draw(Shape) method may alter the state of input Line2D and Rectangle2D shapes

[turnef]

The draw(Shape) method, when the RenderingHints.KEY_STROKE_CONTROL is set to something other than RenderingHints.VALUE_STROKE_PURE, alters the state of input Rectangle2D and Line2D shapes. The code below demonstrates this:

import java.awt.RenderingHints;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;

import org.jfree.fx.FXGraphics2D;

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.stage.Stage;

public class DrawNormalize extends Application {

	public static void main(String[] args) {
		launch(args);
	}

	@Override
	public void start(Stage primaryStage) throws Exception {
		primaryStage.setTitle("DrawStrokeNormalize");
		Group root = new Group();
		Canvas canvas = new Canvas(640, 480);
		GraphicsContext gc = canvas.getGraphicsContext2D();

		FXGraphics2D g2d = new FXGraphics2D(gc);

		/*
		 * Set the stroke control rendering hint to something other than
		 * VALUE_STROKE_PURE to trigger the issue.
		 */
		g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, 
			RenderingHints.VALUE_STROKE_NORMALIZE);

		Line2D.Double line = new Line2D.Double(10.15, 10.15, 470.92, 470.92);
		printLine(line);
		g2d.draw(line);
		printLine(line); // line's state has changed

		Rectangle2D.Double rect = new Rectangle2D.Double(20.57, 20.57, 590.01, 430.3);
		printRect(rect);
		g2d.draw(rect);
		printRect(rect); // rect's state has changed

		root.getChildren().add(canvas);
		primaryStage.setScene(new Scene(root));
		primaryStage.show();
	}

	static void printLine(Line2D line) {
		System.out.println(String.format("(%5.3f, %5.3f) -> (%5.3f, %5.3f)", 
				line.getX1(), line.getY1(), line.getX2(), line.getY2()));
	}

	static void printRect(Rectangle2D rect) {
		System.out.println(String.format("(%5.3f, %5.3f) -> (%5.3f, %5.3f)", 
				rect.getMinX(), rect.getMinY(),
				rect.getMaxX(), rect.getMaxY()));
	}

}

It's not clear that this is exactly a problem that needs to be addressed, but we found the behavior surprising. It was straightforward enough to work around in our code, but I've attached a patch for your consideration that I believe corrects the issue while preserving the original intent of the source:

fxgraphics2d.patch.txt

[jfree]

Thanks for the report. I fixed the issue in the same way that you suggested, but I made use of the existing 'recyclable' line and rect objects that are used elsewhere in the code (this should minimise garbage generation in cases where many shapes are drawn).