cohtml::System

A System owns multiple Views. These Views share resources among them. It is usually enough to have just one System per application run. All System APIs, unless explicitly stated otherwise, can be called on any thread, but should not be used on multiple threads simultaneously.

#include <System.h>

Public Functions

	Name
virtual unsigned	GetId() =0
virtual void	SetId(unsigned id) =0
virtual	~System()
virtual View *	CreateView(const ViewSettings & settings) =0 Creates a new View with the specified options.
virtual View *	CreateView() =0 Creates a new View with default options.
virtual SystemCacheStats *	GetSystemCacheStats() const =0 Returns an objects that holds the current statistics of the system-wide caches. Remember to Release when done.
virtual void	ClearCachedUnusedImages() =0 Removes all unused images (raster and svg) from internal caches.
virtual SystemRenderer *	CreateSystemRenderer(const SystemRendererSettings & settings) =0 Creates a new SystemRenderer. The SystemRenderer will hold rendering resources shared by all view renderers. Can be used on any thread.
virtual SystemRenderer *	CreateSystemRenderer() =0 Creates a new SystemRenderer with default settings.
virtual SystemRenderer *	CreateSystemRendererWithExternalRenderingLibrary(const SystemRendererSettingsWithExternalRenderingLibrary & settings) =0 Creates a new SystemRenderer. The SystemRenderer will hold rendering resources shared by all view renderers. Can be used on any thread.
virtual void	RegisterFont(const char * url, const FontDescription & desc =FontDescription(), Fonts::FontSDF useSDF =Fonts::SDF_Auto) =0 Registers a font that can be later used in the Views. This API is similar to a font-face rule and allows you to prepare font stream readers in advance, so that text can render without delays. Unlike the font-face rule, this API also allows you to load the font with its original description (using ‘Auto’ for weight or/and style with or without specifying specific family name for it). This API will load all available fonts from font collections (ttc, otc) when a specific font description isn’t provided (use ‘Auto’ without family name). If any description is specified for a font collection, only the first font will be loaded under that description (same behavior as a font-face rule with font collection).
virtual bool	UnregisterFont(const char * url) =0 Unregisters all registered fonts by the RegisterFont API for a specific font resource identified by the URL. Font resources are shared between the system and the views, so the font resource may not be freed if there are active at font-face rules using the same URL. Since the font resource is required for rendering, fonts will be freed after all pending frames are painted.
virtual void	AddUserFont(const char ** imagesData, unsigned * imagesDataSize, unsigned imagesCount, const UserFontDescription & description) =0 Load the user font using image files.
virtual void	AddUserFont(const IAsyncResourceResponse::UserImageData * userImages, unsigned imagesCount, const UserFontDescription & description) =0 Load the user font using preloaded images.
virtual bool	RemoveUserFont(const UserFontDescription & description) =0 Unregisters the bitmap font which has been registered by the user.
virtual void	Destroy() =0 Destroys the System.
virtual void	Advance(TimePoint timeMilliseconds) =0 Advances the internal timers and inspector when available.
virtual void	RegisterGamepad(unsigned id, const char * info, unsigned axesCount, unsigned buttonsCount, void * reserved =nullptr) =0 Registers a new gamepad. All views will receive the gamepadconnected event. You can provide any number of axes and buttons though the standard mapping according to the HTML spec has 4 axes and 17 buttons which can be found here https://w3c.github.io/gamepad/#remapping.
virtual void	UnregisterGamepad(unsigned id) =0 Unregisters a gamepad. All views will receive the gamepaddisconnected event.
virtual void	UpdateGamepadState(const cohtml::GamepadState & state) =0 Updates the state of a single gamepad.
virtual void	UpdateGamepadStateExtended(const cohtml::GamepadStateExtended & state) =0 Updates the state of a single gamepad with motion tracking information.
virtual void	UserImagesChanged(const unsigned * images, unsigned count) =0 Trigger repaint of a user provided texture. Call this whenever the image is changed by logic external to the library. Make sure to have ImageHandle set for such images.
virtual void	PreloadAndCacheStylesheet(const char * url) =0 Schedules a preload task for a given stylesheet and caches it upon successful parsing.
virtual bool	RemoveStylesheetCacheEntry(const char * url) =0 Clears data for a given stylesheet from the cache.
virtual void	ClearStylesheetCache() =0 Clears all preloaded stylesheet data from the cache.
virtual void	PreloadAndCacheHTML(const char * url) =0 Schedules a preload task for a given HTML, parses it, and caches it.
virtual bool	RemoveHTMLCacheEntry(const char * url) =0 Clears data for a given HTML from the cache.
virtual void	ClearHTMLCache() =0 Clears all preloaded HTML data from the cache.

Public Functions Documentation

function GetId

virtual unsigned GetId() =0

function SetId

virtual void SetId(
    unsigned id
) =0

function ~System

virtual ~System()

function CreateView

virtual View * CreateView(
    const ViewSettings & settings
) =0

Creates a new View with the specified options.

function CreateView

virtual View * CreateView() =0

Creates a new View with default options.

function GetSystemCacheStats

virtual SystemCacheStats * GetSystemCacheStats() const =0

Returns an objects that holds the current statistics of the system-wide caches. Remember to Release when done.

Note: Waits for style solving generated from previous Advance. Avoid calling it too early.

function ClearCachedUnusedImages

virtual void ClearCachedUnusedImages() =0

Removes all unused images (raster and svg) from internal caches.

Note: Images must be unused (orphaned) for them to be cleared. If you want to force ALL images to be unloaded you need for first call View::UnloadDocument to remove any references the DOM might still hold to the images.

function CreateSystemRenderer

virtual SystemRenderer * CreateSystemRenderer(
    const SystemRendererSettings & settings
) =0

Creates a new SystemRenderer. The SystemRenderer will hold rendering resources shared by all view renderers. Can be used on any thread.

function CreateSystemRenderer

virtual SystemRenderer * CreateSystemRenderer() =0

Creates a new SystemRenderer with default settings.

function CreateSystemRendererWithExternalRenderingLibrary

virtual SystemRenderer * CreateSystemRendererWithExternalRenderingLibrary(
    const SystemRendererSettingsWithExternalRenderingLibrary & settings
) =0

Creates a new SystemRenderer. The SystemRenderer will hold rendering resources shared by all view renderers. Can be used on any thread.

See: cohtml::Library::InitializeWithRenderingLibrary

Note: Use this version when the Library is initialized with an external rendering library.

function RegisterFont

virtual void RegisterFont(
    const char * url,
    const FontDescription & desc =FontDescription(),
    Fonts::FontSDF useSDF =Fonts::SDF_Auto
) =0

Registers a font that can be later used in the Views. This API is similar to a font-face rule and allows you to prepare font stream readers in advance, so that text can render without delays. Unlike the font-face rule, this API also allows you to load the font with its original description (using ‘Auto’ for weight or/and style with or without specifying specific family name for it). This API will load all available fonts from font collections (ttc, otc) when a specific font description isn’t provided (use ‘Auto’ without family name). If any description is specified for a font collection, only the first font will be loaded under that description (same behavior as a font-face rule with font collection).

Parameters:

url URL for the font to be loaded. Must be a valid URL. Spaces aren’t allowed.
desc The description of the font to be loaded
useSDF Controls the method used when rendering fonts, same as the coh-font-sdf font-face property SDF reduces memory consumption but finer font details are lost. If you experience a loss of detail in font rendering, try turning SDF off.

Note: Waits for style solving generated from previous Advance. Avoid calling it too early.

function UnregisterFont

virtual bool UnregisterFont(
    const char * url
) =0

Unregisters all registered fonts by the RegisterFont API for a specific font resource identified by the URL. Font resources are shared between the system and the views, so the font resource may not be freed if there are active at font-face rules using the same URL. Since the font resource is required for rendering, fonts will be freed after all pending frames are painted.

Parameters:

url URL identifying the font resource. Must be a valid URL. Spaces aren’t allowed.

Return: true, if the font was unregistered successfully and false otherwise.

Note: Waits for style solving generated from previous Advance. Avoid calling it too early.

function AddUserFont

virtual void AddUserFont(
    const char ** imagesData,
    unsigned * imagesDataSize,
    unsigned imagesCount,
    const UserFontDescription & description
) =0

Load the user font using image files.

Parameters:

imagesData pointer to image files data.
imagesDataSize pointer to size of the image files.
imagesCount number of images
description Description of the bitmap font.

Note:

The memory can be freed immediately after the call
Images must have the appropriate number of channels Bitmap: 1-channel(A) texture MSDF: 3-channel(RGB) texture
Waits for style solving generated from previous Advance. Avoid calling it too early.

function AddUserFont

virtual void AddUserFont(
    const IAsyncResourceResponse::UserImageData * userImages,
    unsigned imagesCount,
    const UserFontDescription & description
) =0

Load the user font using preloaded images.

Parameters:

userImages pointer to UserImageData structs describing the images.
imagesCount number of images
description Description of the bitmap font.

Note:

After freeing the rendering resources you can call this method again in order to provide new images for the same bitmap font description.
The memory can be freed immediately after the call
Images must have the appropriate number of channels Bitmap: 1-channel(A) texture MSDF: 3-channel(RGB) texture
Waits for style solving generated from previous Advance. Avoid calling it too early.

function RemoveUserFont

virtual bool RemoveUserFont(
    const UserFontDescription & description
) =0

Unregisters the bitmap font which has been registered by the user.

Parameters:

description Description of the bitmap font.

Return: true, if the font was unregistered successfully and false otherwise.

Note: Waits for style solving generated from previous Advance. Avoid calling it too early.

function Destroy

virtual void Destroy() =0

Destroys the System.

function Advance

virtual void Advance(
    TimePoint timeMilliseconds
) =0

Advances the internal timers and inspector when available.

function RegisterGamepad

virtual void RegisterGamepad(
    unsigned id,
    const char * info,
    unsigned axesCount,
    unsigned buttonsCount,
    void * reserved =nullptr
) =0

Registers a new gamepad. All views will receive the gamepadconnected event. You can provide any number of axes and buttons though the standard mapping according to the HTML spec has 4 axes and 17 buttons which can be found here https://w3c.github.io/gamepad/#remapping.

Parameters:

id the unique identifier for the gamepad
info general information for the gamepad such as producer and model
axesCount the number of analog axes the gamepad has
buttonsCount the number of buttons the gamepad has
reserved reserved parameter. Set to nullptr

function UnregisterGamepad

virtual void UnregisterGamepad(
    unsigned id
) =0

Unregisters a gamepad. All views will receive the gamepaddisconnected event.

Parameters:

id the id of the gamepad to unregister

function UpdateGamepadState

virtual void UpdateGamepadState(
    const cohtml::GamepadState & state
) =0

Updates the state of a single gamepad.

Parameters:

state new state of the gamepad

Note: All gamepad-related methods are system-wise. All views will get the new state.

function UpdateGamepadStateExtended

virtual void UpdateGamepadStateExtended(
    const cohtml::GamepadStateExtended & state
) =0

Updates the state of a single gamepad with motion tracking information.

Parameters:

state new state of the gamepad

Note:

All gamepad-related methods are system-wise. All views will get the new state.
If you do not require motion tracking, use System::UpdateGamepadState

function UserImagesChanged

virtual void UserImagesChanged(
    const unsigned * images,
    unsigned count
) =0

Trigger repaint of a user provided texture. Call this whenever the image is changed by logic external to the library. Make sure to have ImageHandle set for such images.

Parameters:

images array of image handles - id-s of the user provided images that are changed
count the number of changed images

function PreloadAndCacheStylesheet

virtual void PreloadAndCacheStylesheet(
    const char * url
) =0

Schedules a preload task for a given stylesheet and caches it upon successful parsing.

Parameters:

url A URL for the stylesheet to be preloaded and cached. Must be a valid URL. Spaces aren’t allowed.

Note: The stylesheet cache is shared among all views

function RemoveStylesheetCacheEntry

virtual bool RemoveStylesheetCacheEntry(
    const char * url
) =0

Clears data for a given stylesheet from the cache.

Parameters:

url The URL for the stylesheet to be cleared from cache. Must be the same URL used for its preloading.

Return: true, if the cache entry corresponding to the given URL was found and cleared successfully

Note:

If a stylesheet that is currently in use by a view is cleared, it won’t affect the view
but a resource request will be fired the next time it is needed

function ClearStylesheetCache

virtual void ClearStylesheetCache() =0

Clears all preloaded stylesheet data from the cache.

Note:

If a stylesheet that is currently in use by a view is cleared, it won’t affect the view
but a resource request will be fired the next time it is needed

function PreloadAndCacheHTML

virtual void PreloadAndCacheHTML(
    const char * url
) =0

Schedules a preload task for a given HTML, parses it, and caches it.

Parameters:

url A URL for the HTML to be preloaded and cached. Must be a valid absolute URL. Spaces aren’t allowed.

Note: The HTML cache is shared among all views

function RemoveHTMLCacheEntry

virtual bool RemoveHTMLCacheEntry(
    const char * url
) =0

Clears data for a given HTML from the cache.

Parameters:

url The URL for the HTML to be cleared from the cache. Must be the same URL used for its preloading.

Return: true, if the cache entry corresponding to the given URL was found and cleared successfully

Note:

Removing HTML from cache that is currently in use by a view won’t free HTML data immediately,
data will be freed after the View finishes DOM building, even if the HTML is not loaded yet.

function ClearHTMLCache

virtual void ClearHTMLCache() =0

Clears all preloaded HTML data from the cache.

Note:

Removing HTML from cache that is currently in use by a view won’t free HTML data immediately,
data will be freed after the View finishes DOM building, even if the HTML is not loaded yet.