Switch Linux to the GTK embedding (flutter#59287)

Updates the tooling to use the GTK embedding, rather than the GLFW embedding:
- Adds new requirements to `doctor`
- Updates the app and plugin templates to make GTK-based runners and plugins
- Stops downloading and installing the GLFW artifacts

Final part of flutter#54860, other than cleanup.

Author: stuartmorgan-g

packages/flutter_tools/lib/src/artifacts.dart

@@ -50,8 +50,6 @@ enum Artifact {
   linuxDesktopPath,
   // The root of the cpp headers for Linux desktop.
   linuxHeaders,
-  // The root of the cpp client code for Linux desktop.
-  linuxCppClientWrapper,
   /// The root of the Windows desktop sources.
   windowsDesktopPath,
   /// The root of the cpp client code for Windows desktop.
@@ -125,8 +123,6 @@ String _artifactToFileName(Artifact artifact, [ TargetPlatform platform, BuildMo
       return '';
     case Artifact.windowsCppClientWrapper:
       return 'cpp_client_wrapper';
-    case Artifact.linuxCppClientWrapper:
-      return 'cpp_client_wrapper_glfw';
     case Artifact.skyEnginePath:
       return 'sky_engine';
     case Artifact.flutterMacOSPodspec:
@@ -370,9 +366,6 @@ class CachedArtifacts extends Artifacts {
       case Artifact.windowsCppClientWrapper:
         final String engineArtifactsPath = _cache.getArtifactDirectory('engine').path;
         return _fileSystem.path.join(engineArtifactsPath, 'windows-x64', _artifactToFileName(artifact, platform, mode));
-      case Artifact.linuxCppClientWrapper:
-        final String engineArtifactsPath = _cache.getArtifactDirectory('engine').path;
-        return _fileSystem.path.join(engineArtifactsPath, 'linux-x64', _artifactToFileName(artifact, platform, mode));
       case Artifact.skyEnginePath:
         final Directory dartPackageDirectory = _cache.getCacheDir('pkg');
         return _fileSystem.path.join(dartPackageDirectory.path,  _artifactToFileName(artifact));
@@ -534,8 +527,6 @@ class LocalEngineArtifacts extends Artifacts {
       case Artifact.linuxDesktopPath:
       case Artifact.linuxHeaders:
         return _fileSystem.path.join(_hostEngineOutPath, artifactFileName);
-      case Artifact.linuxCppClientWrapper:
-        return _fileSystem.path.join(_hostEngineOutPath, artifactFileName);
       case Artifact.windowsDesktopPath:
         return _fileSystem.path.join(_hostEngineOutPath, artifactFileName);
       case Artifact.windowsCppClientWrapper:

packages/flutter_tools/lib/src/base/user_messages.dart

@@ -231,6 +231,13 @@ class UserMessages {
       'It is likely available from your distribution (e.g.: apt install ninja-build), or '
       'can be downloaded from https://github.com/ninja-build/ninja/releases';
   String ninjaTooOld(String minimumVersion) => 'ninja $minimumVersion or later is required.';
+  String pkgConfigVersion(String version) => 'pkg-config version $version';
+  String get pkgConfigMissing => 'pgk-config is required for Linux development.\n'
+      'It is likely available from your distribution (e.g.: apt install pkg-config), or '
+      'can be downloaded from https://www.freedesktop.org/wiki/Software/pkg-config/';
+  String pkgConfigTooOld(String minimumVersion) => 'pkg-config $minimumVersion or later is required.';
+  String get gtkLibrariesMissing => 'GTK 3.0 development libraries are required for Linux development.\n'
+      'They are likely available from your distribution (e.g.: apt install libgtk-3-dev)';
 
   // Messages used in FlutterCommand
   String flutterElapsedTime(String name, String elapsedTime) => '"flutter $name" took $elapsedTime.';

packages/flutter_tools/lib/src/build_system/targets/linux.dart

@@ -15,13 +15,6 @@ import 'icon_tree_shaker.dart';
 
 /// The only files/subdirectories we care out.
 const List<String> _kLinuxArtifacts = <String>[
-  // GLFW. Will be removed after the switch to GTK.
-  'libflutter_linux_glfw.so',
-  'flutter_export.h',
-  'flutter_messenger.h',
-  'flutter_plugin_registrar.h',
-  'flutter_glfw.h',
-  // GTK. Not yet used by the template.
   'libflutter_linux_gtk.so',
 ];
 
@@ -57,14 +50,6 @@ class UnpackLinux extends Target {
         mode: buildMode,
         platform: TargetPlatform.linux_x64,
       );
-    // For the GLFW embedding.
-    final String clientSourcePath = environment.artifacts
-      .getArtifactPath(
-        Artifact.linuxCppClientWrapper,
-        mode: buildMode,
-        platform: TargetPlatform.linux_x64,
-      );
-    // For the GTK embedding.
     final String headersPath = environment.artifacts
       .getArtifactPath(
         Artifact.linuxHeaders,
@@ -83,7 +68,7 @@ class UnpackLinux extends Target {
       engineSourcePath: engineSourcePath,
       outputDirectory: outputDirectory,
       artifacts: _kLinuxArtifacts,
-      clientSourcePaths: <String>[clientSourcePath, headersPath],
+      clientSourcePaths: <String>[headersPath],
       icuDataPath: environment.artifacts.getArtifactPath(
         Artifact.icuData,
         platform: TargetPlatform.linux_x64,

packages/flutter_tools/lib/src/cache.dart

@@ -1400,10 +1400,6 @@ const List<List<String>> _windowsDesktopBinaryDirs = <List<String>>[
 ];
 
 const List<List<String>> _linuxDesktopBinaryDirs = <List<String>>[
-  <String>['linux-x64', 'linux-x64/linux-x64-flutter-glfw.zip'],
-  <String>['linux-x64', 'linux-x64/flutter-cpp-client-wrapper-glfw.zip'],
-  <String>['linux-x64-profile', 'linux-x64-profile/linux-x64-flutter-glfw.zip'],
-  <String>['linux-x64-release', 'linux-x64-release/linux-x64-flutter-glfw.zip'],
   <String>['linux-x64', 'linux-x64/linux-x64-flutter-gtk.zip'],
   <String>['linux-x64-profile', 'linux-x64-profile/linux-x64-flutter-gtk.zip'],
   <String>['linux-x64-release', 'linux-x64-release/linux-x64-flutter-gtk.zip'],

packages/flutter_tools/lib/src/commands/create.dart

@@ -590,6 +590,8 @@ To edit platform code in an IDE see https://flutter.dev/developing-packages/#edi
     final String pluginClass = pluginDartClass.endsWith('Plugin')
         ? pluginDartClass
         : pluginDartClass + 'Plugin';
+    final String pluginClassSnakeCase = snakeCase(pluginClass);
+    final String pluginClassCapitalSnakeCase = pluginClassSnakeCase.toUpperCase();
     final String appleIdentifier = _createUTIIdentifier(organization, projectName);
 
     return <String, dynamic>{
@@ -605,8 +607,9 @@ To edit platform code in an IDE see https://flutter.dev/developing-packages/#edi
       'androidSdkVersion': android_sdk.minimumAndroidSdkVersion,
       'withDriverTest': renderDriverTest,
       'pluginClass': pluginClass,
+      'pluginClassSnakeCase': pluginClassSnakeCase,
+      'pluginClassCapitalSnakeCase': pluginClassCapitalSnakeCase,
       'pluginDartClass': pluginDartClass,
-      'pluginCppHeaderGuard': projectName.toUpperCase(),
       'pluginProjectUUID': Uuid().v4().toUpperCase(),
       'withPluginHook': withPluginHook,
       'androidLanguage': androidLanguage,

packages/flutter_tools/lib/src/linux/linux_doctor.dart

@@ -17,7 +17,7 @@ class _VersionInfo {
   /// This should contain a version number. For example:
   ///     "clang version 9.0.1-6+build1"
   _VersionInfo(this.description) {
-    final String versionString = RegExp(r'[0-9]+\.[0-9]+\.[0-9]+').firstMatch(description).group(0);
+    final String versionString = RegExp(r'[0-9]+\.[0-9]+(?:\.[0-9]+)?').firstMatch(description).group(0);
     number = Version.parse(versionString);
   }
 
@@ -43,13 +43,21 @@ class LinuxDoctorValidator extends DoctorValidator {
   static const String kClangBinary = 'clang++';
   static const String kCmakeBinary = 'cmake';
   static const String kNinjaBinary = 'ninja';
+  static const String kPkgConfigBinary = 'pkg-config';
 
   final Map<String, Version> _requiredBinaryVersions = <String, Version>{
     kClangBinary: Version(3, 4, 0),
     kCmakeBinary: Version(3, 10, 0),
     kNinjaBinary: Version(1, 8, 0),
+    kPkgConfigBinary: Version(0, 29, 0),
   };
 
+  final List<String> _requiredLibraries = <String>[
+    'gtk+-3.0',
+    'glib-2.0',
+    'gio-2.0',
+  ];
+
   @override
   Future<ValidationResult> validate() async {
     ValidationType validationType = ValidationType.installed;
@@ -103,7 +111,7 @@ class LinuxDoctorValidator extends DoctorValidator {
       if (version == null) {
         messages.add(ValidationMessage.error(_userMessages.ninjaMissing));
       } else {
-        // The full version description is just the number, so context.
+        // The full version description is just the number, so add context.
         messages.add(ValidationMessage(_userMessages.ninjaVersion(version.description)));
         final Version requiredVersion = _requiredBinaryVersions[kNinjaBinary];
         if (version.number < requiredVersion) {
@@ -112,6 +120,36 @@ class LinuxDoctorValidator extends DoctorValidator {
       }
     }
 
+    // Message for pkg-config.
+    {
+      final _VersionInfo version = installedVersions[kPkgConfigBinary];
+      if (version == null) {
+        messages.add(ValidationMessage.error(_userMessages.pkgConfigMissing));
+      } else {
+        // The full version description is just the number, so add context.
+        messages.add(ValidationMessage(_userMessages.pkgConfigVersion(version.description)));
+        final Version requiredVersion = _requiredBinaryVersions[kPkgConfigBinary];
+        if (version.number < requiredVersion) {
+          messages.add(ValidationMessage.error(_userMessages.pkgConfigTooOld(requiredVersion.toString())));
+        }
+      }
+    }
+
+    // Message for libraries.
+    {
+      bool libraryMissing = false;
+      for (final String library in _requiredLibraries) {
+        if (!await _libraryIsPresent(library)) {
+          libraryMissing = true;
+          break;
+        }
+      }
+      if (libraryMissing) {
+        validationType = ValidationType.missing;
+        messages.add(ValidationMessage.error(_userMessages.gtkLibrariesMissing));
+      }
+    }
+
     return ValidationResult(validationType, messages);
   }
 
@@ -135,4 +173,19 @@ class LinuxDoctorValidator extends DoctorValidator {
     final String firstLine = (result.stdout as String).split('\n').first.trim();
     return _VersionInfo(firstLine);
   }
+
+  /// Checks that [library] is available via pkg-config.
+  Future<bool> _libraryIsPresent(String library) async {
+    ProcessResult result;
+    try {
+      result = await _processManager.run(<String>[
+        'pkg-config',
+        '--exists',
+        library,
+      ]);
+    } on ArgumentError {
+      // ignore error.
+    }
+    return (result?.exitCode ?? 1) == 0;
+  }
 }

packages/flutter_tools/lib/src/plugins.dart

@@ -793,7 +793,47 @@ void RegisterPlugins(flutter::PluginRegistry* registry) {
 }
 ''';
 
+const String _linuxPluginRegistryHeaderTemplate = '''
+//
+//  Generated file. Do not edit.
+//
+
+#ifndef GENERATED_PLUGIN_REGISTRANT_
+#define GENERATED_PLUGIN_REGISTRANT_
+
+#include <flutter_linux/flutter_linux.h>
+
+// Registers Flutter plugins.
+void fl_register_plugins(FlPluginRegistry* registry);
+
+#endif  // GENERATED_PLUGIN_REGISTRANT_
+''';
+
+const String _linuxPluginRegistryImplementationTemplate = '''
+//
+//  Generated file. Do not edit.
+//
+
+#include "generated_plugin_registrant.h"
+
+{{#plugins}}
+#include <{{name}}/{{filename}}.h>
+{{/plugins}}
+
+void fl_register_plugins(FlPluginRegistry* registry) {
+{{#plugins}}
+  g_autoptr(FlPluginRegistrar) {{name}}_registrar =
+      fl_plugin_registry_get_registrar_for_plugin(registry, "{{class}}");
+  {{filename}}_register_with_registrar({{name}}_registrar);
+{{/plugins}}
+}
+''';
+
 const String _linuxPluginCmakefileTemplate = r'''
+#
+# Generated file, do not edit.
+#
+
 list(APPEND FLUTTER_PLUGIN_LIST
 {{#plugins}}
   {{name}}
@@ -864,10 +904,24 @@ Future<void> _writeLinuxPluginFiles(FlutterProject project, List<Plugin> plugins
       from: makefileDirPath,
     ),
   };
-  await _writeCppPluginRegistrant(project.linux.managedDirectory, context);
+  await _writeLinuxPluginRegistrant(project.linux.managedDirectory, context);
   await _writeLinuxPluginCmakefile(project.linux.generatedPluginCmakeFile, context);
 }
 
+Future<void> _writeLinuxPluginRegistrant(Directory destination, Map<String, dynamic> templateContext) async {
+  final String registryDirectory = destination.path;
+  _renderTemplateToFile(
+    _linuxPluginRegistryHeaderTemplate,
+    templateContext,
+    globals.fs.path.join(registryDirectory, 'generated_plugin_registrant.h'),
+  );
+  _renderTemplateToFile(
+    _linuxPluginRegistryImplementationTemplate,
+    templateContext,
+    globals.fs.path.join(registryDirectory, 'generated_plugin_registrant.cc'),
+  );
+}
+
 Future<void> _writeLinuxPluginCmakefile(File destinationFile, Map<String, dynamic> templateContext) async {
   _renderTemplateToFile(
     _linuxPluginCmakefileTemplate,

packages/flutter_tools/templates/app/linux.tmpl/CMakeLists.txt.tmpl

@@ -28,14 +28,20 @@ set(FLUTTER_MANAGED_DIR "${CMAKE_CURRENT_SOURCE_DIR}/flutter")
 # Flutter library and tool build rules.
 add_subdirectory(${FLUTTER_MANAGED_DIR})
 
+# System-level dependencies.
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(GTK REQUIRED IMPORTED_TARGET gtk+-3.0)
+
 # Application build
 add_executable(${BINARY_NAME}
   "main.cc"
+  "my_application.cc"
   "window_configuration.cc"
   "${FLUTTER_MANAGED_DIR}/generated_plugin_registrant.cc"
 )
 apply_standard_settings(${BINARY_NAME})
-target_link_libraries(${BINARY_NAME} PRIVATE flutter flutter_wrapper_app)
+target_link_libraries(${BINARY_NAME} PRIVATE flutter)
+target_link_libraries(${BINARY_NAME} PRIVATE PkgConfig::GTK)
 add_dependencies(${BINARY_NAME} flutter_assemble)
 
 # Generated plugin build rules, which manage building the plugins and adding

packages/flutter_tools/templates/app/linux.tmpl/flutter/.template_version

@@ -1 +1 @@
-3
+4