1. Mark Dixon, SoCCE SOFT 131Page 1 03 – Debugging, Sound, and Graphics

2. Mark Dixon, SoCCE SOFT 131Page 2 Session Aims & Objectives Aims –introduce you to the fundamentals of: debugging sound, and graphics Objectives, by end of this week’s sessions, you should be able to: –identify & correct simple errors in your applications –put bitmap (raster) graphics into your applications –draw simple vector graphics in your applications –play MP3 and WAV files in your applications

3. Mark Dixon, SoCCE SOFT 131Page 3 Testing & Debugging: Errors 3 error types : –syntax: computer unable to understand your instructions (program does not execute), e.g. variable not defined (probably most common) –run-time: program can't execute instruction and exits (future lecture) Device unavailable (e.g. floppy drive) –logical: program executes but does not not match specification (do what was intended), e.g. clicking on button does nothing, when you thought you attached code to it clicking on blue button changes colour to red (when it should change to blue)

4. Mark Dixon, SoCCE SOFT 131Page 4 Computer –just symbol matching –No intelligence Example: Hello Errors Sub Command1_Cluck LabelL.Caption = "Hello" End Sub L instead of 1: causes syntax error (variable not defined) u instead of i: causes logical error (Command1 button does nothing)

5. Mark Dixon, SoCCE SOFT 131Page 5 Exercise: Errors The following example is from lecture 1, –Spot the errors (you should find 6), and –decide whether they are syntax or logical Private Sub btnBlue_Cluck() lblResult.BackColor = vbRed End Sub Private Sub btnRed_lick() lblResult.BackColor vbRed End Sub Private Sub lb1Result_DblClick() lblResult.BackColour = vbWhite End Sub

6. Mark Dixon, SoCCE SOFT 131Page 6 Debugging: Testing Functional Decomposition –break it into logical chunks Incremental Development –type a bit –test it Testing –test all/most combinations Regression Testing –repeat all previous tests

7. Mark Dixon, SoCCE SOFT 131Page 7 Types of Graphics: Raster Raster graphics – made of dots (pixels – picture elements) –stored in.jpg,.bmp, and.gif files –suitable for complex, static pictures (e.g. photos) –difficult to change programmatically –loses quality when enlarged:

8. Mark Dixon, SoCCE SOFT 131Page 8 Types of Graphics: Vector Vector graphics – made of objects (lines, circles, etc.) –suitable for simple, dynamic pictures (diagrams) –No loss of quality when enlarged

9. Mark Dixon, SoCCE SOFT 131Page 9 Example: PicView - Analysis SPECIFICATION User Requirements –display photos quickly and easily one after another Software Requirements –Functional: –change current folder and drive –display list of picture files in current folder –display picture (*.jpg, *.bmp, and *.gif) from files in current folder –Non-functional should be quick and easy to use PicView

10. Mark Dixon, SoCCE SOFT 131Page 10 Controls Picture Box: display pictures Drive List Box: allow user to select disk drive Directory List Box: allow user to select folder File List Box: allow user to select file

11. Mark Dixon, SoCCE SOFT 131Page 11 Controls' Properties Picture Box (pic) –Picture: allows display of bitmap (raster graphic) as background Drive List Box (drv) –Drive: the currently selected disk drive Directory List Box (dir) –Path: the currently selected directory (folder) File List Box (fil) –Path: the currently selected folder/directory –Pattern: only display this type of file (e.g..jpg) –FileName: the currently selected file

12. Mark Dixon, SoCCE SOFT 131Page 12 Example: PicView - Design User interface design: Functional design: Trigger (when)Actions (what) click event of Drive Boxmake drive current (directory box points to this drive) click event of Directory Boxmake folder current (file box points to this folder) click event of File Boxdisplay selected picture in picture box

13. Mark Dixon, SoCCE SOFT 131Page 13 Example: PicView - Code Option Explicit Private Sub drvMain_Change () dirMain.Path = drvMain.Drive End Sub Private Sub dirMain_Change () filMain.Path = dirMain.Path End Sub Private Sub filMain_Click () picMain.Picture = LoadPicture(filMain.Path & "\" & filMain.FileName) End Sub drvMain dirMain picMain filMain

14. Mark Dixon, SoCCE SOFT 131Page 14 Vector Graphics: Grid System the origin (position 0,0) is at top left –in mathematics it is always bottom left

15. Mark Dixon, SoCCE SOFT 131Page 15 Picture Box: Drawing Methods Methods (vector graphics) –Line: draws a straight line between 2 points –Circle: draws a circle –PSet: draws a dot (point) –Cls: clears (screen) drawing area

16. Mark Dixon, SoCCE SOFT 131Page 16 Example: Shapes Form and Picture Box control support graphics methods: 0 20001000 0 picDisplayArea.Line (500, 200)-(1900, 800) picDisplayArea.Line -(2600, 600) picDisplayArea.Line -Step(-600, -400) picDisplayArea.PSet (1500, 1000) picDisplayArea.Circle (700, 900), 300 Shapes

17. Mark Dixon, SoCCE SOFT 131Page 17 Example: StickMan Enabled property (true or false) StickMan

18. Mark Dixon, SoCCE SOFT 131Page 18 Example: Face Face

19. Mark Dixon, SoCCE SOFT 131Page 19 Example: Music Player - Analysis User Requirement: –to play different music for long time without interruption, at same location (while working or at party) Software Requirements Specification software should: –allow user to: select track (MP3 file) from folder on disk play selected track –automatically move to next track in folder go back to first after last has played later lecture

20. Mark Dixon, SoCCE SOFT 131Page 20 Additional Controls VB has hundreds of controls To include additional controls in your project: –Project menu –Components item Multimedia Control –plays MP3 & WAV files

21. Mark Dixon, SoCCE SOFT 131Page 21 Multimedia Controls' Properties Multi-media Control –FileName: name of file to play –Command: controls playback

22. Mark Dixon, SoCCE SOFT 131Page 22 Example: Music Player - Design Compare the following User Interface Designs: V0 V1

23. Mark Dixon, SoCCE SOFT 131Page 23 Example: Music Player - Code Option Explicit Private Sub drvMain_Change() dirMain.Path = drvMain.Drive End Sub Private Sub dirMain_Change() filMain.Path = dirMain.Path End Sub Private Sub filMain_Click() mmcMain.Command = "Close" mmcMain.FileName = filMain.Path & "\" & filMain.FileName mmcMain.Command = "Open" End Sub drvMaindirMain filMainmmcMain