If a client wants to control the allocation of raster layers in a canvas, it should subclass SkRasterHandleAllocator. More...

#include <SkRasterHandleAllocator.h>

Classes
struct	Rec

Public Types
typedef void *	Handle

Public Member Functions
virtual	~SkRasterHandleAllocator ()=default

virtual bool	allocHandle (const SkImageInfo &, Rec *)=0
	Given a requested info, allocate the corresponding pixels/rowbytes, and whatever handle is desired to give clients access to those pixels. More...

virtual void	updateHandle (Handle, const SkMatrix &, const SkIRect &)=0
	Clients access the handle for a given layer by calling SkCanvas::accessTopRasterHandle(). More...

Static Public Member Functions
static std::unique_ptr< SkCanvas >	MakeCanvas (std::unique_ptr< SkRasterHandleAllocator >, const SkImageInfo &, const Rec rec=nullptr, const SkSurfaceProps props=nullptr)
	This creates a canvas which will use the allocator to manage pixel allocations, including all calls to saveLayer(). More...

Protected Member Functions
	SkRasterHandleAllocator ()=default

	SkRasterHandleAllocator (const SkRasterHandleAllocator &)=delete

SkRasterHandleAllocator &	operator= (const SkRasterHandleAllocator &)=delete

Friends
class	SkBitmapDevice

Detailed Description

If a client wants to control the allocation of raster layers in a canvas, it should subclass SkRasterHandleAllocator.

This allocator performs two tasks:

controls how the memory for the pixels is allocated
associates a "handle" to a private object that can track the matrix/clip of the SkCanvas

This example allocates a canvas, and defers to the allocator to create the base layer.

std::unique_ptr<SkCanvas> canvas = SkRasterHandleAllocator::MakeCanvas(
        SkImageInfo::Make(...),
        std::make_unique<MySubclassRasterHandleAllocator>(...),
        nullptr);

If you have already allocated the base layer (and its handle, release-proc etc.) then you can pass those in using the last parameter to MakeCanvas().

Regardless of how the base layer is allocated, each time canvas->saveLayer() is called, your allocator's allocHandle() will be called.

Member Typedef Documentation

◆ Handle

typedef void* SkRasterHandleAllocator::Handle

Constructor & Destructor Documentation

◆ ~SkRasterHandleAllocator()

virtual SkRasterHandleAllocator::~SkRasterHandleAllocator ( )

virtualdefault

◆ SkRasterHandleAllocator() [1/2]

SkRasterHandleAllocator::SkRasterHandleAllocator ( )

protecteddefault

◆ SkRasterHandleAllocator() [2/2]

SkRasterHandleAllocator::SkRasterHandleAllocator ( const SkRasterHandleAllocator & )

protecteddelete

Member Function Documentation

◆ allocHandle()

virtual bool SkRasterHandleAllocator::allocHandle	(	const SkImageInfo &	,
		Rec *
	)

pure virtual

Given a requested info, allocate the corresponding pixels/rowbytes, and whatever handle is desired to give clients access to those pixels.

The rec also contains a proc and context which will be called when this allocation goes out of scope.

e.g. when canvas->saveLayer() is called, the allocator will be called to allocate the pixels for the layer. When canvas->restore() is called, the fReleaseProc will be called.

◆ MakeCanvas()

static std::unique_ptr<SkCanvas> SkRasterHandleAllocator::MakeCanvas	(	std::unique_ptr< SkRasterHandleAllocator >	,
		const SkImageInfo &	,
		const Rec *	rec = `nullptr`,
		const SkSurfaceProps *	props = `nullptr`
	)

static

This creates a canvas which will use the allocator to manage pixel allocations, including all calls to saveLayer().

If rec is non-null, then it will be used as the base-layer of pixels/handle. If rec is null, then the allocator will be called for the base-layer as well.

◆ operator=()

SkRasterHandleAllocator& SkRasterHandleAllocator::operator= ( const SkRasterHandleAllocator & )

protecteddelete

◆ updateHandle()

virtual void SkRasterHandleAllocator::updateHandle	(	Handle	,
		const SkMatrix &	,
		const SkIRect &
	)

pure virtual

Clients access the handle for a given layer by calling SkCanvas::accessTopRasterHandle().

To allow the handle to reflect the current matrix/clip in the canvs, updateHandle() is is called. The subclass is responsible to update the handle as it sees fit.

Friends And Related Function Documentation

◆ SkBitmapDevice

friend class SkBitmapDevice

friend

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

/CHECKOUT/include/core/SkRasterHandleAllocator.h

Classes

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Friends