net_instaweb::ImageUrlEncoder Class Reference

#include "image_url_encoder.h"

Inheritance diagram for net_instaweb::ImageUrlEncoder:

Public Member Functions
virtual void	Encode (const StringVector &urls, const ResourceContext *dim, GoogleString *rewritten_url) const
virtual bool	Decode (const StringPiece &url_segment, StringVector *urls, ResourceContext *dim, MessageHandler *handler) const

Static Public Member Functions
static void	SetLibWebpLevel (const RewriteOptions &options, const RequestProperties &request_properties, ResourceContext *resource_context)
static void	SetWebpAndMobileUserAgent (const RewriteDriver &driver, ResourceContext *context)
static bool	IsWebpRewrittenUrl (const GoogleUrl &gurl)
	Determines whether the given URL is a pagespeed-rewritten webp URL.
static void	SetSmallScreen (const RewriteDriver &driver, ResourceContext *context)
static GoogleString	CacheKeyFromResourceContext (const ResourceContext &resource_context)
	Helper function to generate Metadata cache key from ResourceContext.
static bool	HasDimensions (const ResourceContext &data)
static bool	HasValidDimensions (const ImageDim &dims)
static bool	HasDimension (const ResourceContext &data)
static bool	HasValidDimension (const ImageDim &dims)
static bool	AllowVaryOnUserAgent (const RewriteOptions &options, const RequestProperties &request_properties)
static bool	AllowVaryOnAccept (const RewriteOptions &options, const RequestProperties &request_properties)

Detailed Description

This class implements the encoding of image urls with optional additional dimension metadata. It basically prepends characters indicating image dimensions on the page, webp eligibility, and mobile user agent eligibility (this information is conveyed in the ResourceContext). http://...path.../50x75xurl... No webp, image is 50x75 on page http://...path.../50x75wurl... Webp requested, image is 50x75 on page http://...path.../50x75mxurl... No webp, for mobile user agent, image is 50x75 on page http://...path.../50x75mwurl... Webp requested, for mobile user agent, image is 50x75 on page http://...path.../50xNxurl.. No webp, image is 50 wide, no height given http://...path.../50xNwurl... Webp, image is 50 wide, no height given http://...path.../Nx75xurl... No webp, image is 75 high, no width given http://...path.../Nx75wurl... Webp, image is 75 high, no width given. http://...path.../50xNmxurl.. No webp, image is 50 wide, mobile http://...path.../50xNmwurl... Webp, image is 50 wide, mobile http://...path.../Nx75mxurl... No webp, image is 75 high, mobile http://...path.../Nx75mwurl... Webp, image is 75 high, mobile http://...path.../xurl... Page does not specify both dimensions. No webp. http://...path.../wurl... Webp requested, page missing dimensions. http://...path.../xurl... Page does not specify any dimension. No webp. http://...path.../wurl... Webp requested, page missing either dimension. http://...path.../mxurl... No webp, for mobile user agent, page does not specify dimensions. http://...path.../mwurl... Webp requested, for mobile user agent, page missing dimensions.

Member Function Documentation

virtual bool net_instaweb::ImageUrlEncoder::Decode ( const StringPiece &  url_segment, StringVector *  urls, ResourceContext *  out_data, MessageHandler *  handler  ) const

virtual

Decode URLs from "url_segment". Note that there may be other meta-data encoded in url_segment, which this function will write into out_data, if present.

Reimplemented from net_instaweb::UrlSegmentEncoder.

virtual void net_instaweb::ImageUrlEncoder::Encode ( const StringVector &  urls, const ResourceContext *  data, GoogleString *  url_segment  ) const

virtual

Encodes arbitrary text so it can be used in a url segment. A url segment must contain only characters that are legal in URLs, and exclude "/" and "." which are used for a higher level encoding scheme into which this must fit.

'data' is optional – it can be NULL and it is up to the encoder to decide what to do.

Reimplemented from net_instaweb::UrlSegmentEncoder.

static void net_instaweb::ImageUrlEncoder::SetLibWebpLevel ( const RewriteOptions &  options, const RequestProperties &  request_properties, ResourceContext *  resource_context  )

static

Set LibWebp level according to the user agent.

Todo:

TODO(poojatandon): Pass a user agent object with its webp-cabaple bits pre-analyzed (not just the string from the request headers), since checking webp level related code doesn't belong here.

static void net_instaweb::ImageUrlEncoder::SetSmallScreen ( const RewriteDriver &  driver, ResourceContext *  context  )

static

Flag whether this device has a small screen, which determines what Jpeg/WebP quality to use.

static void net_instaweb::ImageUrlEncoder::SetWebpAndMobileUserAgent ( const RewriteDriver &  driver, ResourceContext *  context  )

static

Sets webp and mobile capability in resource context.

The parameters to this method are urls, rewrite options & resource context. Since rewrite options are not changed, we have passed const reference and resource context is modified and can be NULL, hence we pass as a pointer.

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The documentation for this class was generated from the following file:

• net/instaweb/rewriter/public/image_url_encoder.h