Learn to Program with Small Basic

Think of the Shapes object as a “shape factory”—a factory that manufactures
lines, triangles, rectangles, ellipses, and other shapes. When you ask
it to create a new shape, it’ll make the shape and return an identifier. Every
time you want to do something with the shape you created, you’ll pass this
identifier to the Shapes object (as an argument to the method you call).
We won’t cover all the methods of the Shapes object here. Instead, we’ll
discuss the ones you’ll use in the next program. You’ll learn the other
methods as you progress through this book.
The two methods we’ll use now are AddImage() and Move(). To understand
how these methods work, open the file ImageDemo.sb from this chapter’s
folder. You’ll see the code shown in Listing 9-5, which moves an image.
1 ' ImageDemo.sb
2 path = Program.Directory + "\Flower.png"
3 imgID = Shapes.AddImage(path)
4 Shapes.Move(imgID, 60, 20)
Listing 9-5: Moving an image using the Shapes object
Click the Run button. The output of this program is illustrated in
Figure 9-7 (we added the gridlines and the numbers to show how the code
works).
20 60 ...
20
40
60
80
...
Figure 9-7: Moving the flower image
Let’s assume that this program is saved to C:\Book\Ch09\ImageDemo.
The imageDemo folder also contains the Flower​.png image file. The
Program.Directory property (line 2) points to the directory C:\Book\Ch09\
ImageDemo, which contains the executable program (the .exe file). Line 2
uses the + symbol to append two things to the directory: a slash (\) and the
image filename (Flower.png). When the program runs line 2, the path variable’s
given the full file path (C:\Book\Ch09\ImageDemo\Flower.png).
Line 3 calls the AddImage() method and passes the path variable as an
argument. This method loads the image from the file and returns an identifier
of the loaded image; this identifier is saved in a variable named imgID.
An identifier is like a tag that the Shapes object uses to keep track of the
shapes it creates (for example, "Image1", "Rectangle3", "Line100", and so on).
The loaded image is displayed in the upper-left corner of the graphics
window.
Using Decisions to Make Games 121