Module java.desktop
Package java.awt

# Class LinearGradientPaint

java.lang.Object
java.awt.MultipleGradientPaint
java.awt.LinearGradientPaint

All Implemented Interfaces:
  `Paint`, `Transparency`

public final class LinearGradientPaint extends MultipleGradientPaint
The `LinearGradientPaint` class provides a way to fill a `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 `LinearGradientPaint` object takes when it is filling the space outside the start and end points by setting `CycleMethod` to either `REFLECTION` or `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, `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 `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 `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:

Since:
  1.6
See Also:
  - `Paint`
  - `Graphics2D.setPaint(java.awt.Paint)`

- ## Nested Class Summary

  ## Nested classes/interfaces declared in class java.awt.MultipleGradientPaint

  `MultipleGradientPaint.ColorSpaceType, MultipleGradientPaint.CycleMethod`

- ## Field Summary

  ### Fields declared in interface java.awt.Transparency

  `BITMASK, OPAQUE, TRANSLUCENT`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `LinearGradientPaint(float startX, float startY, float endX, float endY, float[] fractions, Color[] colors)`
  Constructs a `LinearGradientPaint` with a default `NO_CYCLE` repeating method and `SRGB` color space.
  `LinearGradientPaint(float startX, float startY, float endX, float endY, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)`
  Constructs a `LinearGradientPaint` with a default `SRGB` color space.
  `LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors)`
  Constructs a `LinearGradientPaint` with a default `NO_CYCLE` repeating method and `SRGB` color space.
  `LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)`
  Constructs a `LinearGradientPaint` with a default `SRGB` color space.
  `LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod, MultipleGradientPaint.ColorSpaceType colorSpace, AffineTransform gradientTransform)`
  Constructs a `LinearGradientPaint`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `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.
  `Point2D`
  `getEndPoint()`
  Returns a copy of the end point of the gradient axis.
  `Point2D`
  `getStartPoint()`
  Returns a copy of the start point of the gradient axis.

  ### Methods declared in class java.awt.MultipleGradientPaint

  `getColors, getColorSpace, getCycleMethod, getFractions, getTransform, getTransparency`

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### LinearGradientPaint

    public LinearGradientPaint(float startX, float startY, float endX, float endY, float[] fractions, Color[] colors)
    Constructs a `LinearGradientPaint` with a default `NO_CYCLE` repeating method and `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 `fractions` array is null, or `colors` array is null,
      `IllegalArgumentException` - if start and end points are the same points, or `fractions.length != colors.length`, or `colors` is less than 2 in size, or a `fractions` value is less than 0.0 or greater than 1.0, or the `fractions` are not provided in strictly increasing order

  - ### LinearGradientPaint

    public LinearGradientPaint(float startX, float startY, float endX, float endY, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)
    Constructs a `LinearGradientPaint` with a default `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 `NO_CYCLE`, `REFLECT`, or `REPEAT`
    Throws:
      `NullPointerException` - if `fractions` array is null, or `colors` array is null, or `cycleMethod` is null
      `IllegalArgumentException` - if start and end points are the same points, or `fractions.length != colors.length`, or `colors` is less than 2 in size, or a `fractions` value is less than 0.0 or greater than 1.0, or the `fractions` are not provided in strictly increasing order

  - ### LinearGradientPaint

    public LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors)
    Constructs a `LinearGradientPaint` with a default `NO_CYCLE` repeating method and `SRGB` color space.
    Parameters:
      `start` - the gradient axis start `Point2D` in user space
      `end` - the gradient axis end `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 `fractions` array is null, or `colors` array is null
      `IllegalArgumentException` - if start and end points are the same points, or `fractions.length != colors.length`, or `colors` is less than 2 in size, or a `fractions` value is less than 0.0 or greater than 1.0, or the `fractions` are not provided in strictly increasing order

  - ### LinearGradientPaint

    public LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)
    Constructs a `LinearGradientPaint` with a default `SRGB` color space.
    Parameters:
      `start` - the gradient axis start `Point2D` in user space
      `end` - the gradient axis end `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 `NO_CYCLE`, `REFLECT`, or `REPEAT`
    Throws:
      `NullPointerException` - if one of the points is null, or `fractions` array is null, or `colors` array is null, or `cycleMethod` is null
      `IllegalArgumentException` - if start and end points are the same points, or `fractions.length != colors.length`, or `colors` is less than 2 in size, or a `fractions` value is less than 0.0 or greater than 1.0, or the `fractions` are not provided in strictly increasing order

  - ### LinearGradientPaint

    @ConstructorProperties({"startPoint","endPoint","fractions","colors","cycleMethod","colorSpace","transform"}) public LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod, MultipleGradientPaint.ColorSpaceType colorSpace, AffineTransform gradientTransform)
    Constructs a `LinearGradientPaint`.
    Parameters:
      `start` - the gradient axis start `Point2D` in user space
      `end` - the gradient axis end `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 `NO_CYCLE`, `REFLECT`, or `REPEAT`
      `colorSpace` - which color space to use for interpolation, either `SRGB` or `LINEAR_RGB`
      `gradientTransform` - transform to apply to the gradient
    Throws:
      `NullPointerException` - if one of the points is null, or `fractions` array is null, or `colors` array is null, or `cycleMethod` is null, or `colorSpace` is null, or `gradientTransform` is null
      `IllegalArgumentException` - if start and end points are the same points, or `fractions.length != colors.length`, or `colors` is less than 2 in size, or a `fractions` value is less than 0.0 or greater than 1.0, or the `fractions` are not provided in strictly increasing order

- ## Method Details

  - ### createContext

    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.
    Parameters:
      `cm` - the preferred `ColorModel` which represents the most convenient format for the caller to receive the pixel data, or `null` if there is no preference.
      `deviceBounds` - the device space bounding box of the graphics primitive being rendered.
      `userBounds` - the user space bounding box of the graphics primitive being rendered.
      `transform` - the `AffineTransform` from user space into device space.
      `hints` - the set of hints that the context object can use to choose between rendering alternatives.
    Returns:
      the `PaintContext` for generating color patterns.
    See Also:
      - `Paint`
      - `PaintContext`
      - `ColorModel`
      - `Rectangle`
      - `Rectangle2D`
      - `AffineTransform`
      - `RenderingHints`

  - ### getStartPoint

    public Point2D getStartPoint()
    Returns a copy of the start point of the gradient axis.
    Returns:
      a `Point2D` object that is a copy of the point that anchors the first color of this `LinearGradientPaint`

  - ### getEndPoint

    public Point2D getEndPoint()
    Returns a copy of the end point of the gradient axis.
    Returns:
      a `Point2D` object that is a copy of the point that anchors the last color of this `LinearGradientPaint`