Class SVGRadialGradientPaintContext

java.lang.Object

com.github.weisj.jsvg.paint.impl.jdk.SVGMultipleGradientPaintContext

com.github.weisj.jsvg.paint.impl.jdk.SVGRadialGradientPaintContext

All Implemented Interfaces:

PaintContext

final class SVGRadialGradientPaintContext
extends SVGMultipleGradientPaintContext

Provides the actual implementation for the RadialGradientPaint. This is where the pixel processing is done. A RadialGradientPaint only supports circular gradients, but it should be possible to scale the circle to look approximately elliptical, by means of a gradient transform passed into the RadialGradientPaint constructor.

Field Summary

Fields

Modifier and Type	Field	Description
private final float	centerX	Variables representing center and focus points.
private final float	centerY
private final float	constA	Constant part of X, Y user space coordinates.
private final float	constB
private static final float	FOCUS_CLAMP_DOWNSCALE	Amount for offset when clamping focus.
private final float	focusRadius
private final float	focusRadiusSq
private float	focusX
private float	focusY
private final float	gDeltaDelta	Constant second order delta for simple loop.
private final boolean	isNonCyclic	True when (cycleMethod == NO_CYCLE).
private final boolean	isSimpleFocus	True when (focus == center) and (focus radius == 0).
private final float	radiusSq	Radius of the gradient circle an focus circle squared.
private static final int	SQRT_LUT_SIZE
private static final float[]	sqrtLookup
private final float	trivial	This value represents the solution when focusX == X.

Fields inherited from class SVGMultipleGradientPaintContext

a00, a01, a02, a10, a11, a12, cached, cachedModel, colorSpace, cycleMethod, fastGradientArraySize, gradient, GRADIENT_SIZE, GRADIENT_SIZE_INDEX, isSimpleLookup, model, saved

Constructor Summary

Constructors

Constructor	Description
SVGRadialGradientPaintContext(@NotNull SVGRadialGradientPaint paint, @NotNull AffineTransform t, float cx, float cy, float r, float fx, float fy, float fr, float @NotNull [] fractions, @NotNull Color @NotNull [] colors, MultipleGradientPaint.CycleMethod cycleMethod, MultipleGradientPaint.ColorSpaceType colorSpace)	Constructor for RadialGradientPaintContext.

Method Summary

Modifier and Type	Method	Description
private float	computeGradientPosition(float currentToFocusSq, float intersectToFocusSq)
private void	cyclicCircularGradientFillRaster(int[] pixels, int off, int adjust, int x, int y, int w, int h)	Fill the raster, cycling the gradient colors when a point falls outside the perimeter of the 100% stop circle.
protected void	fillRaster(int[] pixels, int off, int adjust, int x, int y, int w, int h)	Return a Raster containing the colors generated for the graphics operation.
private int	getColorAtPoint(float userX, float userY, float solutionX, float solutionY)
private int	getColorAtPointOutsideFocusCircle(float solutionX, float solutionY, float currentToFocusSq)
private float	getCurrentToFocusSq(float x, float y)
private void	simpleNonCyclicFillRaster(int[] pixels, int off, int adjust, int x, int y, int w, int h)	This code works in the simplest of cases, where the focus == center point, the gradient is non-cyclic, and the gradient lookup method is fast (single array index, no conversion necessary).

Methods inherited from class SVGMultipleGradientPaintContext

dispose, getColorModel, getRaster, indexIntoGradientsArrays

Methods inherited from class Object

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

Field Details

isSimpleFocus

private final boolean isSimpleFocus

True when (focus == center) and (focus radius == 0).

isNonCyclic

private final boolean isNonCyclic

True when (cycleMethod == NO_CYCLE).

centerX

private final float centerX

Variables representing center and focus points.

centerY

private final float centerY

focusX

private float focusX

focusY

private float focusY

radiusSq

private final float radiusSq

Radius of the gradient circle an focus circle squared.

focusRadius

private final float focusRadius

focusRadiusSq

private final float focusRadiusSq

constA

private final float constA

Constant part of X, Y user space coordinates.

constB

private final float constB

gDeltaDelta

private final float gDeltaDelta

Constant second order delta for simple loop.

trivial

private final float trivial

This value represents the solution when focusX == X. It is called trivial because it is easier to calculate than the general case.

FOCUS_CLAMP_DOWNSCALE

private static final float FOCUS_CLAMP_DOWNSCALE

Amount for offset when clamping focus.

See Also:

• Constant Field Values

SQRT_LUT_SIZE

private static final int SQRT_LUT_SIZE

See Also:

• Constant Field Values

sqrtLookup

private static final float[] sqrtLookup

Constructor Details

SVGRadialGradientPaintContext

SVGRadialGradientPaintContext(@NotNull
 @NotNull SVGRadialGradientPaint paint,
 @NotNull
 @NotNull AffineTransform t,
 float cx,
 float cy,
 float r,
 float fx,
 float fy,
 float fr,
 float @NotNull [] fractions,
 @NotNull
 @NotNull Color @NotNull [] colors,
 MultipleGradientPaint.CycleMethod cycleMethod,
 MultipleGradientPaint.ColorSpaceType colorSpace)

Constructor for RadialGradientPaintContext.

Parameters:

paint - the RadialGradientPaint from which this context is created

t - the AffineTransform from user space into device space (gradientTransform should be concatenated with this)

cx - the center X coordinate in user space of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle.

cy - the center Y coordinate in user space of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle.

r - the radius of the circle defining the extents of the color gradient

fx - the X coordinate in user space to which the first color is mapped

fy - the Y coordinate in user space to which the first color is mapped

fractions - the fractions specifying the gradient distribution

colors - the gradient colors

cycleMethod - either NO_CYCLE, REFLECT, or REPEAT

colorSpace - which colorspace to use for interpolation, either SRGB or LINEAR_RGB

Method Details

fillRaster

protected void fillRaster(int[] pixels,
 int off,
 int adjust,
 int x,
 int y,
 int w,
 int h)

Return a Raster containing the colors generated for the graphics operation.

Specified by:

fillRaster in class SVGMultipleGradientPaintContext

Parameters:

x - ,y,w,h the area in device space for which colors are generated.

simpleNonCyclicFillRaster

private void simpleNonCyclicFillRaster(int[] pixels,
 int off,
 int adjust,
 int x,
 int y,
 int w,
 int h)

This code works in the simplest of cases, where the focus == center point, the gradient is non-cyclic, and the gradient lookup method is fast (single array index, no conversion necessary).

cyclicCircularGradientFillRaster

private void cyclicCircularGradientFillRaster(int[] pixels,
 int off,
 int adjust,
 int x,
 int y,
 int w,
 int h)

Fill the raster, cycling the gradient colors when a point falls outside the perimeter of the 100% stop circle.

This calculation first computes the intersection point of the line from the focus through the current point in the raster, and the perimeter of the gradient circle.

Then it determines the percentage distance of the current point along that line (focus is 0%, perimeter is 100%).

Equation of a circle centered at (a,b) with radius r: (x-a)^2 + (y-b)^2 = r^2 Equation of a line with slope m and y-intercept b: y = mx + b Replacing y in the circle equation and solving using the quadratic formula produces the following set of equations. Constant factors have been extracted out of the inner loop.

getColorAtPoint

private int getColorAtPoint(float userX,
 float userY,
 float solutionX,
 float solutionY)

getCurrentToFocusSq

private float getCurrentToFocusSq(float x,
 float y)

getColorAtPointOutsideFocusCircle

private int getColorAtPointOutsideFocusCircle(float solutionX,
 float solutionY,
 float currentToFocusSq)

computeGradientPosition

private float computeGradientPosition(float currentToFocusSq,
 float intersectToFocusSq)