10/UI/DataTable-Ordering touch screen drag and drop 44136

components/ILIAS/UI/resources/js/Table/src/orderingtable.class.js

@@ -25,17 +25,30 @@ export default class OrderingTable {
   #table;
 
   /**
-   * @type {array<HTMLTableRowElement>}
+   * @type {Array<HTMLTableRowElement>}
    */
   #rows;
 
   /**
+   * The original row that is being dragged.
    * @type {HTMLTableRowElement}
    */
-  #tmpDragRow;
+  #originRow;
 
   /**
-   * @param {string} tableId
+   * The clone that will follow the cursor (drag image).
+   * @type {HTMLTableRowElement}
+   */
+  #dragImage;
+
+  /**
+   * The placeholder inserted into the table.
+   * @type {HTMLTableRowElement}
+   */
+  #placeholderRow;
+
+  /**
+   * @param {string} componentId
    * @throws {Error} if DOM element is missing
    */
   constructor(componentId) {
@@ -47,56 +60,163 @@ export default class OrderingTable {
     if (this.#table === null) {
       throw new Error('There is no <table> in the component\'s HTML.');
     }
-
     this.#indexRows();
     this.#rows.forEach((row) => this.#addDraglisteners(row));
   }
 
   #indexRows() {
     this.#rows = Array.from(this.#table.rows);
-    this.#rows.shift();// exclude header
-    this.#rows.pop();// exclude footer
+    this.#rows.shift(); // exclude header
+    this.#rows.pop(); // exclude footer
   }
 
   #addDraglisteners(row) {
     row.setAttribute('draggable', true);
     row.addEventListener('dragstart', (event) => this.dragstart(event));
     row.addEventListener('dragover', (event) => this.dragover(event));
-    row.addEventListener('dragend', () => { this.#indexRows(); this.#renumberAfterDrag(); });
+    row.addEventListener('dragend', (event) => this.dragend(event));
+
+    row.addEventListener('touchstart', (event) => this.touchstart(event));
+    row.addEventListener('touchmove', (event) => this.touchmove(event));
+    row.addEventListener('touchend', (event) => this.touchend(event));
+    row.addEventListener('touchcancel', (event) => this.touchend(event));
   }
 
   dragstart(event) {
-    this.#tmpDragRow = event.target;
-  }
+    this.#component.classList.add('dragInProgress');
+    // Safari requires setting some data
+    event.dataTransfer.setData('text/plain', 'dummy');
 
-  #isDraggedElementValidRow() {
-    return this.#rows.includes(this.#tmpDragRow);
+    this.#originRow = event.target.closest('tr');
+
+    // Create the drag image - cannot use pure browser default because of Safari
+    this.#dragImage = this.#originRow.cloneNode(true);
+    this.#dragImage.classList.add('dragImage');
+    this.#dragImage.style.top = '-9999px';
+    this.#component.appendChild(this.#dragImage);
+    event.dataTransfer.setDragImage(this.#dragImage, 0, 0);
+
+    // Create the placeholder gap between rows to indicate where the item will be dropped
+    this.#placeholderRow = this.#originRow.cloneNode(true);
+    this.#placeholderRow.classList.add('placeholderRow');
+    Array.from(this.#placeholderRow.getElementsByTagName('td'))
+        .forEach((cell) => {
+          cell.innerHTML = '';
+        }
+    );
+
+    // an indicator at the position where the item was before
+    this.#originRow.classList.add('dragOrigin');
   }
 
   dragover(event) {
-    if (!this.#isDraggedElementValidRow()) {
-      return;
+    if (!this.#isDraggedElementValidRow()) return;
+    event.preventDefault();
+    const target = event.target.closest('tr');
+    if (target && target !== this.#placeholderRow) {
+      if (this.#rows.indexOf(target) > this.#rows.indexOf(this.#originRow)) {
+        target.after(this.#placeholderRow);
+      } else {
+        target.before(this.#placeholderRow);
+      }
     }
+  }
 
-    const e = event;
-    e.preventDefault();
-    const target = e.target.closest('tr');
+  dragend(event) {
+    event.preventDefault();
+    this.#component.removeChild(this.#dragImage);
+    this.#placeholderRow.replaceWith(this.#originRow); // drop original where placeholder was
+    this.#originRow.classList.remove('dragOrigin');
+    this.#originRow.classList.add('dragSettle');
+    // this is for the duration of the CSS settle animation
+    setTimeout(
+      () => { this.#originRow.classList.remove('dragSettle'); },
+      200,
+    );
+    this.#component.classList.remove('dragInProgress');
+    this.#indexRows();
+    this.#renumberAfterDrag();
+  }
 
-    if (this.#rows.indexOf(target) > this.#rows.indexOf(this.#tmpDragRow)) {
-      target.after(this.#tmpDragRow);
+  #isDraggedElementValidRow() {
+    return this.#rows.includes(this.#originRow);
+  }
+
+  // Drag and Drop on touch devices
+  touchstart(event) {
+    this.#originRow = event.target.closest('tr');
+
+    this.#placeholderRow = this.#originRow.cloneNode(true);
+    this.#placeholderRow.classList.add('placeholderRow');
+    Array.from(this.#placeholderRow.getElementsByTagName('td'))
+        .forEach(
+            (cell) => {
+              cell.innerHTML = '';}
+        );
+
+    // drag image for touch
+    this.#dragImage = this.#originRow.cloneNode(true);
+    this.#dragImage.classList.add('touchDragImage');
+    this.#component.appendChild(this.#dragImage);
+
+    this.#originRow.classList.add('dragOrigin');
+  }
+
+  touchmove(event) {
+    event.preventDefault();
+    const touch = event.touches[0];
+
+    this.#dragImage.style.left = `${touch.clientX - 50}px`;
+    this.#dragImage.style.top = `${touch.clientY}px`;
+
+    const target = document.elementFromPoint(touch.clientX, touch.clientY)?.closest('tr');
+    if (target && this.#rows.includes(target)) {
+      if (this.#rows.indexOf(target) > this.#rows.indexOf(this.#originRow)) {
+        target.after(this.#placeholderRow);
+      } else {
+        target.before(this.#placeholderRow);
+      }
+    }
+
+    // Scroll viewport if near edges
+    const buffer = 100;
+    const scrollStep = 8;
+    if (touch.clientY < buffer) {
+      this.#startScrolling(-scrollStep);
+    } else if (touch.clientY > window.innerHeight - buffer) {
+      this.#startScrolling(scrollStep);
     } else {
-      target.before(this.#tmpDragRow);
+      this.#stopScrolling();
     }
   }
 
+  touchend() {
+    this.#component.removeChild(this.#dragImage);
+    this.#placeholderRow.replaceWith(this.#originRow);
+    this.#originRow.classList.remove('dragOrigin');
+    this.#indexRows();
+    this.#renumberAfterDrag();
+  }
+
   #renumberAfterDrag() {
     let pos = 10;
-    this.#table.querySelectorAll('input[type="number"]').forEach(
-      (input) => {
-        const field = input;
-        field.value = pos;
-        pos += 10;
-      },
-    );
+    this.#table.querySelectorAll('input[type="number"]').forEach((input) => {
+      input.value = pos;
+      pos += 10;
+    });
+  }
+
+  #startScrolling(step) {
+    if (this.scrollInterval) return;
+    this.scrollInterval = setInterval(() => {
+      window.scrollBy(0, step);
+    }, 16);
+  }
+
+  #stopScrolling() {
+    if (this.scrollInterval) {
+      clearInterval(this.scrollInterval);
+      this.scrollInterval = null;
+    }
   }
 }