From 68d5b60dc0f3fcf5cd5a23fece9bce8994e3b747 Mon Sep 17 00:00:00 2001
From: Michael Dougall <mdougall@atlassian.com>
Date: Thu, 6 Jun 2019 12:45:48 +1000
Subject: [PATCH] feat(move): adds new prop to set stacking context on move
 motion

---
 .../src/__docs__/2-getting-started/docs.mdx   |  4 ++--
 packages/core/src/lib/dom.tsx                 | 10 ++++++++
 packages/core/src/motions/FadeMove/index.tsx  | 23 ++-----------------
 .../core/src/motions/Move/__docs__/docs.mdx   |  7 ++++++
 packages/core/src/motions/Move/index.tsx      | 19 +++++++++++++--
 5 files changed, 38 insertions(+), 25 deletions(-)

diff --git a/packages/core/src/__docs__/2-getting-started/docs.mdx b/packages/core/src/__docs__/2-getting-started/docs.mdx
index 8a92e98..03fe6f4 100644
--- a/packages/core/src/__docs__/2-getting-started/docs.mdx
+++ b/packages/core/src/__docs__/2-getting-started/docs.mdx
@@ -319,7 +319,7 @@ and `false` when you consider it to be hidden.
         <Styled.Root>
           <Styled.ImageContainer>
             <Motion name={src} in={inn}>
-              <Move>
+              <Move zIndex={89}>
                 {({ ref, style }) => (
                   <Styled.Img
                     src={src}
@@ -355,7 +355,7 @@ and `false` when you consider it to be hidden.
               </div>
 
               <Motion name={src}>
-                <Move>
+                <Move zIndex={89} createStackingContext>
                   {({ ref, style }) => <Styled.PageImage src={src} ref={ref} style={style} />}
                 </Move>
               </Motion>
diff --git a/packages/core/src/lib/dom.tsx b/packages/core/src/lib/dom.tsx
index 1dbdc0c..96bead5 100644
--- a/packages/core/src/lib/dom.tsx
+++ b/packages/core/src/lib/dom.tsx
@@ -1,3 +1,13 @@
+export function eventListener<K extends keyof HTMLElementEventMap>(
+  element: HTMLElement,
+  event: K,
+  cb: (this: HTMLElement, ev: HTMLElementEventMap[K]) => any,
+  options?: boolean | AddEventListenerOptions | undefined
+) {
+  element.addEventListener<K>(event, cb, options);
+  return () => element.removeEventListener(event, cb, options);
+}
+
 export function getDocumentScroll() {
   const scrollTop =
     document.documentElement && document.documentElement.scrollTop
diff --git a/packages/core/src/motions/FadeMove/index.tsx b/packages/core/src/motions/FadeMove/index.tsx
index f3cc8d9..cc71dcf 100644
--- a/packages/core/src/motions/FadeMove/index.tsx
+++ b/packages/core/src/motions/FadeMove/index.tsx
@@ -73,7 +73,7 @@ export default class FadeMove extends React.Component<FadeMoveProps> {
         transformOrigin: '0 0',
         transform: 'translate3d(0, 0, 0) scale3d(1, 1, 1)',
         opacity: 1,
-        // Elminate any margins so they don't affect the transition.
+        // Eliminate any margins so they don't affect the transition.
         margin: 0,
         height: `${originTarget.size.height}px`,
         width: `${originTarget.size.width}px`,
@@ -87,14 +87,7 @@ export default class FadeMove extends React.Component<FadeMoveProps> {
     });
   };
 
-  beforeAnimate: MotionCallback = (data, onFinish, setChildProps) => {
-    setChildProps({
-      style: prevStyle => ({
-        ...prevStyle,
-        opacity: 0,
-      }),
-    });
-
+  beforeAnimate: MotionCallback = (data, onFinish) => {
     onFinish();
 
     return this.renderMotion(data);
@@ -105,17 +98,6 @@ export default class FadeMove extends React.Component<FadeMoveProps> {
     return this.renderMotion(data, { moveToTarget: true });
   };
 
-  afterAnimate: MotionCallback = (_, onFinish, setChildProps) => {
-    setChildProps({
-      style: prevStyle => ({
-        ...prevStyle,
-        opacity: 1,
-      }),
-    });
-
-    onFinish();
-  };
-
   render() {
     const { children } = this.props;
 
@@ -126,7 +108,6 @@ export default class FadeMove extends React.Component<FadeMoveProps> {
           payload: {
             beforeAnimate: this.beforeAnimate,
             animate: this.animate,
-            afterAnimate: this.afterAnimate,
           },
         }}
       >
diff --git a/packages/core/src/motions/Move/__docs__/docs.mdx b/packages/core/src/motions/Move/__docs__/docs.mdx
index 1ad4f7e..019c2fe 100644
--- a/packages/core/src/motions/Move/__docs__/docs.mdx
+++ b/packages/core/src/motions/Move/__docs__/docs.mdx
@@ -47,3 +47,10 @@ import { Move } from '@element-motion/core';
 ## Props
 
 <Props of={Move} />
+
+## Gotchas
+
+Noticing that your in transit element isn't being stacked correctly?
+You'll want to create a [stacking context](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Positioning/Understanding_z_index/The_stacking_context) by opting into `createStackingContext` which will set `position: relative` to the inflight element.
+
+This should fix your stacking problems.
diff --git a/packages/core/src/motions/Move/index.tsx b/packages/core/src/motions/Move/index.tsx
index 2f168bf..639fe8f 100644
--- a/packages/core/src/motions/Move/index.tsx
+++ b/packages/core/src/motions/Move/index.tsx
@@ -57,6 +57,13 @@ export interface MoveProps extends CollectorChildrenProps {
    * Defaults to true.
    */
   scaleY?: boolean;
+
+  /**
+   * Will set "position: relative" on the element during a transition.
+   * Useful for creating a stacking context to position the element where you want in the stack.
+   * Use "zIndex" prop to set the appropriate position in the stack.
+   */
+  createStackingContext?: boolean;
 }
 
 export default class Move extends React.Component<MoveProps> {
@@ -74,7 +81,15 @@ export default class Move extends React.Component<MoveProps> {
   abort = noop;
 
   beforeAnimate: MotionCallback = (data, onFinish, setChildProps) => {
-    const { zIndex, useFocalTarget, transformX, transformY, scaleX, scaleY } = this.props;
+    const {
+      zIndex,
+      useFocalTarget,
+      transformX,
+      transformY,
+      scaleX,
+      scaleY,
+      createStackingContext,
+    } = this.props;
 
     if (process.env.NODE_ENV === 'development') {
       throwIf(
@@ -102,7 +117,7 @@ export default class Move extends React.Component<MoveProps> {
       style: prevStyles => ({
         ...prevStyles,
         zIndex,
-        opacity: 1,
+        position: createStackingContext ? 'relative' : undefined,
         transformOrigin: '0 0',
         visibility: 'visible',
         willChange: combine('transform')(prevStyles.willChange),