public void ReplaceCssImagesWithSprite(CombinatorResource resource)
{
Func <RuleSet, Term, bool> noSprite =
(ruleSet, url) =>
{
if (url.Value.Contains("no-sprite") ||
ruleSet.Selectors.Any(selector => selector.SimpleSelectors.Any(simpleSelector => simpleSelector.Class == "no-sprite")))
{
return(true);
}
// Images with a background position are not suitable for sprite generation if they aren't top-left
if (ruleSet.Declarations.Any(declaration => declaration.Name == "background-position" &&
(declaration.Expression.Terms.Count() != 2 ||
!declaration.Expression.Terms.Any(term => term.Value == "top") ||
!declaration.Expression.Terms.Any(term => term.Value == "left"))))
{
return(true);
}
// Images with a background size are not suitable for sprite generation
if (ruleSet.Declarations.Any(declaration => declaration.Name == "background-size"))
{
return(true);
}
// Images with a background repeat are not suitable for sprite generation
if (ruleSet.Declarations.Any(declaration => declaration.Name == "background-repeat" &&
(declaration.Expression.Terms.Count() != 1 || declaration.Expression.Terms.First().Value != "no-repeat")))
{
return(true);
}
var backgroundTerms =
ruleSet.Declarations
.Where(declaration => declaration.Name == "background")
.SelectMany(declaration => declaration.Expression.Terms);
// Sized backgrounds are not suitable either
// LineHeightTerm is filled with a value when if in the shorthand background declaration there's the background size specified, e.g.:
// background: url(url-to-img) 300px 400px / 500px 600px no-repeat;
// Now there will be a term for 400px, having LineHeightTerm specified for 500px.
if (backgroundTerms.Any(term => term.LineHeightTerm != null))
{
return(true);
}
var backgroundTermValues = backgroundTerms.Select(term => term.Value);
// Positioned backgrounds are not suitable either, except top-left ones
if (backgroundTerms
.Any(term =>
term.Value == "center" ||
term.Value == "top" ||
term.Value == "right" ||
term.Value == "bottom" ||
term.Unit != null) &&
!(backgroundTermValues.Contains("top") && backgroundTermValues.Contains("left")))
{
return(true);
}
if (backgroundTermValues.Any(value => value == "repeat-x" || value == "repeat-y" || value == "repeat"))
{
return(true);
}
return(false);
};
var images = new Dictionary <string, CssImage>();
var stylesheet = new StylesheetParser().Parse(resource.Content);
ProcessImageUrls(
resource,
stylesheet,
(ruleSet, urlTerm) =>
{
var url = urlTerm.Value;
if (noSprite(ruleSet, urlTerm))
{
return;
}
var imageContent = _resourceFileService.GetImageContent(InlineUriFactory(resource, url));
if (imageContent.Length / 1024 <= 5000)
{
images[url] = new CssImage {
Content = imageContent
};
}
});
if (images.Count == 0)
{
return;
}
_cacheFileService.WriteSpriteStream(
resource.Content.GetHashCode() + ".jpg",
(stream, publicUrl) =>
{
using (var sprite = new Sprite(images.Values.Select(image => image.Content)))
{
var imageEnumerator = images.Values.GetEnumerator();
foreach (var backgroundImage in sprite.Generate(stream, ImageFormat.Jpeg))
{
imageEnumerator.MoveNext();
imageEnumerator.Current.BackgroundImage = backgroundImage;
imageEnumerator.Current.BackgroundImage.Url = InlineUriFactory(resource, publicUrl);
}
}
});
ProcessImageUrls(
resource,
stylesheet,
(ruleSet, urlTerm) =>
{
var url = urlTerm.Value;
if (images.ContainsKey(url))
{
var backgroundImage = images[url].BackgroundImage;
var imageDeclaration = new Declaration
{
Name = "background-image",
Expression = new Expression
{
Terms = new List <Term>
{
new Term {
Type = TermType.Url, Value = backgroundImage.Url.ToStringWithoutScheme()
}
}
}
};
ruleSet.Declarations.Add(imageDeclaration);
var bgPosition = backgroundImage.Position;
var positionDeclaration = new Declaration
{
Name = "background-position",
Expression = new Expression
{
Terms = new List <Term>
{
new Term {
Type = TermType.Number, Value = bgPosition.X.ToString(), Unit = Unit.Px
},
new Term {
Type = TermType.Number, Value = bgPosition.Y.ToString(), Unit = Unit.Px
}
}
}
};
ruleSet.Declarations.Add(positionDeclaration);
}
});
resource.Content = stylesheet.ToString();
}