FileSystem

#include <Ultralight/platform/FileSystem.h>

Overview

User-defined file system interface.

The library uses this to load file data (ie, raw file bytes) for a given file URL (eg, file:///page.html) .

You can provide the library with your own FileSystem implementation so that file data is provided directly by your application (eg, from memory, from a virtual file system, etc).

Default Implementation

A platform-specific implementation of FileSystem is provided for you when you call App::Create().

If you are using Renderer::Create(), you must provide your own. You can still use AppCore's implementation however– see the helper functions defined in <AppCore/Platform.h>.

Setting the File System

To provide your own custom FileSystem implementation, you should inherit from this class, handle the virtual member functions, and then pass an instance of your class to Platform::set_file_system() before calling Renderer::Create() or App::Create().

Public Member Functions
virtual	~FileSystem ()
virtual bool	FileExists (const String &file_path)=0
	Check if a file exists within the file system.
virtual String	GetFileMimeType (const String &file_path)=0
	Get the mime-type of a file (eg "text/html").
virtual String	GetFileCharset (const String &file_path)=0
	Get the charset / encoding of a file (eg "utf-8", "iso-8859-1").
virtual RefPtr< Buffer >	OpenFile (const String &file_path)=0
	Open a file for reading and map it to a Buffer.

Constructor & Destructor Documentation

~FileSystem()

virtual ~FileSystem ( )

virtual

Member Function Documentation

FileExists()

virtual bool FileExists ( const String & file_path )

pure virtual

Check if a file exists within the file system.

Parameters

file_path

Relative file path (the string following the file:/// prefix)

Returns

Returns whether or not a file exists at the path specified.

GetFileCharset()

virtual String GetFileCharset ( const String & file_path )

pure virtual

Get the charset / encoding of a file (eg "utf-8", "iso-8859-1").

Note

This is only applicable for text-based files (eg, "text/html", "text/plain") and is usually determined by analyzing the contents of the file.

Parameters

file_path

Relative file path (the string following the file:/// prefix)

Returns

Returns the charset of the specified file. If a charset cannot be determined, a safe default to return is "utf-8".

GetFileMimeType()

virtual String GetFileMimeType ( const String & file_path )

pure virtual

Get the mime-type of a file (eg "text/html").

This is usually determined by analyzing the file extension.

If a mime-type cannot be determined, this should return "application/unknown".

Parameters

file_path

Relative file path (the string following the file:/// prefix)

Returns

Returns whether or not a file exists at the path specified.

OpenFile()

virtual RefPtr< Buffer > OpenFile ( const String & file_path )

pure virtual

Open a file for reading and map it to a Buffer.

To minimize copies, you should map the requested file into memory and use Buffer::Create() to wrap the data pointer (unmapping should be performed in the destruction callback).

Note

File data addresses returned from this function should generally be aligned to 16-byte boundaries (the default alignment on most operating systems– if you're using C stdlib or C++ STL functions this is already handled for you).

This requirement is currently necessary when loading the ICU data file (eg, icudt67l.dat), and may be relaxed for other files (but you may still see a performance benefit due to cache line alignment).

If you can't guarantee alignment or are unsure, you can use Buffer::CreateFromCopy to copy the file data content to an aligned block (at the expense of data duplication).

Parameters

file_path

Relative file path (the string following the file:/// prefix)

Returns

If the file was able to be opened, this returns a Buffer object representing the contents of the file. If the file was unable to be opened, you should return nullptr.

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

• Ultralight/platform/FileSystem.h