TypeScript IMouseEvent.preventDefault方法代码示例

	private _sliderMouseDown(e: IMouseEvent): void {
		if (e.leftButton) {
			let initialMouseOrthogonalPosition = this._sliderOrthogonalMousePosition(e);
			let initialScrollPosition = this._getScrollPosition();
			let draggingDelta = this._sliderMousePosition(e) - this._scrollbarState.getSliderPosition();
			this.slider.toggleClassName('active', true);

			this._mouseMoveMonitor.startMonitoring(
				standardMouseMoveMerger,
				(mouseMoveData: IStandardMouseMoveEventData) => {
					let mouseOrthogonalPosition = this._sliderOrthogonalMousePosition(mouseMoveData);
					let mouseOrthogonalDelta = Math.abs(mouseOrthogonalPosition - initialMouseOrthogonalPosition);
					// console.log(initialMouseOrthogonalPosition + ' -> ' + mouseOrthogonalPosition + ': ' + mouseOrthogonalDelta);
					if (Platform.isWindows && mouseOrthogonalDelta > MOUSE_DRAG_RESET_DISTANCE) {
						// The mouse has wondered away from the scrollbar => reset dragging
						this.setDesiredScrollPosition(initialScrollPosition);
					} else {
						let desiredSliderPosition = this._sliderMousePosition(mouseMoveData) - draggingDelta;
						this.setDesiredScrollPosition(this._scrollbarState.convertSliderPositionToScrollPosition(desiredSliderPosition));
					}
				},
				() => {
					this.slider.toggleClassName('active', false);
					this._host.onDragEnd();
				}
			);

			e.preventDefault();
			this._host.onDragStart();
		}
	}

	private _arrowMouseDown(e: IMouseEvent): void {
		let repeater = () => {
			this._parent.onMouseWheel(this._mouseWheelEventFactory());
		};

		let scheduleRepeater = () => {
			this._mousedownRepeatTimer.cancelAndSet(repeater, 1000 / 24);
		};

		repeater();
		this._mousedownRepeatTimer.cancel();
		this._mousedownScheduleRepeatTimer.cancelAndSet(scheduleRepeater, 200);

		this._mouseMoveMonitor.startMonitoring(
			standardMouseMoveMerger,
			(mouseMoveData: IStandardMouseMoveEventData) => {
				/* Intentional empty */
			},
			() => {
				this._mousedownRepeatTimer.cancel();
				this._mousedownScheduleRepeatTimer.cancel();
			}
		);

		e.preventDefault();
	}

	private _onMouseDown(e: IMouseEvent): void {
		let domNodePosition = DomUtils.getDomNodePagePosition(this.domNode.domNode);
		this._setDesiredScrollPositionNow(this._scrollbarState.getDesiredScrollPositionFromOffset(this._mouseDownRelativePosition(e, domNodePosition)));
		if (e.leftButton) {
			e.preventDefault();
			this._sliderMouseDown(e, () => { /*nothing to do*/ });
		}
	}

	public delegateMouseDown(e: IMouseEvent): void {
		let domTop = this.domNode.domNode.getClientRects()[0].top;
		let sliderStart = domTop + this._scrollbarState.getSliderPosition();
		let sliderStop = domTop + this._scrollbarState.getSliderPosition() + this._scrollbarState.getSliderSize();
		let mousePos = this._sliderMousePosition(e);
		if (sliderStart <= mousePos && mousePos <= sliderStop) {
			// Act as if it was a mouse down on the slider
			if (e.leftButton) {
				e.preventDefault();
				this._sliderMouseDown(e, () => { /*nothing to do*/ });
			}
		} else {
			// Act as if it was a mouse down on the scrollbar
			this._onMouseDown(e);
		}
	}

	private _onMouseDown(e: IMouseEvent): void {
		let offsetX: number;
		let offsetY: number;
		if (e.target === this.domNode.domNode && typeof e.browserEvent.offsetX === 'number' && typeof e.browserEvent.offsetY === 'number') {
			offsetX = e.browserEvent.offsetX;
			offsetY = e.browserEvent.offsetY;
		} else {
			const domNodePosition = DomUtils.getDomNodePagePosition(this.domNode.domNode);
			offsetX = e.posx - domNodePosition.left;
			offsetY = e.posy - domNodePosition.top;
		}
		this._setDesiredScrollPositionNow(this._scrollbarState.getDesiredScrollPositionFromOffset(this._mouseDownRelativePosition(offsetX, offsetY)));
		if (e.leftButton) {
			e.preventDefault();
			this._sliderMouseDown(e, () => { /*nothing to do*/ });
		}
	}

	protected onLeftClick(tree: ITree, element: any, event: IMouseEvent, origin: string = 'mouse'): boolean {
		// In file browser, double clicking an element calls tree.dispose(). There should not be any tree events after selection.
		if (event.detail === 2) {
			var payload = { origin: origin, originalEvent: event };
			if (tree.getInput() === element) {
				tree.clearFocus(payload);
				tree.clearSelection(payload);
			} else {
				var isMouseDown = event && event.browserEvent && event.browserEvent.type === 'mousedown';
				if (!isMouseDown) {
					event.preventDefault(); // we cannot preventDefault onMouseDown because this would break DND otherwise
				}
				event.stopPropagation();
				tree.DOMFocus();
				tree.setSelection([element], payload);
			}
			return true;
		} else {
			return super.onLeftClick(tree, element, event, origin);
		}
	}

	private _arrowMouseDown(e: IMouseEvent): void {
		let scheduleRepeater = () => {
			this._mousedownRepeatTimer.cancelAndSet(() => this._onActivate(), 1000 / 24);
		};

		this._onActivate();
		this._mousedownRepeatTimer.cancel();
		this._mousedownScheduleRepeatTimer.cancelAndSet(scheduleRepeater, 200);

		this._mouseMoveMonitor.startMonitoring(
			standardMouseMoveMerger,
			(mouseMoveData: IStandardMouseMoveEventData) => {
				/* Intentional empty */
			},
			() => {
				this._mousedownRepeatTimer.cancel();
				this._mousedownScheduleRepeatTimer.cancel();
			}
		);

		e.preventDefault();
	}