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java.awt
public final class: LinearGradientPaint [javadoc | source]
java.lang.Object
   java.awt.MultipleGradientPaint
      java.awt.LinearGradientPaint

All Implemented Interfaces:
    Paint

The {@code LinearGradientPaint} class provides a way to fill a java.awt.Shape with a linear color gradient pattern. The user may specify two or more gradient colors, and this paint will provide an interpolation between each color. The user also specifies start and end points which define where in user space the color gradient should begin and end.

The user must provide an array of floats specifying how to distribute the colors along the gradient. These values should range from 0.0 to 1.0 and act like keyframes along the gradient (they mark where the gradient should be exactly a particular color).

In the event that the user does not set the first keyframe value equal to 0 and/or the last keyframe value equal to 1, keyframes will be created at these positions and the first and last colors will be replicated there. So, if a user specifies the following arrays to construct a gradient:

    {Color.BLUE, Color.RED}, {.3f, .7f}
this will be converted to a gradient with the following keyframes:
    {Color.BLUE, Color.BLUE, Color.RED, Color.RED}, {0f, .3f, .7f, 1f}

The user may also select what action the {@code LinearGradientPaint} object takes when it is filling the space outside the start and end points by setting {@code CycleMethod} to either {@code REFLECTION} or {@code REPEAT}. The distances between any two colors in any of the reflected or repeated copies of the gradient are the same as the distance between those same two colors between the start and end points. Note that some minor variations in distances may occur due to sampling at the granularity of a pixel. If no cycle method is specified, {@code NO_CYCLE} will be chosen by default, which means the endpoint colors will be used to fill the remaining area.

The colorSpace parameter allows the user to specify in which colorspace the interpolation should be performed, default sRGB or linearized RGB.

The following code demonstrates typical usage of {@code LinearGradientPaint}:

    Point2D start = new Point2D.Float(0, 0);
    Point2D end = new Point2D.Float(50, 50);
    float[] dist = {0.0f, 0.2f, 1.0f};
    Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
    LinearGradientPaint p =
        new LinearGradientPaint(start, end, dist, colors);

This code will create a {@code LinearGradientPaint} which interpolates between red and white for the first 20% of the gradient and between white and blue for the remaining 80%.

This image demonstrates the example code above for each of the three cycle methods:

Fields inherited from java.awt.MultipleGradientPaint:
transparency,  fractions,  colors,  gradientTransform,  cycleMethod,  colorSpace,  model,  normalizedIntervals,  isSimpleLookup,  gradients,  gradient,  fastGradientArraySize
Constructor:
 public LinearGradientPaint(Point2D start,
    Point2D end,
    float[] fractions,
    Color[] colors) 
    Constructs a {@code LinearGradientPaint} with a default {@code NO_CYCLE} repeating method and {@code SRGB} color space.
    Parameters:
    start - the gradient axis start {@code Point2D} in user space
    end - the gradient axis end {@code Point2D} in user space
    fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
    colors - array of colors corresponding to each fractional value
    Throws:
    NullPointerException - if one of the points is null, or {@code fractions} array is null, or {@code colors} array is null
    IllegalArgumentException - if start and end points are the same points, or {@code fractions.length != colors.length}, or {@code colors} is less than 2 in size, or a {@code fractions} value is less than 0.0 or greater than 1.0, or the {@code fractions} are not provided in strictly increasing order
 public LinearGradientPaint(Point2D start,
    Point2D end,
    float[] fractions,
    Color[] colors,
    CycleMethod cycleMethod) 
    Constructs a {@code LinearGradientPaint} with a default {@code SRGB} color space.
    Parameters:
    start - the gradient axis start {@code Point2D} in user space
    end - the gradient axis end {@code Point2D} in user space
    fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
    colors - array of colors corresponding to each fractional value
    cycleMethod - either {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}
    Throws:
    NullPointerException - if one of the points is null, or {@code fractions} array is null, or {@code colors} array is null, or {@code cycleMethod} is null
    IllegalArgumentException - if start and end points are the same points, or {@code fractions.length != colors.length}, or {@code colors} is less than 2 in size, or a {@code fractions} value is less than 0.0 or greater than 1.0, or the {@code fractions} are not provided in strictly increasing order
 public LinearGradientPaint(float startX,
    float startY,
    float endX,
    float endY,
    float[] fractions,
    Color[] colors) 
    Constructs a {@code LinearGradientPaint} with a default {@code NO_CYCLE} repeating method and {@code SRGB} color space.
    Parameters:
    startX - the X coordinate of the gradient axis start point in user space
    startY - the Y coordinate of the gradient axis start point in user space
    endX - the X coordinate of the gradient axis end point in user space
    endY - the Y coordinate of the gradient axis end point in user space
    fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
    colors - array of colors corresponding to each fractional value
    Throws:
    NullPointerException - if {@code fractions} array is null, or {@code colors} array is null,
    IllegalArgumentException - if start and end points are the same points, or {@code fractions.length != colors.length}, or {@code colors} is less than 2 in size, or a {@code fractions} value is less than 0.0 or greater than 1.0, or the {@code fractions} are not provided in strictly increasing order
 public LinearGradientPaint(float startX,
    float startY,
    float endX,
    float endY,
    float[] fractions,
    Color[] colors,
    CycleMethod cycleMethod) 
    Constructs a {@code LinearGradientPaint} with a default {@code SRGB} color space.
    Parameters:
    startX - the X coordinate of the gradient axis start point in user space
    startY - the Y coordinate of the gradient axis start point in user space
    endX - the X coordinate of the gradient axis end point in user space
    endY - the Y coordinate of the gradient axis end point in user space
    fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
    colors - array of colors corresponding to each fractional value
    cycleMethod - either {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}
    Throws:
    NullPointerException - if {@code fractions} array is null, or {@code colors} array is null, or {@code cycleMethod} is null
    IllegalArgumentException - if start and end points are the same points, or {@code fractions.length != colors.length}, or {@code colors} is less than 2 in size, or a {@code fractions} value is less than 0.0 or greater than 1.0, or the {@code fractions} are not provided in strictly increasing order
 public LinearGradientPaint(Point2D start,
    Point2D end,
    float[] fractions,
    Color[] colors,
    CycleMethod cycleMethod,
    ColorSpaceType colorSpace,
    AffineTransform gradientTransform) 
    Constructs a {@code LinearGradientPaint}.
    Parameters:
    start - the gradient axis start {@code Point2D} in user space
    end - the gradient axis end {@code Point2D} in user space
    fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
    colors - array of colors corresponding to each fractional value
    cycleMethod - either {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}
    colorSpace - which color space to use for interpolation, either {@code SRGB} or {@code LINEAR_RGB}
    gradientTransform - transform to apply to the gradient
    Throws:
    NullPointerException - if one of the points is null, or {@code fractions} array is null, or {@code colors} array is null, or {@code cycleMethod} is null, or {@code colorSpace} is null, or {@code gradientTransform} is null
    IllegalArgumentException - if start and end points are the same points, or {@code fractions.length != colors.length}, or {@code colors} is less than 2 in size, or a {@code fractions} value is less than 0.0 or greater than 1.0, or the {@code fractions} are not provided in strictly increasing order
Method from java.awt.LinearGradientPaint Summary:
createContext,   getEndPoint,   getStartPoint
Methods from java.awt.MultipleGradientPaint:
getColorSpace,   getColors,   getCycleMethod,   getFractions,   getTransform,   getTransparency
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from java.awt.LinearGradientPaint Detail:
 public PaintContext createContext(ColorModel cm,
    Rectangle deviceBounds,
    Rectangle2D userBounds,
    AffineTransform transform,
    RenderingHints hints) 
    Creates and returns a PaintContext used to generate a linear color gradient pattern. See the specification of the method in the Paint interface for information on null parameter handling.
 public Point2D getEndPoint() 
    Returns a copy of the end point of the gradient axis.
 public Point2D getStartPoint() 
    Returns a copy of the start point of the gradient axis.