ColourContextList Class Reference

Defines a list of colour contexts, as must be kept on a global basis. This is a perfectly normal list, except it has a special function to add a ColourContext item to the list, which ensures that no duplicate colour contexts are ever used, and that the usage count for any shared context is properly updated. More...

#include <colcontx.h>

Inheritance diagram for ColourContextList:

List of all members.

Public Member Functions
void	AddContext (ColourContext **NewContext)
	"Adds" the given colour context to the global list of available contexts. Note that if an identical context is already present in the list, the passed context will be DELETEd and the existing context will be returned in the given pointer. Thus, you must only ever access the context through the returned pointer, rather than the pointer that you originally allocated with 'new'.
void	RemoveContext (ColourContext **OldContext)
	"Removes" the given colour context to the global list of available contexts. If the context is now no longer in use by anyone, it will be 'delete'd. The context pointer passed in will be set to NULL.
Static Public Member Functions
static BOOL	InitColourContexts (void)
	Initialises the Colour Context system, setting up the global list of default colour contexts which are shared by all documents. Called from app.cpp (must not be called more than once).
static void	DeinitColourContexts (void)
	De-initialises the Colour Context system, deleting the global list of default colour contexts which are shared by all documents. It is assumed that by this time the contexts should not be in use! Called from app.cpp (must not be caled more than once).
static ColourContextList *	GetList (void)
	Find the 'global' list of current colour contexts.
Static Private Attributes
static ColourContextList *	ColContextList = NULL

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Detailed Description

Defines a list of colour contexts, as must be kept on a global basis. This is a perfectly normal list, except it has a special function to add a ColourContext item to the list, which ensures that no duplicate colour contexts are ever used, and that the usage count for any shared context is properly updated.

Author:

Jason_Williams (Xara Group Ltd) <camelotdev@xara.com>

Date:

02/04/94

See also:

ColourContextList::AddContext; ColourContextList::RemoveContext; List; Colour; ColourModel; ColourContext Documentation: HowToUse.doc

Definition at line 831 of file colcontx.h.

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Member Function Documentation

void ColourContextList::AddContext (  ColourContext **  NewContext  )

"Adds" the given colour context to the global list of available contexts. Note that if an identical context is already present in the list, the passed context will be DELETEd and the existing context will be returned in the given pointer. Thus, you must only ever access the context through the returned pointer, rather than the pointer that you originally allocated with 'new'. Author: Jason_Williams (Xara Group Ltd) <camelotdev@xara.com> Date: 11/04/94 Parameters: -  [INPUTS] An  equivalent colour context that may now be used [OUTPUTS] Returns: - i.e. to create and use a new context, you must: { ColourContext *MyContext; MyContext = new ColourContextABCD(1.0); // Create new context if (MyContext == NULL) return(FAILED_MISERABLY); ColContextList->AddContext(&MyContext); // MyContext may change! MyContext->DoSomething... // Use the context ColContextList->RemoveContext(&MyContext); // Have finished with it MyContext is now a NULL pointer, so don't use it! } Notes: You must NOT delete the context when you finish with it. Instead, you must call ColourContextList::RemoveContext() when you have finished with the context. The context will be automatically deleted when it is no longer in use by anyone. (Sharing of contexts is currently disabled - see the comment in the function for details) Returns: Errors: - See also: ColourContext::ConvertColour; ColourContext::ConvertColourInternal Definition at line 323 of file colclist.cpp. { ENSURE(NewContext != NULL && *NewContext != NULL, "ColourContextList::AddContext called with NULL parameter!"); #if FALSE /* Jason 22/5/96 We no longer merge contexts because this makes for danger with the new ColourPlate system - it's now too easy to change a colourcontext by altering its ColourPlate, in which case shared contexts will cause extreme grief. ColourContext *Item; Item = (ColourContext *) GetHead(); while (Item) { if (!Item->IsDifferent(*NewContext)) // Have found identical context { delete *NewContext; // Delete the new context Item->IncrementUsage(); // Increment the new context's usage count *NewContext = Item; // And return the existing one for use return; } Item = (ColourContext *) GetNext(Item); } // We have searched the entore list now but still have no equivalent context // so it is necessary to add this context to the list, and return it. */ #endif // However, we do check that the given context is not already in the list, // and ignore the caller if it's already there. ColourContext *Item; Item = (ColourContext *) GetHead(); while (Item) { if (Item == *NewContext) { Item->IncrementUsage(); // Increment the context's usage count return; } Item = (ColourContext *) GetNext(Item); } AddTail(*NewContext); (*NewContext)->Init(); // And by leaving the contents of the passed pointer alone, we return it. }

void ColourContextList::DeinitColourContexts (  void   )  [static]

De-initialises the Colour Context system, deleting the global list of default colour contexts which are shared by all documents. It is assumed that by this time the contexts should not be in use! Called from app.cpp (must not be caled more than once). Author: Jason_Williams (Xara Group Ltd) <camelotdev@xara.com> Date: 11/04/94 Parameters: -  [INPUTS] -  [OUTPUTS] Returns: - Errors: If any colour contexts are still in use when this function is called, you may get ENSURE failures. Definition at line 228 of file colclist.cpp. { ENSURE(ColContextList != NULL, "ColourContextList::DeinitColourContexts: but I haven't been initialised yet!"); ColourContextArray DefaultCCA; ColourContext *DefaultCC; ColourContext::GetGlobalDefaults(&DefaultCCA); // Delete any of the default colour contexts that actually exist... for (INT32 cm = 0; cm < MAX_COLOURMODELS; cm++) { // Get the default colour context object for this colour model number // I do this via a copy of the real array to avoid the GetDefaultContext() // call giving an ENSURE failure in the case of a NULL context pointer. DefaultCC = DefaultCCA.Context[cm]; if (DefaultCC != NULL) { // Set the default to NULL to ensure fewer rampant pointers are // left lying around (just to be on the safe side) ColourContext::SetGlobalDefault((ColourModel) cm, NULL); // Remove from the list. Note that we use RemoveItem to *force* // removal - RemoveContext only removes it if UsageCount == 0. ColContextList->RemoveItem(DefaultCC); // Decrement usage. This *should* take it down to zero usage, as // it is hoped that by the time we are called, all other users will // have released their claims. We do this to stop the ENSURE from // triggering when we delete the object. DefaultCC->DecrementUsage(); // And delete the object delete DefaultCC; } } ENSURE(ColContextList->IsEmpty(), "ColourContextList::DeinitColourContexts: Some ColourContext(s) have not yet been released"); // And delete the global list of contexts delete ColContextList; ColContextList = NULL; }

ColourContextList * ColourContextList::GetList (  void   )  [inline, static]

Find the 'global' list of current colour contexts. Author: Jason_Williams (Xara Group Ltd) <camelotdev@xara.com> Date: 13/04/94 Parameters: -  [INPUTS] -  [OUTPUTS] Returns: A pointer to the list of colour contexts Errors: - See also: - Definition at line 871 of file colcontx.h. { return(ColContextList); }

BOOL ColourContextList::InitColourContexts (  void   )  [static]

Initialises the Colour Context system, setting up the global list of default colour contexts which are shared by all documents. Called from app.cpp (must not be called more than once). Author: Jason_Williams (Xara Group Ltd) <camelotdev@xara.com> Date: 11/04/94 Parameters: -  [INPUTS] -  [OUTPUTS] Returns: TRUE if initialisation succeeded, else FALSE FALSE if it failed (most likely because of lack of memory) Errors: - Definition at line 149 of file colclist.cpp. { ENSURE(ColContextList == NULL, "ColourContextList::InitColourContexts called more than once!"); // First, create the global Colour context list in which all colour contexts // should be registered. ColContextList = new ColourContextList; if (ColContextList == NULL) return(FALSE); // Now, create an instance of each available colour context to provide the // global set of default colour contexts. Add each to the CCList. ColourContext *tempcc; tempcc = new ColourContextRGBT(NULL, 1.0); // --- RGBT if (tempcc == NULL) return(FALSE); ColContextList->AddContext(&tempcc); ColourContext::SetGlobalDefault(COLOURMODEL_RGBT, tempcc); tempcc = new ColourContextCMYK(NULL); // --- CMYK if (tempcc == NULL) return(FALSE); ColContextList->AddContext(&tempcc); ColourContext::SetGlobalDefault(COLOURMODEL_CMYK, tempcc); tempcc = new ColourContextHSVT(NULL); // --- HSVT if (tempcc == NULL) return(FALSE); ColContextList->AddContext(&tempcc); ColourContext::SetGlobalDefault(COLOURMODEL_HSVT, tempcc); tempcc = new ColourContextGreyT(NULL); // --- GreyT if (tempcc == NULL) return(FALSE); ColContextList->AddContext(&tempcc); ColourContext::SetGlobalDefault(COLOURMODEL_GREYT, tempcc); #ifndef DISABLE_WEBRGBT tempcc = new ColourContextWebRGBT(NULL); // --- WebRBGT if (tempcc == NULL) return(FALSE); ColContextList->AddContext(&tempcc); ColourContext::SetGlobalDefault(COLOURMODEL_WEBRGBT, tempcc); #endif // --- etc... return(TRUE); }

void ColourContextList::RemoveContext (  ColourContext **  OldContext  )

"Removes" the given colour context to the global list of available contexts. If the context is now no longer in use by anyone, it will be 'delete'd. The context pointer passed in will be set to NULL. Author: Jason_Williams (Xara Group Ltd) <camelotdev@xara.com> Date: 11/04/94 Parameters: -  [INPUTS] -  [OUTPUTS] Returns: - Errors: - See also: ColourContextList::AddContext; ColourContext Definition at line 400 of file colclist.cpp. { ENSURE(OldContext != NULL && *OldContext != NULL, "ColourContextList::RemoveContext called with NULL parameter!"); if (!((*OldContext)->DecrementUsage())) // Not still in use, so discard it { RemoveItem(*OldContext); delete *OldContext; } *OldContext = NULL; }

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Member Data Documentation

ColourContextList * ColourContextList::ColContextList = NULL [static, private]

Definition at line 851 of file colcontx.h.

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

• Kernel/colcontx.h (r1785/r1282)
• Kernel/colclist.cpp (r1785/r1282)

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