import type { BrowserWindow, Tray, Display } from 'electron';
+
+export default class WindowController {
+  _window: BrowserWindow;
+  _tray: Tray;
+  _isWindowReady = false;
+
+  get window(): BrowserWindow {
+    return this._window;
+  }
+
+  constructor(window: BrowserWindow, tray: Tray) {
+    this._window = window;
+    this._tray = tray;
+
+    this._installDisplayMetricsHandler();
+    this._installWindowReadyHandlers();
+  }
+
+  show(whenReady: boolean = true) {
+    if (whenReady) {
+      this._executeWhenWindowIsReady(() => this._showImmediately());
+    } else {
+      this._showImmediately();
+    }
+  }
+
+  hide() {
+    this._window.hide();
+  }
+
+  toggle() {
+    if (this._window.isVisible()) {
+      this.hide();
+    } else {
+      this.show();
+    }
+  }
+
+  _showImmediately() {
+    const window = this._window;
+
+    this._updatePosition();
+
+    window.show();
+    window.focus();
+  }
+
+  _updatePosition() {
+    const { x, y } = this._getWindowPosition();
+    this._window.setPosition(x, y, false);
+  }
+
+  _getTrayPlacement() {
+    switch (process.platform) {
+      case 'darwin':
+        // macOS has menubar always placed at the top
+        return 'top';
+
+      case 'win32': {
+        // taskbar occupies some part of the screen excluded from work area
+        const primaryDisplay = electron.screen.getPrimaryDisplay();
+        const displaySize = primaryDisplay.size;
+        const workArea = primaryDisplay.workArea;
+
+        if (workArea.width < displaySize.width) {
+          return workArea.x > 0 ? 'left' : 'right';
+        } else if (workArea.height < displaySize.height) {
+          return workArea.y > 0 ? 'top' : 'bottom';
+        } else {
+          return 'none';
+        }
+      }
+
+      default:
+        return 'none';
+    }
+  }
+
+  _getWindowPosition(): { x: number, y: number } {
+    const windowBounds = this._window.getBounds();
+    const trayBounds = this._tray.getBounds();
+
+    const primaryDisplay = electron.screen.getPrimaryDisplay();
+    const workArea = primaryDisplay.workArea;
+    const placement = this._getTrayPlacement();
+    const maxX = workArea.x + workArea.width - windowBounds.width;
+    const maxY = workArea.y + workArea.height - windowBounds.height;
+
+    let x = 0,
+      y = 0;
+    switch (placement) {
+      case 'top':
+        x = trayBounds.x + (trayBounds.width - windowBounds.width) * 0.5;
+        y = workArea.y;
+        break;
+
+      case 'bottom':
+        x = trayBounds.x + (trayBounds.width - windowBounds.width) * 0.5;
+        y = workArea.y + workArea.height - windowBounds.height;
+        break;
+
+      case 'left':
+        x = workArea.x;
+        y = trayBounds.y + (trayBounds.height - windowBounds.height) * 0.5;
+        break;
+
+      case 'right':
+        x = workArea.width - windowBounds.width;
+        y = trayBounds.y + (trayBounds.height - windowBounds.height) * 0.5;
+        break;
+
+      case 'none':
+        x = workArea.x + (workArea.width - windowBounds.width) * 0.5;
+        y = workArea.y + (workArea.height - windowBounds.height) * 0.5;
+        break;
+    }
+
+    x = Math.min(Math.max(x, workArea.x), maxX);
+    y = Math.min(Math.max(y, workArea.y), maxY);
+
+    return {
+      x: Math.round(x),
+      y: Math.round(y),
+    };
+  }
+
+  // Installs display event handlers to update the window position on any changes in the display or workarea dimensions.
+  _installDisplayMetricsHandler() {
+    screen.addListener('display-metrics-changed', this._onDisplayMetricsChanged);
+    this._window.once('closed', () => {
+      screen.removeListener('display-metrics-changed', this._onDisplayMetricsChanged);
+    });
+  }
+
+  _onDisplayMetricsChanged = (_event: any, _display: Display, changedMetrics: Array<string>) => {
+    if (changedMetrics.includes('workArea') && this._window.isVisible()) {
+      this._updatePosition();
+    }
+  };
+
+  _installWindowReadyHandlers() {
+    this._window.once('ready-to-show', () => {
+      this._isWindowReady = true;
+    });
+  }
+
+  _executeWhenWindowIsReady(closure: () => any) {
+    if (this._isWindowReady) {
+      closure();
+    } else {
+      this._window.once('ready-to-show', () => {
+        closure();
+      });
+    }
+  }
+}