OEColor¶

class OEColor

The OEColor class represents colors in terms of RGBA (red, green, blue, alpha) components, where alpha is used as an opacity channel. Each color component is represented by one byte in the range of 0 to 255. Meaning that \(2^8*2^8*2^8 = 16,777,216\) different colors can be represented.

The value of alpha is also in the range of 0 to 255. If a color has an alpha value of 0, then the color is fully transparent, i.e., invisible. If a color has an alpha value 255, then the color is fully opaque.

OESystem provides many predefined colors. For example, the color black is represented by OEBlack (R=0, G=0, B=0), and the color white is represented by OEWhite (R=255, G=255, B=255). The full list of pre-defined colors is shown in Figure: List of pre-defined colors

List of pre-defined colors¶

Note

The alpha for all pre-defined colors is 255, entirely opaque.

Constructors¶

OEColor()

The default constructor initializes the color object to white (R=255, B=255, G=255, A=255).

OEColor(const OEColor &rhs)

Copy constructor.

OEColor(unsigned int packed)

Create a color object from a packed 32-bit integer. Each 8-bit byte of the integer is assumed to contain a different component of the color.

OEColor(const std::string &text)

Create a color object that is initialized with an RGB or an RGBA hexadecimal string. The format of an RGB string is #RRGGBB and format of an RGBA string is #RRGGBBAA, where R,G,B and A are hexadecimal numbers. For example, the string #FF0000 represents the color red.

OEColor(const unsigned char *rgba)

Create a color object from an array of unsigned char. The array is assumed to contain at least 4 bytes, where each byte corresponds to RGBA components respectively.

OEColor(unsigned int red, unsigned int green, unsigned int blue)

Create a color object with a specified red, green, and blue color components, the alpha component is set to 255. Each argument should be in the range of 0 to 255.

OEColor(unsigned int red, unsigned int green, unsigned int blue, unsigned int alpha)

Create a color object with a specified red, green, blue, and alpha components.

operator!=¶

bool operator!=(const OEColor &rhs) const

Determines whether two OEColor objects are different. Two OEColor objects are considered different, if any of their color components (red, green, blue, or alpha) are different.

operator==¶

bool operator==(const OEColor &rhs) const

Determines whether two OEColor objects are equal. Two OEColor objects are considered equivalent if all of their color components (red, green, blue, and alpha) are identical.

CreateCopy¶

OEColor *CreateCopy() const

Deep copy constructor that returns a pointer to a copy of the object. The memory for the returned OEColor object is dynamically allocated and owned by the caller.

GetR¶

unsigned int GetR() const

Returns the red component of the OEColor object in the range of [0, 255].

See also

OEColor::SetR method

GetG¶

unsigned int GetG() const

Returns the green component of the OEColor object in the range of [0, 255].

See also

OEColor::SetG method

GetB¶

unsigned int GetB() const

Returns the blue component of the OEColor object in the range of [0, 255].

See also

OEColor::SetB method

GetA¶

unsigned int GetA() const

Returns the alpha component of the OEColor object in the range of [0, 255].

See also

OEColor::SetA method

GetPackedColor¶

unsigned int GetPackedColor() const

Returns all the components of the OEColor object packed into a single 32-bit integer. Each 8-bit byte of the integer contains a different component of the color.

GetRGBA¶

const unsigned char *GetRGBA() const

Returns all the components of the OEColor object as an array of 4 bytes. The array contains 4 bytes, where each byte corresponds to RGBA components respectively. The pointer returned is owned by the OEColor object and should not be deallocated by the user.

GetText¶

std::string GetText(bool alpha=false) const

Returns the hexadecimal string representation of the OEColor object. By default the format is #RRGGBB. If the alpha argument is set to true the returned string will include the alpha component in the format #RRGGBBAA.

Set¶

OEColor &Set(unsigned int r, unsigned int g, unsigned int b)
OEColor &Set(unsigned int r, unsigned int g, unsigned int b, unsigned int a)

Sets all the components of the OEColor object. Each argument is assumed to be in the range of 0 to 255. Returns a reference to the OEColor object.

SetR¶

OEColor &SetR(unsigned int r)

Sets the red component of the OEColor object. The given value is clamped into the range of [0, 255]. Returns a reference to the OEColor object.

Examples of changing the red color component¶

See also

OEColor::GetR method

SetG¶

OEColor &SetG(unsigned int g)

Sets the green component of the OEColor object. The given value is clamped into the range of [0, 255]. Returns a reference to the OEColor object.

Examples of changing the green color component¶

See also

OEColor::SetG method

SetB¶

OEColor &SetB(unsigned int b)

Sets the blue component of the OEColor object. The given value is clamped into the range of [0, 255]. Returns a reference to the OEColor object.

Examples of changing the blue color component¶

See also

OEColor::SetB method

SetA¶

OEColor &SetA(unsigned int a)

Sets the alpha component of the OEColor object. The given value is clamped into the range of [0, 255]. Returns a reference to the OEColor object.

Examples of changing the alpha (transparency) color component¶

See also

OEColor::SetA method

SetPackedColor¶

OEColor &SetPackedColor(unsigned int color)

Sets all the components of the OEColor object from a packed 32-bit integer. Each 8-bit byte of the integer is assumed to contain a different component of the color. Returns a reference to the OEColor object.

SetRGBA¶

OEColor &SetRGBA(const unsigned char *rgba)

Sets all the components of the OEColor object from an array of unsigned char. The array is assumed to contain at least 4 bytes, where each byte corresponds to RGBA components respectively. Returns a reference to the OEColor object.

SetText¶

OEColor &SetText(const std::string &text)

Sets all the components of the OEColor object from a RGB or RGBA hexadecimal string. The format of an RGB string is #RRGGBB and format of an RGBA string is #RRGGBBAA, where R,G,B and A are hexadecimal numbers. For example, the string #FF0000 represents the color red. Returns a reference to the OEColor object.