Class LinearGradientPaint

  • All Implemented Interfaces:
    java.awt.Paint, java.awt.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 should take when filling color outside the start and end points. 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)
    • Constructor Detail

      • LinearGradientPaint

        public LinearGradientPaint​(float startX,
                                   float startY,
                                   float endX,
                                   float endY,
                                   float[] fractions,
                                   java.awt.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:
        java.lang.NullPointerException - if fractions array is null, or colors array is null,
        java.lang.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,
                                   java.awt.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:
        java.lang.NullPointerException - if fractions array is null, or colors array is null, or cycleMethod is null
        java.lang.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​(java.awt.geom.Point2D start,
                                   java.awt.geom.Point2D end,
                                   float[] fractions,
                                   java.awt.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:
        java.lang.NullPointerException - if one of the points is null, or fractions array is null, or colors array is null
        java.lang.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​(java.awt.geom.Point2D start,
                                   java.awt.geom.Point2D end,
                                   float[] fractions,
                                   java.awt.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:
        java.lang.NullPointerException - if one of the points is null, or fractions array is null, or colors array is null, or cycleMethod is null
        java.lang.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​(java.awt.geom.Point2D start,
                                   java.awt.geom.Point2D end,
                                   float[] fractions,
                                   java.awt.Color[] colors,
                                   MultipleGradientPaint.CycleMethod cycleMethod,
                                   MultipleGradientPaint.ColorSpaceType colorSpace,
                                   java.awt.geom.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:
        java.lang.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
        java.lang.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 Detail

      • createContext

        public java.awt.PaintContext createContext​(java.awt.image.ColorModel cm,
                                                   java.awt.Rectangle deviceBounds,
                                                   java.awt.geom.Rectangle2D userBounds,
                                                   java.awt.geom.AffineTransform transform,
                                                   java.awt.RenderingHints hints)
      • getStartPoint

        public java.awt.geom.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 java.awt.geom.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