ColdFusion: Basic example - Positioning buttons with iText

Recently, a poster named Brook asked about positioning PushButtonFields with iText. Positioning is relatively simple once you understand the default coordinate system. However, if you are like me, that may initially require a slight adjustment in thinking. Unlike top-down systems, the pdf coordinates work from the bottom up, where 0,0 signifies the lower left corner. Also, the default measurement is in points. So you must take both of these things into account in order to position elements.


I threw together a very simple example to demonstrate. The example adds a few buttons to a blank pdf. Each button is placed on a separate page, in the lower right corner. In terms of coordinates, the key part of the code is the section below. It uses a Rectangle object to determine the placement and dimensions of the buttons. The four (4) values passed into the Rectangle represent: the lower left x, lower left y, upper right x and upper right y coordinates.

<cfscript>
box = Rectangle.init(     document.right()-72,   // llx = lower left x position
                       document.bottom(),      // lly = lower left y position
                       document.right(),       // urx = upper right x position
                       document.bottom() + 36  // ury = upper right y position
                    );
// ...
</cfscript>

If you look at the blue angular brackets in the image below, you can easily see how these values combine to determine both size and position of the buttons.



Note, this example uses the JavaLoader.cfc to load a newer version of iText.

<cfscript>
 javaLoader = server[MyUniqueKeyForJavaLoader];
 fullPathToOutputFile = ExpandPath("./Buttonapalooza.pdf");

 PageSize = javaLoader.create("com.lowagie.text.PageSize");
 document = javaLoader.create("com.lowagie.text.Document").init(PageSize.LETTER);
 outStream = javaLoader.create("java.io.FileOutputStream").init(fullPathToOutputFile);
 writer = javaLoader.create("com.lowagie.text.pdf.PdfWriter").getInstance(document, outStream);
 Color = javaLoader.create("java.awt.Color");

 PushbuttonField = javaloader.create("com.lowagie.text.pdf.PushbuttonField");
 Rectangle = javaloader.create("com.lowagie.text.Rectangle");
 // the coordinates define both position and size of the field
 box = Rectangle.init(     document.right()-72,    // lower left
                           document.bottom(),      // lower right
                           document.right(),       // upper x
                           document.bottom() + 36  // upper y
                        );

 document.open();
 for (i = 1; i lte 5; i = i+1)
 {
     button = PushbuttonField.init(writer, box, "buttonField"& i);
     button.setText("Button "& i);
     button.setBackgroundColor(Color.GRAY);
     document.newPage();
     writer.addAnnotation(button.getField());
 }

 document.close();
 WriteOutput("Finished!");
</cfscript>

Related articles

• iText - Measurements
• iText - Coordinates (iText site)