Filing and Printing Documents - Beginning Java - page 1167

A starting point is to figure out the extent of the sketch. Ideally you need a rectangle that encloses all the
elements in the sketch. It's really surprisingly easy to get that. Every element has a getBounds() method
that returns a java.awt.Rectangle object enclosing the element. As you saw in Chapter 17, the Rectangle
class defines an add() method that combines the Rectangle object that you pass as the argument with the
Rectangle object for which you called the method, and returns the smallest Rectangle object that encloses
both; this is referred to as the union of the two rectangles. With these two bits of information and by ac-
cessing the elements in the list in the SketcherModel object, you can get a rectangle that encloses the entire
sketch by implementing the following method in the SketcherModel class:

// Get the rectangle enclosing an entire sketch
Rectangle getModelExtent() {
Rectangle rect = new Rectangle(); // An empty rectangle

for(Element element : elements) { // Go through the list

rect.add(element.getBounds()); // Expand union

}
if(rect.width == 0) { // Make sure width

rect.width = 2; // is non-zero

}
if(rect.height == 0) { // and the height

rect.height = 2;

}
return rect;

}

Directory "Sketcher 7 printing the whole sketch"

Don't forget to add an import statement for the Rectangle class name to the SketcherModel source
file:
import java.awt.Rectangle;

Using the collection-based for loop to iterate over the elements in the list, you generate the union of
the bounding rectangles for all the elements, so you end up with a rectangle that bounds everything in the
sketch. A zero width or height for the rectangle is unlikely, but you want to be sure it can't happen because
you use these values as divisors later. A minimum width and height of 2 ensures that the rectangle has an
interior.
You can see from Figure 21-8 how the rectangle returned by the getModelExtent() method is simply
the rectangle that encloses all the bounding rectangles for the individual elements. If you visualize the origin
of the user coordinate system being placed at the top-left corner of the printable area on the page, you can
appreciate that a section of the sketch in the illustration is hanging out to the left outside the printable area.
This can arise quite easily in Sketcher — when you are drawing a circle with the center close to either of the
axes, for example, or if you move a shape so this is the case. You can avoid missing part of the sketch from
the printed output by first translating the origin of the graphics context to the top-left corner of the printable
area on the page and then translating the origin of the coordinate system to the top-left corner of rect .

FIGURE 21-8