From 5b128196517f671fa09e8379b2c5b05f6f3b90f9 Mon Sep 17 00:00:00 2001
From: "Robert W. Pearce" <me@robertwpearce.com>
Date: Fri, 5 Apr 2024 22:14:39 -0400
Subject: [PATCH] chore: backfill docs and style for 2 new swipe to unzoom
 features

---
 README.md               |  8 +++++++
 source/Controlled.tsx   | 20 ++++++++--------
 stories/Img.stories.tsx | 52 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+), 10 deletions(-)

diff --git a/README.md b/README.md
index 8fb3b7b7..fded92af 100644
--- a/README.md
+++ b/README.md
@@ -74,6 +74,10 @@ export interface UncontrolledProps {
   // Default: 'Expand image'
   a11yNameButtonZoom?: string
 
+  // Allow swipe gesture to unzoom.
+  // Default: true
+  canSwipeToUnzoom?: boolean
+
   // Your image (required).
   children: ReactNode
 
@@ -88,6 +92,10 @@ export interface UncontrolledProps {
   // Default: IEnlarge
   IconZoom?: ElementType
 
+  // Swipe gesture threshold after which to unzoom.
+  // Default: 10
+  swipeToUnzoomThreshold?: number
+
   // Specify what type of element should be used for
   // internal component usage. This is useful if the
   // image is inside a <p> or <button>, for example.
diff --git a/source/Controlled.tsx b/source/Controlled.tsx
index 226fc3eb..8843d3d4 100644
--- a/source/Controlled.tsx
+++ b/source/Controlled.tsx
@@ -55,13 +55,13 @@ const defaultBodyAttrs: BodyAttrs = {
 export interface ControlledProps {
   a11yNameButtonUnzoom?: string
   a11yNameButtonZoom?: string
+  canSwipeToUnzoom?: boolean
   children: React.ReactNode
   classDialog?: string
   IconUnzoom?: React.ElementType
   IconZoom?: React.ElementType
   isZoomed: boolean
   onZoomChange?: (value: boolean) => void
-  canSwipeToUnzoom?: boolean
   swipeToUnzoomThreshold?: number
   wrapElement?: 'div' | 'span'
   ZoomContent?: (data: {
@@ -82,9 +82,9 @@ interface ControlledDefaultProps {
   a11yNameButtonUnzoom: string
   a11yNameButtonZoom: string
   canSwipeToUnzoom: boolean
-  swipeToUnzoomThreshold: number
   IconUnzoom: React.ElementType
   IconZoom: React.ElementType
+  swipeToUnzoomThreshold: number
   wrapElement: 'div' | 'span'
   zoomMargin: number
 }
@@ -103,9 +103,9 @@ class ControlledBase extends React.Component<ControlledPropsWithDefaults, Contro
   static defaultProps: ControlledDefaultProps = {
     a11yNameButtonUnzoom: 'Minimize image',
     a11yNameButtonZoom: 'Expand image',
+    canSwipeToUnzoom: true,
     IconUnzoom: ICompress,
     IconZoom: IEnlarge,
-    canSwipeToUnzoom: true,
     swipeToUnzoomThreshold: 10,
     wrapElement: 'div',
     zoomMargin: 0,
@@ -549,21 +549,21 @@ class ControlledBase extends React.Component<ControlledPropsWithDefaults, Contro
    * and unzoom if we detect a swipe
    */
   handleTouchMove = (e: TouchEvent) => {
-    if (!this.props.canSwipeToUnzoom) {
-      return
-    }
-
     const browserScale = window.visualViewport?.scale ?? 1
 
-    if (!this.isScaling && browserScale <= 1 && this.touchYStart != null && e.changedTouches[0]) {
+    if (
+      this.props.canSwipeToUnzoom &&
+      !this.isScaling &&
+      browserScale <= 1 && this.touchYStart != null &&
+      e.changedTouches[0]
+    ) {
       this.touchYEnd = e.changedTouches[0].screenY
 
       const max = Math.max(this.touchYStart, this.touchYEnd)
       const min = Math.min(this.touchYStart, this.touchYEnd)
       const delta = Math.abs(max - min)
-      const { swipeToUnzoomThreshold } = this.props
 
-      if (delta > swipeToUnzoomThreshold) {
+      if (delta > this.props.swipeToUnzoomThreshold) {
         this.touchYStart = undefined
         this.touchYEnd = undefined
         this.handleUnzoom()
diff --git a/stories/Img.stories.tsx b/stories/Img.stories.tsx
index da986d7d..e06b0c49 100644
--- a/stories/Img.stories.tsx
+++ b/stories/Img.stories.tsx
@@ -451,6 +451,58 @@ export const InlineImage = (props) => (
   </main>
 )
 
+// =============================================================================
+
+export const SwipeToUnzoomDisabled = (props) => (
+  <main aria-label="Story">
+    <h1>Swipe to Unzoom Disabled</h1>
+    <p>
+      This example demonstrates preventing swipe gestures from
+      unzooming when an image is zoomed. This is best tested on
+      a touchscreen device!
+    </p>
+    <div>
+      <Zoom {...props} canSwipeToUnzoom={false}>
+        <img
+          alt={imgThatWanakaTree.alt}
+          src={imgThatWanakaTree.src}
+          decoding="async"
+          height="320"
+          loading="lazy"
+        />
+      </Zoom>
+    </div>
+  </main>
+)
+
+export const SwipeToUnzoomThreshold = (props) => (
+  <main aria-label="Story">
+    <h1>Swipe to Unzoom Threshold</h1>
+    <p>
+      This example demonstrates increasing the threshold
+      required for a swipe gesture on a touchscreen device to
+      unzoom when an image is zoomed. This is best tested on
+      a touchscreen device!
+    </p>
+    <p>
+      The default is <code>10</code> (px), but this example
+      is set to <code>200</code> (px); that&apos;s how far
+      you&apos;ll have to move your finger across the screen.
+    </p>
+    <div>
+      <Zoom {...props} swipeToUnzoomThreshold={200}>
+        <img
+          alt={imgThatWanakaTree.alt}
+          src={imgThatWanakaTree.src}
+          decoding="async"
+          height="320"
+          loading="lazy"
+        />
+      </Zoom>
+    </div>
+  </main>
+)
+
 // =============================================================================
 // INTERACTIONS