// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview This file provides utility functions for position popups.
*/
/**
* Enum for defining how to anchor a popup to an anchor element.
*/
export enum AnchorType {
/**
* The popup's right edge is aligned with the left edge of the anchor.
* The popup's top edge is aligned with the top edge of the anchor.
*/
BEFORE = 1, // p: right, a: left, p: top, a: top
/**
* The popop's left edge is aligned with the right edge of the anchor.
* The popup's top edge is aligned with the top edge of the anchor.
*/
AFTER = 2, // p: left, a: right, p: top, a: top
/**
* The popop's bottom edge is aligned with the top edge of the anchor.
* The popup's left edge is aligned with the left edge of the anchor.
*/
ABOVE = 3, // p: bottom, a: top, p: left, a: left
/**
* The popop's top edge is aligned with the bottom edge of the anchor.
* The popup's left edge is aligned with the left edge of the anchor.
*/
BELOW = 4, // p: top, a: bottom, p: left, a: left
}
/**
* Helper function for positionPopupAroundElement and positionPopupAroundRect.
* @param anchorRect The rect for the anchor.
* @param popupElement The element used for the popup.
* @param type The type of anchoring to do.
* @param invertLeftRight [Optional] Whether to invert the right/left
* alignment.
*/
function positionPopupAroundRect(
anchorRect: DOMRect, popupElement: HTMLElement, type: AnchorType,
invertLeftRight?: boolean) {
const popupRect = popupElement.getBoundingClientRect();
let availRect;
const ownerDoc = popupElement.ownerDocument;
const cs = ownerDoc.defaultView!.getComputedStyle(popupElement);
const docElement = ownerDoc.documentElement;
if (cs.position === 'fixed') {
// For 'fixed' positioned popups, the available rectangle should be based
// on the viewport rather than the document.
availRect = {
height: docElement.clientHeight,
width: docElement.clientWidth,
top: 0,
bottom: docElement.clientHeight,
left: 0,
right: docElement.clientWidth,
};
} else {
availRect = popupElement.offsetParent!.getBoundingClientRect();
}
if (cs.direction === 'rtl') {
invertLeftRight = !invertLeftRight;
}
// Flip BEFORE, AFTER based on alignment.
if (invertLeftRight) {
if (type === AnchorType.BEFORE) {
type = AnchorType.AFTER;
} else if (type === AnchorType.AFTER) {
type = AnchorType.BEFORE;
}
}
// Flip type based on available size
switch (type) {
case AnchorType.BELOW:
if (anchorRect.bottom + popupRect.height > availRect.height &&
popupRect.height <= anchorRect.top) {
type = AnchorType.ABOVE;
}
break;
case AnchorType.ABOVE:
if (popupRect.height > anchorRect.top &&
anchorRect.bottom + popupRect.height <= availRect.height) {
type = AnchorType.BELOW;
}
break;
case AnchorType.AFTER:
if (anchorRect.right + popupRect.width > availRect.width &&
popupRect.width <= anchorRect.left) {
type = AnchorType.BEFORE;
}
break;
case AnchorType.BEFORE:
if (popupRect.width > anchorRect.left &&
anchorRect.right + popupRect.width <= availRect.width) {
type = AnchorType.AFTER;
}
break;
}
// flipping done
const style = popupElement.style;
// Reset all directions.
style.left = style.right = style.top = style.bottom = 'auto';
// Primary direction
switch (type) {
case AnchorType.BELOW:
if (anchorRect.bottom + popupRect.height <= availRect.height) {
style.top = anchorRect.bottom + 'px';
} else {
style.bottom = '0';
}
break;
case AnchorType.ABOVE:
if (availRect.height - anchorRect.top >= 0) {
style.bottom = availRect.height - anchorRect.top + 'px';
} else {
style.top = '0';
}
break;
case AnchorType.AFTER:
if (anchorRect.right + popupRect.width <= availRect.width) {
style.left = anchorRect.right + 'px';
} else {
style.right = '0';
}
break;
case AnchorType.BEFORE:
if (availRect.width - anchorRect.left >= 0) {
style.right = availRect.width - anchorRect.left + 'px';
} else {
style.left = '0';
}
break;
}
// Secondary direction
switch (type) {
case AnchorType.BELOW:
case AnchorType.ABOVE:
if (invertLeftRight) {
// align right edges
if (anchorRect.right - popupRect.width >= 0) {
style.right = availRect.width - anchorRect.right + 'px';
// align left edges
} else if (anchorRect.left + popupRect.width <= availRect.width) {
style.left = anchorRect.left + 'px';
// not enough room on either side
} else {
style.right = '0';
}
} else {
// align left edges
if (anchorRect.left + popupRect.width <= availRect.width) {
style.left = anchorRect.left + 'px';
// align right edges
} else if (anchorRect.right - popupRect.width >= 0) {
style.right = availRect.width - anchorRect.right + 'px';
// not enough room on either side
} else {
style.left = '0';
}
}
break;
case AnchorType.AFTER:
case AnchorType.BEFORE:
// align top edges
if (anchorRect.top + popupRect.height <= availRect.height) {
style.top = anchorRect.top + 'px';
// align bottom edges
} else if (anchorRect.bottom - popupRect.height >= 0) {
style.bottom = availRect.height - anchorRect.bottom + 'px';
// not enough room on either side
} else {
style.top = '0';
}
break;
}
}
/**
* Positions a popup element relative to an anchor element. The popup element
* should have position set to absolute and it should be a child of the body
* element.
* @param anchorElement The element that the popup is anchored
* to.
* @param popupElement The popup element we are positioning.
* @param type The type of anchoring we want.
* @param invertLeftRight [Optional] Whether to invert the right/left
* alignment.
*/
export function positionPopupAroundElement(
anchorElement: HTMLElement, popupElement: HTMLElement, type: AnchorType,
invertLeftRight?: boolean) {
const anchorRect = anchorElement.getBoundingClientRect();
positionPopupAroundRect(anchorRect, popupElement, type, !!invertLeftRight);
}
/**
* Positions a popup around a point.
* @param x The client x position.
* @param y The client y position.
* @param popupElement The popup element we are positioning.
* @param anchorType [Optional] The type of anchoring we want.
*/
export function positionPopupAtPoint(
x: number, y: number, popupElement: HTMLElement,
anchorType: AnchorType = AnchorType.BELOW) {
positionPopupAroundRect(new DOMRect(x, y, 0, 0), popupElement, anchorType);
}
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