Flutter RawKeyboardListener无法与条形码扫描仪设备一起使用

问题描述

我使用外部条形码设备进行输入（带有扫描+提交（输入）组合）。 我将RawKeyboardListener作为TextField父级，但是在扫描时不起作用。它看到回车键但没有条形码并给出一些错误；

对Android的平台键支持产生了不受支持的修饰符 组合。 'package：flutter / src / services / raw_keyboard.dart'：失败 断言：721行pos 11：“空”

raw_keyboard.dart

final Map<ModifierKey,KeyboardSide> modifiersPressed =
    event.data.modifiersPressed;
final Map<PhysicalKeyboardKey,LogicalKeyboardKey> modifierKeys =
    <PhysicalKeyboardKey,LogicalKeyboardKey>{};
for (final ModifierKey key in modifiersPressed.keys) {
  final Set<PhysicalKeyboardKey> mappedKeys =
      _modifierKeyMap[_ModifierSidePair(key,modifiersPressed[key])];
  assert(
//Line 721;
          mappedKeys != null,'Platform key support for ${Platform.operatingSystem} is '
          'producing unsupported modifier combinations.');
      for (final PhysicalKeyboardKey physicalModifier in mappedKeys) {
        modifierKeys[physicalModifier] = _allModifiers[physicalModifier];
      }
    }
    _allModifiersExceptFn.keys.forEach(_keysPressed.remove);
    if (event.data is! RawKeyEventDataFuchsia &&
        event.data is! RawKeyEventDataMacOs) {
      // On Fuchsia and macOS,the Fn key is not considered a modifier key.
      _keysPressed.remove(PhysicalKeyboardKey.fn);
    }
    _keysPressed.addAll(modifierKeys);

Btw条码扫描器在Google搜索或其他应用上运行良好

这是我的代码；

child: Container(
                  width: 300,height: 35,child: RawKeyboardListener(
                    focusNode: barkodFocus,autofocus: true,onKey: (key) {
                      print(key.toString());
                    },child: TextField(
                      decoration: InputDecoration(
                          contentPadding: EdgeInsets.all(8),border: OutlineInputBorder(
                              borderRadius:
                                  BorderRadius.all(Radius.circular(5)))),textAlign: TextAlign.left,keyboardType: TextInputType.text,readOnly: false,controller: barkodController,onSubmitted: (value) {
                        MusteriSiparisiRowModel satirModel =
                            MusteriSiparisiRowModel();
                        satirModel.setData(value,model).then((sonModel) {
                          setState(() {
                            barkod = value;
                            barkodFocus.requestFocus();
                            barkodController.selection = TextSelection(
                                baseOffset: 0,extentOffset: barkodController.text.length);
                            if (sonModel != null) {
                              satirModel = sonModel;
                              bool add = true;
                              for (var i = 0;
                                  i < satirlarModel.length;
                                  i++) {
                                MusteriSiparisiRowModel m =
                                    satirlarModel[i];
                                if (m.barkod == satirModel.barkod) {
                                  m.setMiktar = m.getMiktar + 1;
                                  add = false;
                                }
                              }
                              if (add == true) {
                                satirlarModel.add(satirModel);
                              }
                            } else {
                              scaffoldKey.currentState
                                  .showSnackBar(SnackBar(
                                      content: Row(
                                children: [
                                  Icon(Icons.announcement),Padding(padding: EdgeInsets.all(20)),Text("Barkod Bulunamadı."),],)));
                            }
                          });
                        });
                      },),)),

打印（键）可用于输入，但不适用于条形码

[√] Flutter (Channel stable,1.20.2,on Microsoft Windows [Version 10.0.18363.1016],locale tr-TR)
    • Flutter version 1.20.2 at C:\src\flutter\flutter_windows_v1.12.13+hotfix.5-stable\flutter
    • Framework revision bbfbf1770c (3 weeks ago),2020-08-13 08:33:09 -0700
    • Engine revision 9d5b21729f
    • Dart version 2.9.1

 
[√] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
    • Android SDK at C:\Users\DELL\AppData\Local\Android\sdk
    • Platform android-29,build-tools 29.0.2
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
    • All Android licenses accepted.

[√] Android Studio (version 3.5)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin version 42.1.1
    • Dart plugin version 191.8593
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)

[√] VS Code (version 1.48.2)
    • VS Code at C:\Users\DELL\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.13.2

[√] Connected device (2 available)
    • G0550 (mobile)                     • SAN8PSS5S5PMVEUKRCY • android-arm • Android 4.2.2 (API 17)
    • Android SDK built for x86 (mobile) • emulator-5554       • android-x86 • Android 10 (API 29) (emulator)

• No issues found!

解决方法

如果要从RawKeyboardListener获取条形码作为String，则必须将每个字符附加到现有的String。 RawKeyboardListener侦听“按下”的键，因此您不能插入整个条形码。

有一些工作示例：

String inputK = "";  
FocusNode focusNode = FocusNode();
RawKeyboardListener(
  autofocus: true,focusNode: focusNode,onKey: (RawKeyEvent event){
    if(event.runtimeType.toString() == 'RawKeyDownEvent'){
    String key = event.logicalKey.keyLabel;
    if(key != null){
      setState(() {
          inputK += key;
      });
    }
}
  },child: Container(),);

,

这个问题有解决方案吗？我在使用 datalogic memor k 扫描仪时遇到了同样的问题。我只收到最后一次进入的事件。实际条形码编号不会触发事件。

更新... 我在扫描仪中找到了一个设置，可以将键盘输入模式从文本注入更改为按键压力，然后原始键盘侦听器开始工作:-)