Merge branch 'master' into move_doc_get_out_the_way

1 files changed, 155 insertions, 0 deletions

diff --git a/src/util/DragManager.ts b/src/util/DragManager.ts
new file mode 100644
index 000000000..3111d589f
--- /dev/null
+++ b/src/util/DragManager.ts
@@ -0,0 +1,155 @@
+import { Opt } from "../fields/Field";
+
+export namespace DragManager {
+    export let rootId = "root";
+    let dragDiv: HTMLDivElement;
+
+    export enum DragButtons {
+        Left = 1, Right = 2, Both = Left | Right
+    }
+
+    interface DragOptions {
+        handlers: DragHandlers;
+
+        buttons: number;
+    }
+
+    export interface DragDropDisposer {
+        (): void;
+    }
+
+    export class DragStartEvent {
+        private _cancelled: boolean = false;
+        get cancelled() { return this._cancelled };
+
+        cancel() { this._cancelled = true; };
+    }
+
+    export class DragCompleteEvent {
+
+    }
+
+    export interface DragHandlers {
+        dragStart: (e: DragStartEvent) => void;
+        dragComplete: (e: DragCompleteEvent) => void;
+    }
+
+    export interface DropOptions {
+        handlers: DropHandlers;
+    }
+
+    export class DropEvent {
+        constructor(readonly x: number, readonly y: number) { }
+    }
+
+    export interface DropHandlers {
+        drop: (e: DropEvent) => void;
+    }
+
+    export function MakeDraggable(element: HTMLElement, options: DragOptions): DragDropDisposer {
+        if ("draggable" in element.dataset) {
+            throw new Error("Element is already draggable, can't make it draggable again");
+        }
+        element.dataset["draggable"] = "true";
+        const dispose = () => {
+            document.removeEventListener("pointerup", upHandler);
+            document.removeEventListener("pointermove", startDragHandler);
+        }
+        const startDragHandler = (e: PointerEvent) => {
+            e.stopPropagation();
+            e.preventDefault();
+            dispose();
+            StartDrag(element, e, options);
+        }
+        const upHandler = (e: PointerEvent) => {
+            dispose();
+        };
+        const downHandler = (e: PointerEvent) => {
+            e.stopPropagation();
+            document.addEventListener("pointermove", startDragHandler);
+            document.addEventListener("pointerup", upHandler);
+        };
+        element.addEventListener("pointerdown", downHandler);
+
+        return () => {
+            element.removeEventListener("pointerdown", downHandler);
+            delete element.dataset["draggable"];
+        }
+    }
+
+    export function MakeDropTarget(element: HTMLElement, options: DropOptions): DragDropDisposer {
+        if ("draggable" in element.dataset) {
+            throw new Error("Element is already droppable, can't make it droppable again");
+        }
+        element.dataset["canDrop"] = "true";
+        const handler = (e: Event) => {
+            const ce = e as CustomEvent<DropEvent>;
+            options.handlers.drop(ce.detail);
+        };
+        element.addEventListener("dashOnDrop", handler);
+        return () => {
+            element.removeEventListener("dashOnDrop", handler);
+            delete element.dataset["canDrop"]
+        };
+    }
+
+    function StartDrag(ele: HTMLElement, e: PointerEvent, options: DragOptions) {
+        if (!dragDiv) {
+            const root = document.getElementById(rootId);
+            if (!root) {
+                throw new Error("No root element found");
+            }
+            dragDiv = document.createElement("div");
+            root.appendChild(dragDiv);
+        }
+        if ((e.buttons & options.buttons) === 0) {
+            return;
+        }
+        let event = new DragStartEvent();
+        options.handlers.dragStart(event);
+        if (event.cancelled) {
+            return;
+        }
+        const w = ele.offsetWidth, h = ele.offsetHeight;
+        const rect = ele.getBoundingClientRect();
+        const scaleX = rect.width / w, scaleY = rect.height / h;
+        let x = rect.left, y = rect.top;
+        // const offsetX = e.x - rect.left, offsetY = e.y - rect.top;
+        let dragElement = ele.cloneNode(true) as HTMLElement;
+        dragElement.style.opacity = "0.7";
+        dragElement.style.position = "absolute";
+        dragElement.style.transformOrigin = "0 0";
+        dragElement.style.transform = `translate(${x}px, ${y}px) scale(${scaleX}, ${scaleY})`;
+        dragDiv.appendChild(dragElement);
+
+        const moveHandler = (e: PointerEvent) => {
+            e.stopPropagation();
+            e.preventDefault();
+            x += e.movementX;
+            y += e.movementY;
+            dragElement.style.transform = `translate(${x}px, ${y}px) scale(${scaleX}, ${scaleY})`;
+        };
+        const upHandler = (e: PointerEvent) => {
+            document.removeEventListener("pointermove", moveHandler, true);
+            document.removeEventListener("pointerup", upHandler);
+            FinishDrag(dragElement, e, options);
+        };
+        document.addEventListener("pointermove", moveHandler, true);
+        document.addEventListener("pointerup", upHandler);
+    }
+
+    function FinishDrag(ele: HTMLElement, e: PointerEvent, options: DragOptions) {
+        dragDiv.removeChild(ele);
+        const target = document.elementFromPoint(e.x, e.y);
+        if (!target) {
+            return;
+        }
+        target.dispatchEvent(new CustomEvent<DropEvent>("dashOnDrop", {
+            bubbles: true,
+            detail: {
+                x: e.x,
+                y: e.y,
+            }
+        }));
+    }
+}
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