wehub-resource-sync
77 lines
1.7 KiB
TypeScript
77 lines
1.7 KiB
TypeScript
export type ComponentLayerAction =
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| "send-to-back"
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| "send-backward"
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| "bring-forward"
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| "bring-to-front";
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export type ComponentLayerReorderResult<T> = {
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components: T[];
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componentIndex: number;
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};
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export function canApplyComponentLayerAction(
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componentIndex: number,
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componentCount: number,
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action: ComponentLayerAction,
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) {
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if (
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componentCount <= 1 ||
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componentIndex < 0 ||
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componentIndex >= componentCount
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) {
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return false;
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}
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if (action === "send-to-back" || action === "send-backward") {
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return componentIndex > 0;
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}
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return componentIndex < componentCount - 1;
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}
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export function reorderComponentLayer<T>(
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components: readonly T[],
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componentIndex: number,
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action: ComponentLayerAction,
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): ComponentLayerReorderResult<T> | null {
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if (!canApplyComponentLayerAction(componentIndex, components.length, action)) {
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return null;
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}
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const targetIndex = targetLayerIndex(componentIndex, components.length, action);
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if (targetIndex === componentIndex) return null;
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return {
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components: moveArrayItem(components, componentIndex, targetIndex),
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componentIndex: targetIndex,
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};
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}
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function targetLayerIndex(
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componentIndex: number,
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componentCount: number,
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action: ComponentLayerAction,
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) {
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switch (action) {
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case "send-to-back":
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return 0;
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case "send-backward":
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return componentIndex - 1;
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case "bring-forward":
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return componentIndex + 1;
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case "bring-to-front":
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return componentCount - 1;
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}
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}
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function moveArrayItem<T>(
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items: readonly T[],
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fromIndex: number,
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toIndex: number,
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) {
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const next = [...items];
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const [item] = next.splice(fromIndex, 1);
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next.splice(toIndex, 0, item);
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return next;
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}
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