Deprecate XOR-related methods in Shape

[ptziegler]

This is a continuation of f7a00b18852d83a98b4fb11aea0d9c6f4186cba5. XOR is unsupported on Windows when GDI+ (advanced mode) is enabled and returns a black shadow, rather than a blending of the figure and its background. Due to the support for fractional scaling (and the deprecation of ScaledGraphics), advanced mode is almost always active on Windows.

[ptziegler]

Just as an example on how this looks like. The biggest topics is the dark/light theme and how it looks in "real" editors.

[ptziegler]

With the dark theme:

[ptziegler]

Especially when it comes to resizing, the outline is the essential part. Otherwise you have no idea what you're doing. Using two contrasting colors seems to work well because one will always try to draw your attention.

[Phillipus]

Also here:

gef-classic/org.eclipse.gef/src/org/eclipse/gef/editpolicies/LayoutEditPolicy.java

Lines 326 to 335 in 91c3f5a

	protected IFigure getSizeOnDropFeedback() {
	if (sizeOnDropFeedback == null) {
	sizeOnDropFeedback = new RectangleFigure();
	FigureUtilities.makeGhostShape((Shape) sizeOnDropFeedback);
	((Shape) sizeOnDropFeedback).setLineStyle(Graphics.LINE_DASHDOT);
	sizeOnDropFeedback.setForegroundColor(ColorConstants.white);
	addFeedback(sizeOnDropFeedback);
	}
	return sizeOnDropFeedback;
	}

[ptziegler]

Every class that uses XOR needs to be adapted. Also including these:

gef-classic/org.eclipse.gef/src/org/eclipse/gef/editpolicies/ConnectionEndpointEditPolicy.java

Lines 62 to 67 in 91c3f5a

	ConnectionFocus() {
	setFill(false);
	setForegroundColor(ColorConstants.white);
	setXOR(true);
	setOutline(true);
	}

gef-classic/org.eclipse.gef.examples.logic/src/org/eclipse/gef/examples/logicdesigner/edit/LogicResizableEditPolicy.java

Lines 116 to 120 in 91c3f5a

	figure = new RectangleFigure();
	((RectangleFigure) figure).setXOR(true);
	((RectangleFigure) figure).setFill(true);
	figure.setBackgroundColor(LogicColorConstants.ghostFillColor);
	figure.setForegroundColor(ColorConstants.white);

gef-classic/org.eclipse.gef.examples.logic/src/org/eclipse/gef/examples/logicdesigner/edit/LogicXYLayoutEditPolicy.java

Lines 225 to 229 in 91c3f5a

	figure = new RectangleFigure();
	((RectangleFigure) figure).setXOR(true);
	((RectangleFigure) figure).setFill(true);
	figure.setBackgroundColor(LogicColorConstants.ghostFillColor);
	figure.setForegroundColor(ColorConstants.white);

gef-classic/org.eclipse.gef.examples.logic/src/org/eclipse/gef/examples/logicdesigner/figures/CircuitFeedbackFigure.java

Lines 19 to 23 in 91c3f5a

	public CircuitFeedbackFigure() {
	this.setFill(false);
	this.setXOR(true);
	setBorder(new CircuitFeedbackBorder());
	}

gef-classic/org.eclipse.gef.examples.logic/src/org/eclipse/gef/examples/logicdesigner/figures/LogicFlowFeedbackFigure.java

Lines 19 to 23 in 91c3f5a

	public LogicFlowFeedbackFigure() {
	this.setFill(false);
	this.setXOR(true);
	setBorder(new LogicFlowFeedbackBorder());
	}

(Though the figures are already updated by #704).

This is first and foremost just an idea to explore alternatives.

[azoitl]

For that problem. HSL shines. There are several options to create contrast or complementary colors, either by tweaking the hue part or by working with saturation and luminosity combined.

In 4diac IDE we use now for quite some time the selection color for the border and fill with selection color with alpha. Even with colored background and in darkmode this works really good. We have a border of width 2 and the alpha is 50.

[Phillipus]

Using a RectangleFigure leads to the same problem I reported in #1020 The rectangle line width is clipped on the top and left sides:

[ptziegler]

I've rebased this PR so that now only deprecation of the XOR-related methods in the Shape class remain.