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gxt jglayout » org » gwt » formlayout » client » util » AbstractUnitConverter.java
/*
 * Copyright (c) 2002-2008 JGoodies Karsten Lentzsch. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  o Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  o Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 *  o Neither the name of JGoodies Karsten Lentzsch nor the names of
 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.gwt.formlayout.client.util;

import org.gwt.formlayout.client.layout.Size;
import org.gwt.formlayout.client.layout.Sizes;

import com.extjs.gxt.ui.client.widget.Component;

/**
 * An abstract implementation of the {@link UnitConverter} interface that
 * minimizes the effort required to convert font-dependent sizes to pixels.
 * 
 * @author Flavius Burca (flavius.burca@gmail.com)
 * @version GXT JGLayout 1.0
 * 
 * @author Karsten Lentzsch
 * @version JGoodies Formlayout $Revision: 1.5 $
 * 
 * @see DefaultUnitConverter
 * @see Size
 * @see Sizes
 */
public abstract class AbstractUnitConverter implements UnitConverter {
  private static final int DTP_RESOLUTION = 72;

    // Unit Converter Implementation *********************************************

    /**
     * Converts Inches and returns pixels using the specified resolution.
     *
     * @param in         the Inches
     * @return the given Inches as pixels
     */
    public int inchAsPixel(double in) {
        return inchAsPixel(in, getDefaultScreenResolution());
    }


    /**
     * Converts Millimeters and returns pixels using the resolution of the
     * given component's graphics object.
     *
     * @param mm            Millimeters
     * @return the given Millimeters as pixels
     */
    public int millimeterAsPixel(double mm) {
      return millimeterAsPixel(mm, getDefaultScreenResolution());
    }


    /**
     * Converts Centimeters and returns pixels using the resolution of the
     * given component's graphics object.
     *
     * @param cm            Centimeters
     * @return the given Centimeters as pixels
     */
    public int centimeterAsPixel(double cm) {
      return centimeterAsPixel(cm, getDefaultScreenResolution());
    }


    /**
     * Converts DTP Points and returns pixels using the resolution of the
     * given component's graphics object.
     *
     * @param pt            DTP Points
     * @return the given Points as pixels
     */
    public int pointAsPixel(int pt) {
      return pointAsPixel(pt, getDefaultScreenResolution());
    }

    /**
     * Converts horizontal dialog units and returns pixels.
     * Honors the resolution, dialog font size, platform, and l&f.
     *
     * @param dluX  the horizontal dialog units
     * @return the given horizontal dialog units as pixels
     */
    public int dialogUnitXAsPixel(int dluX) {
      return dialogUnitXAsPixel(dluX, getDialogBaseUnitsX());
    }


    /**
     * Converts vertical dialog units and returns pixels.
     * Honors the resolution, dialog font size, platform, and l&f.
     *
     * @param dluY  the vertical dialog units
     * @return the given vertical dialog units as pixels
     */
    public int dialogUnitYAsPixel(int dluY) {
      return dialogUnitYAsPixel(dluY, getDialogBaseUnitsY());
    }


    // Abstract Behavior *****************************************************

    /**
     * Gets and returns the horizontal dialog base units.
     * Implementations are encouraged to cache previously computed
     * dialog base units.
     *
     * @return the horizontal dialog base units
     */
    protected abstract double getDialogBaseUnitsX();


    /**
     * Gets and returns the vertical dialog base units.
     * Implementations are encouraged to cache previously computed
     * dialog base units.
     *
     * @return the vertical dialog base units
     */
    protected abstract double getDialogBaseUnitsY();


    // Convenience Methods ***************************************************

    /**
     * Converts Inches and returns pixels using the specified resolution.
     *
     * @param in    the Inches
     * @param dpi   the resolution


     * @return the given Inches as pixels
     */
    protected final int inchAsPixel(double in, int dpi) {
      return (int) Math.round(dpi * in);
    }


    /**
     * Converts Millimeters and returns pixels using the specified resolution.
     *
     * @param mm    Millimeters
     * @param dpi   the resolution


     * @return the given Millimeters as pixels
     */
    protected final int millimeterAsPixel(double mm, int dpi) {
      return (int) Math.round(dpi * mm * 10 / 254);
    }


    /**
     * Converts Centimeters and returns pixels using the specified resolution.
     *
     * @param cm    Centimeters
     * @param dpi   the resolution


     * @return the given Centimeters as pixels
     */
    protected final int centimeterAsPixel(double cm, int dpi) {
        return (int) Math.round(dpi * cm * 100 / 254);
    }


    /**
     * Converts DTP Points and returns pixels using the specified resolution.
     *
     * @param pt    DTP Points
     * @param dpi   the resolution in dpi


     * @return the given Points as pixels
     */
    protected final int pointAsPixel(int pt, int dpi) {
        return Math.round(dpi * pt / DTP_RESOLUTION);
    }


    /**
     * Converts horizontal dialog units and returns pixels.
     *
     * @param dluX                  the horizontal dialog units
     * @param dialogBaseUnitsX      the horizontal dialog base units


     * @return the given dialog base units as pixels
     */
    protected int dialogUnitXAsPixel(int dluX, double dialogBaseUnitsX) {
        return (int) Math.round(dluX * dialogBaseUnitsX / 4);
    }


    /**
     * Converts vertical dialog units and returns pixels.
     *
     * @param dluY                  the vertical dialog units
     * @param dialogBaseUnitsY      the vertical dialog base units


     * @return the given dialog base units as pixels
     */
    protected int dialogUnitYAsPixel(int dluY, double dialogBaseUnitsY) {
        return (int) Math.round(dluY * dialogBaseUnitsY / 8);
    }

    // Helper Code ************************************************************
    private static int defaultScreenResolution = -1;
    private int getDefaultScreenResolution() {
        if (defaultScreenResolution == -1) {
          defaultScreenResolution = DOM.getScreenResolution();
        }
        return defaultScreenResolution;
    }
}
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