Image transformation
[Video]

Typedefs
typedef struct gavl_image_transform_s	gavl_image_transform_t
	Opaque image transformation engine.
typedef void(*	gavl_image_transform_func )(void *priv, double xdst, double ydst, double *xsrc, double *ysrc)
	Function describing the method.
Functions
gavl_image_transform_t *	gavl_image_transform_create ()
	Create a transformation engine.
void	gavl_image_transform_destroy (gavl_image_transform_t *t)
	Destroy a transformation engine.
void	gavl_image_transform_init (gavl_image_transform_t *t, gavl_video_format_t *format, gavl_image_transform_func func, void *priv)
	Destroy a transformation engine.
void	gavl_image_transform_transform (gavl_image_transform_t *t, gavl_video_frame_t *in_frame, gavl_video_frame_t *out_frame)
	Transform an image.
gavl_video_options_t *	gavl_image_transform_get_options (gavl_image_transform_t *t)
	Get transformation options.

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Detailed Description

gavl includes a generic image transformation engine. You pass a function pointer to the init function, which transforms the destination coordinates into source coordinates.

The interpolation method is set with gavl_video_options_set_scale_mode, but not all modes are supported. When initialized with an invalid scale mode, the transformation engine will silently choose the closest one.

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Typedef Documentation

typedef struct gavl_image_transform_s gavl_image_transform_t

Opaque image transformation engine.

You don't want to know what's inside.

typedef void(* gavl_image_transform_func)(void *priv, double xdst, double ydst, double *xsrc, double *ysrc)

Function describing the method.

Parameters:

	priv	User data
	xdst	X-coordinate of the destination
	ydst	Y-coordinate of the destination
	xsrc	Returns X-coordinate of the source
	ysrc	Returns Y-coordinate of the source

All coordinates are in fractional pixels. 0,0 is the upper left corner. Return negative values or values larger than the dimesion to signal that a pixel is outside the source image.

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Function Documentation

gavl_image_transform_t* gavl_image_transform_create

(

)

Create a transformation engine.

Returns:

A newly allocated transformation engine

Since 1.1.0.

void gavl_image_transform_destroy

(

gavl_image_transform_t *

t

)

Destroy a transformation engine.

Parameters:

t

A transformation engine Since 1.1.0.

void gavl_image_transform_init	(	gavl_image_transform_t *	t,
		gavl_video_format_t *	format,
		gavl_image_transform_func	func,
		void *	priv
	)

Destroy a transformation engine.

Parameters:

	t	A transformation engine
	Format	(can be changed)
	func	Coordinate transform function
	priv	The priv argument for func Since 1.1.0.

void gavl_image_transform_transform	(	gavl_image_transform_t *	t,
		gavl_video_frame_t *	in_frame,
		gavl_video_frame_t *	out_frame
	)

Transform an image.

Parameters:

	t	A transformation engine
	Input	frame
	Output	frame Since 1.1.0.

gavl_video_options_t* gavl_image_transform_get_options

(

gavl_image_transform_t *

t

)

Get transformation options.

Parameters:

t

A transformation engine

Returns:

Options

After you called this, you can use the gavl_video_options_set_*() functions to change the options. Options will become valid with the next call to gavl_image_transform_init.

Since 1.1.0.