mirror of
https://github.com/netsurf-browser/netsurf
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57 lines
2.2 KiB
Plaintext
57 lines
2.2 KiB
Plaintext
NetSurf fetch, cache, and content system
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========================================
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There is a one-to-one mapping between URLs and content structures.
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The resource at a URL may be required for two reasons:
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1. The user requests a URL in the GUI by entering it or following a link.
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2. A page contains an object (such as an image).
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When a URL is required, call fetchcache() as follows:
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c = fetchcache(url, referer, callback, p1, p2, width, height);
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p1 and p2 are the callers private pointers used to identify the resource, and
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they are passed to the callback. The triple (callback, p1, p2) must be unique.
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The call returns immediately with a struct content. The structure may be in the
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following states (c->status):
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CONTENT_STATUS_TYPE_UNKNOWN -- the MIME type of the resource has not been
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determined yet.
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CONTENT_STATUS_LOADING -- the resource is being fetched or converted, and can
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not be displayed.
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CONTENT_STATUS_READY -- the resource is still loading, but may be displayed.
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CONTENT_STATUS_DONE -- the resource has loaded completely.
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States may only follow in the above order (but some may be skipped). The
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callback function is called when the state changes or at other times as follows:
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CONTENT_MSG_LOADING -- state has changed from CONTENT_STATUS_TYPE_UNKNOWN to
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CONTENT_STATUS_LOADING. If the type is not acceptable content_remove_user()
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should be called (see below).
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CONTENT_MSG_READY -- state has changed to CONTENT_STATUS_READY.
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CONTENT_MSG_DONE -- state has changed to CONTENT_STATUS_DONE.
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CONTENT_MSG_ERROR -- a fatal error with the resource has occurred. The error
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message is in the callback parameter. The content structure will be
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destroyed after this message and must not be used.
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CONTENT_MSG_STATUS -- the content structure's status message has changed.
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CONTENT_MSG_REDIRECT -- the server has sent a replacement URL for the content.
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This message may only occur in CONTENT_STATUS_TYPE_UNKNOWN. The content
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will be destroyed and must not be used.
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If at any time the resource is no longer required, call content_remove_user():
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content_remove_user(c, callback, p1, p2);
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with the same callback, p1, p2 as passed to fetchcache().
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