feat: Initial clean release of CHM

packages/lib/utils/focusHandler.ts

@@ -0,0 +1,51 @@
+// The purpose of this handler is to have all focus/blur calls go through the same place, which
+// makes it easier to log what happens. This is useful when one unknown component is stealing focus
+// from another component. Potentially it could also be used to resolve conflict situations when
+// multiple components try to set the focus at the same time.
+
+import Logger from '@joplin/utils/Logger';
+
+const logger = Logger.create('focusHandler');
+
+enum ToggleFocusAction {
+	Focus = 'focus',
+	Blur = 'blur',
+}
+
+interface FocusOptions {
+	preventScroll: boolean;
+}
+
+type MaybeFocusable = {
+	focus?: (...args: unknown[])=> void;
+	blur?: (...args: unknown[])=> void;
+};
+
+const toggleFocus = (source: string, element: unknown, action: ToggleFocusAction, options: FocusOptions|null) => {
+	if (!element) {
+		logger.warn(`Tried action "${action}" on an undefined element: ${source}`);
+		return;
+	}
+
+	const focusable = element as MaybeFocusable;
+	const fn = focusable[action];
+	if (typeof fn !== 'function') {
+		logger.warn(`Element does not have a "${action}" method: ${source}`);
+		return;
+	}
+
+	logger.debug(`Action "${action}" from "${source}"`);
+	if (options) {
+		fn.call(focusable, options);
+	} else {
+		fn.call(focusable);
+	}
+};
+
+export const focus = (source: string, element: unknown, options: FocusOptions|null = null) => {
+	toggleFocus(source, element, ToggleFocusAction.Focus, options);
+};
+
+export const blur = (source: string, element: unknown) => {
+	toggleFocus(source, element, ToggleFocusAction.Blur, null);
+};