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interactive/form_textfield_height

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/* $Id: form_textfield_height.java,v 1.8 2013/01/15 10:12:00 stm Exp $
 * Form text field height:
 * Determine the height of a form field of type "textfield" with respect to
 * the font size and vice versa 
 * 
 * Create a text field with a defined field height and no font size specified.
 * Create a text field with a defined field height and calculate the
 * appropriate font size from the field height. Create a text field with a
 * defined font size and calculate the appropriate field height from the font
 * size.
 *
 * Required software: PDFlib/PDFlib+PDI/PPS 9
 * Required data: none
 */
package com.pdflib.cookbook.pdflib.interactive;

import com.pdflib.pdflib;
import com.pdflib.PDFlibException;

public class form_textfield_height
{
    public static void main (String argv[])
    {
    /* This is where the data files are. Adjust as necessary */
    String searchpath = "../input";
    String outfile = "form_textfield_height.pdf";
    String title = "Form Textfield Height";
    
    pdflib p = null;

    String optlist;
    int font;
    double fontsize;
    double ascender, descender;
    double width=160, height=30;
    double llx = 10, lly = 700;
    String text = "Enter text here";

    try {
        p = new pdflib();

        /* This means we must check return values of load_font() etc. */
        p.set_option("errorpolicy=return");

        p.set_option("searchpath={" + searchpath + "}");

        if (p.begin_document(outfile, "") == -1)
            throw new Exception("Error: " + p.get_errmsg());

        p.set_info("Creator", "PDFlib Cookbook");
        p.set_info("Title", title + " $Revision: 1.8 $");

        font = p.load_font("Helvetica", "winansi", "");
        if (font == -1)
            throw new Exception("Error: " + p.get_errmsg());

        p.begin_page_ext(0, 0, "width=a4.width height=a4.height");
        
        
        /* ------------------------------------------
         * Field height given. No font size specified
         * ------------------------------------------
         *
         * Create a form field of type "textfield" called "date". 
         * Provide it with a light blue background and a black border.
         * Allow a maximum of 25 characters to be entered (maxchar=20).
         * If we don't supply any further options the font size will be
         * automatically adjusted to ensure the text being completely fit into
         * the text field. This means that the text get smaller when entering
         * more text. 
         */   
        optlist = "backgroundcolor={rgb 0.95 0.95 1} bordercolor={gray 0} " +
            "maxchar=25 currentvalue={" + text + "} font=" + font;
        
        p.create_field(llx, lly, llx + width, lly + height, "date", "textfield",
            optlist);
        lly-=40;
        
        p.fit_textline("Field height given, no font size specified; a " +
            "maximum of 25 characters is allowed.", llx, lly, "font=" + font + 
            " fontsize=12");
        p.fit_textline("Acrobat automatically decreases the font size when " +
            "more text is entered.", llx, lly-=20, "font=" + font +
            " fontsize=12");
        
        lly-=100;
        
        
        /* ---------------------------------------------------
         * Field height given. Calculate appropriate font size
         * ---------------------------------------------------
         */
        
        /* Create another text field "date2" of a given size. Adjust the font
         * size to match the field height: Retrieve the ascender and the
         * descender (the latter is usually negative) of a hypothetical font
         * size equal to the field height and use the font size resulting from
         * the sum of ascender and (positive) descender as a starting point.
         * Then, descrease the font size by e.g. 20% to leave some empty space
         * from the field borders.
         */
        ascender = p.info_font(font, "ascender", "fontsize=" + height);
        descender = p.info_font(font, "descender", "fontsize=" + height);
        
        fontsize = (ascender - descender) * 0.8;
        
        optlist = "backgroundcolor={rgb 0.95 0.95 1}  bordercolor={gray 0} " +
        "currentvalue={" + text + "} font=" + font + " fontsize=" + fontsize;
        p.create_field(llx, lly, llx + width, lly + height, "date2",
            "textfield", optlist);
        lly-=40;
        p.fit_textline("Field height of 30 is given. Acrobat uses an " +
            "appropriate font size.", llx, lly, "font=" + font +
            " fontsize=12");
        
        lly-=100;
        
        
        /* --------------------------------------------------------
         * Font size given. Calculate appropriate field height size
         * --------------------------------------------------------
         */
        
        /* Create another text field "date3". In this case, the font size is
         * given as a fixed value of 24 and the field height should be chosen
         * appropriately: Retrieve the ascender and descender (which is usually
         * negative) of the font size 24. The resulting value will be a good
         * starting point for determining the field height, for example.
         * 
         * Since the behaviour of Acrobat regarding the chosen font and 
         * baseline is not obvious, the field height will be too small in many
         * cases. To avoid that we add a margin of an appropriate percentage of
         * the field height, e.g. 50%.
         */
        ascender = p.info_font(font, "ascender", "fontsize=24");
        descender = p.info_font(font, "descender", "fontsize=24");
        
        height = (ascender - descender) * 1.5;
        
        optlist = "backgroundcolor={rgb 0.95 0.95 1}  bordercolor={gray 0} " +
        "currentvalue={" + text + "} font=" + font + " fontsize=24";
        p.create_field(llx, lly, llx + width, lly + height, "date3",
            "textfield", optlist);
        lly-=40;
        
        p.fit_textline("Font size of 24 is given. We calculate the field " +
        	"height based on the font's ascender and descender.", llx, lly,
            "font=" + font + " fontsize=12");
         
        p.end_page_ext("");

        p.end_document("");

        } catch (PDFlibException e) {
            System.err.print("PDFlib exception occurred:\n");
            System.err.print("[" + e.get_errnum() + "] " + e.get_apiname() +
                ": " + e.get_errmsg() + "\n");
        } catch (Exception e) {
            System.err.println(e.getMessage());
        } finally {
            if (p != null) {
                p.delete();
            }
        }
    }
}