From f466f55ff5313aa98c7a41c0db2456e7399c1437 Mon Sep 17 00:00:00 2001
From: Thea Flowers <thea@winterbloom.com>
Date: Tue, 17 Oct 2023 23:20:11 -0400
Subject: [PATCH] Add kc-ui-focus-overlay

---
 src/kc-ui/focus-overlay.ts | 121 +++++++++++++++++++++++++++++++++++++
 src/kc-ui/index.ts         |   1 +
 src/kc-ui/kc-ui.css        |   4 ++
 3 files changed, 126 insertions(+)
 create mode 100644 src/kc-ui/focus-overlay.ts

diff --git a/src/kc-ui/focus-overlay.ts b/src/kc-ui/focus-overlay.ts
new file mode 100644
index 00000000..82718437
--- /dev/null
+++ b/src/kc-ui/focus-overlay.ts
@@ -0,0 +1,121 @@
+/*
+    Copyright (c) 2023 Alethea Katherine Flowers.
+    Published under the standard MIT License.
+    Full text available at: https://opensource.org/licenses/MIT
+*/
+
+import { listen } from "../base/events";
+import { css, html } from "../base/web-components";
+import { KCUIElement } from "./element";
+
+/**
+ * kc-ui-focus-overlay is an element that shows an overlay over its siblings
+ * until the user clicks within.
+ */
+export class KCUIFocusOverlay extends KCUIElement {
+    static override styles = [
+        ...KCUIElement.styles,
+        css`
+            :host {
+                z-index: 10;
+                user-select: none;
+                position: absolute;
+                top: 0;
+                left: 0;
+                width: 100%;
+                height: 100%;
+                display: flex;
+                align-items: center;
+                justify-content: center;
+                pointer-events: initial;
+                background: transparent;
+                contain: paint;
+            }
+
+            :host(.has-focus) {
+                z-index: -10;
+                pointer-events: none;
+            }
+
+            .bg {
+                background: var(--focus-overlay-bg);
+                opacity: 0;
+                transition: opacity var(--transition-time-short);
+                position: absolute;
+                top: 0;
+                left: 0;
+                width: 100%;
+                height: 100%;
+                pointer-events: none;
+            }
+
+            :host(:hover) .bg {
+                opacity: var(--focus-overlay-opacity);
+            }
+
+            :host(.has-focus) .bg {
+                opacity: 0;
+            }
+
+            .fg {
+                position: absolute;
+                font-size: 1.5rem;
+                color: var(--focus-overlay-fg);
+                text-shadow: rgba(0, 0, 0, 0.5) 0px 0px 15px;
+                opacity: 0;
+                pointer-events: none;
+            }
+
+            :host(:hover) .fg {
+                opacity: 1;
+            }
+
+            :host(.has-focus) .fg {
+                opacity: 0;
+            }
+        `,
+    ];
+
+    #intersection_observer: IntersectionObserver;
+
+    override initialContentCallback(): void | undefined {
+        this.addEventListener("click", () => {
+            this.classList.add("has-focus");
+        });
+
+        this.addDisposable(
+            listen(document, "click", (e) => {
+                const outside = !e.composedPath().includes(this.parentElement!);
+                if (outside) {
+                    this.classList.remove("has-focus");
+                }
+            }),
+        );
+
+        this.#intersection_observer = new IntersectionObserver((entries) => {
+            for (const entry of entries) {
+                console.log(entry);
+                if (!entry.isIntersecting) {
+                    this.classList.remove("has-focus");
+                }
+            }
+        });
+
+        this.#intersection_observer.observe(this);
+
+        this.addDisposable({
+            dispose: () => {
+                this.#intersection_observer.disconnect();
+            },
+        });
+    }
+
+    override render() {
+        return html`
+            <div class="bg"></div>
+            <div class="fg">Click or tap to interact</div>
+        `;
+    }
+}
+
+window.customElements.define("kc-ui-focus-overlay", KCUIFocusOverlay);
diff --git a/src/kc-ui/index.ts b/src/kc-ui/index.ts
index 22e64e0d..654ea504 100644
--- a/src/kc-ui/index.ts
+++ b/src/kc-ui/index.ts
@@ -12,6 +12,7 @@ export * from "./dropdown";
 export * from "./element";
 export * from "./filtered-list";
 export * from "./floating-toolbar";
+export * from "./focus-overlay";
 export * from "./icon";
 export * from "./menu";
 export * from "./panel";
diff --git a/src/kc-ui/kc-ui.css b/src/kc-ui/kc-ui.css
index bb5cafde..69d9fb09 100644
--- a/src/kc-ui/kc-ui.css
+++ b/src/kc-ui/kc-ui.css
@@ -200,6 +200,10 @@
 
     --list-item-hover-bg: var(--gradient-purple-green-highlight);
     --list-item-active-bg: var(--gradient-cyan-blue-light);
+
+    --focus-overlay-bg: var(--gradient-purple-green-light);
+    --focus-overlay-opacity: 0.5;
+    --focus-overlay-fg: #f8f8f0;
 }
 
 /*