bundles/org.eclipse.wst.css.ui/src/org/eclipse/wst/css/ui/internal/text/hover/CSSColorHover.java

/*******************************************************************************
 * Copyright (c) 2011 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.wst.css.ui.internal.text.hover;

import org.eclipse.jface.text.AbstractInformationControl;
import org.eclipse.jface.text.AbstractReusableInformationControlCreator;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IInformationControl;
import org.eclipse.jface.text.IInformationControlCreator;
import org.eclipse.jface.text.IInformationControlExtension2;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextHover;
import org.eclipse.jface.text.ITextHoverExtension;
import org.eclipse.jface.text.ITextHoverExtension2;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Region;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.wst.css.core.internal.provisional.document.ICSSPrimitiveValue;
import org.eclipse.wst.sse.core.StructuredModelManager;
import org.eclipse.wst.sse.core.internal.provisional.IStructuredModel;
import org.eclipse.wst.sse.core.internal.provisional.IndexedRegion;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocument;
import org.w3c.dom.css.CSSPrimitiveValue;
import org.w3c.dom.css.RGBColor;

public class CSSColorHover implements ITextHover, ITextHoverExtension, ITextHoverExtension2 {

	private IInformationControlCreator fInformationControlCreator;

	public CSSColorHover() {
		
	}

	public Object getHoverInfo2(ITextViewer textViewer, IRegion hoverRegion) {
		final IDocument document = textViewer.getDocument();
		if (document instanceof IStructuredDocument) {
			IStructuredModel model = StructuredModelManager.getModelManager().getModelForRead((IStructuredDocument) document);
			try {
				final IndexedRegion region = model.getIndexedRegion(hoverRegion.getOffset());
				if (region instanceof ICSSPrimitiveValue) {
					return getColorValue((ICSSPrimitiveValue) region);
				}
			}
			finally {
				if (model != null)
					model.releaseFromRead();
			}
		}
		return null;
	}

	public IInformationControlCreator getHoverControlCreator() {
		if (fInformationControlCreator == null) {
			fInformationControlCreator = new CSSColorInformationControlCreator();
		}
		return fInformationControlCreator;
	}

	public String getHoverInfo(ITextViewer textViewer, IRegion hoverRegion) {
		Object result = getHoverInfo2(textViewer, hoverRegion);
		return result != null ? result.toString() : null;
	}

	/**
	 * Gets an {@link RGB} color value from the primitive value
	 * 
	 * @param value the primitive CSS value
	 * @return an RGB value if it can be extracted from the primitive
	 */
	private RGB getColorValue(ICSSPrimitiveValue value) {
		if (value.getParentNode() instanceof RGBColor) {
			value = (ICSSPrimitiveValue) value.getParentNode();
		}
		RGB rgb = null;
		switch (value.getPrimitiveType()) {
			case CSSPrimitiveValue.CSS_RGBCOLOR:
				rgb = getRGB((RGBColor) value);
				break;
			case ICSSPrimitiveValue.CSS_HASH:
				rgb = getRGBFromHex(value.getStringValue());
				break;
			case CSSPrimitiveValue.CSS_IDENT:
				rgb = CSSColorNames.getInstance().getRGB(value.getStringValue());
				break;
		}
		return rgb;
	}

	/**
	 * Converts a hex string (either 3-digit or 6-digit notation) into an {@link RGB}. Any
	 * invalid hex color will result in a null RGB value.
	 * @param hex rgb value in hexadecimal notation (3- or 6-digit)
	 * @return an {@link RGB} based on the hexadecimal value. <code>null</code> if the
	 * rgb value is invalid 
	 */
	private RGB getRGBFromHex(String hex) {
		try {
			final int length = hex.length();
			if (length == 4) { // convert 3-digit notation
				final int r = Integer.parseInt(hex.substring(1, 2), 16);
				final int g = Integer.parseInt(hex.substring(2, 3), 16);
				final int b = Integer.parseInt(hex.substring(3, 4), 16);
				return new RGB((r << 4) | r, (g << 4) | g, (b << 4) | b);
			}
			else if (length == 7) { // convert 6-digit notation
				return new RGB(Integer.parseInt(hex.substring(1, 3), 16), Integer.parseInt(hex.substring(3, 5), 16), Integer.parseInt(hex.substring(5, 7), 16));
			}
		}
		catch (NumberFormatException e) {} // Invalid hexcode used
		return null;
	}

	/**
	 * Provides an {@link RGB} based on an {@link RGBColor}
	 * @param color The {@link RGBColor} to extra RGB information from
	 * @return an {@link RGB} based on an {@link RGBColor}
	 */
	private RGB getRGB(RGBColor color) {
		final int red = getColorInt(color.getRed());
		final int green = getColorInt(color.getGreen());
		final int blue = getColorInt(color.getBlue());
		if (red >= 0 && green >= 0 && blue >= 0)
			return new RGB(red, green, blue);
		return null;
	}

	private int getColorInt(CSSPrimitiveValue value) {
		if (value.getPrimitiveType() == CSSPrimitiveValue.CSS_PERCENTAGE) { // Percentage of 255
			final float percentage = value.getFloatValue(CSSPrimitiveValue.CSS_NUMBER);
			return capIntValue((int) (percentage / 100 * 255));
		}
		else if (value.getPrimitiveType() == ICSSPrimitiveValue.CSS_INTEGER) {
			return capIntValue((int) value.getFloatValue(CSSPrimitiveValue.CSS_NUMBER));
		}
		return -1;
	}

	/**
	 * Caps the integer value between the ranges of 0 and 255, inclusive.
	 * @param value integer value to cap
	 * @return a value between 0 and 255, inclusive
	 */
	private int capIntValue(int value) {
		if (value > 255) value = 255;
		else if (value < 0) value = 0;
		return value;
	}

	public IRegion getHoverRegion(ITextViewer textViewer, int offset) {
		final IDocument document = textViewer.getDocument();
		if (document instanceof IStructuredDocument) {
			IStructuredModel model = StructuredModelManager.getModelManager().getModelForRead((IStructuredDocument) document);
			try {
				IndexedRegion region = model.getIndexedRegion(offset);
				if (region instanceof ICSSPrimitiveValue) {
					// Shift the hover region to the rgb() function instead of the individual numbers
					if (((ICSSPrimitiveValue) region).getParentNode() instanceof RGBColor) {
						region = (IndexedRegion) ((ICSSPrimitiveValue) region).getParentNode();
					}
				}
				if (region != null) {
					return new Region(region.getStartOffset(), region.getLength());
				}
			}
			finally {
				if (model != null)
					model.releaseFromRead();
			}
		}
		return null;
	}

	private class CSSColorInformationControlCreator extends AbstractReusableInformationControlCreator {

		protected IInformationControl doCreateInformationControl(Shell parent) {
			return new CSSColorInformationControl(parent);
		}
		
	}

	/**
	 * An information control that simply displays color information.
	 * The control takes an {@link RGB} input value and sets its background
	 * to the corresponding color.
	 *
	 */
	private class CSSColorInformationControl extends AbstractInformationControl implements IInformationControlExtension2 {

		private Color fColor;

		CSSColorInformationControl(Shell shell) {
			super(shell, false);
			create();
		}

		public Point computeSizeConstraints(int widthInChars, int heightInChars) {
			return new Point(50, 50);
		}

		public boolean hasContents() {
			return fColor != null;
		}

		protected void createContent(Composite parent) {
		}

		public void setInformation(String information) {
		}

		public void dispose() {
			if (fColor != null) {
				fColor.dispose();
				fColor = null;
			}
			super.dispose();
		}

		public void setInput(Object input) {
			if (input instanceof RGB) {
				RGB rgb = (RGB) input;
				if (fColor == null || !rgb.equals(fColor.getRGB())) {
					if (fColor != null) { // Cleanup any old color
						fColor.dispose();
					}
					fColor = new Color(getShell().getDisplay(), rgb);
					setBackgroundColor(fColor);
				}
			}
		}

		public IInformationControlCreator getInformationPresenterControlCreator() {
			return new CSSColorInformationControlCreator();
		}

	}
}