小编Joa*_*ria的帖子

这是我的问题。

我正在制作一个小应用程序，它使用 JS-OCR 来拍照并检测单词。它运行良好，但我只能使用前置摄像头。我的想法是仅使用后置摄像头，不需要切换摄像头的选项。

我正在阅读有关该getUserMedia()功能的信息，但无法解决问题。这是涉及的代码段（函数searchForRearCamera()）：

function searchForRearCamera() {
    var deferred = new $.Deferred();

    //         Check that the browser supports getUserMedia.
    // If it doesn't show an alert, otherwise continue.
    if (navigator.getUserMedia) {
        // Request the camera.
        navigator.getUserMedia(
            // Constraints
            {
                video: true
            },

            // Success Callback
            function (localMediaStream) {

            },

            // Error Callback
            function (err) {
                // Log the error to the console.
                console.log('The following error occurred when trying to use getUserMedia: ' + err);
            } …

嗨，大家好！这是我的问题。我有两个屏幕：home-screen.dart和all-categories.dart。\n当我从一个屏幕导航到CategoriesWidget()使用HeroAnimation. 动画有效，但我在物理设备和 iOS 模拟器中都遇到此错误。这CategoriesWidget()相同，只是卡片的数量发生了变化，但我认为这不是问题，因为如果我在两个屏幕中放入相同数量的卡片，问题仍然会发生。

HomeScreen\n\nbody: ListView(\n        padding: EdgeInsets.only(left: 20.0, top: 50.0, right: 20.0),\n        children: <Widget>[\n          Column(\n            crossAxisAlignment: CrossAxisAlignment.start,\n            children: <Widget>[\n              // navBar\n              randomPhrase(),\n              searchBarHome(),\n            ],\n          ),\n          Hero(\n            tag: \'categories\',\n              child: CategoriesWidget(5, true)),\n        ],\n      ),\n

AllCategories Screen\n\nbody: ListView(\n        padding: EdgeInsets.only(left: 20.0, top: 50.0, right: 20.0),\n        children: <Widget>[\n          Column(\n            crossAxisAlignment: CrossAxisAlignment.start,\n            children: <Widget>[\n              SizedBox(height: 10.0),\n              Text(\n                \'Explora nuestras categorias\',\n                style: kSubheadingextStyle.copyWith(\n                  fontSize: 22.0,\n                  height: 1.5,\n                ),\n              ),\n              Hero(\n                  tag: …

从昨天开始，当我使用带有 url_launcher 包的 GestureDetector 时，我收到此错误：

E/flutter (17573): #0      _musicAreaState._launchURL (package:GiramosApp/ui/views/home_screen/widgets/music_area.dart:37:7)
E/flutter (17573): <asynchronous suspension>
E/flutter (17573): #1      _musicAreaState.build.<anonymous closure> (package:GiramosApp/ui/views/home_screen/widgets/music_area.dart:55:13)
E/flutter (17573): #2      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:183:24)
E/flutter (17573): #3      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:598:11)
E/flutter (17573): #4      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:287:5)
E/flutter (17573): #5      BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:259:7)
E/flutter (17573): #6      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:157:27)
E/flutter (17573): #7      GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:224:20)
E/flutter (17573): #8      GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:200:22)
E/flutter (17573): #9      RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:263:11)
E/flutter (17573): #10     GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:157:7)
E/flutter (17573): #11     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:103:7)
E/flutter (17573): #12     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:87:7)
E/flutter (17573): #13     _rootRunUnary (dart:async/zone.dart:1206:13) …