arrayfontdescriptor.java

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/*******************************************************************************
 * Copyright (c) 2004, 2005 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.jface.resource;

import org.eclipse.swt.graphics.Device;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;

/**
 * Describes a Font using an array of FontData
 * 
 * @since 3.1
 */
final class ArrayFontDescriptor extends FontDescriptor {

    private FontData[] data;
    private Font originalFont = null;
    private Device originalDevice = null;
    
    /**
     * Creates a font descriptor for a font with the given name, height,
     * and style. These arguments are passed directly to the constructor
     * of Font.
     * 
     * @param data FontData describing the font to create
     * 
     * @see org.eclipse.swt.graphics.Font#Font(org.eclipse.swt.graphics.Device, org.eclipse.swt.graphics.FontData)
     * @since 3.1
     */
    public ArrayFontDescriptor(FontData[] data) {
        this.data = data;
    }
 
    /**
     * Creates a font descriptor that describes the given font.
     * 
     * @param originalFont font to be described
     * 
     * @see FontDescriptor#createFrom(org.eclipse.swt.graphics.Font)
     * @since 3.1
     */
    public ArrayFontDescriptor(Font originalFont) {
        this(originalFont.getFontData());
        this.originalFont = originalFont;
    }
    
    /**
     * Creates a font descriptor that describes the given font on the
     * specified device.
     * 
     * @param originalFont font to be described
     * @param originalDevice must be the same Device that was passed into
     * the font's constructor when it was first created.
     * 
     * @see FontDescriptor#createFrom(org.eclipse.swt.graphics.Font, org.eclipse.swt.graphics.Device)
     * @since 3.1
     */
     public ArrayFontDescriptor(Font originalFont, Device originalDevice) {
        this(originalFont);
        this.originalDevice = originalDevice;
    }
    
    /* (non-Javadoc)
     * @see org.eclipse.jface.resource.FontDescriptor#createFont(org.eclipse.swt.graphics.Device)
     */
    public Font createFont(Device device) {
        
        // If this descriptor is an existing font, then we can return the original font
        // if this is the same device.
        if (originalFont != null) {

            // If we don't know what device the original was allocated on, we can't tell if we
            // can reuse the original until we try to create a new one.
            if (originalDevice == null) {
                // Create a new font
                Font result = new Font(device, data);
                
                // If this new font was equal to the original, then it must have been allocated
                // on the same device. 
                if (result.equals(originalFont)) {
                    // We now know the original device. We can reuse the original font,
                    // discard the temporary Font, and remember the device for the next time
                    // this descriptor is used.
                    result.dispose();
                    originalDevice = device;
                    return originalFont;
                }
                // The newly created font ended up being different from the original, so
                // it may have been allocated on a different device. Return the new version.
                return result;
            }
         
            // If we're allocating on the same device as the original font, return the original.
            if (originalDevice == device) {
                return originalFont;
            }            
        }
        
        return new Font(device, data);
    }

    /* (non-Javadoc)
     * @see java.lang.Object#equals(java.lang.Object)
     */
    public boolean equals(Object obj) {
        if ((obj.getClass() == ArrayFontDescriptor.class)) {
            ArrayFontDescriptor descr = (ArrayFontDescriptor)obj;
            
            if (descr.originalFont != originalFont) {
                return false;
            }
            
            if (originalFont != null) {
                return true;
            }
            
            if (data.length != descr.data.length) {
                return false;
            }
            
            for (int i = 0; i < data.length; i++) {
                FontData fd = data[i];
                FontData fd2 = descr.data[i];
                
                if (!fd.equals(fd2)) {
                    return false;
                }
            }
            
            return true;
        }
        
        return false;
    }
    
    /* (non-Javadoc)
     * @see java.lang.Object#hashCode()
     */
    public int hashCode() {
        if (originalFont != null) {
            return originalFont.hashCode();
        }
        
        int code = 0;
        
        for (int i = 0; i < data.length; i++) {
            FontData fd = data[i];
            code += fd.hashCode();
        }
        return code;
    }

    /* (non-Javadoc)
     * @see org.eclipse.jface.resource.FontDescriptor#destroyFont(org.eclipse.swt.graphics.Font)
     */
    public void destroyFont(Font previouslyCreatedFont) {
        if (previouslyCreatedFont == originalFont) {
            return;
        }
        previouslyCreatedFont.dispose();
    }

}