CrystalSpace

Public API Reference

csGradient Class Reference

A simple color gradient. More...

#include <csgfx/gradient.h>

List of all members.

Public Member Functions

void AddShade (csGradientShade shade)
 Add a shade.
void Clear ()
 Clear all shades.
 csGradient (csColor first, csColor last)
 Construct with first at position 0 and last at 1.
 csGradient ()
 Construct an empty gradient.
const csArray< csGradientShade > & GetShades () const
 Get the array of shades.
bool Render (csRGBcolor *pal, size_t count, float begin=0.0f, float end=1.0f) const
 Interpolate the colors over a part of the gradient.

Protected Attributes

csArray< csGradientShadeshades
 The entries in this gradient.


Detailed Description

A simple color gradient.

If you ever have worked with an image creation/manipulation program with a slightly higher niveau than Windows Paint then you probably know what this is.

Colors(here called 'shades') can be placed at arbitrary positions; although commonly a range of [0;1] is used, negative positions and positions larger than 1 are supported.

Shades contain actually two colors, a 'left' and 'right' one. You can think of this as, when approaching from one side, you'll get closer and closer to the respective color. If you step over a shade, you have the other color, but you're getting farther and farther from it (and towards the next color) when moving on. This feature can be used for sharp transitions; for smooth ones they are simply set to the same value.

Examples:

 csGradient grad;
 // Rainbow-ish
 grad.AddShade (csGradientShade (csColor (1.0f, 0.0f, 0.0f), 0.0f)));
 grad.AddShade (csGradientShade (csColor (1.0f, 1.0f, 0.0f), 0.2f)));
 grad.AddShade (csGradientShade (csColor (0.0f, 1.0f, 0.0f), 0.4f)));
 grad.AddShade (csGradientShade (csColor (0.0f, 1.0f, 1.0f), 0.6f)));
 grad.AddShade (csGradientShade (csColor (0.0f, 0.0f, 1.0f), 0.8f)));
 grad.AddShade (csGradientShade (csColor (1.0f, 0.0f, 1.0f), 1.0f)));

 // German flag
 grad.Clear ();
 grad.AddShade (csGradientShade (csColor (0.0f, 0.0f, 0.0f), 0.0f)));
 grad.AddShade (csGradientShade (csColor (0.0f, 0.0f, 0.0f), 
  csGradientShade (csColor (1.0f, 0.0f, 0.0f)
  0.33f)));
 grad.AddShade (csGradientShade (csColor (1.0f, 0.0f, 0.0f), 
  csGradientShade (csColor (1.0f, 1.0f, 0.0f)
  0.66f)));
 grad.AddShade (csGradientShade (csColor (1.0f, 1.0f, 0.0f), 1.0f)));
Todo:
More shade management (e.g. getting, deleting of single shades.)

Definition at line 96 of file gradient.h.


Constructor & Destructor Documentation

csGradient::csGradient  ) 
 

Construct an empty gradient.

csGradient::csGradient csColor  first,
csColor  last
 

Construct with first at position 0 and last at 1.


Member Function Documentation

void csGradient::AddShade csGradientShade  shade  ) 
 

Add a shade.

void csGradient::Clear  ) 
 

Clear all shades.

const csArray<csGradientShade>& csGradient::GetShades  )  const [inline]
 

Get the array of shades.

Definition at line 133 of file gradient.h.

bool csGradient::Render csRGBcolor pal,
size_t  count,
float  begin = 0.0f,
float  end = 1.0f
const
 

Interpolate the colors over a part of the gradient.

Parameters:
pal Array of csRGBcolor the gradient should be rendered to.
count Number of palette entries to render.
begin Start position. Can be anywhere in the gradient.
end End position. Can be anywhere in the gradient.
Remarks:
At least 1 shade has to be present in the gradient to have this function succeed.

Makes heavy use of floating point calculations, so you might want to use this function in a precalc phase.

begin doesn't have to be smaller than end.

begin and end can both lie completely 'outside' the gradient (i.e. both smaller/large than the first resp. last shade's position.)


Member Data Documentation

csArray<csGradientShade> csGradient::shades [protected]
 

The entries in this gradient.

Definition at line 100 of file gradient.h.


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