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Merge pull request #929 from tracerstar/svg-gradient

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Adds gradient export to SVG library
This commit is contained in:
Stef Tervelde
2025-01-21 18:00:40 +01:00
committed by GitHub
parent 78ef9f555c c8a85e3a58
commit b024526466
4 changed files with 329 additions and 8 deletions
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209
java/libraries/svg/src/processing/svg/GradientExtensionHandler.java Normal file
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@@ -0,0 +1,209 @@
package processing.svg;
import static org.apache.batik.util.SVGConstants.*;
import processing.awt.PShapeJava2D.LinearGradientPaint;
import processing.awt.PShapeJava2D.RadialGradientPaint;
import java.awt.Color;
import java.awt.MultipleGradientPaint;
import java.awt.Paint;
import java.awt.geom.AffineTransform;
import java.awt.geom.Point2D;
import java.util.Objects;
import org.apache.batik.svggen.DefaultExtensionHandler;
import org.apache.batik.svggen.SVGColor;
import org.apache.batik.svggen.SVGGeneratorContext;
import org.apache.batik.svggen.SVGPaintDescriptor;
import org.w3c.dom.Element;
/**
* Extension of Batik's {@link DefaultExtensionHandler} which handles different kinds of Paint objects
* based on the extenstion by Martin Steiger https://gist.github.com/msteiger/4509119
* modified to work with Processing's SVG export library, by Benjamin Fox https://github.com/tracerstar
*/
public class GradientExtensionHandler extends DefaultExtensionHandler {
@Override
public SVGPaintDescriptor handlePaint(Paint paint, SVGGeneratorContext genCtx) {
// Handle LinearGradientPaint
if (paint instanceof LinearGradientPaint) {
return getLgpDescriptor((LinearGradientPaint) paint, genCtx);
}
// Handle RadialGradientPaint
if (paint instanceof RadialGradientPaint) {
return getRgpDescriptor((RadialGradientPaint) paint, genCtx);
}
return super.handlePaint(paint, genCtx);
}
private SVGPaintDescriptor getLgpDescriptor(LinearGradientPaint gradient, SVGGeneratorContext genCtx) {
Element gradElem = genCtx.getDOMFactory().createElementNS(SVG_NAMESPACE_URI, SVG_LINEAR_GRADIENT_TAG);
// Create and set unique XML id
String id = genCtx.getIDGenerator().generateID("gradient");
gradElem.setAttribute(SVG_ID_ATTRIBUTE, id);
// Set x,y pairs
Point2D startPt = gradient.getStartPoint();
gradElem.setAttribute("x1", String.valueOf(startPt.getX()));
gradElem.setAttribute("y1", String.valueOf(startPt.getY()));
Point2D endPt = gradient.getEndPoint();
gradElem.setAttribute("x2", String.valueOf(endPt.getX()));
gradElem.setAttribute("y2", String.valueOf(endPt.getY()));
//TODO: change this to be: addMgpAttributes after refactoring the paint methods
addLgpAttributes(gradElem, genCtx, gradient);
return new SVGPaintDescriptor("url(#" + id + ")", SVG_OPAQUE_VALUE, gradElem);
}
private SVGPaintDescriptor getRgpDescriptor(RadialGradientPaint gradient, SVGGeneratorContext genCtx) {
Element gradElem = genCtx.getDOMFactory().createElementNS(SVG_NAMESPACE_URI, SVG_RADIAL_GRADIENT_TAG);
// Create and set unique XML id
String id = genCtx.getIDGenerator().generateID("gradient");
gradElem.setAttribute(SVG_ID_ATTRIBUTE, id);
// Set x,y pairs
Point2D centerPt = gradient.getCenterPoint();
gradElem.setAttribute("cx", String.valueOf(centerPt.getX()));
gradElem.setAttribute("cy", String.valueOf(centerPt.getY()));
Point2D focusPt = gradient.getFocusPoint();
gradElem.setAttribute("fx", String.valueOf(focusPt.getX()));
gradElem.setAttribute("fy", String.valueOf(focusPt.getY()));
gradElem.setAttribute("r", String.valueOf(gradient.getRadius()));
//TODO: change this to be: addMgpAttributes after refactoring the paint methods
addRgpAttributes(gradElem, genCtx, gradient);
return new SVGPaintDescriptor("url(#" + id + ")", SVG_OPAQUE_VALUE, gradElem);
}
/*
Being lazy here to duplicate the methods so we don't have to refactor the two gradient paints
to implement java.awt.MultipleGradientPaint
TODO: make the effort to refactor them to properly implement java.awt.MultipleGradientPaint
*/
private void addLgpAttributes(Element gradElem, SVGGeneratorContext genCtx, LinearGradientPaint gradient) {
gradElem.setAttribute(SVG_GRADIENT_UNITS_ATTRIBUTE, SVG_USER_SPACE_ON_USE_VALUE);
// Set cycle method
switch (gradient.getCycleMethod()) {
case REFLECT:
gradElem.setAttribute(SVG_SPREAD_METHOD_ATTRIBUTE, SVG_REFLECT_VALUE);
break;
case REPEAT:
gradElem.setAttribute(SVG_SPREAD_METHOD_ATTRIBUTE, SVG_REPEAT_VALUE);
break;
case NO_CYCLE:
default:
gradElem.setAttribute(SVG_SPREAD_METHOD_ATTRIBUTE, SVG_PAD_VALUE); // this is the default
break;
}
// Set color space
switch (gradient.getColorSpace()) {
case LINEAR_RGB:
gradElem.setAttribute(SVG_COLOR_INTERPOLATION_ATTRIBUTE, SVG_LINEAR_RGB_VALUE);
break;
case SRGB:
default:
gradElem.setAttribute(SVG_COLOR_INTERPOLATION_ATTRIBUTE, SVG_SRGB_VALUE);
break;
}
// Set transform matrix if not identity
AffineTransform tf = gradient.getTransform();
if (!Objects.isNull(tf) && !tf.isIdentity()) {
String matrix = "matrix(" +
tf.getScaleX() + " " + tf.getShearX() + " " + tf.getTranslateX() + " " +
tf.getScaleY() + " " + tf.getShearY() + " " + tf.getTranslateY() + ")";
gradElem.setAttribute(SVG_TRANSFORM_ATTRIBUTE, matrix);
}
// Convert gradient stops
Color[] colors = gradient.getColors();
float[] fracs = gradient.getFractions();
for (int i = 0; i < colors.length; i++) {
Element stop = genCtx.getDOMFactory().createElementNS(SVG_NAMESPACE_URI, SVG_STOP_TAG);
SVGPaintDescriptor pd = SVGColor.toSVG(colors[i], genCtx);
stop.setAttribute(SVG_OFFSET_ATTRIBUTE, (int) (fracs[i] * 100.0f) + "%");
stop.setAttribute(SVG_STOP_COLOR_ATTRIBUTE, pd.getPaintValue());
if (colors[i].getAlpha() != 255) {
stop.setAttribute(SVG_STOP_OPACITY_ATTRIBUTE, pd.getOpacityValue());
}
gradElem.appendChild(stop);
}
}
private void addRgpAttributes(Element gradElem, SVGGeneratorContext genCtx, RadialGradientPaint gradient) {
gradElem.setAttribute(SVG_GRADIENT_UNITS_ATTRIBUTE, SVG_USER_SPACE_ON_USE_VALUE);
// Set cycle method
switch (gradient.getCycleMethod()) {
case REFLECT:
gradElem.setAttribute(SVG_SPREAD_METHOD_ATTRIBUTE, SVG_REFLECT_VALUE);
break;
case REPEAT:
gradElem.setAttribute(SVG_SPREAD_METHOD_ATTRIBUTE, SVG_REPEAT_VALUE);
break;
case NO_CYCLE:
default:
gradElem.setAttribute(SVG_SPREAD_METHOD_ATTRIBUTE, SVG_PAD_VALUE); // this is the default
break;
}
// Set color space
switch (gradient.getColorSpace()) {
case LINEAR_RGB:
gradElem.setAttribute(SVG_COLOR_INTERPOLATION_ATTRIBUTE, SVG_LINEAR_RGB_VALUE);
break;
case SRGB:
default:
gradElem.setAttribute(SVG_COLOR_INTERPOLATION_ATTRIBUTE, SVG_SRGB_VALUE);
break;
}
// Set transform matrix if not identity
AffineTransform tf = gradient.getTransform();
if (!Objects.isNull(tf) && !tf.isIdentity()) {
String matrix = "matrix(" +
tf.getScaleX() + " " + tf.getShearX() + " " + tf.getTranslateX() + " " +
tf.getScaleY() + " " + tf.getShearY() + " " + tf.getTranslateY() + ")";
gradElem.setAttribute(SVG_TRANSFORM_ATTRIBUTE, matrix);
}
// Convert gradient stops
Color[] colors = gradient.getColors();
float[] fracs = gradient.getFractions();
for (int i = 0; i < colors.length; i++) {
Element stop = genCtx.getDOMFactory().createElementNS(SVG_NAMESPACE_URI, SVG_STOP_TAG);
SVGPaintDescriptor pd = SVGColor.toSVG(colors[i], genCtx);
stop.setAttribute(SVG_OFFSET_ATTRIBUTE, (int) (fracs[i] * 100.0f) + "%");
stop.setAttribute(SVG_STOP_COLOR_ATTRIBUTE, pd.getPaintValue());
if (colors[i].getAlpha() != 255) {
stop.setAttribute(SVG_STOP_OPACITY_ATTRIBUTE, pd.getOpacityValue());
}
gradElem.appendChild(stop);
}
}
}

4
java/libraries/svg/src/processing/svg/PGraphicsSVG.java
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@@ -87,6 +87,10 @@ public class PGraphicsSVG extends PGraphicsJava2D {
g2 = new SVGGraphics2D(document);
((SVGGraphics2D) g2).setSVGCanvasSize(new Dimension(width, height));
//set the extension handler to allow linear and radial gradients to be exported as svg
GradientExtensionHandler gradH = new GradientExtensionHandler();
((SVGGraphics2D) g2).setExtensionHandler(gradH);
// Done with our work, let's check on defaults and the rest
//super.beginDraw();
// Can't call super.beginDraw() because it'll nuke our g2