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feat(dragging): Introduce Dragger, implementing IDragger (#7956)

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* feat(dragging): Introduce Dragger, implementing iDragger

* docs(dragging): JSDoc for Dragger's .startLoc
This commit is contained in:
Christopher Allen
2024-03-22 20:03:57 +01:00
committed by GitHub
parent d01f9a73fe
commit 0588dfade8
1 changed files with 77 additions and 0 deletions
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core/dragging/dragger.ts Normal file
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/**
* @license
* Copyright 2024 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import {IDragger} from '../interfaces/i_dragger.js';
import {IDraggable} from '../interfaces/i_draggable.js';
import {Coordinate} from '../utils/coordinate.js';
import {WorkspaceSvg} from '../workspace_svg.js';
export class Dragger implements IDragger {
/** Starting location of the draggable, in workspace coordinates. */
private startLoc: Coordinate;
constructor(
private draggable: IDraggable,
private workspace: WorkspaceSvg,
) {
this.startLoc = draggable.getLocation();
}
/**
* Handles any drag startup.
*
* @param e PointerEvent that started the drag.
*/
onDragStart(e: PointerEvent) {
this.draggable.startDrag(e);
}
/**
* Handles dragging, including calculating where the element should
* actually be moved to.
*
* @param e PointerEvent that continued the drag.
* @param totalDelta The total distance, in pixels, that the mouse
* has moved since the start of the drag.
*/
onDrag(e: PointerEvent, totalDelta: Coordinate) {
this.draggable.drag(this.newLoc(totalDelta), e);
}
/**
* Handles any drag cleanup.
*
* @param e PointerEvent that finished the drag.
* @param totalDelta The total distance, in pixels, that the mouse
* has moved since the start of the drag.
*/
onDragEnd(e: PointerEvent, totalDelta: Coordinate) {
this.draggable.endDrag(this.newLoc(totalDelta), e);
}
/**
* Calculates where the IDraggable should actually be moved to.
*
* @param totalDelta The total distance, in pixels, that the mouse
* has moved since the start of the drag.
* @returns The new location, in workspace coordinates.
*/
protected newLoc(totalDelta: Coordinate): Coordinate {
const result = new Coordinate(
totalDelta.x / this.workspace.scale,
totalDelta.y / this.workspace.scale,
);
if (this.workspace.isMutator) {
// If we're in a mutator, its scale is always 1, purely because of some
// oddities in our rendering optimizations. The actual scale is the same
// as the scale on the parent workspace. Fix that for dragging.
const mainScale = this.workspace.options.parentWorkspace!.scale;
result.scale(1 / mainScale);
}
result.translate(this.startLoc.x, this.startLoc.y);
return result;
}
}