Adding in Drag and Drop support to fix #45 (#56)

* Merging file drop * Fixing double drop
2018-06-29 16:37:48 +01:00
parent 3035a68b90
commit 7c220b1a92
7 changed files with 386 additions and 209 deletions
--- a/src/components/app/custom-els/FileDrop/index.ts
+++ b/src/components/app/custom-els/FileDrop/index.ts
@@ -0,0 +1,116 @@
+import { bind } from '../../../../lib/util';
+import './styles.css';
+
+function firstMatchingItem(list: DataTransferItemList, acceptVal: string): DataTransferItem | undefined {
+  // Split accepts values by ',' then by '/'. Trim everything & lowercase.
+  const accepts = acceptVal.toLowerCase().split(',').map(accept => {
+    return accept.trim().split('/').map(part => part.trim());
+  }).filter(acceptParts => acceptParts.length === 2); // Filter invalid values
+
+  return Array.from(list).find(item => {
+    if (item.kind !== 'file') return false;
+
+    // 'Parse' the type.
+    const [typeMain, typeSub] = item.type.toLowerCase().split('/').map(s => s.trim());
+
+    for (const [acceptMain, acceptSub] of accepts) {
+      // Look for an exact match, or a partial match if * is accepted, eg image/*.
+      if (typeMain === acceptMain && (acceptSub === '*' || typeSub === acceptSub)) {
+        return true;
+      }
+    }
+    return false;
+  });
+}
+
+interface FileDropEventInit extends EventInit {
+  file: File;
+}
+
+export class FileDropEvent extends Event {
+  private _file: File;
+  constructor(typeArg: string, eventInitDict: FileDropEventInit) {
+    super(typeArg, eventInitDict);
+    this._file = eventInitDict.file;
+  }
+
+  get file(): File {
+    return this._file;
+  }
+}
+
+/*
+  Example Usage.
+  <file-drop
+    accept='image/*'
+    class='drop-valid|drop-invalid'
+  >
+   [everything in here is a drop target.]
+  </file-drop>
+
+  dropElement.addEventListner('dropfile', (event) => console.log(event.detail))
+*/
+export class FileDrop extends HTMLElement {
+
+  private _dragEnterCount = 0;
+
+  constructor() {
+    super();
+    this.addEventListener('dragover', (event) => event.preventDefault());
+    this.addEventListener('drop', this._onDrop);
+    this.addEventListener('dragenter', this._onDragEnter);
+    this.addEventListener('dragend', () => this._reset());
+    this.addEventListener('dragleave', this._onDragLeave);
+  }
+
+  get accept() {
+    return this.getAttribute('accept') || '';
+  }
+
+  set accept(val: string) {
+    this.setAttribute('accept', val);
+  }
+
+  @bind
+  private _onDragEnter(event: DragEvent) {
+    this._dragEnterCount++;
+    if (this._dragEnterCount > 1) return;
+
+    // We don't have data, attempt to get it and if it matches, set the correct state.
+    const dragDataItem = firstMatchingItem(event.dataTransfer.items, this.accept);
+    if (dragDataItem) {
+      this.classList.add('drop-valid');
+    } else {
+      this.classList.add('drop-invalid');
+    }
+  }
+
+  @bind
+  private _onDragLeave() {
+    this._dragEnterCount--;
+    if (this._dragEnterCount === 0) {
+      this._reset();
+    }
+  }
+
+  @bind
+  private _onDrop(event: DragEvent) {
+    event.preventDefault();
+    this._reset();
+    const dragDataItem = firstMatchingItem(event.dataTransfer.items, this.accept);
+    if (!dragDataItem) return;
+
+    const file = dragDataItem.getAsFile();
+    if (file === null) return;
+
+    this.dispatchEvent(new FileDropEvent('filedrop', { file }));
+  }
+
+  private _reset() {
+    this._dragEnterCount = 0;
+    this.classList.remove('drop-valid');
+    this.classList.remove('drop-invalid');
+  }
+}
+
+customElements.define('file-drop', FileDrop);