First version

tp-vsplitter.js

@@ -0,0 +1,99 @@
+/**
+@license
+Copyright (c) 2023 trading_peter
+*/
+
+import { LitElement, html, css } from 'lit';
+
+class TpVSplitter extends LitElement {
+  static get styles() {
+    return [
+      css`
+        :host {
+          display: grid;
+          grid-template-columns: 1fr 5px 1fr;
+        }
+
+        #left,
+        #right {
+          position: relative;
+          overflow: hidden;
+        }
+
+        .splitter {
+          background: var(--lighter-black);
+          cursor: col-resize;
+          opacity: 1;
+        }
+
+        .splitter:hover {
+          background: var(--hl-color);
+          opacity: 0.5;
+        }
+      `
+    ];
+  }
+
+  render() {
+    return html`
+      <div id="left"><slot name="left"></slot></div>
+      <div class="splitter" @mousedown=${this._enableDrag}></div>
+      <div id="right"><slot name="right"></slot></div>
+    `;
+  }
+
+  static get properties() {
+    return {
+      columns: { type: String },
+      _dragging: { type: Boolean },
+    };
+  }
+
+  constructor() {
+    super();
+
+    this._disableDrag = this._disableDrag.bind(this);
+    this._resize = this._resize.bind(this);
+  }
+
+  get left() {
+    return this.shadowRoot.querySelector('#left');
+  }
+
+  get right() {
+    return this.shadowRoot.querySelector('#right');
+  }
+
+  shouldUpdate(changes) {
+    if (changes.has('columns')) {
+      this.style.gridTemplateColumns = this.columns;
+    }
+
+    return true;
+  }
+
+  _enableDrag(e) {
+    document.addEventListener('mouseup', this._disableDrag)
+    document.addEventListener('mousemove', this._resize);
+    document.body.style['userSelect'] = 'none';
+    this._startX = e.clientX;
+    this._topWidth = this.left.offsetWidth;
+    this._dragging = true;
+  }
+
+  _disableDrag() {
+    document.removeEventListener('mouseup', this._disableDrag)
+    document.removeEventListener('mousemove', this._resize);
+    document.body.style['userSelect'] = '';
+    this._dragging = false;
+    this.dispatchEvent(new CustomEvent('resize-done', { detail: this.style.gridTemplateColumns, bubbles: true, composed: true }));
+  }
+
+  _resize(e) {
+    const delta = e.clientX - this._startX;
+    this.style.gridTemplateColumns = `${this._topWidth + delta}px 5px 1fr`;
+    this.dispatchEvent(new CustomEvent('resized', { detail: null, bubbles: true, composed: true }));
+  }
+}
+
+window.customElements.define('tp-vsplitter', TpVSplitter);