Java example source code file (PiscesRenderingEngine.java)
The PiscesRenderingEngine.java Java example source code
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* accompanied this code).
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package sun.java2d.pisces;
import java.awt.Shape;
import java.awt.BasicStroke;
import java.awt.geom.Path2D;
import java.awt.geom.AffineTransform;
import java.awt.geom.PathIterator;
import sun.awt.geom.PathConsumer2D;
import sun.java2d.pipe.Region;
import sun.java2d.pipe.RenderingEngine;
import sun.java2d.pipe.AATileGenerator;
public class PiscesRenderingEngine extends RenderingEngine {
private static enum NormMode {OFF, ON_NO_AA, ON_WITH_AA}
/**
* Create a widened path as specified by the parameters.
* <p>
* The specified {@code src} {@link Shape} is widened according
* to the specified attribute parameters as per the
* {@link BasicStroke} specification.
*
* @param src the source path to be widened
* @param width the width of the widened path as per {@code BasicStroke}
* @param caps the end cap decorations as per {@code BasicStroke}
* @param join the segment join decorations as per {@code BasicStroke}
* @param miterlimit the miter limit as per {@code BasicStroke}
* @param dashes the dash length array as per {@code BasicStroke}
* @param dashphase the initial dash phase as per {@code BasicStroke}
* @return the widened path stored in a new {@code Shape} object
* @since 1.7
*/
public Shape createStrokedShape(Shape src,
float width,
int caps,
int join,
float miterlimit,
float dashes[],
float dashphase)
{
final Path2D p2d = new Path2D.Float();
strokeTo(src,
null,
width,
NormMode.OFF,
caps,
join,
miterlimit,
dashes,
dashphase,
new PathConsumer2D() {
public void moveTo(float x0, float y0) {
p2d.moveTo(x0, y0);
}
public void lineTo(float x1, float y1) {
p2d.lineTo(x1, y1);
}
public void closePath() {
p2d.closePath();
}
public void pathDone() {}
public void curveTo(float x1, float y1,
float x2, float y2,
float x3, float y3) {
p2d.curveTo(x1, y1, x2, y2, x3, y3);
}
public void quadTo(float x1, float y1, float x2, float y2) {
p2d.quadTo(x1, y1, x2, y2);
}
public long getNativeConsumer() {
throw new InternalError("Not using a native peer");
}
});
return p2d;
}
/**
* Sends the geometry for a widened path as specified by the parameters
* to the specified consumer.
* <p>
* The specified {@code src} {@link Shape} is widened according
* to the parameters specified by the {@link BasicStroke} object.
* Adjustments are made to the path as appropriate for the
* {@link VALUE_STROKE_NORMALIZE} hint if the {@code normalize}
* boolean parameter is true.
* Adjustments are made to the path as appropriate for the
* {@link VALUE_ANTIALIAS_ON} hint if the {@code antialias}
* boolean parameter is true.
* <p>
* The geometry of the widened path is forwarded to the indicated
* {@link PathConsumer2D} object as it is calculated.
*
* @param src the source path to be widened
* @param bs the {@code BasicSroke} object specifying the
* decorations to be applied to the widened path
* @param normalize indicates whether stroke normalization should
* be applied
* @param antialias indicates whether or not adjustments appropriate
* to antialiased rendering should be applied
* @param consumer the {@code PathConsumer2D} instance to forward
* the widened geometry to
* @since 1.7
*/
public void strokeTo(Shape src,
AffineTransform at,
BasicStroke bs,
boolean thin,
boolean normalize,
boolean antialias,
final PathConsumer2D consumer)
{
NormMode norm = (normalize) ?
((antialias) ? NormMode.ON_WITH_AA : NormMode.ON_NO_AA)
: NormMode.OFF;
strokeTo(src, at, bs, thin, norm, antialias, consumer);
}
void strokeTo(Shape src,
AffineTransform at,
BasicStroke bs,
boolean thin,
NormMode normalize,
boolean antialias,
PathConsumer2D pc2d)
{
float lw;
if (thin) {
if (antialias) {
lw = userSpaceLineWidth(at, 0.5f);
} else {
lw = userSpaceLineWidth(at, 1.0f);
}
} else {
lw = bs.getLineWidth();
}
strokeTo(src,
at,
lw,
normalize,
bs.getEndCap(),
bs.getLineJoin(),
bs.getMiterLimit(),
bs.getDashArray(),
bs.getDashPhase(),
pc2d);
}
private float userSpaceLineWidth(AffineTransform at, float lw) {
double widthScale;
if ((at.getType() & (AffineTransform.TYPE_GENERAL_TRANSFORM |
AffineTransform.TYPE_GENERAL_SCALE)) != 0) {
widthScale = Math.sqrt(at.getDeterminant());
} else {
/* First calculate the "maximum scale" of this transform. */
double A = at.getScaleX(); // m00
double C = at.getShearX(); // m01
double B = at.getShearY(); // m10
double D = at.getScaleY(); // m11
/*
* Given a 2 x 2 affine matrix [ A B ] such that
* [ C D ]
* v' = [x' y'] = [Ax + Cy, Bx + Dy], we want to
* find the maximum magnitude (norm) of the vector v'
* with the constraint (x^2 + y^2 = 1).
* The equation to maximize is
* |v'| = sqrt((Ax+Cy)^2+(Bx+Dy)^2)
* or |v'| = sqrt((AA+BB)x^2 + 2(AC+BD)xy + (CC+DD)y^2).
* Since sqrt is monotonic we can maximize |v'|^2
* instead and plug in the substitution y = sqrt(1 - x^2).
* Trigonometric equalities can then be used to get
* rid of most of the sqrt terms.
*/
double EA = A*A + B*B; // x^2 coefficient
double EB = 2*(A*C + B*D); // xy coefficient
double EC = C*C + D*D; // y^2 coefficient
/*
* There is a lot of calculus omitted here.
*
* Conceptually, in the interests of understanding the
* terms that the calculus produced we can consider
* that EA and EC end up providing the lengths along
* the major axes and the hypot term ends up being an
* adjustment for the additional length along the off-axis
* angle of rotated or sheared ellipses as well as an
* adjustment for the fact that the equation below
* averages the two major axis lengths. (Notice that
* the hypot term contains a part which resolves to the
* difference of these two axis lengths in the absence
* of rotation.)
*
* In the calculus, the ratio of the EB and (EA-EC) terms
* ends up being the tangent of 2*theta where theta is
* the angle that the long axis of the ellipse makes
* with the horizontal axis. Thus, this equation is
* calculating the length of the hypotenuse of a triangle
* along that axis.
*/
double hypot = Math.sqrt(EB*EB + (EA-EC)*(EA-EC));
/* sqrt omitted, compare to squared limits below. */
double widthsquared = ((EA + EC + hypot)/2.0);
widthScale = Math.sqrt(widthsquared);
}
return (float) (lw / widthScale);
}
void strokeTo(Shape src,
AffineTransform at,
float width,
NormMode normalize,
int caps,
int join,
float miterlimit,
float dashes[],
float dashphase,
PathConsumer2D pc2d)
{
// We use strokerat and outat so that in Stroker and Dasher we can work only
// with the pre-transformation coordinates. This will repeat a lot of
// computations done in the path iterator, but the alternative is to
// work with transformed paths and compute untransformed coordinates
// as needed. This would be faster but I do not think the complexity
// of working with both untransformed and transformed coordinates in
// the same code is worth it.
// However, if a path's width is constant after a transformation,
// we can skip all this untransforming.
// If normalization is off we save some transformations by not
// transforming the input to pisces. Instead, we apply the
// transformation after the path processing has been done.
// We can't do this if normalization is on, because it isn't a good
// idea to normalize before the transformation is applied.
AffineTransform strokerat = null;
AffineTransform outat = null;
PathIterator pi = null;
if (at != null && !at.isIdentity()) {
final double a = at.getScaleX();
final double b = at.getShearX();
final double c = at.getShearY();
final double d = at.getScaleY();
final double det = a * d - c * b;
if (Math.abs(det) <= 2 * Float.MIN_VALUE) {
// this rendering engine takes one dimensional curves and turns
// them into 2D shapes by giving them width.
// However, if everything is to be passed through a singular
// transformation, these 2D shapes will be squashed down to 1D
// again so, nothing can be drawn.
// Every path needs an initial moveTo and a pathDone. If these
// are not there this causes a SIGSEGV in libawt.so (at the time
// of writing of this comment (September 16, 2010)). Actually,
// I am not sure if the moveTo is necessary to avoid the SIGSEGV
// but the pathDone is definitely needed.
pc2d.moveTo(0, 0);
pc2d.pathDone();
return;
}
// If the transform is a constant multiple of an orthogonal transformation
// then every length is just multiplied by a constant, so we just
// need to transform input paths to stroker and tell stroker
// the scaled width. This condition is satisfied if
// a*b == -c*d && a*a+c*c == b*b+d*d. In the actual check below, we
// leave a bit of room for error.
if (nearZero(a*b + c*d, 2) && nearZero(a*a+c*c - (b*b+d*d), 2)) {
double scale = Math.sqrt(a*a + c*c);
if (dashes != null) {
dashes = java.util.Arrays.copyOf(dashes, dashes.length);
for (int i = 0; i < dashes.length; i++) {
dashes[i] = (float)(scale * dashes[i]);
}
dashphase = (float)(scale * dashphase);
}
width = (float)(scale * width);
pi = src.getPathIterator(at);
if (normalize != NormMode.OFF) {
pi = new NormalizingPathIterator(pi, normalize);
}
// by now strokerat == null && outat == null. Input paths to
// stroker (and maybe dasher) will have the full transform at
// applied to them and nothing will happen to the output paths.
} else {
if (normalize != NormMode.OFF) {
strokerat = at;
pi = src.getPathIterator(at);
pi = new NormalizingPathIterator(pi, normalize);
// by now strokerat == at && outat == null. Input paths to
// stroker (and maybe dasher) will have the full transform at
// applied to them, then they will be normalized, and then
// the inverse of *only the non translation part of at* will
// be applied to the normalized paths. This won't cause problems
// in stroker, because, suppose at = T*A, where T is just the
// translation part of at, and A is the rest. T*A has already
// been applied to Stroker/Dasher's input. Then Ainv will be
// applied. Ainv*T*A is not equal to T, but it is a translation,
// which means that none of stroker's assumptions about its
// input will be violated. After all this, A will be applied
// to stroker's output.
} else {
outat = at;
pi = src.getPathIterator(null);
// outat == at && strokerat == null. This is because if no
// normalization is done, we can just apply all our
// transformations to stroker's output.
}
}
} else {
// either at is null or it's the identity. In either case
// we don't transform the path.
pi = src.getPathIterator(null);
if (normalize != NormMode.OFF) {
pi = new NormalizingPathIterator(pi, normalize);
}
}
// by now, at least one of outat and strokerat will be null. Unless at is not
// a constant multiple of an orthogonal transformation, they will both be
// null. In other cases, outat == at if normalization is off, and if
// normalization is on, strokerat == at.
pc2d = TransformingPathConsumer2D.transformConsumer(pc2d, outat);
pc2d = TransformingPathConsumer2D.deltaTransformConsumer(pc2d, strokerat);
pc2d = new Stroker(pc2d, width, caps, join, miterlimit);
if (dashes != null) {
pc2d = new Dasher(pc2d, dashes, dashphase);
}
pc2d = TransformingPathConsumer2D.inverseDeltaTransformConsumer(pc2d, strokerat);
pathTo(pi, pc2d);
}
private static boolean nearZero(double num, int nulps) {
return Math.abs(num) < nulps * Math.ulp(num);
}
private static class NormalizingPathIterator implements PathIterator {
private final PathIterator src;
// the adjustment applied to the current position.
private float curx_adjust, cury_adjust;
// the adjustment applied to the last moveTo position.
private float movx_adjust, movy_adjust;
// constants used in normalization computations
private final float lval, rval;
NormalizingPathIterator(PathIterator src, NormMode mode) {
this.src = src;
switch (mode) {
case ON_NO_AA:
// round to nearest (0.25, 0.25) pixel
lval = rval = 0.25f;
break;
case ON_WITH_AA:
// round to nearest pixel center
lval = 0f;
rval = 0.5f;
break;
case OFF:
throw new InternalError("A NormalizingPathIterator should " +
"not be created if no normalization is being done");
default:
throw new InternalError("Unrecognized normalization mode");
}
}
public int currentSegment(float[] coords) {
int type = src.currentSegment(coords);
int lastCoord;
switch(type) {
case PathIterator.SEG_CUBICTO:
lastCoord = 4;
break;
case PathIterator.SEG_QUADTO:
lastCoord = 2;
break;
case PathIterator.SEG_LINETO:
case PathIterator.SEG_MOVETO:
lastCoord = 0;
break;
case PathIterator.SEG_CLOSE:
// we don't want to deal with this case later. We just exit now
curx_adjust = movx_adjust;
cury_adjust = movy_adjust;
return type;
default:
throw new InternalError("Unrecognized curve type");
}
// normalize endpoint
float x_adjust = (float)Math.floor(coords[lastCoord] + lval) +
rval - coords[lastCoord];
float y_adjust = (float)Math.floor(coords[lastCoord+1] + lval) +
rval - coords[lastCoord + 1];
coords[lastCoord ] += x_adjust;
coords[lastCoord + 1] += y_adjust;
// now that the end points are done, normalize the control points
switch(type) {
case PathIterator.SEG_CUBICTO:
coords[0] += curx_adjust;
coords[1] += cury_adjust;
coords[2] += x_adjust;
coords[3] += y_adjust;
break;
case PathIterator.SEG_QUADTO:
coords[0] += (curx_adjust + x_adjust) / 2;
coords[1] += (cury_adjust + y_adjust) / 2;
break;
case PathIterator.SEG_LINETO:
break;
case PathIterator.SEG_MOVETO:
movx_adjust = x_adjust;
movy_adjust = y_adjust;
break;
case PathIterator.SEG_CLOSE:
throw new InternalError("This should be handled earlier.");
}
curx_adjust = x_adjust;
cury_adjust = y_adjust;
return type;
}
public int currentSegment(double[] coords) {
float[] tmp = new float[6];
int type = this.currentSegment(tmp);
for (int i = 0; i < 6; i++) {
coords[i] = (float) tmp[i];
}
return type;
}
public int getWindingRule() {
return src.getWindingRule();
}
public boolean isDone() {
return src.isDone();
}
public void next() {
src.next();
}
}
static void pathTo(PathIterator pi, PathConsumer2D pc2d) {
RenderingEngine.feedConsumer(pi, pc2d);
pc2d.pathDone();
}
/**
* Construct an antialiased tile generator for the given shape with
* the given rendering attributes and store the bounds of the tile
* iteration in the bbox parameter.
* The {@code at} parameter specifies a transform that should affect
* both the shape and the {@code BasicStroke} attributes.
* The {@code clip} parameter specifies the current clip in effect
* in device coordinates and can be used to prune the data for the
* operation, but the renderer is not required to perform any
* clipping.
* If the {@code BasicStroke} parameter is null then the shape
* should be filled as is, otherwise the attributes of the
* {@code BasicStroke} should be used to specify a draw operation.
* The {@code thin} parameter indicates whether or not the
* transformed {@code BasicStroke} represents coordinates smaller
* than the minimum resolution of the antialiasing rasterizer as
* specified by the {@code getMinimumAAPenWidth()} method.
* <p>
* Upon returning, this method will fill the {@code bbox} parameter
* with 4 values indicating the bounds of the iteration of the
* tile generator.
* The iteration order of the tiles will be as specified by the
* pseudo-code:
* <pre>
* for (y = bbox[1]; y < bbox[3]; y += tileheight) {
* for (x = bbox[0]; x < bbox[2]; x += tilewidth) {
* }
* }
* </pre>
* If there is no output to be rendered, this method may return
* null.
*
* @param s the shape to be rendered (fill or draw)
* @param at the transform to be applied to the shape and the
* stroke attributes
* @param clip the current clip in effect in device coordinates
* @param bs if non-null, a {@code BasicStroke} whose attributes
* should be applied to this operation
* @param thin true if the transformed stroke attributes are smaller
* than the minimum dropout pen width
* @param normalize true if the {@code VALUE_STROKE_NORMALIZE}
* {@code RenderingHint} is in effect
* @param bbox returns the bounds of the iteration
* @return the {@code AATileGenerator} instance to be consulted
* for tile coverages, or null if there is no output to render
* @since 1.7
*/
public AATileGenerator getAATileGenerator(Shape s,
AffineTransform at,
Region clip,
BasicStroke bs,
boolean thin,
boolean normalize,
int bbox[])
{
Renderer r;
NormMode norm = (normalize) ? NormMode.ON_WITH_AA : NormMode.OFF;
if (bs == null) {
PathIterator pi;
if (normalize) {
pi = new NormalizingPathIterator(s.getPathIterator(at), norm);
} else {
pi = s.getPathIterator(at);
}
r = new Renderer(3, 3,
clip.getLoX(), clip.getLoY(),
clip.getWidth(), clip.getHeight(),
pi.getWindingRule());
pathTo(pi, r);
} else {
r = new Renderer(3, 3,
clip.getLoX(), clip.getLoY(),
clip.getWidth(), clip.getHeight(),
PathIterator.WIND_NON_ZERO);
strokeTo(s, at, bs, thin, norm, true, r);
}
r.endRendering();
PiscesTileGenerator ptg = new PiscesTileGenerator(r, r.MAX_AA_ALPHA);
ptg.getBbox(bbox);
return ptg;
}
public AATileGenerator getAATileGenerator(double x, double y,
double dx1, double dy1,
double dx2, double dy2,
double lw1, double lw2,
Region clip,
int bbox[])
{
// REMIND: Deal with large coordinates!
double ldx1, ldy1, ldx2, ldy2;
boolean innerpgram = (lw1 > 0 && lw2 > 0);
if (innerpgram) {
ldx1 = dx1 * lw1;
ldy1 = dy1 * lw1;
ldx2 = dx2 * lw2;
ldy2 = dy2 * lw2;
x -= (ldx1 + ldx2) / 2.0;
y -= (ldy1 + ldy2) / 2.0;
dx1 += ldx1;
dy1 += ldy1;
dx2 += ldx2;
dy2 += ldy2;
if (lw1 > 1 && lw2 > 1) {
// Inner parallelogram was entirely consumed by stroke...
innerpgram = false;
}
} else {
ldx1 = ldy1 = ldx2 = ldy2 = 0;
}
Renderer r = new Renderer(3, 3,
clip.getLoX(), clip.getLoY(),
clip.getWidth(), clip.getHeight(),
PathIterator.WIND_EVEN_ODD);
r.moveTo((float) x, (float) y);
r.lineTo((float) (x+dx1), (float) (y+dy1));
r.lineTo((float) (x+dx1+dx2), (float) (y+dy1+dy2));
r.lineTo((float) (x+dx2), (float) (y+dy2));
r.closePath();
if (innerpgram) {
x += ldx1 + ldx2;
y += ldy1 + ldy2;
dx1 -= 2.0 * ldx1;
dy1 -= 2.0 * ldy1;
dx2 -= 2.0 * ldx2;
dy2 -= 2.0 * ldy2;
r.moveTo((float) x, (float) y);
r.lineTo((float) (x+dx1), (float) (y+dy1));
r.lineTo((float) (x+dx1+dx2), (float) (y+dy1+dy2));
r.lineTo((float) (x+dx2), (float) (y+dy2));
r.closePath();
}
r.pathDone();
r.endRendering();
PiscesTileGenerator ptg = new PiscesTileGenerator(r, r.MAX_AA_ALPHA);
ptg.getBbox(bbox);
return ptg;
}
/**
* Returns the minimum pen width that the antialiasing rasterizer
* can represent without dropouts occurring.
* @since 1.7
*/
public float getMinimumAAPenSize() {
return 0.5f;
}
static {
if (PathIterator.WIND_NON_ZERO != Renderer.WIND_NON_ZERO ||
PathIterator.WIND_EVEN_ODD != Renderer.WIND_EVEN_ODD ||
BasicStroke.JOIN_MITER != Stroker.JOIN_MITER ||
BasicStroke.JOIN_ROUND != Stroker.JOIN_ROUND ||
BasicStroke.JOIN_BEVEL != Stroker.JOIN_BEVEL ||
BasicStroke.CAP_BUTT != Stroker.CAP_BUTT ||
BasicStroke.CAP_ROUND != Stroker.CAP_ROUND ||
BasicStroke.CAP_SQUARE != Stroker.CAP_SQUARE)
{
throw new InternalError("mismatched renderer constants");
}
}
}
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