55 lines
2.1 KiB
TypeScript
55 lines
2.1 KiB
TypeScript
/*
|
|
Copyright 2024 New Vector Ltd.
|
|
Copyright 2015, 2016 , 2020 Copyright 2020 The Matrix.org Foundation C.I.C.
|
|
|
|
SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only
|
|
Please see LICENSE files in the repository root for full details.
|
|
*/
|
|
|
|
/**
|
|
* Returns the actual height that an image of dimensions (fullWidth, fullHeight)
|
|
* will occupy if resized to fit inside a thumbnail bounding box of size
|
|
* (thumbWidth, thumbHeight).
|
|
*
|
|
* If the aspect ratio of the source image is taller than the aspect ratio of
|
|
* the thumbnail bounding box, then we return the thumbHeight parameter unchanged.
|
|
* Otherwise we return the thumbHeight parameter scaled down appropriately to
|
|
* reflect the actual height the scaled thumbnail occupies.
|
|
*
|
|
* This is very useful for calculating how much height a thumbnail will actually
|
|
* consume in the timeline, when performing scroll offset calculations
|
|
* (e.g. scroll locking)
|
|
*/
|
|
export function thumbHeight(fullWidth: number, fullHeight: number, thumbWidth: number, thumbHeight: number): number;
|
|
export function thumbHeight(
|
|
fullWidth: number | undefined,
|
|
fullHeight: number | undefined,
|
|
thumbWidth: number,
|
|
thumbHeight: number,
|
|
): null;
|
|
export function thumbHeight(
|
|
fullWidth: number | undefined,
|
|
fullHeight: number | undefined,
|
|
thumbWidth: number,
|
|
thumbHeight: number,
|
|
): number | null {
|
|
if (!fullWidth || !fullHeight) {
|
|
// Cannot calculate thumbnail height for image: missing w/h in metadata. We can't even
|
|
// log this because it's spammy
|
|
return null;
|
|
}
|
|
if (fullWidth < thumbWidth && fullHeight < thumbHeight) {
|
|
// no scaling needs to be applied
|
|
return fullHeight;
|
|
}
|
|
const widthMulti = thumbWidth / fullWidth;
|
|
const heightMulti = thumbHeight / fullHeight;
|
|
if (widthMulti < heightMulti) {
|
|
// width is the dominant dimension so scaling will be fixed on that
|
|
return Math.floor(widthMulti * fullHeight);
|
|
} else {
|
|
// height is the dominant dimension so scaling will be fixed on that
|
|
return Math.floor(heightMulti * fullHeight);
|
|
}
|
|
}
|