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Week Five Homework

Week 5 Homework Assignment

Liberty BASIC programming course

More on Programming Graphics

In the first part of week 5 we covered turtle graphics, drawing segments, drawing with color, and displaying text. Now we will examine the use of bitmaps in Liberty BASIC.

NOTICE: This week's homework includes four bitmap files named LETTER.BMP, CALL.BMP, BROCHURE.BMP, and SALE.BMP for use in your assignment. Use your print screen key to do a screen capture, then open your favorite paint program and choose Paste. Then, simply copy the images below individually and name them as above.

Using Bitmaps

In WINDOWS, a bitmap is a rectangular area containing an image. WINDOWS supports bitmaps made up of just two colors (black & white), bitmaps made up of millions of colors, and everything in between. Anyone can create their own bitmaps using WINDOWS Paintbrush and save them as *.BMP files. There are other ways to create bitmap files, including the use of scanning equipment to produce an image from paper. Electronic cameras are also becoming very popular.

Here we will examine Liberty BASIC's commands for loading bitmaps from a disk file and for displaying bitmaps into a graphics window or graphicbox control.

Here is a short program that loads one of the bitmaps that comes with Liberty BASIC and displays it in a graphics window:

'open a graphics window

open "Display a bitmap" for graphics as #bitmap

'load a bmp file, calling it "aBitmap"

loadbmp "aBitmap", "bmp\titlettt.bmp"

'draw the bitmap named aBitmap at position 50, 50 and flush it

print #bitmap, "drawbmp aBitmap 50 50"

print #bitmap, "flush"

wait

The LOADBMP statement is used to load the bitmap "bmp\titlettt.bmp" into memory. Liberty BASIC gives this bitmap the name "aBitmap" ("aBitmap" is NOT the filename of the bitmap file). See how this is used when sending the DRAWBMP command to the graphics window.

We can combine drawn graphics and bitmaps. Here is a small program that combines a drawn spiral and a bitmap file.

'combine graphics

open "Draw combined graphics" for graphics as #draw

'draw a spiral

print #draw, " home ; down"

for x = 1 to 100

print #draw, "turn 91 ; go "; x * 2

next x

'load a bmp file, calling it "aBitmap"

loadbmp "aBitmap", "bmp\titlettt.bmp"

'display the bitmap named aBitmap at position 100, 100

print #draw, "drawbmp aBitmap 100 100"

'flush the combined drawing

print #draw, "flush"

wait

Here's an example of this program that draws in a graphicbox instead of a graphics window type:

'draw in a graphicbox

graphicbox #main.draw, 10, 10, 150, 150

open "Graphicbox example" for dialog as #main

'draw a spiral

print #main.draw, " home ; down"

for x = 1 to 100

print #main.draw, "turn 91 ; go "; x * 2

next x

'load a bmp file, calling it "aBitmap"

loadbmp "aBitmap", "bmp\titlettt.bmp"

'display the bitmap named aBitmap at position 100, 100

print #main.draw, "drawbmp aBitmap 25 45"

'flush the combined drawing

print #main.draw, "flush"

wait

Using the idea above, a drawn graphic doesn't have to dominate the entire window.

Homework assignment

Write a program called STATUS.BAS that displays a graphic for one of these four status items:

- initial letter

- phone call

- mail information pack

- sale made

A dialog box should contain a graphicbox control to display the graphic, a listbox control to contain a list of the status item, and a statictext control to instruct the user to select a status item.

Four bitmap files have been included with this week's homework assignment. Their names are LETTER.BMP, CALL.BMP, BROCHURE.BMP, and SALE.BMP. You may use these files to display the graphic for each status item. Here is a short program that shows how to use a listbox control:

This let's take this idea and add some other controls to the dialog box:

'setup some colors

dim color$(5)

color$(0) = "red"

color$(1) = "green"

color$(2) = "blue"

statictext #main, "Pick a color:", 10, 10, 120, 20

listbox #main.colors, color$(, [loop], 10, 35, 120, 60

open "Listbox example" for dialog as #main

'tell the listbox where to branch on a single-click

print #main.colors, "singleclickselect [colorSelected]"

'wait here for user input

wait

[colorSelected] 'draw spiral in the selected color

print #main.colors, "selection? selectedColor$"

notice "You selected " + selectedColor$

wait

Week Five Homework Solution