lib/web_ui/test/html/compositing/canvas_blend_golden_test.dart

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:html' as html;
import 'dart:js_util' as js_util;

import 'package:test/bootstrap/browser.dart';
import 'package:test/test.dart';
import 'package:ui/src/engine.dart';
import 'package:ui/ui.dart' hide TextStyle;

import '../screenshot.dart';

void main() {
  internalBootstrapBrowserTest(() => testMain);
}

Future<void> testMain() async {

  setUp(() async {
    debugEmulateFlutterTesterEnvironment = true;
    await webOnlyInitializePlatform();
    webOnlyFontCollection.debugRegisterTestFonts();
    await webOnlyFontCollection.ensureFontsLoaded();
  });

  test('Blend circles with difference and color', () async {
    final RecordingCanvas rc =
        RecordingCanvas(const Rect.fromLTRB(0, 0, 400, 300));
    rc.save();
    rc.drawRect(
        const Rect.fromLTRB(0, 0, 400, 400),
        SurfacePaint()
          ..style = PaintingStyle.fill
          ..color = const Color.fromARGB(255, 255, 255, 255));
    rc.drawCircle(
        const Offset(100, 100),
        80.0,
        SurfacePaint()
          ..style = PaintingStyle.fill
          ..color = const Color.fromARGB(128, 255, 0, 0)
          ..blendMode = BlendMode.difference);

    rc.drawCircle(
        const Offset(170, 100),
        80.0,
        SurfacePaint()
          ..style = PaintingStyle.fill
          ..blendMode = BlendMode.color
          ..color = const Color.fromARGB(128, 0, 255, 0));

    rc.drawCircle(
        const Offset(135, 170),
        80.0,
        SurfacePaint()
          ..style = PaintingStyle.fill
          ..color = const Color.fromARGB(128, 255, 0, 0));
    rc.restore();

    await canvasScreenshot(rc, 'canvas_blend_circle_diff_color',
        region: const Rect.fromLTWH(0, 0, 500, 500),
        maxDiffRatePercent: operatingSystem == OperatingSystem.macOs ? 2.95 :
            operatingSystem == OperatingSystem.iOs ? 1.0 : 0);
  });

  test('Blend circle and text with multiply', () async {
    final RecordingCanvas rc =
        RecordingCanvas(const Rect.fromLTRB(0, 0, 400, 300));
    rc.save();
    rc.drawRect(
        const Rect.fromLTRB(0, 0, 400, 400),
        SurfacePaint()
          ..style = PaintingStyle.fill
          ..color = const Color.fromARGB(255, 255, 255, 255));
    rc.drawCircle(
        const Offset(100, 100),
        80.0,
        SurfacePaint()
          ..style = PaintingStyle.fill
          ..color = const Color.fromARGB(128, 255, 0, 0)
          ..blendMode = BlendMode.difference);
    rc.drawCircle(
        const Offset(170, 100),
        80.0,
        SurfacePaint()
          ..style = PaintingStyle.fill
          ..blendMode = BlendMode.color
          ..color = const Color.fromARGB(128, 0, 255, 0));

    rc.drawCircle(
        const Offset(135, 170),
        80.0,
        SurfacePaint()
          ..style = PaintingStyle.fill
          ..color = const Color.fromARGB(128, 255, 0, 0));
    rc.drawImage(createTestImage(), const Offset(135.0, 130.0),
        SurfacePaint()..blendMode = BlendMode.multiply);
    rc.restore();
    await canvasScreenshot(rc, 'canvas_blend_image_multiply',
        region: const Rect.fromLTWH(0, 0, 500, 500),
        maxDiffRatePercent: operatingSystem == OperatingSystem.macOs ? 2.95 :
        operatingSystem == OperatingSystem.iOs ? 2.0 : 0);
  });
}

HtmlImage createTestImage() {
  const int width = 100;
  const int height = 50;
  final html.CanvasElement canvas =
      html.CanvasElement(width: width, height: height);
  final html.CanvasRenderingContext2D ctx = canvas.context2D;
  ctx.fillStyle = '#E04040';
  ctx.fillRect(0, 0, 33, 50);
  ctx.fill();
  ctx.fillStyle = '#40E080';
  ctx.fillRect(33, 0, 33, 50);
  ctx.fill();
  ctx.fillStyle = '#2040E0';
  ctx.fillRect(66, 0, 33, 50);
  ctx.fill();
  final html.ImageElement imageElement = html.ImageElement();
  imageElement.src = js_util.callMethod(canvas, 'toDataURL', <dynamic>[]);
  return HtmlImage(imageElement, width, height);
}