at.spardat.xma.page.Scaler Maven / Gradle / Ivy

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/*******************************************************************************
 * Copyright (c) 2003, 2007 s IT Solutions AT Spardat GmbH .
 * 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:
 *     s IT Solutions AT Spardat GmbH - initial API and implementation
 *******************************************************************************/

/*
 * @(#) $Id: Scaler.java 2089 2007-11-28 13:56:13Z s3460 $
 *
 * 
 * 
 * 
 */
package at.spardat.xma.page;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Label;

/**
 * Implements scaling methods which can be used to scale pixel values the same amount as the
 * current system font differs from the standard font (on Windows: small fonts 96 DPI).
 * If the system font is set to 125% (big fonts 120 DPI), the scaling funtions multiply their
 * input by 1.25.
 * The methods convertXToCurrent() and convertYToCurrent() do the scaling.
 * The methods convertXToStandard() and convertYToStandard() do the inverse operation.
 * Ther are different methods for X and Y directions because there may be different scaling
 * factors in the future.
 * 
 * @author s2877
 */
public class Scaler {

    static final String scaleText = "The quick brown fox jumped over the lazy dog.";
    static Scaler instance;
    
    //current scaling factors (aprox.: current base / small base)
    double factorX = 1.0;
    double factorY = 1.0;
    //base values in case of small font
    //double smallBaseX = 4.9382716049382722; //Sans Serif
    double smallBaseX = 5.050505050505051; //Tahoma 8pt 96dpi
    double smallBaseY = 12.0;

    // standard DPI used as baseline for scalings
    double standardDPI = 96;
    
    
    /**
     * constructs a scaler
     */
    Scaler(Composite comp) {
        PageClient page = null;
        for(Control c = comp;page==null&c!=null;c=c.getParent()) {
            page = (PageClient) c.getData();
        }
        if(page!=null) {
            String alg = page.getComponent().getSession().getRuntimeProperty("scalerAlgorithm");
            if("scalebyLabel".equals(alg)) {
                scalebyLabel(comp);
            } else {
                scalebyDPI(comp);
            }
        } else {
            scalebyDPI(comp);
        }
    }
    
    private void scalebyLabel(Composite comp) {
        Label label = new Label(comp,SWT.NONE);
        label.setText(scaleText);
        Point p = label.computeSize(SWT.DEFAULT,SWT.DEFAULT);
        double fx = (p.x-1)/44.55;
        double fy = p.y-1;
        //rem: divide first to overcome rounding errors in case of fx==SmallBaseX and fy==SmallBaseY
        factorX = (fx/smallBaseX); //+0.08;
        factorY = (fy/smallBaseY); //+0.08;
        label.dispose();
    }
    
    private void scalebyDPI(Composite comp) {
        Point p = comp.getDisplay().getDPI();
        factorX = p.x/standardDPI;
        factorY = p.y/standardDPI;
    }

//    scaling accessors

    /**
     * Returns the scaling factor in X-direction.
     */
    public double getFactorX() { 
        return factorX; 
    }

    /**
     * Returns the scaling factor in Y-direction.
     */
    public double getFactorY() { 
        return factorY; 
    }

    /**
     * Determine if the scaling-factors are different from 1.
     * @return true if the convert-Methods will change values
     */
    public boolean isScalingNecessary() {
        return factorX!=1.0 || factorY!=1.0;
    }

//    scaling core methods 
    /**
     * scales the given value in X-direction.
     */
    public int convertXToCurrent(int x) {
        if (x<0) {
            return -(int)(-x*factorX+0.5);
        }
        return (int)(x*factorX+0.5);
    }

    /**
     * scales the given value in Y-direction.
     */
    public int convertYToCurrent(int y) {
        if (y<0) {
            return -(int)(-y*factorY+0.5);
        }
        return (int)(y*factorY+0.5);
    }

    /**
     * converts back the given scaled value
     */
    public int convertXToStandard(int x) {
        if (x<0) {
            return -(int)(-x/factorX+0.5);
        }
        return (int)(x/factorX+0.5);
    }

    /**
     * converts back the given scaled value
     */
    public int convertYToStandard(int y) {
        if (y<0) {
            return -(int)(-y/factorY+0.5);
        }
        return (int)(y/factorY+0.5);
    }

    /**
     * Get an instance of the scaler. 
     * @param comp one Composite or Shell of the application.
     * @return the scaler
     */
    public static Scaler getInstance(Composite comp) {
        if(instance==null) {
            instance = new Scaler(comp);
        }
        return instance;
    }
}