LayoutTests/fast/canvas/canvas-lineDash_t01.dart

/*
 * Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 * for details. All rights reserved. Use of this source code is governed by a
 * BSD-style license that can be found in the LICENSE file.
 */
/** 
 * @description Basic test for setLineDash, getLineDash and lineDashOffset
 */
import "dart:html";
import "../../testcommon.dart";
import "../../../Utils/async_utils.dart";

main() {
  var canvas = document.createElement('canvas');
  document.body.append(canvas);
  canvas.setAttribute('width', '700');
  canvas.setAttribute('height', '700');
  var ctx = canvas.getContext('2d');

  dataToArray(data) {
    var result = new List(data.length);
    for (var i = 0; i < data.length; i++)
      result[i] = data[i];
    return result;
  }

  getPixel(x, y) {
    var data = ctx.getImageData(x,y,1,1);
    if (data == null) // getImageData failed, which should never happen
      return [-1,-1,-1,-1];
    return dataToArray(data.data);
  }

  pixelShouldBe(x, y, colour) {
    shouldBeList(getPixel(x, y), colour);
  }

  // Verify default values.
  shouldBe(ctx.lineDashOffset, 0);

  // Set dash-style.
  ctx.setLineDash([15, 10]);
  ctx.lineDashOffset = 5;
  ctx.strokeRect (10,10,100,100);

  // Verify dash and offset.
  var lineDash;
  lineDash = ctx.getLineDash();
  shouldBe(lineDash[0], 15);
  shouldBe(lineDash[1], 10);
  shouldBe(ctx.lineDashOffset, 5);

  // Set dash style to even number
  ctx.setLineDash([5, 10, 15]);
  ctx.strokeRect(20, 20, 120, 120);

  // Verify dash pattern is normalized
  lineDash = ctx.getLineDash();
  shouldBe(lineDash[0], 5);
  shouldBe(lineDash[1], 10);
  shouldBe(lineDash[2], 15);
  shouldBe(lineDash[3], 5);
  shouldBe(lineDash[4], 10);
  shouldBe(lineDash[5], 15);

  // Verify that line dash offset persists after
  // clearRect (which causes a save/restore of the context
  // state to the stack).
  ctx.clearRect(0, 0, 700, 700);
  shouldBe(ctx.lineDashOffset, 5);

  // Verify dash rendering
  ctx.setLineDash([20, 10]);
  ctx.lineDashOffset = 0;
  ctx.lineWidth = 4; // To make the test immune to plaform anti-aliasing discrepancies
  ctx.strokeStyle = '#00FF00';
  ctx.strokeRect(10.5, 10.5, 30, 30);

  pixelShouldBe(25, 10, [0, 255, 0, 255]);
  pixelShouldBe(35, 10, [0, 0, 0, 0]);
  pixelShouldBe(40, 25, [0, 255, 0, 255]);
  pixelShouldBe(40, 35, [0, 0, 0, 0]);
  pixelShouldBe(25, 40, [0, 255, 0, 255]);
  pixelShouldBe(15, 40, [0, 0, 0, 0]);
  pixelShouldBe(10, 25, [0, 255, 0, 255]);
  pixelShouldBe(10, 15, [0, 0, 0, 0]);

  // Verify that lineDashOffset works as expected
  ctx.lineDashOffset = 20;
  ctx.strokeRect(50.5, 10.5, 30, 30);
  pixelShouldBe(55, 10, [0, 0, 0, 0]);
  pixelShouldBe(65, 10, [0, 255, 0, 255]);
  pixelShouldBe(80, 15, [0, 0, 0, 0]);
  pixelShouldBe(80, 25, [0, 255, 0, 255]);
  pixelShouldBe(75, 40, [0, 0, 0, 0]);
  pixelShouldBe(65, 40, [0, 255, 0, 255]);
  pixelShouldBe(50, 35, [0, 0, 0, 0]);
  pixelShouldBe(50, 25, [0, 255, 0, 255]);

  // Verify negative lineDashOffset
  ctx.lineDashOffset = -10;
  ctx.strokeRect(90.5, 10.5, 30, 30);
  pixelShouldBe(95, 10, [0, 0, 0, 0]);
  pixelShouldBe(105, 10, [0, 255, 0, 255]);
  pixelShouldBe(120, 15, [0, 0, 0, 0]);
  pixelShouldBe(120, 25, [0, 255, 0, 255]);
  pixelShouldBe(115, 40, [0, 0, 0, 0]);
  pixelShouldBe(105, 40, [0, 255, 0, 255]);
  pixelShouldBe(90, 35, [0, 0, 0, 0]);
  pixelShouldBe(90, 25, [0, 255, 0, 255]);
}