j3g
/
lum_platform_image_converter
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

feat: Support web

This commit is contained in:
Koji Wakamiya 2025-12-08 21:26:53 +09:00
parent 8b47d1295b
commit c0f8076b56
No known key found for this signature in database
25 changed files with 318 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
README.md
View File

@ -15,9 +15,12 @@ A high-performance Flutter plugin for cross-platform image format conversion usi
| iOS | 14.0 | ImageIO (CoreFoundation, CoreGraphics) |
| macOS | 10.15 | ImageIO (CoreFoundation, CoreGraphics) |
| Android | 7 | BitmapFactory, Bitmap compression |
| Web | N/A | Not supported |
| Web | - | Canvas API |
on Android, HEIC input is supported on Android 9+ but HEIC output is not supported.
**Note:**
- On iOS and macOS, WebP input is supported but WebP output is not supported.
- On Android, HEIC input is supported on Android 9+ but HEIC output is not supported.
- On Web, HEIC is not supported.
## Getting Started
@ -137,3 +140,22 @@ The Android implementation uses [BitmapFactory](https://developer.android.com/re
**Key Limitations:**
- HEIC can be read (input only) but cannot be written (output format not supported)
- Requires Android 9+ for full HEIC support
### Web Implementation
The Web implementation uses the [Canvas API](https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API) for image conversion:
1. **Decoding**: `HTMLImageElement` loads image data via Blob URL
2. **Rendering**: `CanvasRenderingContext2D.drawImage` renders the image to canvas
3. **Encoding**: `HTMLCanvasElement.toBlob` encodes to target format
4. **Quality**: Supports quality parameter for JPEG and WebP (0.0-1.0 scale)
**Key Steps:**
- `Blob` and `URL.createObjectURL`: Create temporary URL from input bytes
- `HTMLImageElement.onLoad`: Wait for image to load asynchronously
- `canvas.width/height = img.width/height`: Set canvas size to match image dimensions
- `canvas.toBlob`: Convert canvas content to target format
**Key Limitations:**
- HEIC format is not supported on Web platform
- Output format depends on browser support (JPEG and PNG are universally supported, WebP is widely supported)

36
example/.metadata Normal file
View File

@ -0,0 +1,36 @@
# This file tracks properties of this Flutter project.
# Used by Flutter tool to assess capabilities and perform upgrades etc.
#
# This file should be version controlled and should not be manually edited.
version:
revision: "66dd93f9a27ffe2a9bfc8297506ce066ff51265f"
channel: "stable"
project_type: app
# Tracks metadata for the flutter migrate command
migration:
platforms:
- platform: root
create_revision: 66dd93f9a27ffe2a9bfc8297506ce066ff51265f
base_revision: 66dd93f9a27ffe2a9bfc8297506ce066ff51265f
- platform: android
create_revision: 66dd93f9a27ffe2a9bfc8297506ce066ff51265f
base_revision: 66dd93f9a27ffe2a9bfc8297506ce066ff51265f
- platform: ios
create_revision: 66dd93f9a27ffe2a9bfc8297506ce066ff51265f
base_revision: 66dd93f9a27ffe2a9bfc8297506ce066ff51265f
- platform: web
create_revision: 66dd93f9a27ffe2a9bfc8297506ce066ff51265f
base_revision: 66dd93f9a27ffe2a9bfc8297506ce066ff51265f
# User provided section
# List of Local paths (relative to this file) that should be
# ignored by the migrate tool.
#
# Files that are not part of the templates will be ignored by default.
unmanaged_files:
- 'lib/main.dart'
- 'ios/Runner.xcodeproj/project.pbxproj'

4
example/android/app/build.gradle.kts
View File

@ -6,7 +6,7 @@ plugins {
}
android {
namespace = "dr1009.com.image_ffi_example"
namespace = "com.example.image_ffi_example"
compileSdk = flutter.compileSdkVersion
ndkVersion = flutter.ndkVersion
@ -21,7 +21,7 @@ android {
defaultConfig {
// TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
applicationId = "dr1009.com.image_ffi_example"
applicationId = "com.example.image_ffi_example"
// You can update the following values to match your application needs.
// For more information, see: https://flutter.dev/to/review-gradle-config.
minSdk = flutter.minSdkVersion

2
example/android/app/src/main/kotlin/dr1009/com/image_ffi_example/MainActivity.kt → example/android/app/src/main/kotlin/com/example/image_ffi_example/MainActivity.kt
View File

@ -1,4 +1,4 @@
package dr1009.com.image_ffi_example
package com.example.image_ffi_example
import io.flutter.embedding.android.FlutterActivity

30
example/ios/Runner.xcodeproj/project.pbxproj
View File

@ -11,10 +11,10 @@
331C808B294A63AB00263BE5 /* RunnerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 331C807B294A618700263BE5 /* RunnerTests.swift */; };
3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };
74858FAF1ED2DC5600515810 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 74858FAE1ED2DC5600515810 /* AppDelegate.swift */; };
78A318202AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage in Frameworks */ = {isa = PBXBuildFile; productRef = 78A3181F2AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage */; };
97C146FC1CF9000F007C117D /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FA1CF9000F007C117D /* Main.storyboard */; };
97C146FE1CF9000F007C117D /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FD1CF9000F007C117D /* Assets.xcassets */; };
97C147011CF9000F007C117D /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FF1CF9000F007C117D /* LaunchScreen.storyboard */; };
78A318202AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage in Frameworks */ = {isa = PBXBuildFile; productRef = 78A3181F2AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage */; };
/* End PBXBuildFile section */
/* Begin PBXContainerItemProxy section */
@ -48,6 +48,7 @@
3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };
74858FAD1ED2DC5600515810 /* Runner-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "Runner-Bridging-Header.h"; sourceTree = "<group>"; };
74858FAE1ED2DC5600515810 /* AppDelegate.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
78E0A7A72DC9AD7400C4905E /* FlutterGeneratedPluginSwiftPackage */ = {isa = PBXFileReference; lastKnownFileType = wrapper; name = FlutterGeneratedPluginSwiftPackage; path = Flutter/ephemeral/Packages/FlutterGeneratedPluginSwiftPackage; sourceTree = "<group>"; };
7AFA3C8E1D35360C0083082E /* Release.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; name = Release.xcconfig; path = Flutter/Release.xcconfig; sourceTree = "<group>"; };
9740EEB21CF90195004384FC /* Debug.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Debug.xcconfig; path = Flutter/Debug.xcconfig; sourceTree = "<group>"; };
9740EEB31CF90195004384FC /* Generated.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Generated.xcconfig; path = Flutter/Generated.xcconfig; sourceTree = "<group>"; };
@ -56,7 +57,6 @@
97C146FD1CF9000F007C117D /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
97C147001CF9000F007C117D /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/LaunchScreen.storyboard; sourceTree = "<group>"; };
97C147021CF9000F007C117D /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
78E0A7A72DC9AD7400C4905E /* FlutterGeneratedPluginSwiftPackage */ = {isa = PBXFileReference; lastKnownFileType = wrapper; name = FlutterGeneratedPluginSwiftPackage; path = Flutter/ephemeral/Packages/FlutterGeneratedPluginSwiftPackage; sourceTree = "<group>"; };
/* End PBXFileReference section */
/* Begin PBXFrameworksBuildPhase section */
@ -146,9 +146,6 @@
productType = "com.apple.product-type.bundle.unit-test";
};
97C146ED1CF9000F007C117D /* Runner */ = {
packageProductDependencies = (
78A3181F2AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage */,
);
isa = PBXNativeTarget;
buildConfigurationList = 97C147051CF9000F007C117D /* Build configuration list for PBXNativeTarget "Runner" */;
buildPhases = (
@ -164,6 +161,9 @@
dependencies = (
);
name = Runner;
packageProductDependencies = (
78A3181F2AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage */,
);
productName = Runner;
productReference = 97C146EE1CF9000F007C117D /* Runner.app */;
productType = "com.apple.product-type.application";
@ -172,9 +172,6 @@
/* Begin PBXProject section */
97C146E61CF9000F007C117D /* Project object */ = {
packageReferences = (
781AD8BC2B33823900A9FFBB /* XCLocalSwiftPackageReference "Flutter/ephemeral/Packages/FlutterGeneratedPluginSwiftPackage" */,
);
isa = PBXProject;
attributes = {
BuildIndependentTargetsInParallel = YES;
@ -200,6 +197,9 @@
Base,
);
mainGroup = 97C146E51CF9000F007C117D;
packageReferences = (
781AD8BC2B33823900A9FFBB /* XCLocalSwiftPackageReference "Flutter/ephemeral/Packages/FlutterGeneratedPluginSwiftPackage" */,
);
productRefGroup = 97C146EF1CF9000F007C117D /* Products */;
projectDirPath = "";
projectRoot = "";
@ -378,7 +378,7 @@
"$(inherited)",
"@executable_path/Frameworks",
);
PRODUCT_BUNDLE_IDENTIFIER = dr1009.com.imageFfiExample;
PRODUCT_BUNDLE_IDENTIFIER = com.example.imageFfiExample;
PRODUCT_NAME = "$(TARGET_NAME)";
SWIFT_OBJC_BRIDGING_HEADER = "Runner/Runner-Bridging-Header.h";
SWIFT_VERSION = 5.0;
@ -394,7 +394,7 @@
CURRENT_PROJECT_VERSION = 1;
GENERATE_INFOPLIST_FILE = YES;
MARKETING_VERSION = 1.0;
PRODUCT_BUNDLE_IDENTIFIER = dr1009.com.imageFfiExample.RunnerTests;
PRODUCT_BUNDLE_IDENTIFIER = com.example.imageFfiExample.RunnerTests;
PRODUCT_NAME = "$(TARGET_NAME)";
SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
SWIFT_OPTIMIZATION_LEVEL = "-Onone";
@ -411,7 +411,7 @@
CURRENT_PROJECT_VERSION = 1;
GENERATE_INFOPLIST_FILE = YES;
MARKETING_VERSION = 1.0;
PRODUCT_BUNDLE_IDENTIFIER = dr1009.com.imageFfiExample.RunnerTests;
PRODUCT_BUNDLE_IDENTIFIER = com.example.imageFfiExample.RunnerTests;
PRODUCT_NAME = "$(TARGET_NAME)";
SWIFT_VERSION = 5.0;
TEST_HOST = "$(BUILT_PRODUCTS_DIR)/Runner.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/Runner";
@ -426,7 +426,7 @@
CURRENT_PROJECT_VERSION = 1;
GENERATE_INFOPLIST_FILE = YES;
MARKETING_VERSION = 1.0;
PRODUCT_BUNDLE_IDENTIFIER = dr1009.com.imageFfiExample.RunnerTests;
PRODUCT_BUNDLE_IDENTIFIER = com.example.imageFfiExample.RunnerTests;
PRODUCT_NAME = "$(TARGET_NAME)";
SWIFT_VERSION = 5.0;
TEST_HOST = "$(BUILT_PRODUCTS_DIR)/Runner.app/$(BUNDLE_EXECUTABLE_FOLDER_PATH)/Runner";
@ -557,7 +557,7 @@
"$(inherited)",
"@executable_path/Frameworks",
);
PRODUCT_BUNDLE_IDENTIFIER = dr1009.com.imageFfiExample;
PRODUCT_BUNDLE_IDENTIFIER = com.example.imageFfiExample;
PRODUCT_NAME = "$(TARGET_NAME)";
SWIFT_OBJC_BRIDGING_HEADER = "Runner/Runner-Bridging-Header.h";
SWIFT_OPTIMIZATION_LEVEL = "-Onone";
@ -579,7 +579,7 @@
"$(inherited)",
"@executable_path/Frameworks",
);
PRODUCT_BUNDLE_IDENTIFIER = dr1009.com.imageFfiExample;
PRODUCT_BUNDLE_IDENTIFIER = com.example.imageFfiExample;
PRODUCT_NAME = "$(TARGET_NAME)";
SWIFT_OBJC_BRIDGING_HEADER = "Runner/Runner-Bridging-Header.h";
SWIFT_VERSION = 5.0;
@ -621,12 +621,14 @@
defaultConfigurationName = Release;
};
/* End XCConfigurationList section */
/* Begin XCLocalSwiftPackageReference section */
781AD8BC2B33823900A9FFBB /* XCLocalSwiftPackageReference "Flutter/ephemeral/Packages/FlutterGeneratedPluginSwiftPackage" */ = {
isa = XCLocalSwiftPackageReference;
relativePath = Flutter/ephemeral/Packages/FlutterGeneratedPluginSwiftPackage;
};
/* End XCLocalSwiftPackageReference section */
/* Begin XCSwiftPackageProductDependency section */
78A3181F2AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage */ = {
isa = XCSwiftPackageProductDependency;

2
example/ios/Runner/Info.plist
View File

@ -5,7 +5,7 @@
<key>CFBundleDevelopmentRegion</key>
<string>$(DEVELOPMENT_LANGUAGE)</string>
<key>CFBundleDisplayName</key>
<string>Image Ffi</string>
<string>Image Ffi Example</string>
<key>CFBundleExecutable</key>
<string>$(EXECUTABLE_NAME)</string>
<key>CFBundleIdentifier</key>

BIN
example/web/favicon.png Normal file
View File

Binary file not shown.
Side by Side

After

Width:  |  Height:  |  Size: 917 B

BIN
example/web/icons/Icon-192.png Normal file
View File

Binary file not shown.
Side by Side

After

Width:  |  Height:  |  Size: 5.2 KiB

BIN
example/web/icons/Icon-512.png Normal file
View File

Binary file not shown.
Side by Side

After

Width:  |  Height:  |  Size: 8.1 KiB

BIN
example/web/icons/Icon-maskable-192.png Normal file
View File

Binary file not shown.
Side by Side

After

Width:  |  Height:  |  Size: 5.5 KiB

BIN
example/web/icons/Icon-maskable-512.png Normal file
View File

Binary file not shown.
Side by Side

After

Width:  |  Height:  |  Size: 20 KiB

38
example/web/index.html Normal file
View File

@ -0,0 +1,38 @@
<!DOCTYPE html>
<html>
<head>
<!--
If you are serving your web app in a path other than the root, change the
href value below to reflect the base path you are serving from.
The path provided below has to start and end with a slash "/" in order for
it to work correctly.
For more details:
* https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
This is a placeholder for base href that will be replaced by the value of
the `--base-href` argument provided to `flutter build`.
-->
<base href="$FLUTTER_BASE_HREF">
<meta charset="UTF-8">
<meta content="IE=Edge" http-equiv="X-UA-Compatible">
<meta name="description" content="A new Flutter project.">
<!-- iOS meta tags & icons -->
<meta name="mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<meta name="apple-mobile-web-app-title" content="image_ffi_example">
<link rel="apple-touch-icon" href="icons/Icon-192.png">
<!-- Favicon -->
<link rel="icon" type="image/png" href="favicon.png"/>
<title>image_ffi_example</title>
<link rel="manifest" href="manifest.json">
</head>
<body>
<script src="flutter_bootstrap.js" async></script>
</body>
</html>

35
example/web/manifest.json Normal file
View File

@ -0,0 +1,35 @@
{
"name": "image_ffi_example",
"short_name": "image_ffi_example",
"start_url": ".",
"display": "standalone",
"background_color": "#0175C2",
"theme_color": "#0175C2",
"description": "A new Flutter project.",
"orientation": "portrait-primary",
"prefer_related_applications": false,
"icons": [
{
"src": "icons/Icon-192.png",
"sizes": "192x192",
"type": "image/png"
},
{
"src": "icons/Icon-512.png",
"sizes": "512x512",
"type": "image/png"
},
{
"src": "icons/Icon-maskable-192.png",
"sizes": "192x192",
"type": "image/png",
"purpose": "maskable"
},
{
"src": "icons/Icon-maskable-512.png",
"sizes": "512x512",
"type": "image/png",
"purpose": "maskable"
}
]
}

11
lib/image_ffi.dart
View File

@ -3,10 +3,11 @@ library;
import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:image_ffi/src/image_converter_android.dart';
import 'package:image_ffi/src/image_converter_darwin.dart';
import 'package:image_ffi/src/image_converter_platform_interface.dart';
import 'package:image_ffi/src/output_format.dart';
import 'package:image_ffi/src/android/shared.dart';
import 'package:image_ffi/src/darwin/shared.dart';
import 'package:image_ffi/src/web/shared.dart';
export 'src/output_format.dart';
@ -99,11 +100,11 @@ class _ConvertRequest {
/// Returns the platform-specific converter instance.
ImageConverterPlatform _getPlatformForTarget(TargetPlatform platform) {
if (kIsWeb) {
throw UnsupportedError('Image conversion is not supported on the web.');
return const ImageConverterWeb();
}
return switch (platform) {
TargetPlatform.android => ImageConverterAndroid(),
TargetPlatform.iOS || TargetPlatform.macOS => ImageConverterDarwin(),
TargetPlatform.android => const ImageConverterAndroid(),
TargetPlatform.iOS || TargetPlatform.macOS => const ImageConverterDarwin(),
_ => throw UnsupportedError(
'Image conversion is not supported on this platform: $platform',
),

2
lib/src/image_converter_android.dart → lib/src/android/native.dart
View File

@ -28,6 +28,8 @@ import 'package:jni/jni.dart';
/// - Native image decoding via BitmapFactory
/// - Efficient compression with quality adjustment
final class ImageConverterAndroid implements ImageConverterPlatform {
const ImageConverterAndroid();
@override
Future<Uint8List> convert({
required Uint8List inputData,

3
lib/src/android/shared.dart Normal file
View File

@ -0,0 +1,3 @@
export 'stub.dart'
if (dart.library.io) 'native.dart'
if (dart.library.js_interop) 'stub.dart';

15
lib/src/android/stub.dart Normal file
View File

@ -0,0 +1,15 @@
import 'dart:typed_data';
import 'package:image_ffi/src/image_converter_platform_interface.dart';
import 'package:image_ffi/src/output_format.dart';
final class ImageConverterAndroid implements ImageConverterPlatform {
const ImageConverterAndroid();
@override
Future<Uint8List> convert({
required Uint8List inputData,
OutputFormat format = OutputFormat.jpeg,
int quality = 100,
}) async => throw UnimplementedError();
}

2
lib/src/image_converter_darwin.dart → lib/src/darwin/native.dart
View File

@ -29,6 +29,8 @@ import 'package:objective_c/objective_c.dart';
/// - In-memory processing
/// - Adjustable JPEG/WebP quality for size optimization
final class ImageConverterDarwin implements ImageConverterPlatform {
const ImageConverterDarwin();
@override
Future<Uint8List> convert({
required Uint8List inputData,

3
lib/src/darwin/shared.dart Normal file
View File

@ -0,0 +1,3 @@
export 'stub.dart'
if (dart.library.io) 'native.dart'
if (dart.library.js_interop) 'stub.dart';

15
lib/src/darwin/stub.dart Normal file
View File

@ -0,0 +1,15 @@
import 'dart:typed_data';
import 'package:image_ffi/src/image_converter_platform_interface.dart';
import 'package:image_ffi/src/output_format.dart';
final class ImageConverterDarwin implements ImageConverterPlatform {
const ImageConverterDarwin();
@override
Future<Uint8List> convert({
required Uint8List inputData,
OutputFormat format = OutputFormat.jpeg,
int quality = 100,
}) async => throw UnimplementedError();
}

15
lib/src/output_format.dart
View File

@ -3,17 +3,18 @@
/// Specifies the target format when converting images.
///
/// **Format Support:**
/// | Format | iOS/macOS | Android |
/// |--------|-----------|---------|
/// | jpeg | ✓ | ✓ |
/// | png | ✓ | ✓ |
/// | webp | | ✓ |
/// | heic | ✓ | |
/// | Format | iOS/macOS | Android | Web |
/// |--------|-----------|---------| ----|
/// | jpeg | ✓ | ✓ | ✓ |
/// | png | ✓ | ✓ | ✓ |
/// | webp | | ✓ | ✓ |
/// | heic | ✓ | | |
///
/// **Notes:**
/// - [jpeg]: Good compression with adjustable quality
/// - [png]: Lossless compression, supports transparency
/// - [webp]: Modern format with better compression than JPEG
/// - [heic]: High Efficiency Image Format, not supported on Android
enum OutputFormat {
/// JPEG format (.jpg, .jpeg)
/// Lossy compression, suitable for photos
@ -28,6 +29,6 @@ enum OutputFormat {
webp,
/// HEIC format (.heic)
/// High Efficiency Image Format (not supported on Android)
/// High Efficiency Image Format (not supported on Android and Web)
heic,
}

3
lib/src/web/shared.dart Normal file
View File

@ -0,0 +1,3 @@
export 'stub.dart'
if (dart.library.io) 'stub.dart'
if (dart.library.js_interop) 'web.dart';

15
lib/src/web/stub.dart Normal file
View File

@ -0,0 +1,15 @@
import 'dart:typed_data';
import 'package:image_ffi/src/image_converter_platform_interface.dart';
import 'package:image_ffi/src/output_format.dart';
final class ImageConverterWeb implements ImageConverterPlatform {
const ImageConverterWeb();
@override
Future<Uint8List> convert({
required Uint8List inputData,
OutputFormat format = OutputFormat.jpeg,
int quality = 100,
}) async => throw UnimplementedError();
}

92
lib/src/web/web.dart Normal file
View File

@ -0,0 +1,92 @@
import 'dart:async';
import 'dart:js_interop';
import 'dart:typed_data';
import 'package:image_ffi/src/image_converter_platform_interface.dart';
import 'package:image_ffi/src/output_format.dart';
import 'package:web/web.dart';
/// Web image converter using Canvas API.
///
/// Implements image conversion for web platforms using the HTML5 Canvas API
/// for decoding and encoding images in the browser.
///
/// **Features:**
/// - Supports JPEG, PNG, WebP formats (browser-dependent)
/// - HEIC format not supported on Web
/// - Adjustable quality for JPEG and WebP compression
/// - Asynchronous image loading and encoding
///
/// **API Stack:**
/// - `HTMLImageElement`: Load and decode input image via Blob URL
/// - `CanvasRenderingContext2D.drawImage`: Render image to canvas
/// - `HTMLCanvasElement.toBlob`: Encode canvas to target format
///
/// **Limitations:**
/// - HEIC not supported (throws UnsupportedError)
/// - Output format support depends on browser capabilities
/// - JPEG and PNG are universally supported
/// - WebP is widely supported in modern browsers
///
/// **Performance:**
/// - Browser-native image decoding and encoding
/// - In-memory processing with Blob/ArrayBuffer
/// - Quality parameter controls compression ratio
final class ImageConverterWeb implements ImageConverterPlatform {
const ImageConverterWeb();
@override
Future<Uint8List> convert({
required Uint8List inputData,
OutputFormat format = OutputFormat.jpeg,
int quality = 100,
}) async {
final img = HTMLImageElement();
final decodeCompeleter = Completer<void>();
final blob = Blob([inputData.toJS].toJS);
final url = URL.createObjectURL(blob);
img.onLoad.listen((_) => decodeCompeleter.complete());
img.onError.listen((e) {
URL.revokeObjectURL(url);
decodeCompeleter.completeError('Failed to load image: $e');
});
img.src = url;
await decodeCompeleter.future;
URL.revokeObjectURL(url);
final canvas = HTMLCanvasElement();
canvas.width = img.width;
canvas.height = img.height;
final ctx = canvas.getContext('2d') as CanvasRenderingContext2D;
ctx.drawImage(img, 0, 0);
final encodeCompleter = Completer<Blob>();
final type = switch (format) {
OutputFormat.jpeg => 'image/jpeg',
OutputFormat.png => 'image/png',
OutputFormat.webp => 'image/webp',
OutputFormat.heic => throw UnsupportedError(
'HEIC output format is not supported on Web.',
),
};
canvas.toBlob(
(Blob? blob) {
if (blob != null) {
encodeCompleter.complete(blob);
} else {
encodeCompleter.completeError(
'Failed to convert canvas to JPEG Blob.',
);
}
}.toJS,
type,
(quality / 100).toJS,
);
final result = await encodeCompleter.future;
final arrayBuffer = await result.arrayBuffer().toDart;
return arrayBuffer.toDart.asUint8List();
}
}

1
pubspec.yaml
View File

@ -13,6 +13,7 @@ dependencies:
jni: ^0.15.2
ffi: ^2.1.4
objective_c: ^9.2.1
web: ^1.0.0
dev_dependencies:
flutter_test: