Add touch number change callback

example/ios/Flutter/Debug.xcconfig

@@ -1 +1,2 @@
+#include? "Pods/Target Support Files/Pods-Runner/Pods-Runner.debug.xcconfig"
 #include "Generated.xcconfig"

example/ios/Flutter/Release.xcconfig

@@ -1 +1,2 @@
+#include? "Pods/Target Support Files/Pods-Runner/Pods-Runner.release.xcconfig"
 #include "Generated.xcconfig"

example/ios/Podfile

@@ -0,0 +1,41 @@
+# Uncomment this line to define a global platform for your project
+# platform :ios, '11.0'
+
+# CocoaPods analytics sends network stats synchronously affecting flutter build latency.
+ENV['COCOAPODS_DISABLE_STATS'] = 'true'
+
+project 'Runner', {
+  'Debug' => :debug,
+  'Profile' => :release,
+  'Release' => :release,
+}
+
+def flutter_root
+  generated_xcode_build_settings_path = File.expand_path(File.join('..', 'Flutter', 'Generated.xcconfig'), __FILE__)
+  unless File.exist?(generated_xcode_build_settings_path)
+    raise "#{generated_xcode_build_settings_path} must exist. If you're running pod install manually, make sure flutter pub get is executed first"
+  end
+
+  File.foreach(generated_xcode_build_settings_path) do |line|
+    matches = line.match(/FLUTTER_ROOT\=(.*)/)
+    return matches[1].strip if matches
+  end
+  raise "FLUTTER_ROOT not found in #{generated_xcode_build_settings_path}. Try deleting Generated.xcconfig, then run flutter pub get"
+end
+
+require File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)
+
+flutter_ios_podfile_setup
+
+target 'Runner' do
+  use_frameworks!
+  use_modular_headers!
+
+  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
+end
+
+post_install do |installer|
+  installer.pods_project.targets.each do |target|
+    flutter_additional_ios_build_settings(target)
+  end
+end

example/lib/main.dart

@@ -31,6 +31,12 @@ class MyHomePage extends StatefulWidget {
 }
 
 class _MyHomePageState extends State<MyHomePage> {
+
+  // this is used to enable and disable scroll of the listview
+  // we can disable the listview scroll if the number of touch is 2 or more
+  // this will trigger zoom if the image is touched with two finger.
+  bool isZooming = false;
+
   Widget listRow(int profile, int image, int likes, String name, String text) {
     return Column(
         crossAxisAlignment: CrossAxisAlignment.start,
@@ -50,7 +56,7 @@ class _MyHomePageState extends State<MyHomePage> {
               modalBarrierColor: Colors.black12, // optional
               minScale: 0.5, // optional
               maxScale: 3.0, // optional
-              twoTouchOnly: true,
+              twoTouchOnly: false,
               animationDuration: Duration(milliseconds: 300),
               animationCurve: Curves.fastOutSlowIn,
               onScaleStart: () {
@@ -59,6 +65,11 @@ class _MyHomePageState extends State<MyHomePage> {
               onScaleStop: () {
                 debugPrint('zooming ended!');
               }, // optional
+              onTouchCountChanged: (count) {
+                setState(() {
+                  isZooming = count > 1;
+                });
+              },
               child: CachedNetworkImage(
                   imageUrl: 'https://picsum.photos/800?image=$image')),
           Padding(
@@ -129,6 +140,8 @@ class _MyHomePageState extends State<MyHomePage> {
                     fontSize: 38)),
             systemOverlayStyle: SystemUiOverlayStyle.dark),
         body: ListView(
+          // this disables the scroll which makes it easier for image to zoom.
+          physics: isZooming ? NeverScrollableScrollPhysics() : ScrollPhysics(),
           children: <Widget>[
             listRow(1027, 1062, 36, 'mary.porter',
                 'Lucy doesnt want to get out of bed today, its far too cold for the little darling.'),

lib/zoom_pinch_overlay.dart

@@ -53,6 +53,7 @@ class ZoomOverlay extends StatefulWidget {
     this.modalBarrierColor,
     this.onScaleStart,
     this.onScaleStop,
+    this.onTouchCountChanged,
   }) : super(key: key);
 
   /// A widget to make zoomable.
@@ -83,6 +84,10 @@ class ZoomOverlay extends StatefulWidget {
   final VoidCallback? onScaleStart;
   final VoidCallback? onScaleStop;
 
+  /// callback when the touch pointer changes
+  /// the parameter gives the number of current touch
+  final Function(int)? onTouchCountChanged;
+
   @override
   _ZoomOverlayState createState() => _ZoomOverlayState();
 }
@@ -254,7 +259,13 @@ class _ZoomOverlayState extends State<ZoomOverlay>
     _overlayEntry = null;
   }
 
-  void _incrementEnter(PointerEvent details) => _touchCount++;
+  void _incrementEnter(PointerEvent details) {
+    _touchCount++;
+    widget.onTouchCountChanged?.call(_touchCount);
+  }
 
-  void _incrementExit(PointerEvent details) => _touchCount--;
+  void _incrementExit(PointerEvent details) {
+    _touchCount--;
+    widget.onTouchCountChanged?.call(_touchCount);
+  }
 }