examples/org.eclipse.gmf.examples.ocldriven.diagram/custom-src/org/eclipse/gmf/examples/ocldriven/diagram/figures/AbstractProportionalShape.java

package org.eclipse.gmf.examples.ocldriven.diagram.figures;

import org.eclipse.draw2d.Shape;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Rectangle;

public abstract class AbstractProportionalShape extends Shape {

	public AbstractProportionalShape() {
	}

	protected void setW2HRatio(float w2hRatio) {
		myW2HRatio = w2hRatio;
		myIsKeepingProportions = true;
	}

	protected void setKeepingProportions(boolean newValue) {
		myIsKeepingProportions = newValue;
	}

	protected boolean isKeepingProportions() {
		return myIsKeepingProportions;
	}

	/**
	 * If keeping proportions, returns the maximum rectangle that is fully
	 * inside the bounds and has the specified proportions. Otherwise, returns
	 * the bounds.
	 */
	public Rectangle getProportionalBounds() {
		Rectangle area = getClientArea();
		if (!myIsKeepingProportions || myW2HRatio == 0.0f || area.height == 0) {
			return new Rectangle(area);
		}

		int newX = area.x;
		int newY = area.y;
		int newW = area.width;
		int newH = area.height;

		float currentRatio = ((float) newW) / ((float) newH);
		float discrepancy = currentRatio / myW2HRatio;

		if (discrepancy < 1) {
			// we are too high.
			newH = Math.round(newH * discrepancy);
			newY += (area.height - newH) / 2;
		} else {
			// we are too wide
			newW = Math.round(newW / discrepancy);
			newX += (area.width - newW) / 2;
		}
		return new Rectangle(newX, newY, newW, newH);
	}

	/**
	 * If keeping proportions, returns the dimension tweaked by the same factor
	 * as the proportional bounds relate to the original bounds. Otherwise,
	 * returns the original dimension.
	 */
	public Dimension adjustDimension(Dimension d) {
		Rectangle area = getClientArea();
		if (!myIsKeepingProportions || myW2HRatio == 0.0f || area.height == 0) {
			return new Dimension(d);
		}

		float currentRatio = ((float) area.width) / ((float) area.height);
		float discrepancy = currentRatio / myW2HRatio;

		if (discrepancy < 1) {
			return new Dimension(d.width, (int) (d.height * discrepancy));
		} else {
			return new Dimension((int) (d.width / discrepancy), d.height);
		}
	}

	private float myW2HRatio = 1.0f;

	private boolean myIsKeepingProportions;
}