dnd-core
Version:
Drag and drop sans the GUI
47 lines (46 loc) • 1.44 kB
JavaScript
/**
* Coordinate addition
* @param a The first coordinate
* @param b The second coordinate
*/ export function add(a, b) {
return {
x: a.x + b.x,
y: a.y + b.y
};
}
/**
* Coordinate subtraction
* @param a The first coordinate
* @param b The second coordinate
*/ export function subtract(a, b) {
return {
x: a.x - b.x,
y: a.y - b.y
};
}
/**
* Returns the cartesian distance of the drag source component's position, based on its position
* at the time when the current drag operation has started, and the movement difference.
*
* Returns null if no item is being dragged.
*
* @param state The offset state to compute from
*/ export function getSourceClientOffset(state) {
const { clientOffset , initialClientOffset , initialSourceClientOffset } = state;
if (!clientOffset || !initialClientOffset || !initialSourceClientOffset) {
return null;
}
return subtract(add(clientOffset, initialSourceClientOffset), initialClientOffset);
}
/**
* Determines the x,y offset between the client offset and the initial client offset
*
* @param state The offset state to compute from
*/ export function getDifferenceFromInitialOffset(state) {
const { clientOffset , initialClientOffset } = state;
if (!clientOffset || !initialClientOffset) {
return null;
}
return subtract(clientOffset, initialClientOffset);
}
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