juce::OpenGLFrameBuffer Class Reference

Creates an openGL frame buffer. More...

Public Types
enum class	RowOrder { fromBottomUp , fromTopDown }

Public Member Functions
	OpenGLFrameBuffer ()
	Creates an uninitialised buffer.
	~OpenGLFrameBuffer ()
	Destructor.
bool	initialise (OpenGLContext &context, int width, int height)
	Tries to allocates a buffer of the given size.
bool	initialise (OpenGLContext &context, const Image &content)
	Tries to allocates a buffer containing a copy of a given image.
bool	initialise (OpenGLFrameBuffer &other)
	Tries to allocate a copy of another framebuffer.
void	release ()
	Releases the buffer, if one has been allocated.
void	saveAndRelease ()
	If the framebuffer is active, this will save a stashed copy of its contents in main memory, and will release the GL buffer.
bool	reloadSavedCopy (OpenGLContext &context)
	Restores the framebuffer content that was previously saved using saveAndRelease().
bool	isValid () const noexcept
	Returns true if a valid buffer has been allocated.
int	getWidth () const noexcept
	Returns the width of the buffer.
int	getHeight () const noexcept
	Returns the height of the buffer.
GLuint	getTextureID () const noexcept
	Returns the texture ID number for using this buffer as a texture.
int	getTextureWidth () const noexcept
	Returns the width of the texture that backs this buffer.
int	getTextureHeight () const noexcept
	Returns the height of the texture that backs this buffer.
bool	makeCurrentRenderingTarget ()
	Selects this buffer as the current OpenGL rendering target.
void	releaseAsRenderingTarget ()
	Deselects this buffer as the current OpenGL rendering target.
GLuint	getFrameBufferID () const noexcept
	Returns the ID of this framebuffer, or 0 if it isn't initialised.
void	clear (Colour colour)
	Clears the framebuffer with the specified colour.
void	makeCurrentAndClear ()
	Selects the framebuffer as the current target, and clears it to transparent.
bool	readPixels (PixelARGB *targetData, const Rectangle< int > &sourceArea, RowOrder order)
	Reads an area of pixels from the framebuffer into a 32-bit ARGB pixel array.
bool	writePixels (const PixelARGB *srcData, const Rectangle< int > &targetArea, RowOrder order)
	Writes an area of pixels into the framebuffer from a specified pixel array.

Static Public Member Functions
static GLuint	getCurrentFrameBufferTarget () noexcept
	Returns the current frame buffer ID for the current context.

Detailed Description

Creates an openGL frame buffer.

Member Enumeration Documentation

RowOrder

enum class juce::OpenGLFrameBuffer::RowOrder

strong

Enumerator
fromBottomUp
fromTopDown

Constructor & Destructor Documentation

OpenGLFrameBuffer()

juce::OpenGLFrameBuffer::OpenGLFrameBuffer

(

)

Creates an uninitialised buffer.

To actually allocate the buffer, use initialise().

~OpenGLFrameBuffer()

juce::OpenGLFrameBuffer::~OpenGLFrameBuffer

(

)

Destructor.

Member Function Documentation

initialise() [1/3]

bool juce::OpenGLFrameBuffer::initialise	(	OpenGLContext &	context,
		int	width,
		int	height
	)

Tries to allocates a buffer of the given size.

Note that a valid openGL context must be selected when you call this method, or it will fail.

initialise() [2/3]

bool juce::OpenGLFrameBuffer::initialise	(	OpenGLContext &	context,
		const Image &	content
	)

Tries to allocates a buffer containing a copy of a given image.

Note that a valid openGL context must be selected when you call this method, or it will fail.

initialise() [3/3]

bool juce::OpenGLFrameBuffer::initialise

(

OpenGLFrameBuffer &

other

)

Tries to allocate a copy of another framebuffer.

release()

void juce::OpenGLFrameBuffer::release

(

)

Releases the buffer, if one has been allocated.

Any saved state that was created with saveAndRelease() will also be freed by this call.

saveAndRelease()

void juce::OpenGLFrameBuffer::saveAndRelease

(

)

If the framebuffer is active, this will save a stashed copy of its contents in main memory, and will release the GL buffer.

After saving, the original state can be restored again by calling reloadSavedCopy().

reloadSavedCopy()

bool juce::OpenGLFrameBuffer::reloadSavedCopy

(

OpenGLContext &

context

)

Restores the framebuffer content that was previously saved using saveAndRelease().

isValid()

bool juce::OpenGLFrameBuffer::isValid ( ) const

noexcept

Returns true if a valid buffer has been allocated.

getWidth()

int juce::OpenGLFrameBuffer::getWidth ( ) const

noexcept

Returns the width of the buffer.

getHeight()

int juce::OpenGLFrameBuffer::getHeight ( ) const

noexcept

Returns the height of the buffer.

getTextureID()

GLuint juce::OpenGLFrameBuffer::getTextureID ( ) const

noexcept

Returns the texture ID number for using this buffer as a texture.

The texture may be larger than the buffer itself, see getTextureWidth() and getTextureHeight(). The buffer's content occupies the top-left corner of the texture, so the top-left pixel of the buffer is at texture coordinate (0, 1).

getTextureWidth()

int juce::OpenGLFrameBuffer::getTextureWidth ( ) const

noexcept

Returns the width of the texture that backs this buffer.

This is normally the same as getWidth(), but if the GL implementation is unable to create a texture with the exact size that was requested, a larger texture will be used instead, and this will return the actual width of that texture.

getTextureHeight()

int juce::OpenGLFrameBuffer::getTextureHeight ( ) const

noexcept

Returns the height of the texture that backs this buffer.

See also

getTextureWidth

makeCurrentRenderingTarget()

bool juce::OpenGLFrameBuffer::makeCurrentRenderingTarget

(

)

Selects this buffer as the current OpenGL rendering target.

releaseAsRenderingTarget()

void juce::OpenGLFrameBuffer::releaseAsRenderingTarget

(

)

Deselects this buffer as the current OpenGL rendering target.

getFrameBufferID()

GLuint juce::OpenGLFrameBuffer::getFrameBufferID ( ) const

noexcept

Returns the ID of this framebuffer, or 0 if it isn't initialised.

getCurrentFrameBufferTarget()

static GLuint juce::OpenGLFrameBuffer::getCurrentFrameBufferTarget ( )

staticnoexcept

Returns the current frame buffer ID for the current context.

clear()

void juce::OpenGLFrameBuffer::clear

(

Colour

colour

)

Clears the framebuffer with the specified colour.

makeCurrentAndClear()

void juce::OpenGLFrameBuffer::makeCurrentAndClear

(

)

Selects the framebuffer as the current target, and clears it to transparent.

readPixels()

bool juce::OpenGLFrameBuffer::readPixels	(	PixelARGB *	targetData,
		const Rectangle< int > &	sourceArea,
		RowOrder	order
	)

Reads an area of pixels from the framebuffer into a 32-bit ARGB pixel array.

Parameters

targetData	the array to fill. It must have room for at least sourceArea.getWidth() * sourceArea.getHeight() pixels, which are written contiguously with no padding between rows.
sourceArea	the area to read, in OpenGL coordinates, with its origin at the bottom-left corner of the framebuffer.
order	the order in which the rows of the area are written to targetData.

Returns

true if the pixels were read, or false if the framebuffer isn't currently allocated.

writePixels()

bool juce::OpenGLFrameBuffer::writePixels	(	const PixelARGB *	srcData,
		const Rectangle< int > &	targetArea,
		RowOrder	order
	)

Writes an area of pixels into the framebuffer from a specified pixel array.

Parameters

srcData	the pixels to write. It must contain at least targetArea.getWidth() * targetArea.getHeight() pixels, stored contiguously with no padding between rows.
targetArea	the area to write, in OpenGL coordinates, with its origin at the bottom-left corner of the framebuffer.
order	the order of the rows in srcData.

Returns

true if the pixels were written, or false if the framebuffer isn't currently allocated.

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

• juce_opengl/opengl/juce_OpenGLFrameBuffer.h