EPSClipContext Class Reference

Used to maintain clipping regions (masks) while importing Illustrator EPS. A stack of regions is maintained, similar to attribute rendering, with the usual save/restore semantics. Adding a new clipping region results in the new clipping region being merged with the current clipping region. In this way complex paths can be used to build up complex masks (this is the brain-damaged way AI EPS does it anyway). More...

#include <epsfiltr.h>

Inheritance diagram for EPSClipContext:

List of all members.

Public Member Functions
	EPSClipContext ()
	Initialise the context to a sensible state, i.e. a zero context level.
void	SaveContext ()
	Save the current clipping state for future use - no matter how many clip regions are added to the current context, the exact state of the current clipping context can be restore with a (balanced) call to EPSClipContext::RestoreContext().
BOOL	RestoreContext ()
	Restores the clipping context to the state it was in the last time SaveContext() was called on this clip context.
BOOL	AddNewClippingPath (Path *pNewClipPath)
	Takes a copy of the path passed in and merges it with the current clipping context.
BOOL	StartComplexClipRegion ()
	Indicates that we are about to start constructing a complex clipping region. All future calls to AddNewClippingPath() will be joined into the current clipping region until EndComplexRegion is called. Note that you cannot interleave these calls with Save/Restore context calls; complex regions cannot be unbalanced across context levels.
BOOL	EndComplexClipRegion ()
	See StartComplexClipRegion().
BOOL	ClipPathToRegion (Path *pPathToClip)
	Given a path, clip it to the current clipping region specified by this object.
Path *	GetClipRegion ()
	Get the path which defines the current clipping region ofheld by this object.
void	SetClippingFlags (UINT32 NewFlags)
Protected Attributes
INT32	ContextLevel
INT32	ComplexRegionLevel
Path *	pCachedClipPath
BOOL	CacheIsValid
UINT32	ClippingFlags

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Detailed Description

Used to maintain clipping regions (masks) while importing Illustrator EPS. A stack of regions is maintained, similar to attribute rendering, with the usual save/restore semantics. Adding a new clipping region results in the new clipping region being merged with the current clipping region. In this way complex paths can be used to build up complex masks (this is the brain-damaged way AI EPS does it anyway).

Author:

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

Date:

05/22/95

See also:

EPSFilter

Definition at line 356 of file epsfiltr.h.

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Constructor & Destructor Documentation

EPSClipContext::EPSClipContext (   )

Initialise the context to a sensible state, i.e. a zero context level. Author: Tim_Browse (Xara Group Ltd) <camelotdev@xara.com> Date: 05/22/95 Definition at line 436 of file epsfiltr.cpp. { ContextLevel = 0; ComplexRegionLevel = 0; // Initially there is no clip region. pCachedClipPath = NULL; CacheIsValid = TRUE; // set default clipping flags ClippingFlags = 2 | CLIPPING_CLIP_WINDING; }

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Member Function Documentation

BOOL EPSClipContext::AddNewClippingPath (  Path *  pNewClipPath  )

Takes a copy of the path passed in and merges it with the current clipping context. Author: Tim_Browse (Xara Group Ltd) <camelotdev@xara.com> Date: 05/22/95 Parameters: The  path to augment the current clipping region with. [INPUTS] Returns: TRUE if clipping region updated ok; FALSE if not, i.e. out of memory => ERROR1 Errors: Out of memory => ERROR1 Definition at line 591 of file epsfiltr.cpp. { // Invalidate cache CacheIsValid = FALSE; // Flag to indicate if we just do a straightforward copy BOOL SimpleCopy = FALSE; EPSClipContextItem *pItem = NULL; if (ComplexRegionLevel > 0) { // We are building a complex region, so join the new path with the existing one. // First, make sure we have a clip path already? pItem = (EPSClipContextItem *) GetTail(); if (pItem->pClipPath == NULL) { // No clip path - just copy the new path and use that. SimpleCopy = TRUE; } else { // Already have a clip path - join with new one to form a complex path. if (!pItem->pClipPath->MergeTwoPaths(*pNewClipPath)) // Error occured (i.e. out of memory) return FALSE; } } else { // Just a simple clipping region pItem = new EPSClipContextItem(ContextLevel, NULL); if (pItem == NULL) // Out of memory return FALSE; // Add to end of list AddTail(pItem); // Just copy the path passed in SimpleCopy = TRUE; } // Should we just copy the path into the list item? if (SimpleCopy) { // Sanity check ERROR2IF(pItem == NULL, FALSE, "No clipping item found!"); // (yes, this code is pretty tedious!) pItem->pClipPath = new Path; if (pItem->pClipPath == NULL) // Out of memory return FALSE; // Graeme (26/7/00) - Added a test for a NULL pointer to prevent access violations. if ( pNewClipPath != NULL && !pItem->pClipPath->Initialise ( pNewClipPath->GetNumCoords () + 3, 12 ) ) { // Failed to initialise - out of memory return FALSE; } if (!pItem->pClipPath->CopyPathDataFrom(pNewClipPath)) // Failed to copy - out of memory - but this shouldn't happen as // we made sure we had enough space with the initialise call! ERROR2(FALSE, "Unexpected out-of-space error when copying clipping path"); } // If we've got here, it must have worked... return TRUE; }

BOOL EPSClipContext::ClipPathToRegion (  Path *  pPathToClip  )

Given a path, clip it to the current clipping region specified by this object. Author: Tim_Browse (Xara Group Ltd) <camelotdev@xara.com> Date: 05/22/95 Parameters: pPathToClip  - the path object that we want to clip [INPUTS] pPathToClip  - the clipped version of the path [OUTPUTS] Returns: TRUE if clipped ok; FALSE if not. See also: EPSClipContext::GetClipRegion Definition at line 684 of file epsfiltr.cpp. { // Cope with NULL clip region first if (GetClipRegion() == NULL) // Path is already 'clipped' return TRUE; // Ensure GetClipRegion validated the cache ERROR2IF(!CacheIsValid, FALSE, "Could not get valid clipping path in EPSClipContext::ClipPathToRegion()"); // We now have a valid region, so use it to clip the given path // NB. we do an intersection using the cliping path's winding, with a tolerance of 0, // and flatness of 128 millipoints (arbitrary). if (pCachedClipPath->ClipPathToPath(*pPathToClip, pPathToClip, ClippingFlags, 128, 256, 256) == -1) { // An error occured... return FALSE; } // Initialise flags so the bezier tool is happy // [see comment for Path::ClipPathToPath()]. pPathToClip->InitialiseFlags(); // If we get this far, it worked! return TRUE; }

BOOL EPSClipContext::EndComplexClipRegion (   )

See StartComplexClipRegion(). Author: Tim_Browse (Xara Group Ltd) <camelotdev@xara.com> Date: 05/22/95 Returns: TRUE if ok; FALSE if no corresponding call to StartComplexClipRegion() has been encountered => ERROR2 Errors: If unbalanced call is made => ERROR2 See also: EPSClipContext::StartComplexClipRegion Definition at line 563 of file epsfiltr.cpp. { ERROR2IF(ComplexRegionLevel == 0, FALSE, "Unbalanced call to EPSClipContext::EndComplexClipRegion()"); // Adjust complex region level. ComplexRegionLevel--; // All ok return TRUE; }

Path * EPSClipContext::GetClipRegion (   )

Get the path which defines the current clipping region ofheld by this object. Author: Tim_Browse (Xara Group Ltd) <camelotdev@xara.com> Date: 05/22/95 Returns: Pointer to the clipping path, or NULL if no clipping region is specified by this object. See also: EPSClipContext::ClipPathToRegion Definition at line 727 of file epsfiltr.cpp. { if (!CacheIsValid) { // Cache is invalid - if there is no path in the cache, get a new one, otherwise // empty the one in the cache and use that. if (pCachedClipPath == NULL) { pCachedClipPath = new Path; if (pCachedClipPath == NULL) // Out of memory return NULL; if (!pCachedClipPath->Initialise(12, 12)) // Failed to initialise - out of memory return NULL; } else { // Just clear this path out so we can use it to build a clipping region. pCachedClipPath->ClearPath(); } // Calculate the current clipping path - we do this by going along the region // list and combining the clip regions. EPSClipContextItem *pItem = (EPSClipContextItem *) GetHead(); while (pItem != NULL) { if (pItem->pClipPath != NULL) { // Do we already have a clipping region? if (pCachedClipPath->GetNumCoords() > 0) { // Combine this clipping region with the region being constructed... if (pItem->pClipPath->ClipPathToPath(*pCachedClipPath, pCachedClipPath, 2 | CLIPPING_CLIP_WINDING, 128, 256, 256) == -1) { // An error occured... return FALSE; } } else { // No clipping region yet - just copy the data from this path if (!pCachedClipPath->MakeSpaceInPath(pItem->pClipPath->GetNumCoords() + 3)) // Failed to initialise - out of memory return FALSE; if (!pCachedClipPath->CopyPathDataFrom(pItem->pClipPath)) // Failed to copy - out of memory - but this shouldn't happen as // we made sure we had enough space with the initialise call! ERROR2(FALSE, "Unexpected out-of-space error when copying clipping path"); } } // Get the next item pItem = (EPSClipContextItem *) GetNext(pItem); } // Did we get any clipping at all? if (pCachedClipPath->GetNumCoords() == 0) { // No clip region - delete and use NULL to indicate this. delete pCachedClipPath; pCachedClipPath = NULL; } // Validate cache CacheIsValid = TRUE; } // Cache must be valid, so return the contents of the cache. return pCachedClipPath; }

BOOL EPSClipContext::RestoreContext (   )

Restores the clipping context to the state it was in the last time SaveContext() was called on this clip context. Author: Tim_Browse (Xara Group Ltd) <camelotdev@xara.com> Date: 05/22/95 Returns: Errors: No call to SaveContext() has been made => ERROR2 See also: EPSClipContext::SaveContext Definition at line 481 of file epsfiltr.cpp. { // Invalidate cache CacheIsValid = FALSE; // Sanity check ERROR2IF(ContextLevel == 0, FALSE, "Unbalanced call to EPSClipContext::RestoreContext()"); // Decrement context level ContextLevel--; // Delete all items added since save context was last called... EPSClipContextItem *pItem = (EPSClipContextItem *) GetTail(); while ((pItem != NULL) && (pItem->ContextLevel > ContextLevel)) { delete RemoveTail(); // Get the next item pItem = (EPSClipContextItem *) GetTail(); } // If we get here then it's ok return TRUE; }

void EPSClipContext::SaveContext (   )

Save the current clipping state for future use - no matter how many clip regions are added to the current context, the exact state of the current clipping context can be restore with a (balanced) call to EPSClipContext::RestoreContext(). Author: Tim_Browse (Xara Group Ltd) <camelotdev@xara.com> Date: 05/22/95 See also: EPSClipContext::RestoreContext Definition at line 463 of file epsfiltr.cpp. { ContextLevel++; }

void EPSClipContext::SetClippingFlags (  UINT32  NewFlags  )  [inline]

Definition at line 369 of file epsfiltr.h. {ClippingFlags = NewFlags;};

BOOL EPSClipContext::StartComplexClipRegion (   )

Indicates that we are about to start constructing a complex clipping region. All future calls to AddNewClippingPath() will be joined into the current clipping region until EndComplexRegion is called. Note that you cannot interleave these calls with Save/Restore context calls; complex regions cannot be unbalanced across context levels. Author: Tim_Browse (Xara Group Ltd) <camelotdev@xara.com> Date: 05/22/95 Returns: TRUE if ok; FALSE if out of memory. Errors: Out of memory => ERROR1 See also: EPSClipContext::EndComplexClipRegion() Definition at line 526 of file epsfiltr.cpp. { // Update complex region count ComplexRegionLevel++; // We need to create a record to hold this complex region // (it has a NULL clipping region initially) EPSClipContextItem *pItem = new EPSClipContextItem(ContextLevel, NULL); if (pItem == NULL) // Out of memory return FALSE; // It's a complex region so save the level pItem->ComplexRegionLevel = ComplexRegionLevel; // Add to end of list AddTail(pItem); // All ok return TRUE; }

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Member Data Documentation

BOOL EPSClipContext::CacheIsValid [protected]

Definition at line 375 of file epsfiltr.h.

UINT32 EPSClipContext::ClippingFlags [protected]

Definition at line 376 of file epsfiltr.h.

INT32 EPSClipContext::ComplexRegionLevel [protected]

Definition at line 373 of file epsfiltr.h.

INT32 EPSClipContext::ContextLevel [protected]

Definition at line 369 of file epsfiltr.h.

Path* EPSClipContext::pCachedClipPath [protected]

Definition at line 374 of file epsfiltr.h.

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

• Kernel/epsfiltr.h (r1785/r1302)
• Kernel/epsfiltr.cpp (r1785/r1668)

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