protected override void Render (HtmlTextWriter writer)
{
ConfigSection cs = ConfigSection.CurrentConfigSection ();
// If we are not active, render the head section to the writer as is.
if (!ConfigSection.OptionIsActive (cs.Active)) {
base.Render (writer);
return;
}
// --------------
UrlProcessor urlProcessor =
new UrlProcessor (
cs.CookielessDomains, cs.MakeImageUrlsLowercase, cs.InsertVersionIdInImageUrls,
ConfigSection.OptionIsActive (cs.EnableCookielessDomains), cs.PreloadAllImages,
ConfigSection.OptionIsActive (cs.ExceptionOnMissingFile));
// --------------
// headHtml holds the html on the page making up the
// head element, including the <head> tag itself.
StringBuilder headHtmlSb = new StringBuilder ();
base.Render (new HtmlTextWriter (new StringWriter (headHtmlSb)));
// ------------
HeadAnalysis headAnalysis = null;
if (cs.HeadCaching == ConfigSection.HeadCachingOption.None) {
headAnalysis = new HeadAnalysis (
headHtmlSb.ToString (), null, cs.CombineCSSFiles, cs.CombineJavaScriptFiles,
cs.MinifyCSS, cs.MinifyJavaScript,
urlProcessor);
} else {
string headCacheKey = HeadCacheKey (HttpContext.Current.Request.Url, cs.HeadCaching);
headAnalysis = (HeadAnalysis)HttpContext.Current.Cache [headCacheKey];
if (headAnalysis == null) {
// The urls of the combined CSS and JavaScript files in the new head
// are dependent on the versions of the actual files (because they contain the version
// ids).
// totalFileNames will be filled with a list of the names of all
// CSS and JavaScript files loaded in the head (that is, those
// that get combined and/or minified).
List<string> totalFileNames = new List<string> ();
headAnalysis = new HeadAnalysis (
headHtmlSb.ToString (), totalFileNames, cs.CombineCSSFiles, cs.CombineJavaScriptFiles,
cs.MinifyCSS, cs.MinifyJavaScript,
urlProcessor);
AddPageFilePaths (totalFileNames);
CacheDependency cd = new CacheDependency (totalFileNames.ToArray ());
HttpContext.Current.Cache.Insert (headCacheKey, headAnalysis, cd);
}
}
// ------------
// Do all replacements in the head specified in headAnalysis
foreach (HeadAnalysis.Replacement r in headAnalysis.Replacements) {
headHtmlSb.Replace (r.original, r.replacement);
}
// ------------
// Process all images in the page if needed.
if (cs.RemoveWhitespace || urlProcessor.ImagesNeedProcessing ()) {
ProcessAllImages (Control.Page.Controls, urlProcessor, cs.RemoveWhitespace);
}
// ------------
string headHtml = headHtmlSb.ToString ();
// At this point, urlProcessor and headAnalysis contains all image urls.
// Build the JavaScript to preload any images that need to be preloaded,
// and insert it at the start of the head, just after the initial head tag.
string preloadJS1 = PreloadJS (cs.PreloadAllImages, cs.PrioritizedImages, headAnalysis.ProcessedImageUrls);
string preloadJS2 = PreloadJS (cs.PreloadAllImages, cs.PrioritizedImages, urlProcessor.ProcessedImageUrls);
string preloadJS = preloadJS1 + preloadJS2;
// If any urls need to be preloaded, insert the JavaScript block after the first > (that is, after the
// head tag).
if (!string.IsNullOrEmpty (preloadJS)) {
headHtml = InsertedAfterFirstTag (headHtml, preloadJS);
}
writer.Write (headHtml);
}
private void ProcessAllImages (ControlCollection cc, UrlProcessor urlProcessor, bool removeWhitespace)
{
bool imagesNeedProcessing = urlProcessor.ImagesNeedProcessing ();
foreach (Control c in cc) {
if (c is LiteralControl) {
LiteralControl lit = (LiteralControl)c;
string literalContent = lit.Text;
string newLiteralContent = literalContent;
if (imagesNeedProcessing) {
// The "src" group in this regexp doesn't just contain the image url, but also the src= and the quotes.
// That allows us to replace the entire src="...", instead of the url.
// If you only replace the old url with the new url, than if you have a tag with url "images/ball3.png" after a tag with "/images/ball3.png"
// when the second url ("images/ball3.png") gets replaced, it alsos replace part of the first tag "/images/ball3.png" (because the first tag
// contains the second tag).
const string regexpImgGroup =
@"<img[^>]*?(?<src>src[^=]*?=[^""']*?(?:""|')(?<url>[^""']*?)(?:""|'))[^>]*?>";
Regex r = new Regex (regexpImgGroup, RegexOptions.IgnoreCase);
Match m = r.Match (literalContent);
while (m.Success) {
string oldSrc = m.Groups ["src"].Value;
string oldUrl = m.Groups ["url"].Value;
string newUrl = urlProcessor.ProcessedUrl (oldUrl, true, false, Control.Page.Request.Url, null);
string newSrc = @"src=""" + newUrl + @"""";
newLiteralContent = newLiteralContent.Replace (oldSrc, newSrc);
m = m.NextMatch ();
}
}
if (removeWhitespace) {
newLiteralContent = CollapsedWhitespace (newLiteralContent);
}
lit.Text = newLiteralContent;
} else if ((c is HtmlImage) && imagesNeedProcessing) {
HtmlImage hi = (HtmlImage)c;
string versionId = LastUpdateTimeImageControl (hi.Src, hi, urlProcessor.ThrowExceptionOnMissingFile);
hi.Src = urlProcessor.ProcessedUrl (hi.Src, true, false, Control.Page.Request.Url, versionId);
} else if ((c is HyperLink) && imagesNeedProcessing) {
HyperLink hl = (HyperLink)c;
string versionId = LastUpdateTimeImageControl (hl.ImageUrl, hl, urlProcessor.ThrowExceptionOnMissingFile);
hl.ImageUrl = urlProcessor.ProcessedUrl (hl.ImageUrl, true, false, Control.Page.Request.Url, versionId);
} else if ((c is Image) && imagesNeedProcessing) {
Image i = (Image)c;
string versionId = LastUpdateTimeImageControl (i.ImageUrl, i, urlProcessor.ThrowExceptionOnMissingFile);
i.ImageUrl = urlProcessor.ProcessedUrl (i.ImageUrl, true, false, Control.Page.Request.Url, versionId);
} else {
ProcessAllImages (c.Controls, urlProcessor, removeWhitespace);
}
}
}
