Class SVGMultipleGradientPaintContext
- All Implemented Interfaces:
PaintContext
- Direct Known Subclasses:
SVGRadialGradientPaintContext
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected float
Elements of the inverse transform matrix.protected float
Elements of the inverse transform matrix.protected float
Elements of the inverse transform matrix.protected float
Elements of the inverse transform matrix.protected float
Elements of the inverse transform matrix.protected float
Elements of the inverse transform matrix.protected static WeakReference
<Raster> The cached raster, which is reusable among instances.protected static ColorModel
The cached ColorModel.protected MultipleGradientPaint.ColorSpaceType
The ColorSpace in which to perform the interpolationprotected MultipleGradientPaint.CycleMethod
The method to use when painting out of the gradient bounds.protected int
Size of gradients array for scaling the 0-1 index when looking up colors the fast way.private final float[]
Fractions array.protected int[]
Array which contains the interpolated color values for each interval, used by calculateSingleArrayGradient().protected static final int
Constant number of max colors between any 2 arbitrary colors.protected static final int
private int[][]
Array of gradient arrays, one array for each interval.protected boolean
This boolean specifies whether we are in simple lookup mode, where an input value between 0 and 1 may be used to directly index into a single array of gradient colors.private static final int
Maximum length of the fast single-array.private static final float
protected ColorModel
The PaintContext's ColorModel.private float[]
Normalized intervals array.protected Raster
Raster is reused whenever possible.private int
Used to determine if gradient colors are all opaque.private static final ColorModel
Color model used if gradient colors are all opaque. -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotected
SVGMultipleGradientPaintContext
(@NotNull SVGMultipleGradientPaint mgp, @NotNull AffineTransform t, float @NotNull [] fractions, @NotNull Color @NotNull [] colors, MultipleGradientPaint.CycleMethod cycleMethod, MultipleGradientPaint.ColorSpaceType colorSpace) Constructor for MultipleGradientPaintContext superclass. -
Method Summary
Modifier and TypeMethodDescriptionprivate void
calculateLookupData
(Color[] colors) This function is the meat of this class.private void
calculateMultipleArrayGradient
(Color[] colors) SLOW LOOKUP METHODprivate void
calculateSingleArrayGradient
(Color[] colors, float Imin) FAST LOOKUP METHODfinal void
dispose()
protected abstract void
fillRaster
(int[] pixels, int off, int adjust, int x, int y, int w, int h) private static Raster
getCachedRaster
(ColorModel cm, int w, int h) Took this cacheRaster code from GradientPaint.final ColorModel
final Raster
getRaster
(int x, int y, int w, int h) protected final int
indexIntoGradientsArrays
(float position) Helper function to index into the gradients array.private void
interpolate
(int rgb1, int rgb2, int[] output) Yet another helper function.private static void
putCachedRaster
(ColorModel cm, Raster ras) Took this cacheRaster code from GradientPaint.
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Field Details
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MIN_INTERVAL_LENGTH
private static final float MIN_INTERVAL_LENGTH- See Also:
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model
The PaintContext's ColorModel. This is ARGB if colors are not all opaque, otherwise it is RGB. -
XRGB_MODEL
Color model used if gradient colors are all opaque. -
cachedModel
The cached ColorModel. -
cached
The cached raster, which is reusable among instances. -
saved
Raster is reused whenever possible. -
cycleMethod
The method to use when painting out of the gradient bounds. -
colorSpace
The ColorSpace in which to perform the interpolation -
a00
protected float a00Elements of the inverse transform matrix. -
a01
protected float a01Elements of the inverse transform matrix. -
a10
protected float a10Elements of the inverse transform matrix. -
a11
protected float a11Elements of the inverse transform matrix. -
a02
protected float a02Elements of the inverse transform matrix. -
a12
protected float a12Elements of the inverse transform matrix. -
isSimpleLookup
protected boolean isSimpleLookupThis boolean specifies whether we are in simple lookup mode, where an input value between 0 and 1 may be used to directly index into a single array of gradient colors. If this boolean value is false, then we have to use a 2-step process where we have to determine which gradient array we fall into, then determine the index into that array. -
fastGradientArraySize
protected int fastGradientArraySizeSize of gradients array for scaling the 0-1 index when looking up colors the fast way. -
gradient
protected int[] gradientArray which contains the interpolated color values for each interval, used by calculateSingleArrayGradient(). It is protected for possible direct access by subclasses. -
gradients
private int[][] gradientsArray of gradient arrays, one array for each interval. Used by calculateMultipleArrayGradient(). -
normalizedIntervals
private float[] normalizedIntervalsNormalized intervals array. -
fractions
private final float[] fractionsFractions array. -
transparencyTest
private int transparencyTestUsed to determine if gradient colors are all opaque. -
GRADIENT_SIZE
protected static final int GRADIENT_SIZEConstant number of max colors between any 2 arbitrary colors. Used for creating and indexing gradients arrays.- See Also:
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GRADIENT_SIZE_INDEX
protected static final int GRADIENT_SIZE_INDEX- See Also:
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MAX_GRADIENT_ARRAY_SIZE
private static final int MAX_GRADIENT_ARRAY_SIZEMaximum length of the fast single-array. If the estimated array size is greater than this, switch over to the slow lookup method. No particular reason for choosing this number, but it seems to provide satisfactory performance for the common case (fast lookup).- See Also:
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Constructor Details
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SVGMultipleGradientPaintContext
protected SVGMultipleGradientPaintContext(@NotNull @NotNull SVGMultipleGradientPaint mgp, @NotNull @NotNull AffineTransform t, float @NotNull [] fractions, @NotNull @NotNull Color @NotNull [] colors, MultipleGradientPaint.CycleMethod cycleMethod, MultipleGradientPaint.ColorSpaceType colorSpace) Constructor for MultipleGradientPaintContext superclass.
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Method Details
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calculateLookupData
This function is the meat of this class. It calculates an array of gradient colors based on an array of fractions and color values at those fractions. -
calculateSingleArrayGradient
FAST LOOKUP METHODThis method calculates the gradient color values and places them in a single int array, gradient[]. It does this by allocating space for each interval based on its size relative to the smallest interval in the array. The smallest interval is allocated 255 interpolated values (the maximum number of unique in-between colors in a 24 bit color system), and all other intervals are allocated size = (255 * the ratio of their size to the smallest interval).
This scheme expedites a speedy retrieval because the colors are distributed along the array according to their user-specified distribution. All that is needed is a relative index from 0 to 1.
The only problem with this method is that the possibility exists for the array size to balloon in the case where there is a disproportionately small gradient interval. In this case the other intervals will be allocated huge space, but much of that data is redundant. We thus need to use the space conserving scheme below.
- Parameters:
Imin
- the size of the smallest interval
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calculateMultipleArrayGradient
SLOW LOOKUP METHODThis method calculates the gradient color values for each interval and places each into its own 255 size array. The arrays are stored in gradients[][]. (255 is used because this is the maximum number of unique colors between 2 arbitrary colors in a 24 bit color system.)
This method uses the minimum amount of space (only 255 * number of intervals), but it aggravates the lookup procedure, because now we have to find out which interval to select, then calculate the index within that interval. This causes a significant performance hit, because it requires this calculation be done for every point in the rendering loop.
For those of you who are interested, this is a classic example of the time-space tradeoff.
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interpolate
private void interpolate(int rgb1, int rgb2, int[] output) Yet another helper function. This one linearly interpolates between 2 colors, filling up the output array.- Parameters:
rgb1
- the start colorrgb2
- the end coloroutput
- the output array of colors; must not be null
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indexIntoGradientsArrays
protected final int indexIntoGradientsArrays(float position) Helper function to index into the gradients array. This is necessary because each interval has an array of colors with uniform size 255. However, the color intervals are not necessarily of uniform length, so a conversion is required.- Parameters:
position
- the unmanipulated position, which will be mapped into the range 0 to 1- Returns:
- integer color to display
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getRaster
- Specified by:
getRaster
in interfacePaintContext
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fillRaster
protected abstract void fillRaster(int[] pixels, int off, int adjust, int x, int y, int w, int h) -
getCachedRaster
Took this cacheRaster code from GradientPaint. It appears to recycle rasters for use by any other instance, as long as they are sufficiently large. -
putCachedRaster
Took this cacheRaster code from GradientPaint. It appears to recycle rasters for use by any other instance, as long as they are sufficiently large. -
dispose
public final void dispose()- Specified by:
dispose
in interfacePaintContext
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getColorModel
- Specified by:
getColorModel
in interfacePaintContext
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