API reference - Class PixelBuffer

Notation used in Ruby API documentation

Module: lay

Description: A simplistic pixel buffer representing an image of ARGB32 or RGB32 values

This object is mainly provided for offline rendering of layouts in Qt-less environments. It supports a rectangular pixel space with color values encoded in 32bit integers. It supports transparency through an optional alpha channel. The color format for a pixel is "0xAARRGGBB" where 'AA' is the alpha value which is ignored in non-transparent mode.

This class supports basic operations such as initialization, single-pixel access and I/O to PNG.

This class has been introduced in version 0.28.

Public constructors

new PixelBuffer ptrnew(unsigned int width,
unsigned int height)
Creates a pixel buffer object

Public methods

[const]bool!=(const PixelBuffer other)Returns a value indicating whether self is not identical to the other image
[const]bool==(const PixelBuffer other)Returns a value indicating whether self is identical to the other image
[const]PixelBuffer ptr_const_castReturns a non-const reference to self.
void_createEnsures the C++ object is created
void_destroyExplicitly destroys the object
[const]bool_destroyed?Returns a value indicating whether the object was already destroyed
[const]bool_is_const_object?Returns a value indicating whether the reference is a const reference
void_manageMarks the object as managed by the script side.
void_unmanageMarks the object as no longer owned by the script side.
voidassign(const PixelBuffer other)Assigns another object to self
[const]PixelBufferdiff(const PixelBuffer other)Creates a difference image
[const]new PixelBuffer ptrdupCreates a copy of self
voidfill(unsigned int color)Fills the pixel buffer with the given pixel value
voidfill(QColor color)Fills the pixel buffer with the given QColor
[const]unsigned intheightGets the height of the pixel buffer in pixels
voidpatch(const PixelBuffer other)Patches another pixel buffer into this one
[const]unsigned intpixel(unsigned int x,
unsigned int y)
Gets the value of the pixel at position x, y
voidset_pixel(unsigned int x,
unsigned int y,
unsigned int c)
Sets the value of the pixel at position x, y
voidswap(PixelBuffer other)Swaps data with another PixelBuffer object
[const]bytesto_png_dataConverts the pixel buffer to a PNG byte stream
[const]QImageto_qimageConverts the pixel buffer to a QImage object
[const]booltransparentGets a flag indicating whether the pixel buffer supports an alpha channel
voidtransparent=(bool t)Sets a flag indicating whether the pixel buffer supports an alpha channel
[const]unsigned intwidthGets the width of the pixel buffer in pixels
[const]voidwrite_png(string file)Writes the pixel buffer to a PNG file

Public static methods and constants

PixelBufferfrom_png_data(bytes data)Reads the pixel buffer from a PNG byte stream
PixelBufferfrom_qimage(const QImage qimage)Creates a pixel buffer object from a QImage object
PixelBufferread_png(string file)Reads the pixel buffer from a PNG file

Deprecated methods (protected, public, static, non-static and constructors)

voidcreateUse of this method is deprecated. Use _create instead
voiddestroyUse of this method is deprecated. Use _destroy instead
[const]booldestroyed?Use of this method is deprecated. Use _destroyed? instead
[const]boolis_const_object?Use of this method is deprecated. Use _is_const_object? instead

Detailed description

!=

Signature: [const] bool != (const PixelBuffer other)

Description: Returns a value indicating whether self is not identical to the other image

==

Signature: [const] bool == (const PixelBuffer other)

Description: Returns a value indicating whether self is identical to the other image

_const_cast

Signature: [const] PixelBuffer ptr _const_cast

Description: Returns a non-const reference to self.

Basically, this method allows turning a const object reference to a non-const one. This method is provided as last resort to remove the constness from an object. Usually there is a good reason for a const object reference, so using this method may have undesired side effects.

This method has been introduced in version 0.29.6.

_create

Signature: void _create

Description: Ensures the C++ object is created

Use this method to ensure the C++ object is created, for example to ensure that resources are allocated. Usually C++ objects are created on demand and not necessarily when the script object is created.

_destroy

Signature: void _destroy

Description: Explicitly destroys the object

Explicitly destroys the object on C++ side if it was owned by the script interpreter. Subsequent access to this object will throw an exception. If the object is not owned by the script, this method will do nothing.

_destroyed?

Signature: [const] bool _destroyed?

Description: Returns a value indicating whether the object was already destroyed

This method returns true, if the object was destroyed, either explicitly or by the C++ side. The latter may happen, if the object is owned by a C++ object which got destroyed itself.

_is_const_object?

Signature: [const] bool _is_const_object?

Description: Returns a value indicating whether the reference is a const reference

This method returns true, if self is a const reference. In that case, only const methods may be called on self.

_manage

Signature: void _manage

Description: Marks the object as managed by the script side.

After calling this method on an object, the script side will be responsible for the management of the object. This method may be called if an object is returned from a C++ function and the object is known not to be owned by any C++ instance. If necessary, the script side may delete the object if the script's reference is no longer required.

Usually it's not required to call this method. It has been introduced in version 0.24.

_unmanage

Signature: void _unmanage

Description: Marks the object as no longer owned by the script side.

Calling this method will make this object no longer owned by the script's memory management. Instead, the object must be managed in some other way. Usually this method may be called if it is known that some C++ object holds and manages this object. Technically speaking, this method will turn the script's reference into a weak reference. After the script engine decides to delete the reference, the object itself will still exist. If the object is not managed otherwise, memory leaks will occur.

Usually it's not required to call this method. It has been introduced in version 0.24.

assign

Signature: void assign (const PixelBuffer other)

Description: Assigns another object to self

create

Signature: void create

Description: Ensures the C++ object is created

Use of this method is deprecated. Use _create instead

Use this method to ensure the C++ object is created, for example to ensure that resources are allocated. Usually C++ objects are created on demand and not necessarily when the script object is created.

destroy

Signature: void destroy

Description: Explicitly destroys the object

Use of this method is deprecated. Use _destroy instead

Explicitly destroys the object on C++ side if it was owned by the script interpreter. Subsequent access to this object will throw an exception. If the object is not owned by the script, this method will do nothing.

destroyed?

Signature: [const] bool destroyed?

Description: Returns a value indicating whether the object was already destroyed

Use of this method is deprecated. Use _destroyed? instead

This method returns true, if the object was destroyed, either explicitly or by the C++ side. The latter may happen, if the object is owned by a C++ object which got destroyed itself.

diff

Signature: [const] PixelBuffer diff (const PixelBuffer other)

Description: Creates a difference image

This method is provided to support transfer of image differences - i.e. small updates instead of full images. It works for non-transparent images only and generates an image with transpareny enabled and with the new pixel values for pixels that have changed. The alpha value will be 0 for identical images and 255 for pixels with different values. This way, the difference image can be painted over the original image to generate the new image.

dup

Signature: [const] new PixelBuffer ptr dup

Description: Creates a copy of self

Python specific notes:
This method also implements '__copy__' and '__deepcopy__'.

fill

(1) Signature: void fill (unsigned int color)

Description: Fills the pixel buffer with the given pixel value

(2) Signature: void fill (QColor color)

Description: Fills the pixel buffer with the given QColor

from_png_data

Signature: [static] PixelBuffer from_png_data (bytes data)

Description: Reads the pixel buffer from a PNG byte stream

This method may not be available if PNG support is not compiled into KLayout.

from_qimage

Signature: [static] PixelBuffer from_qimage (const QImage qimage)

Description: Creates a pixel buffer object from a QImage object

height

Signature: [const] unsigned int height

Description: Gets the height of the pixel buffer in pixels

is_const_object?

Signature: [const] bool is_const_object?

Description: Returns a value indicating whether the reference is a const reference

Use of this method is deprecated. Use _is_const_object? instead

This method returns true, if self is a const reference. In that case, only const methods may be called on self.

new

Signature: [static] new PixelBuffer ptr new (unsigned int width, unsigned int height)

Description: Creates a pixel buffer object

width:The width in pixels
height:The height in pixels

The pixels are basically uninitialized. You will need to use fill to initialize them to a certain value.

Python specific notes:
This method is the default initializer of the object.

patch

Signature: void patch (const PixelBuffer other)

Description: Patches another pixel buffer into this one

This method is the inverse of diff - it will patch the difference image created by diff into this pixel buffer. Note that this method will not do true alpha blending and requires the other pixel buffer to have the same format than self. Self will be modified by this operation.

pixel

Signature: [const] unsigned int pixel (unsigned int x, unsigned int y)

Description: Gets the value of the pixel at position x, y

read_png

Signature: [static] PixelBuffer read_png (string file)

Description: Reads the pixel buffer from a PNG file

This method may not be available if PNG support is not compiled into KLayout.

set_pixel

Signature: void set_pixel (unsigned int x, unsigned int y, unsigned int c)

Description: Sets the value of the pixel at position x, y

swap

Signature: void swap (PixelBuffer other)

Description: Swaps data with another PixelBuffer object

to_png_data

Signature: [const] bytes to_png_data

Description: Converts the pixel buffer to a PNG byte stream

This method may not be available if PNG support is not compiled into KLayout.

to_qimage

Signature: [const] QImage to_qimage

Description: Converts the pixel buffer to a QImage object

transparent

Signature: [const] bool transparent

Description: Gets a flag indicating whether the pixel buffer supports an alpha channel

Python specific notes:
The object exposes a readable attribute 'transparent'. This is the getter.

transparent=

Signature: void transparent= (bool t)

Description: Sets a flag indicating whether the pixel buffer supports an alpha channel

By default, the pixel buffer does not support an alpha channel.

Python specific notes:
The object exposes a writable attribute 'transparent'. This is the setter.

width

Signature: [const] unsigned int width

Description: Gets the width of the pixel buffer in pixels

write_png

Signature: [const] void write_png (string file)

Description: Writes the pixel buffer to a PNG file

This method may not be available if PNG support is not compiled into KLayout.