Paint

An abstract class for managing graphical elements. More...

Inheritance diagram for Paint:

Public Member Functions
Result	rotate (float degree) noexcept
	Sets the angle by which the object is rotated. More...
Result	scale (float factor) noexcept
	Sets the scale value of the object. More...
Result	translate (float x, float y) noexcept
	Sets the values by which the object is moved in a two-dimensional space. More...
Result	transform (const Matrix &m) noexcept
	Sets the matrix of the affine transformation for the object. More...
Result	opacity (uint8_t o) noexcept
	Sets the opacity of the object. More...
Result	composite (std::unique_ptr< Paint > target, CompositeMethod method) const noexcept
	Sets the composition target object and the composition method. More...
Result	bounds (float *x, float *y, float *w, float *h) const noexcept
	Gets the bounding box of the paint object before any transformation. More...
Paint *	duplicate () const noexcept
	Duplicates the object. More...
uint8_t	opacity () const noexcept
	Gets the opacity value of the object. More...

Detailed Description

An abstract class for managing graphical elements.

A graphical element in TVG is any object composed into a Canvas. Paint represents such a graphical object and its behaviors such as duplication, transformation and composition. TVG recommends the user to regard a paint as a set of volatile commands. They can prepare a Paint and then request a Canvas to run them.

Member Function Documentation

bounds()

Result bounds ( float *  x, float *  y, float *  w, float *  h  ) const

noexcept

Gets the bounding box of the paint object before any transformation.

Parameters

[out]	x	The x coordinate of the upper left corner of the object.
[out]	y	The y coordinate of the upper left corner of the object.
[out]	w	The width of the object.
[out]	h	The height of the object.

Returns

Result::Success when succeed, Result::InsufficientCondition otherwise.

Note

The bounding box doesn't indicate the final rendered region. It's the smallest rectangle that encloses the object.

composite()

Result composite ( std::unique_ptr< Paint >  target, CompositeMethod  method  ) const

noexcept

Sets the composition target object and the composition method.

Parameters

[in]	target	The paint of the target object.
[in]	method	The method used to composite the source object with the target.

Returns

Result::Success when succeed, Result::InvalidArguments otherwise.

duplicate()

Paint* duplicate ( ) const

noexcept

Duplicates the object.

Creates a new object and sets its all properties as in the original object.

Returns

The created object when succeed, nullptr otherwise.

opacity() [1/2]

Result opacity ( uint8_t  o )

noexcept

Sets the opacity of the object.

Parameters

[in]

o

The opacity value in the range [0 ~ 255], where 0 is completely transparent and 255 is opaque.

Returns

Result::Success when succeed.

Note

Setting the opacity with this API may require multiple render pass for composition. It is recommended to avoid changing the opacity if possible.

opacity() [2/2]

uint8_t opacity ( ) const

noexcept

Gets the opacity value of the object.

Returns

The opacity value in the range [0 ~ 255], where 0 is completely transparent and 255 is opaque.

rotate()

Result rotate ( float  degree )

noexcept

Sets the angle by which the object is rotated.

The angle in measured clockwise from the horizontal axis. The rotational axis passes through the point on the object with zero coordinates.

Parameters

[in]

degree

The value of the angle in degrees.

Returns

Result::Success when succeed, Result::FailedAllocation otherwise.

scale()

Result scale ( float  factor )

noexcept

Sets the scale value of the object.

Parameters

[in]

factor

The value of the scaling factor. The default value is 1.

Returns

Result::Success when succeed, Result::FailedAllocation otherwise.

transform()

Result transform ( const Matrix &  m )

noexcept

Sets the matrix of the affine transformation for the object.

The augmented matrix of the transformation is expected to be given.

Parameters

[in]

m

The 3x3 augmented matrix.

Returns

Result::Success when succeed, Result::FailedAllocation otherwise.

translate()

Result translate ( float  x, float  y  )

noexcept

Sets the values by which the object is moved in a two-dimensional space.

The origin of the coordinate system is in the upper left corner of the canvas. The horizontal and vertical axes point to the right and down, respectively.

Parameters

[in]	x	The value of the horizontal shift.
[in]	y	The value of the vertical shift.

Returns

Result::Success when succeed, Result::FailedAllocation otherwise.