fix: measure elements before taking siblings out of the flow (#11216)

* Revert "fix: take outroing elements out of the flow when animating siblings (#11208)"

This reverts commit c44234d.

* fix: measure elements before taking siblings out of the flow

* lint

* add changeset back

* changeset

Author: Rich-Harris

.changeset/lemon-trees-act.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: measure elements before taking siblings out of the flow

packages/svelte/src/internal/client/dom/blocks/each.js

@@ -71,7 +71,7 @@ function pause_effects(items, controlled_anchor, callback) {
 		parent_node.append(controlled_anchor);
 	}
 
-	run_out_transitions(transitions, true, () => {
+	run_out_transitions(transitions, () => {
 		for (var i = 0; i < length; i++) {
 			destroy_effect(items[i].e);
 		}
@@ -312,7 +312,10 @@ function reconcile(array, state, anchor, render_fn, flags, get_key) {
 
 		if ((item.e.f & INERT) !== 0) {
 			resume_effect(item.e);
-			to_animate.delete(item);
+			if (is_animated) {
+				item.a?.unfix();
+				to_animate.delete(item);
+			}
 		}
 
 		if (item !== current) {
@@ -391,6 +394,16 @@ function reconcile(array, state, anchor, render_fn, flags, get_key) {
 
 	var controlled_anchor = (flags & EACH_IS_CONTROLLED) !== 0 && length === 0 ? anchor : null;
 
+	if (is_animated) {
+		for (i = 0; i < to_destroy.length; i += 1) {
+			to_destroy[i].a?.measure();
+		}
+
+		for (i = 0; i < to_destroy.length; i += 1) {
+			to_destroy[i].a?.fix();
+		}
+	}
+
 	pause_effects(to_destroy, controlled_anchor, () => {
 		for (var i = 0; i < to_destroy.length; i += 1) {
 			var item = to_destroy[i];

packages/svelte/src/internal/client/dom/elements/transitions.js

@@ -88,6 +88,9 @@ export function animation(element, get_fn, get_params) {
 	/** @type {import('#client').Animation | undefined} */
 	var animation;
 
+	/** @type {null | { position: string, width: string, height: string }} */
+	var original_styles = null;
+
 	item.a ??= {
 		element,
 		measure() {
@@ -106,11 +109,43 @@ export function animation(element, get_fn, get_params) {
 			) {
 				const options = get_fn()(this.element, { from, to }, get_params?.());
 
-				animation = animate(this.element, options, false, undefined, 1, () => {
+				animation = animate(this.element, options, undefined, 1, () => {
 					animation?.abort();
 					animation = undefined;
 				});
 			}
+		},
+		fix() {
+			var computed_style = getComputedStyle(element);
+
+			if (computed_style.position !== 'absolute' && computed_style.position !== 'fixed') {
+				var style = /** @type {HTMLElement | SVGElement} */ (element).style;
+
+				original_styles = {
+					position: style.position,
+					width: style.width,
+					height: style.height
+				};
+
+				style.position = 'absolute';
+				style.width = computed_style.width;
+				style.height = computed_style.height;
+				var to = element.getBoundingClientRect();
+
+				if (from.left !== to.left || from.top !== to.top) {
+					var transform = `translate(${from.left - to.left}px, ${from.top - to.top}px)`;
+					style.transform = style.transform ? `${style.transform} ${transform}` : transform;
+				}
+			}
+		},
+		unfix() {
+			if (original_styles) {
+				var style = /** @type {HTMLElement | SVGElement} */ (element).style;
+
+				style.position = original_styles.position;
+				style.width = original_styles.width;
+				style.height = original_styles.height;
+			}
 		}
 	};
 
@@ -169,7 +204,7 @@ export function transition(flags, element, get_fn, get_params) {
 
 			if (is_intro) {
 				dispatch_event(element, 'introstart');
-				intro = animate(element, get_options(), false, outro, 1, () => {
+				intro = animate(element, get_options(), outro, 1, () => {
 					dispatch_event(element, 'introend');
 					intro = current_options = undefined;
 				});
@@ -178,12 +213,12 @@ export function transition(flags, element, get_fn, get_params) {
 				reset?.();
 			}
 		},
-		out(fn, position_absolute = false) {
+		out(fn) {
 			if (is_outro) {
 				element.inert = true;
 
 				dispatch_event(element, 'outrostart');
-				outro = animate(element, get_options(), position_absolute, intro, 0, () => {
+				outro = animate(element, get_options(), intro, 0, () => {
 					dispatch_event(element, 'outroend');
 					outro = current_options = undefined;
 					fn?.();
@@ -229,13 +264,12 @@ export function transition(flags, element, get_fn, get_params) {
  * Animates an element, according to the provided configuration
  * @param {Element} element
  * @param {import('#client').AnimationConfig | ((opts: { direction: 'in' | 'out' }) => import('#client').AnimationConfig)} options
- * @param {boolean} position_absolute
  * @param {import('#client').Animation | undefined} counterpart The corresponding intro/outro to this outro/intro
  * @param {number} t2 The target `t` value — `1` for intro, `0` for outro
  * @param {(() => void) | undefined} callback
  * @returns {import('#client').Animation}
  */
-function animate(element, options, position_absolute, counterpart, t2, callback) {
+function animate(element, options, counterpart, t2, callback) {
 	if (is_function(options)) {
 		// In the case of a deferred transition (such as `crossfade`), `option` will be
 		// a function rather than an `AnimationConfig`. We need to call this function
@@ -245,7 +279,7 @@ function animate(element, options, position_absolute, counterpart, t2, callback)
 
 		effect(() => {
 			var o = untrack(() => options({ direction: t2 === 1 ? 'in' : 'out' }));
-			a = animate(element, o, position_absolute, counterpart, t2, callback);
+			a = animate(element, o, counterpart, t2, callback);
 		});
 
 		// ...but we want to do so without using `async`/`await` everywhere, so
@@ -285,9 +319,6 @@ function animate(element, options, position_absolute, counterpart, t2, callback)
 	/** @type {import('#client').Task} */
 	var task;
 
-	/** @type {null | { position: string, width: string, height: string }} */
-	var original_styles = null;
-
 	if (css) {
 		// WAAPI
 		var keyframes = [];
@@ -299,37 +330,6 @@ function animate(element, options, position_absolute, counterpart, t2, callback)
 			keyframes.push(css_to_keyframe(styles));
 		}
 
-		if (position_absolute) {
-			// we take the element out of the flow, so that sibling elements with an `animate:`
-			// directive can transform to the correct position
-			var computed_style = getComputedStyle(element);
-
-			if (computed_style.position !== 'absolute' && computed_style.position !== 'fixed') {
-				var style = /** @type {HTMLElement | SVGElement} */ (element).style;
-
-				original_styles = {
-					position: style.position,
-					width: style.width,
-					height: style.height
-				};
-
-				var rect_a = element.getBoundingClientRect();
-				style.position = 'absolute';
-				style.width = computed_style.width;
-				style.height = computed_style.height;
-				var rect_b = element.getBoundingClientRect();
-
-				if (rect_a.left !== rect_b.left || rect_a.top !== rect_b.top) {
-					var transform = `translate(${rect_a.left - rect_b.left}px, ${rect_a.top - rect_b.top}px)`;
-					for (var keyframe of keyframes) {
-						keyframe.transform = keyframe.transform
-							? `${keyframe.transform} ${transform}`
-							: transform;
-					}
-				}
-			}
-		}
-
 		animation = element.animate(keyframes, {
 			delay,
 			duration,
@@ -340,6 +340,10 @@ function animate(element, options, position_absolute, counterpart, t2, callback)
 		animation.finished
 			.then(() => {
 				callback?.();
+
+				if (t2 === 1) {
+					animation.cancel();
+				}
 			})
 			.catch((e) => {
 				// Error for DOMException: The user aborted a request. This results in two things:
@@ -380,15 +384,6 @@ function animate(element, options, position_absolute, counterpart, t2, callback)
 			task?.abort();
 		},
 		deactivate: () => {
-			if (original_styles) {
-				// revert `animate:` position fixing
-				var style = /** @type {HTMLElement | SVGElement} */ (element).style;
-
-				style.position = original_styles.position;
-				style.width = original_styles.width;
-				style.height = original_styles.height;
-			}
-
 			callback = undefined;
 		},
 		reset: () => {

packages/svelte/src/internal/client/reactivity/effects.js

@@ -334,23 +334,22 @@ export function pause_effect(effect, callback) {
 
 	pause_children(effect, transitions, true);
 
-	run_out_transitions(transitions, false, () => {
+	run_out_transitions(transitions, () => {
 		destroy_effect(effect);
 		if (callback) callback();
 	});
 }
 
 /**
  * @param {import('#client').TransitionManager[]} transitions
- * @param {boolean} position_absolute
  * @param {() => void} fn
  */
-export function run_out_transitions(transitions, position_absolute, fn) {
+export function run_out_transitions(transitions, fn) {
 	var remaining = transitions.length;
 	if (remaining > 0) {
 		var check = () => --remaining || fn();
 		for (var transition of transitions) {
-			transition.out(check, position_absolute);
+			transition.out(check);
 		}
 	} else {
 		fn();

packages/svelte/src/internal/client/types.d.ts

@@ -79,7 +79,7 @@ export interface TransitionManager {
 	/** Called inside `resume_effect` */
 	in: () => void;
 	/** Called inside `pause_effect` */
-	out: (callback?: () => void, position_absolute?: boolean) => void;
+	out: (callback?: () => void) => void;
 	/** Called inside `destroy_effect` */
 	stop: () => void;
 }
@@ -91,6 +91,10 @@ export interface AnimationManager {
 	measure: () => void;
 	/** Called during keyed each block reconciliation, after updates — this triggers the animation */
 	apply: () => void;
+	/** Fix the element position, so that siblings can move to the correct destination */
+	fix: () => void;
+	/** Unfix the element position if the outro is aborted */
+	unfix: () => void;
 }
 
 export interface Animation {