From d522fb67cf7e3a3b28a9b657a46db738c260864e Mon Sep 17 00:00:00 2001
From: Joao Moreno <jomo@microsoft.com>
Date: Sun, 17 Sep 2017 16:59:11 +0200
Subject: [PATCH] panelview: dnd

---
 src/vs/base/browser/ui/splitview/panelview.ts | 120 +++++++++++++++++-
 1 file changed, 116 insertions(+), 4 deletions(-)

diff --git a/src/vs/base/browser/ui/splitview/panelview.ts b/src/vs/base/browser/ui/splitview/panelview.ts
index 157be8261dc..97c8e20274c 100644
--- a/src/vs/base/browser/ui/splitview/panelview.ts
+++ b/src/vs/base/browser/ui/splitview/panelview.ts
@@ -6,13 +6,14 @@
 'use strict';
 
 import 'vs/css!./splitview';
-import { IDisposable, dispose } from 'vs/base/common/lifecycle';
+import { IDisposable, dispose, combinedDisposable } from 'vs/base/common/lifecycle';
 import Event, { Emitter, chain } from 'vs/base/common/event';
 import { domEvent } from 'vs/base/browser/event';
 import { StandardKeyboardEvent } from 'vs/base/browser/keyboardEvent';
 import { KeyCode } from 'vs/base/common/keyCodes';
 import { $, append, addClass, removeClass, toggleClass } from 'vs/base/browser/dom';
 import { firstIndex } from 'vs/base/common/arrays';
+import { Color } from 'vs/base/common/color';
 import { SplitView, IView } from './splitview2';
 
 enum PanelState {
@@ -36,7 +37,7 @@ export abstract class Panel implements IView {
 	private _minimumBodySize: number;
 	private _maximumBodySize: number;
 	private ariaHeaderLabel: string;
-	private header: HTMLElement;
+	readonly header: HTMLElement;
 	private disposables: IDisposable[] = [];
 
 	get minimumBodySize(): number {
@@ -155,6 +156,95 @@ export abstract class Panel implements IView {
 	}
 }
 
+interface IDndContext {
+	draggable: PanelDraggable | null;
+}
+
+class PanelDraggable implements IDisposable {
+
+	// see https://github.com/Microsoft/vscode/issues/14470
+	private dragOverCounter = 0;
+	private dropBackground: Color | undefined;
+	private disposables: IDisposable[] = [];
+
+	private _onDidDrop = new Emitter<{ from: Panel, to: Panel }>();
+	readonly onDidDrop = this._onDidDrop.event;
+
+	constructor(private panel: Panel, private context: IDndContext) {
+		domEvent(panel.header, 'dragstart')(this.onDragStart, this, this.disposables);
+		domEvent(panel.header, 'dragenter')(this.onDragEnter, this, this.disposables);
+		domEvent(panel.header, 'dragleave')(this.onDragLeave, this, this.disposables);
+		domEvent(panel.header, 'dragend')(this.onDragEnd, this, this.disposables);
+		domEvent(panel.header, 'drop')(this.onDrop, this, this.disposables);
+	}
+
+	private onDragStart(e: DragEvent): void {
+		e.dataTransfer.effectAllowed = 'move';
+
+		const dragImage = append(document.body, $('.monaco-panel-drag-image', {}, this.panel.header.textContent));
+		e.dataTransfer.setDragImage(dragImage, -10, -10);
+		setTimeout(() => document.body.removeChild(dragImage), 0);
+
+		this.context.draggable = this;
+	}
+
+	private onDragEnter(e: DragEvent): void {
+		if (!this.context.draggable || this.context.draggable === this) {
+			return;
+		}
+
+		this.dragOverCounter++;
+		this.renderHeader();
+	}
+
+	private onDragLeave(e: DragEvent): void {
+		if (!this.context.draggable || this.context.draggable === this) {
+			return;
+		}
+
+		this.dragOverCounter--;
+
+		if (this.dragOverCounter === 0) {
+			this.renderHeader();
+		}
+	}
+
+	private onDragEnd(e: DragEvent): void {
+		if (!this.context.draggable) {
+			return;
+		}
+
+		this.dragOverCounter = 0;
+		this.renderHeader();
+		this.context.draggable = null;
+	}
+
+	private onDrop(e: DragEvent): void {
+		if (!this.context.draggable) {
+			return;
+		}
+
+		this.dragOverCounter = 0;
+		this.renderHeader();
+
+		if (this.context.draggable !== this) {
+			this._onDidDrop.fire({ from: this.context.draggable.panel, to: this.panel });
+		}
+
+		this.context.draggable = null;
+	}
+
+	private renderHeader(): void {
+		this.panel.header.style.backgroundColor = this.dragOverCounter === 0 && this.dropBackground
+			? this.dropBackground.toString()
+			: null;
+	}
+
+	dispose(): void {
+		this.disposables = dispose(this.disposables);
+	}
+}
+
 export class IPanelViewOptions {
 	dnd?: boolean;
 }
@@ -166,19 +256,30 @@ interface IPanelItem {
 
 export class PanelView implements IDisposable {
 
+	private dnd: boolean;
+	private dndContext: IDndContext = { draggable: null };
 	private el: HTMLElement;
 	private panelItems: IPanelItem[] = [];
 	private splitview: SplitView;
 	private animationTimer: number | null = null;
 
 	constructor(private container: HTMLElement, options?: IPanelViewOptions) {
+		this.dnd = !!options.dnd;
 		this.el = append(container, $('.monaco-panel-view'));
 		this.splitview = new SplitView(container);
 	}
 
 	addPanel(panel: Panel, size: number, index = this.splitview.length): void {
-		const disposable = panel.onDidChange(this.setupAnimation, this);
-		const panelItem = { panel, disposable };
+		const disposables: IDisposable[] = [];
+		panel.onDidChange(this.setupAnimation, this, disposables);
+
+		if (this.dnd) {
+			const draggable = new PanelDraggable(panel, this.dndContext);
+			disposables.push(draggable);
+			draggable.onDidDrop(({ from, to }) => this.movePanel(from, to), null, disposables);
+		}
+
+		const panelItem = { panel, disposable: combinedDisposable(disposables) };
 
 		this.panelItems.splice(index, 0, panelItem);
 		this.splitview.addView(panel, size, index);
@@ -196,6 +297,17 @@ export class PanelView implements IDisposable {
 		panelItem.disposable.dispose();
 	}
 
+	movePanel(from: Panel, to: Panel): void {
+		const fromIndex = firstIndex(this.panelItems, item => item.panel === from);
+		const toIndex = firstIndex(this.panelItems, item => item.panel === to);
+
+		if (fromIndex === -1 || toIndex === -1) {
+			return;
+		}
+
+		this.splitview.moveView(fromIndex, toIndex);
+	}
+
 	layout(size: number): void {
 		this.splitview.layout(size);
 	}