<p dir="auto">Internal: b/144873050</p>
<p dir="auto">Hey, looks like there is a bug preventing gesture detection on right side of the widget inside page view with only one element and viewport fraction smaller than 1.0.</p>
<p dir="auto">This is how my widget tree looks like:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="column
  - page view
    - gesture detector
      - green container
    - gesture detector
      - blue container
  - page view
    - gesture detector
      - red container"><pre class="notranslate"><code class="notranslate">column
  - page view
    - gesture detector
      - green container
    - gesture detector
      - blue container
  - page view
    - gesture detector
      - red container
</code></pre></div>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/2051417/47923808-a6e35600-deba-11e8-8149-d45601aa6027.png"><img src="https://user-images.githubusercontent.com/2051417/47923808-a6e35600-deba-11e8-8149-d45601aa6027.png" alt="screenshot from 2018-11-02 16-14-59" style="max-width: 100%;"></a></p>
<p dir="auto">Top gesture detectors (green&amp;blue widgets) work fine, I can click anywhere and I can see debug logs in console.<br>
Bottom gesture detector (red widget) works fine only for left half of the widget. When I click on the right half then onTap callback is not fired. Looks like something is preventing gesture detector from getting input.</p>
<p dir="auto">flutter doctor output:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="[✓] Flutter (Channel beta, v0.9.4, on Linux, locale en_US.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK 27.0.3)
[✓] Android Studio (version 3.1)
[!] IntelliJ IDEA Community Edition (version 2018.2)
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
[✓] Connected devices (1 available)"><pre class="notranslate"><code class="notranslate">[✓] Flutter (Channel beta, v0.9.4, on Linux, locale en_US.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK 27.0.3)
[✓] Android Studio (version 3.1)
[!] IntelliJ IDEA Community Edition (version 2018.2)
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
[✓] Connected devices (1 available)
</code></pre></div>
<p dir="auto">Source code to reproduce bug:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="import 'package:flutter/material.dart';

void main() =&gt; runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Column(children: &lt;Widget&gt;[
        Expanded(
          child: ColorPages(
            colors: &lt;Color&gt;[
              Colors.green,
              Colors.blue,
            ],
          ),
        ),
        Expanded(
          child: ColorPages(
            colors: &lt;Color&gt;[
              Colors.red,
            ],
          ),
        ),
      ]),
    );
  }
}

class ColorPages extends StatefulWidget {
  final List&lt;Color&gt; colors;

  const ColorPages({Key key, this.colors}) : super(key: key);

  @override
  ColorPagesState createState() {
    return new ColorPagesState();
  }
}

class ColorPagesState extends State&lt;ColorPages&gt; {
  PageController _pageController;

  @override
  void initState() {
    super.initState();

    _pageController = new PageController(
      viewportFraction: 0.5,
    );
  }

  @override
  Widget build(BuildContext context) {
    return PageView.builder(
      controller: _pageController,
      itemBuilder: (context, index) {
        return GestureDetector(
          onTap: () {
            print(DateTime.now().toIso8601String() + &quot; &quot; + widget.colors[index].toString());
          },
          child: Container(
            color: widget.colors[index],
          ),
        );
      },
      itemCount: widget.colors.length,
    );
  }
}"><pre class="notranslate"><code class="notranslate">import 'package:flutter/material.dart';

void main() =&gt; runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Column(children: &lt;Widget&gt;[
        Expanded(
          child: ColorPages(
            colors: &lt;Color&gt;[
              Colors.green,
              Colors.blue,
            ],
          ),
        ),
        Expanded(
          child: ColorPages(
            colors: &lt;Color&gt;[
              Colors.red,
            ],
          ),
        ),
      ]),
    );
  }
}

class ColorPages extends StatefulWidget {
  final List&lt;Color&gt; colors;

  const ColorPages({Key key, this.colors}) : super(key: key);

  @override
  ColorPagesState createState() {
    return new ColorPagesState();
  }
}

class ColorPagesState extends State&lt;ColorPages&gt; {
  PageController _pageController;

  @override
  void initState() {
    super.initState();

    _pageController = new PageController(
      viewportFraction: 0.5,
    );
  }

  @override
  Widget build(BuildContext context) {
    return PageView.builder(
      controller: _pageController,
      itemBuilder: (context, index) {
        return GestureDetector(
          onTap: () {
            print(DateTime.now().toIso8601String() + " " + widget.colors[index].toString());
          },
          child: Container(
            color: widget.colors[index],
          ),
        );
      },
      itemCount: widget.colors.length,
    );
  }
}
</code></pre></div>
<p dir="auto"><code class="notranslate">InkWell</code> will not work if <code class="notranslate">_file.length</code> is 1;<br>
but it will work if length is greater than or equal to 2;</p>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="  Container(
    height: 200,
    child: PageView.builder(
      itemCount: _file.length,
      controller: PageController(viewportFraction: 0.4),
      itemBuilder: (context, index) {
        return Card(
          child: InkWell(
            onTap: () =&gt; _picImage(),
            child: Center(
              child: Icon(
                Icons.add,
                size: 40,
              ),
            ),
          ),
        );
      },
    ),
  )"><pre class="notranslate">  <span class="pl-c1">Container</span>(
    height<span class="pl-k">:</span> <span class="pl-c1">200</span>,
    child<span class="pl-k">:</span> <span class="pl-c1">PageView</span>.<span class="pl-en">builder</span>(
      itemCount<span class="pl-k">:</span> _file.length,
      controller<span class="pl-k">:</span> <span class="pl-c1">PageController</span>(viewportFraction<span class="pl-k">:</span> <span class="pl-c1">0.4</span>),
      itemBuilder<span class="pl-k">:</span> (context, index) {
        <span class="pl-k">return</span> <span class="pl-c1">Card</span>(
          child<span class="pl-k">:</span> <span class="pl-c1">InkWell</span>(
            onTap<span class="pl-k">:</span> () <span class="pl-k">=&gt;</span> <span class="pl-en">_picImage</span>(),
            child<span class="pl-k">:</span> <span class="pl-c1">Center</span>(
              child<span class="pl-k">:</span> <span class="pl-c1">Icon</span>(
                <span class="pl-c1">Icons</span>.add,
                size<span class="pl-k">:</span> <span class="pl-c1">40</span>,
              ),
            ),
          ),
        );
      },
    ),
  )</pre></div>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="flutter doctor -v

[√] Flutter (Channel beta, v1.0.0, on Microsoft Windows [Version 10.0.17758.1], locale en-AS)
    • Flutter version 1.0.0 at C:\flutter
    • Framework revision 5391447fae (2 months ago), 2018-11-29 19:41:26 -0800
    • Engine revision 7375a0f414
    • Dart version 2.1.0 (build 2.1.0-dev.9.4 f9ebf21297)

[√] Android toolchain - develop for Android devices (Android SDK 28.0.3)
    • Android SDK at C:\Users\Suraj\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
    • All Android licenses accepted.

[√] Android Studio (version 3.3)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin version 32.0.1
    • Dart plugin version 182.5215
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)

[!] IntelliJ IDEA Ultimate Edition (version 2018.2)
    • IntelliJ at C:\Program Files\JetBrains\IntelliJ IDEA 2018.2.3
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
    • For information about installing plugins, see
      https://flutter.io/intellij-setup/#installing-the-plugins"><pre class="notranslate"><code class="notranslate">flutter doctor -v

[√] Flutter (Channel beta, v1.0.0, on Microsoft Windows [Version 10.0.17758.1], locale en-AS)
    • Flutter version 1.0.0 at C:\flutter
    • Framework revision 5391447fae (2 months ago), 2018-11-29 19:41:26 -0800
    • Engine revision 7375a0f414
    • Dart version 2.1.0 (build 2.1.0-dev.9.4 f9ebf21297)

[√] Android toolchain - develop for Android devices (Android SDK 28.0.3)
    • Android SDK at C:\Users\Suraj\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
    • All Android licenses accepted.

[√] Android Studio (version 3.3)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin version 32.0.1
    • Dart plugin version 182.5215
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)

[!] IntelliJ IDEA Ultimate Edition (version 2018.2)
    • IntelliJ at C:\Program Files\JetBrains\IntelliJ IDEA 2018.2.3
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
    • For information about installing plugins, see
      https://flutter.io/intellij-setup/#installing-the-plugins
</code></pre></div>
<p dir="auto">PS: Using Android Studio Not Intellij for Flutter</p>