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configurable allowance

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This commit is contained in:
Ryan Di 2025-05-02 17:52:14 +10:00
parent 2d0c0afa34
commit 4208c97b62
1 changed files with 16 additions and 8 deletions
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24
packages/excalidraw/scene/scrollConstraints.ts
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@ -11,6 +11,7 @@ import { getNormalizedZoom } from "./normalize";
*
* @param scrollConstraints - The constraints of the scrollable area including width, height, and position.
* @param appState - An object containing the current horizontal and vertical scroll positions.
* @param overscrollAllowance - Optional parameter to specify the overscroll allowance percentage.
* @returns An object containing the calculated optimal horizontal and vertical scroll positions and zoom level.
*
* @example
@ -20,6 +21,7 @@ import { getNormalizedZoom } from "./normalize";
export const calculateConstrainedScrollCenter = (
state: AppState,
{ scrollX, scrollY }: Pick<AppState, "scrollX" | "scrollY">,
overscrollAllowance?: number,
): {
scrollX: AppState["scrollX"];
scrollY: AppState["scrollY"];
@ -57,6 +59,7 @@ export const calculateConstrainedScrollCenter = (
height,
zoom: _zoom,
allowOverscroll: false,
overscrollAllowance,
});
return {
@ -167,15 +170,22 @@ const calculateConstraints = ({
height,
zoom,
allowOverscroll,
overscrollAllowance,
}: {
scrollConstraints: ScrollConstraints;
width: AppState["width"];
height: AppState["height"];
zoom: AppState["zoom"];
allowOverscroll: boolean;
overscrollAllowance?: number;
}) => {
// Set the overscroll allowance percentage
const OVERSCROLL_ALLOWANCE_PERCENTAGE = 0.2;
// Validate the overscroll allowance percentage
const validatedOverscroll =
overscrollAllowance != null &&
overscrollAllowance >= 0 &&
overscrollAllowance <= 1
? overscrollAllowance
: 0.2;
/**
* Calculates the center position of the constrained scroll area.
@ -194,10 +204,8 @@ const calculateConstraints = ({
* @returns The overscroll allowance values for the X and Y axes.
*/
const calculateOverscrollAllowance = () => {
const overscrollAllowanceX =
OVERSCROLL_ALLOWANCE_PERCENTAGE * scrollConstraints.width;
const overscrollAllowanceY =
OVERSCROLL_ALLOWANCE_PERCENTAGE * scrollConstraints.height;
const overscrollAllowanceX = validatedOverscroll * scrollConstraints.width;
const overscrollAllowanceY = validatedOverscroll * scrollConstraints.height;
return Math.min(overscrollAllowanceX, overscrollAllowanceY);
};
@ -284,14 +292,14 @@ const calculateConstraints = ({
);
const { constrainedScrollCenterX, constrainedScrollCenterY } =
calculateConstrainedScrollCenter(constrainedZoom);
const overscrollAllowance = calculateOverscrollAllowance();
const overscrollAllowanceValue = calculateOverscrollAllowance();
const shouldAdjustForCenteredViewX = constrainedZoom <= zoomLevelX;
const shouldAdjustForCenteredViewY = constrainedZoom <= zoomLevelY;
const { maxScrollX, minScrollX, maxScrollY, minScrollY } =
calculateMinMaxScrollValues(
shouldAdjustForCenteredViewX,
shouldAdjustForCenteredViewY,
overscrollAllowance,
overscrollAllowanceValue,
constrainedScrollCenterX,
constrainedScrollCenterY,
constrainedZoom,