Learn to Program with Small Basic

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Note You’ll need Small Basic version 1.1 or later to use the Flickr object. The ImageViewer.sb program includes a text box into which the user enters the search tag and a button (labeled Next). When the user clicks the button, the program uses the Flickr object to get (and display) an image that matches the user’s search tag. The program is shown in Listing 12-7. 1 ' ImageViewer.sb 2 GraphicsWindow.DrawText(10, 14, "Search for an image:") 3 tagText = Controls.AddTextBox(140, 10) 4 Controls.SetSize(tagText, 160, 26) 5 Controls.AddButton("Next", 305, 10) 6 7 Controls.ButtonClicked = OnButtonClicked 8 9 Sub OnButtonClicked 10 tag = Controls.GetTextBoxText(tagText) 11 If (tag "") Then 12 img = ImageList.LoadImage(Flickr.GetRandomPicture(tag)) 13 If (img = "") Then 14 GraphicsWindow.ShowMessage("No images found.", "Sorry.") 15 Else 16 GraphicsWindow.Width = ImageList.GetWidthOfImage(img) 17 GraphicsWindow.Height = ImageList.GetHeightOfImage(img) + 40 18 GraphicsWindow.DrawImage(img, 0, 40) 19 EndIf 20 EndIf 21 EndSub Listing 12-7: Loading images from Flickr The program starts by designing the GUI (lines 2–5) and registering the ButtonClicked event handler (line 7). When the button is clicked, the OnButtonClicked() subroutine gets the search text from the text box and saves it in the tag variable (line 10). If tag isn’t empty (line 11), the code searches Flickr using the given tag text for a random picture and then grabs the URL (line 12) by using Flickr.GetRandomPicture(). That URL is passed to ImageList.LoadImage(), which loads an image from a file or the Internet and saves it into the img variable (line 12). If img is empty, which means Flickr didn’t find an image with the user’s tag, you let the user know in a message box (line 14). If Flickr found an image, you resize the graphics window to the dimensions of the loaded image (lines 16–17) and draw the image directly below the text box and the button (line 18). Building Graphical User Interfaces 177
TRY IT OUT 12-4 Write a program to ask the user what their favorite animal is. Then search for that animal using the Flickr object and display the returned image. Next, ask the user, “Like this one?” and show them two buttons labeled Yes and No. If the user clicks Yes, display Hooray! in a message box. If they click No, display a different random picture of that animal and ask, “How about this one?” Continue these steps until the user clicks Yes. You’ve just turned a simple program into a game! Programming Challenges If you get stuck, check out http://nostarch.com/smallbasic/ for the solutions and for more resources and review questions for teachers and students. 1. In this program, you’ll create a hidden treasure game. Open the file HiddenTreasure_Incomplete.sb from this chapter’s folder. When you run the program, you’ll see the following interface. The purpose of the game is to guess the location of a hidden treasure. The player makes a guess by pressing one of the four buttons. If they guess correctly, they gain $10. Otherwise, they lose $5. The game ends after 10 rounds. Follow the comments shown in the program’s source code to write the missing code and complete the program. 178 Chapter 12
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Learn to Program with Small Basic A
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Learn to Program with Small Basic A
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Brief Contents Foreword by Vijaye R
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Exploring Other Features. .........
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7 Empowering Programs with math 83
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12 building Graphical User Interfac
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Storing Records. ..................
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Foreword Computer programming is ma
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Acknowledgments This book represent
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Introduction Have you ever wondered
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• In Chapter 11: Event-Driven Pro
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1 Introducing Small Basic Bill Gate
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BASIC language that would help kids
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Toolbar Help Area Editor Surface Fi
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Then click the New button to open a
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Helping Hands: IntelliSense and Syn
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Programming Challenges If you get s
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The Parts of a Program Let’s expl
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The method’s name and a brief des
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5 + 7 12 Here’s the output of thi
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For example, to make the TextWindow
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TRY IT OUT 2-3 Now you have a chanc
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Programming Errors Just because a p
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26 Chapter 2 4. Write a program tha
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In the system you use at school, po
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Drawing Shapes You can draw lots of
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Figure 3-6 shows what the output lo
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22 GraphicsWindow.BrushColor = "Lig
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DrawText() takes three arguments. T
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GraphicsWindow provides two methods
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6. Write a program that draws this
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4 Using Variables Have you ever wan
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Try changing the value in karenBear
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These two ways of updating the scor
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Figure 4-2: How a variable is added
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TRY IT OUT 4-3 Write a program that
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Two Kinds of Data Programs use all
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5 Drawing Shapes with Turtle Graphi
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Absolute Motion With absolute motio
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North 0 (360) 315 (-45) 45 (-315) W
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GraphicsWindow.PenColor = "Red" Gra
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The For loop runs Turtle.Move(60) a
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y 5). For the hexagon (the polygon
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Creating Polygon Art Using Nested L
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Endless Graphics In Listing 5-10 yo
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Write a program to have the turtle
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Talking to the Computer Until now,
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Figure 6-2: The text window waiting
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4 C = (5 / 9) * (F - 32) 5 C = Math
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9 noun = TextWindow.Read() 10 11 Te
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7 Empowering Programs with Math If
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Here’s a sample run of our progra
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Round() -4 -3.5 -3 0 3 3.5 4 Round(
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This code snippet shows you some ex
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Let’s walk through this program l
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Trigonometric Methods Trigonometric
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Programming Challenges If you get s
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Small Basic uses a few different wa
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You can test all sorts of condition
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Small Basic first finds the value o
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Your mom’s instructions assume th
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But wait, your mom just realized th
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This code asks the user to enter a
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9 Using Decisions to Make Games Som
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Condition 1 True Statement set 1 If
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This change to the program means th
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Door 1 Door 2 Door 3 Figure 9-6: Pe
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Listing 9-4 shows an example of usi
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Think of the Shapes object as a “
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Background image (Grid.png) Star.pn
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In Figure 9-8, you see that the gri
Page 152 and 153: This code asks the player to enter
Page 154 and 155: 10 Solving Problems with Subroutine
Page 156 and 157: Gulliver later learned that 1 glum-
Page 158 and 159: TRY IT OUT 10-1 When Gulliver asked
Page 160 and 161: variables that belong to the main p
Page 162 and 163: 4 TextWindow.WriteLine("Your turn.
Page 164 and 165: 1 step away). If the arrow hits the
Page 166 and 167: Then you set the graphics window’
Page 168 and 169: 24 Shapes.SetText(msgText, "") 25 T
Page 170 and 171: Step 8: Shoot Arrows with ShootArro
Page 172 and 173: Lines 3-7 animate the dragon’s fi
Page 174 and 175: 11 Event-Driven Programming So far,
Page 176 and 177: GraphicsWindow Events Let’s start
Page 178 and 179: 4 5 Sub OnKeyDown 6 GraphicsWindow.
Page 180 and 181: 13 Else 14 GraphicsWindow.DrawText(
Page 182 and 183: Useful Tips Before moving on, we’
Page 184 and 185: 21 GraphicsWindow.BrushColor = "Red
Page 186 and 187: 4 XG = Math.GetRandomNumber(8) - 1
Page 188: Programming Challenges If you get s
Page 191 and 192: Today, most programs use a graphica
Page 193 and 194: located at (100, 100). By default,
Page 195 and 196: 9 GraphicsWindow.MouseMove = OnMous
Page 197 and 198: Let’s look at the computations. Y
Page 199 and 200: You start by loading the two backgr
Page 201: (line 8). If the total resistance i
Page 206 and 207: 13 Repeating For Loops Have you eve
Page 208 and 209: Each For loop starts with the keywo
Page 210 and 211: The program uses a variable named s
Page 212 and 213: TRY IT OUT 13-5 What does the follo
Page 214 and 215: Nested Loops The statements in the
Page 216 and 217: Figure 13-7: The output of Stamp.sb
Page 218: 2. Although the pizza in the previo
Page 221 and 222: In this chapter, you’ll learn how
Page 223 and 224: Note Although it’s not required b
Page 225 and 226: asks the user for the correct answe
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Page 229 and 230: Step 4: Announce the Winner The las
Page 232 and 233: 15 Grouping Data in One-Dimensional
Page 234 and 235: One way to think of an array is as
Page 236 and 237: The string initializer lets you fil
Page 238 and 239: TextWindow.WriteLine("Enter 5 numbe
Page 240 and 241: how much money was rescued from eac
Page 242 and 243: To create this program, we’ll use
Page 244 and 245: The apples fall from the trees. Usi
Page 246 and 247: The subroutine uses a For loop to c
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Associative Arrays In the previous
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The expression If("ernie" = "Ernie"
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Here’s the output from a sample r
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The ContainsIndex() method takes tw
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Figure 16-1 shows the user interfac
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1 Sub OnButtonClicked 2 GraphicsWin
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17 Expanding to Higher-Dimension Ar
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1 ' Random2DArray.sb 2 For r = 1 To
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Animated Squares Let’s write a pr
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12 TextWindow.Write("Enter student
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(line 8). Line 9 displays Scott's M
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You start by initializing the sum v
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4 For col = 1 To 4 ' For each colum
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note If you run into any problems,
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First, you set all the elements of
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11 If ((rowP < 1) Or (rowP > 10) Or
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Open the file Okla.sb from this cha
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(both uppercase and lowercase), dig
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Taking Strings Apart: Substrings Ju
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two arguments: the source string th
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Here’s an output example: Who's y
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More on Code Points The Unicode cod
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Line 7 gets the Nth character of th
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Igpay Atinlay Let’s teach the com
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17 TextWindow.WriteLine("Good Job!"
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9 pos = Math.GetRandomNumber(len) '
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When you continue with the second a
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TRY IT OUT 18-10 Use the techniques
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19 Receiving File Input and Output
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and their meanings. File extensions
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program’s folder (right-click the
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in the file would run together in o
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Let’s experiment with the first p
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line number. As with the WriteLine(
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WARNING If the destination path poi
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6 For N = 1 To count ' Displays the
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wizard asks the user to perform. Th
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Figure 19-8 shows a sample run of t
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Where to Go from Here So you’ve m
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Index Numbers and Symbols 3DArrayDe
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squares, 31-32 star, 65-66 triangle
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integrated development environment
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parts of, 14-16 publishing, 5-6 run
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NewGame() subroutine, 255-256 OnBut
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ages 10 and up “Welcome to the ma
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Learn to Program with Small Basic

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