Make pdfrx support Flutter Web with wasm

[thudaydelight]

I need to use Flutter Web with wasm for the application.

``

../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:7:1: Error: JS interop library 'dart:js_util' can't be imported when compiling to Wasm.
Try using 'dart:js_interop' or 'dart:js_interop_unsafe' instead.
import 'dart:js_util';
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:122:14: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
double offsetX = 0,
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:123:14: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
double offsetY = 0,
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:124:12: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
bool dontFlip = false});
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:168:14: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
String intent = 'display',
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:169:11: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
int annotationMode = 1,
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:170:12: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
bool renderInteractiveForms = false,
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:207:10: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
bool includeMarkedContent = false,
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:208:10: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
bool disableNormalization = false,
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdf.js.dart:267:12: Warning: Initializers for parameters are ignored on static interop external functions.
Declare a forwarding non-external function with this initializer, or remove the initializer.
String intent = 'display',
^
../../.pub-cache/hosted/pub.dev/pdfrx-1.0.50/lib/src/web/pdfrx_web.dart:6:1: Error: JS interop library 'dart:js_util' can't be imported when compiling to Wasm.
Try using 'dart:js_interop' or 'dart:js_interop_unsafe' instead.
import 'dart:js_util' as js_util;
^
Command: /Users/daydelight/fvm/versions/master/bin/cache/dart-sdk/bin/dart compile wasm --packages=.dart_tool/package_config.json
--extra-compiler-option=--dart-sdk=/Users/daydelight/fvm/versions/master/bin/cache/dart-sdk
--extra-compiler-option=--platform=/Users/daydelight/fvm/versions/master/bin/cache/flutter_web_sdk/kernel/dart2wasm_platform.dill --extra-compiler-option=--delete-tostring-package-uri=dart:ui
--extra-compiler-option=--delete-tostring-package-uri=package:flutter --extra-compiler-option=--import-shared-memory --extra-compiler-option=--shared-memory-max-pages=32768 -Ddart.vm.product=true
-DFLUTTER_WEB_CANVASKIT_URL=https://www.gstatic.com/flutter-canvaskit/4f6b832c8e333775f2c217a821050543a110826e/ -DFLUTTER_WEB_AUTO_DETECT=false -DFLUTTER_WEB_USE_SKIA=false
-DFLUTTER_WEB_USE_SKWASM=true --extra-compiler-option=--depfile=/Users/daydelight/study/webassembly/.dart_tool/flutter_build/b49f125fa6955c85159dd2d865c4d882/dart2wasm.d -O4 --no-name-section -o
/Users/daydelight/study/webassembly/.dart_tool/flutter_build/b49f125fa6955c85159dd2d865c4d882/main.dart.wasm
/Users/daydelight/study/webassembly/.dart_tool/flutter_build/b49f125fa6955c85159dd2d865c4d882/main.dart
#0 RunResult.throwException (package:flutter_tools/src/base/process.dart:125:5)
#1 _DefaultProcessUtils.run (package:flutter_tools/src/base/process.dart:321:19)

#2 Dart2WasmTarget.build (package:flutter_tools/src/build_system/targets/web.dart:297:5)

#3 _BuildInstance._invokeInternal (package:flutter_tools/src/build_system/build_system.dart:875:9)

#4 Future.wait. (dart:async/future.dart:524:21)

#5 _BuildInstance.invokeTarget (package:flutter_tools/src/build_system/build_system.dart:813:32)

#6 Future.wait. (dart:async/future.dart:524:21)

#7 _BuildInstance.invokeTarget (package:flutter_tools/src/build_system/build_system.dart:813:32)

#8 FlutterBuildSystem.build (package:flutter_tools/src/build_system/build_system.dart:642:16)

#9 WebBuilder.buildWeb (package:flutter_tools/src/web/compile.dart:92:34)

#10 BuildWebCommand.runCommand (package:flutter_tools/src/commands/build_web.dart:230:5)

#11 FlutterCommand.run. (package:flutter_tools/src/runner/flutter_command.dart:1394:27)

#12 AppContext.run. (package:flutter_tools/src/base/context.dart:153:19)

#13 CommandRunner.runCommand (package:args/command_runner.dart:212:13)

#14 FlutterCommandRunner.runCommand. (package:flutter_tools/src/runner/flutter_command_runner.dart:372:9)

#15 AppContext.run. (package:flutter_tools/src/base/context.dart:153:19)

#16 FlutterCommandRunner.runCommand (package:flutter_tools/src/runner/flutter_command_runner.dart:308:5)

#17 run.. (package:flutter_tools/runner.dart:119:9)

#18 AppContext.run. (package:flutter_tools/src/base/context.dart:153:19)

#19 main (package:flutter_tools/executable.dart:93:3)

Compiling lib/main.dart for the Web... 17.2s
Error: Failed to compile application for the Web.

``

[espresso3389]

Basically, because wasm build is not supported on stable channel, I don't ensure that pdfrx runs on it. But I've just removed dependency on js_util.

[thudaydelight]

@espresso3389

Thank you, i am waiting pdfrx support wasm when wasm will be supported on stable channel

[davestimpert]

What's the likelihood of getting wasm support, now that it is supported on the stable channel?

[espresso3389]

There are several pieces that can be building blocks of pdfrx wasm support:

• Flutter's support for WebAssembly (Wasm)
• wasm_ffi
• bblanchon/pdfium-binaries has precompiled wasm module

I didn't check the things deeply, but wasm_ffi lacks struct support and it may be a major blocking issue for the support.

[espresso3389]

And, wasm_ffi 0.9.4 was released 16 months ago. The maintainer is not actively maintaining it.
Do you guys know any kind of alternative to wasm_ffi or should we (I or someone) fork it to add support of struct??