同步颤振pdfviewer查看器库

Question

我在我的项目中使用了syncfusion_flutter_pdfviewer库。我需要阅读pdf文件，并把那里的页面在我的应用程序中添加一些(文本-图形-链接) (pdf编辑器)，我发现了这个库，但与一些错误，我不知道为什么。有什么需要帮忙的吗？

../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:959:29: Error: Method 'addObserver' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addObserver(this);
                            ^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:1046:16: Error: Method 'clear' cannot be called on 'ImageCache?' because it is potentially null.
 - 'ImageCache' is from 'package:flutter/src/painting/image_cache.dart' ('../../flutter/packages/flutter/lib/src/painting/image_cache.dart').
Try calling using ?. instead.
    imageCache.clear();
               ^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:1066:29: Error: Method 'removeObserver' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.removeObserver(this);
                            ^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:1096:16: Error: Method 'clear' cannot be called on 'ImageCache?' because it is potentially null.
 - 'ImageCache' is from 'package:flutter/src/painting/image_cache.dart' ('../../flutter/packages/flutter/lib/src/painting/image_cache.dart').
Try calling using ?. instead.
    imageCache.clear();
               ^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:1918:51: Error: Property 'window' cannot be accessed on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try accessing using ?. instead.
                          WidgetsBinding.instance.window.viewInsets.bottom !=
                                                  ^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:1924:57: Error: Property 'window' cannot be accessed on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try accessing using ?. instead.
                                WidgetsBinding.instance.window.viewInsets,
                                                        ^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:1925:57: Error: Property 'window' cannot be accessed on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try accessing using ?. instead.
                                WidgetsBinding.instance.window.devicePixelRatio)
                                                        ^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:2736:31: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
      WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                              ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:2751:37: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
            WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                                    ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:2775:35: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
          WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                                  ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:2873:31: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
      WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                              ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:2888:16: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
              .addPostFrameCallback((Duration timeStamp) async {
               ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:3404:31: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
      WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                              ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/pdfviewer.dart:3414:33: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
        WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                                ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/common/pdfviewer_plugin.dart:106:16: Error: Method 'clear' cannot be called on 'ImageCache?' because it is potentially null.
 - 'ImageCache' is from 'package:flutter/src/painting/image_cache.dart' ('../../flutter/packages/flutter/lib/src/painting/image_cache.dart').
Try calling using ?. instead.
    imageCache.clear();
               ^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/common/pdfviewer_plugin.dart:153:16: Error: Method 'clear' cannot be called on 'ImageCache?' because it is potentially null.
 - 'ImageCache' is from 'package:flutter/src/painting/image_cache.dart' ('../../flutter/packages/flutter/lib/src/painting/image_cache.dart').
Try calling using ?. instead.
    imageCache.clear();
               ^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_page_view.dart:204:30: Error: Property 'imageCache' cannot be accessed on 'PaintingBinding?' because it is potentially null.
 - 'PaintingBinding' is from 'package:flutter/src/painting/binding.dart' ('../../flutter/packages/flutter/lib/src/painting/binding.dart').
Try accessing using ?. instead.
    PaintingBinding.instance.imageCache.clear();
                             ^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_page_view.dart:204:41: Error: Method 'clear' cannot be called on 'ImageCache?' because it is potentially null.
 - 'ImageCache' is from 'package:flutter/src/painting/image_cache.dart' ('../../flutter/packages/flutter/lib/src/painting/image_cache.dart').
Try calling using ?. instead.
    PaintingBinding.instance.imageCache.clear();
                                        ^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_page_view.dart:205:30: Error: Property 'imageCache' cannot be accessed on 'PaintingBinding?' because it is potentially null.
 - 'PaintingBinding' is from 'package:flutter/src/painting/binding.dart' ('../../flutter/packages/flutter/lib/src/painting/binding.dart').
Try accessing using ?. instead.
    PaintingBinding.instance.imageCache.clearLiveImages();
                             ^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_page_view.dart:205:41: Error: Method 'clearLiveImages' cannot be called on 'ImageCache?' because it is potentially null.
 - 'ImageCache' is from 'package:flutter/src/painting/image_cache.dart' ('../../flutter/packages/flutter/lib/src/painting/image_cache.dart').
Try calling using ?. instead.
    PaintingBinding.instance.imageCache.clearLiveImages();
                                        ^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_page_view.dart:213:32: Error: Property 'imageCache' cannot be accessed on 'PaintingBinding?' because it is potentially null.
 - 'PaintingBinding' is from 'package:flutter/src/painting/binding.dart' ('../../flutter/packages/flutter/lib/src/painting/binding.dart').
Try accessing using ?. instead.
      PaintingBinding.instance.imageCache.clear();
                               ^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_page_view.dart:213:43: Error: Method 'clear' cannot be called on 'ImageCache?' because it is potentially null.
 - 'ImageCache' is from 'package:flutter/src/painting/image_cache.dart' ('../../flutter/packages/flutter/lib/src/painting/image_cache.dart').
Try calling using ?. instead.
      PaintingBinding.instance.imageCache.clear();
                                          ^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_page_view.dart:214:32: Error: Property 'imageCache' cannot be accessed on 'PaintingBinding?' because it is potentially null.
 - 'PaintingBinding' is from 'package:flutter/src/painting/binding.dart' ('../../flutter/packages/flutter/lib/src/painting/binding.dart').
Try accessing using ?. instead.
      PaintingBinding.instance.imageCache.clearLiveImages();
                               ^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_page_view.dart:214:43: Error: Method 'clearLiveImages' cannot be called on 'ImageCache?' because it is potentially null.
 - 'ImageCache' is from 'package:flutter/src/painting/image_cache.dart' ('../../flutter/packages/flutter/lib/src/painting/image_cache.dart').
Try calling using ?. instead.
      PaintingBinding.instance.imageCache.clearLiveImages();
                                          ^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdf_scrollable.dart:453:31: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
      WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                              ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/pdfviewer_canvas.dart:1211:31: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
      WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                              ^^^^^^^^^^^^^^^^^^^^
../../flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_pdfviewer-20.2.36-beta/lib/src/control/scroll_head_overlay.dart:290:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
                            ^^^^^^^^^^^^^^^^^^^^


FAILURE: Build failed with an exception.

* Where:
Script 'C:\Users\Ghina\flutter\packages\flutter_tools\gradle\flutter.gradle' line: 1102

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command 'C:\Users\Ghina\flutter\bin\flutter.bat'' finished with non-zero exit value 1

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 24s
Exception: Gradle task assembleDebug failed with exit code 1

Answer 1

尝试运行flutter pub upgrade