16.9 Introduction to Multimedia

• Visual Basic offers many convenient ways to include images and animations in programs

• Computing field decades ago mainly used computers to perform arithmetic calculations– We are beginning to realize the importance of computer’s

data-manipulation capabilities

• Multimedia programming presents many challenges• Multimedia applications demand extraordinary

computing power

16.10 Loading, Displaying and Scrolling Images

• Visual Basic’s multimedia capabilities– Graphics– Images– Animations– Video

• Image manipulation

1 ' Fig. 16.23: DisplayLogo.vb2 ' Displaying and resizing an image.3 4 Public Class FrmDisplayLogo5 Inherits System.Windows.Forms.Form6 15 Private mGraphicsObject As Graphics16 Private mImage As Image17 18 ' sets member variables on form load19 Private Sub FrmDisplayLogo_Load(ByVal sender As _20 System.Object, ByVal e As System.EventArgs) _21 Handles MyBase.Load22 23 ' get Form's graphics object24 mGraphicsObject = Me.CreateGraphics25 26 ' load image27 mImage = Image.FromFile("images/Logo.gif")28 29 End Sub ' FrmDisplayLogo_Load30

Uses Form method CreateGraphics to create a Graphics object associated with the Form

The Image method FromFile retrieves an image stored on disk and assigns it to mImage

33 Private Sub cmdSetButton_Click (ByVal sender As System.Object, _34 ByVal e As System.EventArgs) Handles cmdSetButton.Click35 36 ' get user input37 Dim width As Integer = Convert.ToInt32(txtWidth.Text)38 Dim height As Integer = Convert.ToInt32(txtHeight.Text)39 40 ' if specified dimensions are too large display problem41 If (width > 375 OrElse height > 225) Then42 MessageBox.Show("Height or Width too large")43 44 Return45 End If46 mGraphicsObject.Clear(Me.BackColor) ' clear Windows Form47 48 ' draw image49 mGraphicsObject.DrawImage(mImage, 5, 5, width, height)50 End Sub ' cmdSetButton_Click51 52 End Class ' FrmDisplayLogo

If the parameters are valid, Graphics method Clear is called to paint the entire Form in the current background color

Graphics method DrawImage is called with the following parameters: the image to draw, the x-coordinate of the upper-left corner, y-coordinate of the upper-left corner, width of the image, and height of the image

16.11 Animating a Series of Images

• Two-dimensional collision detection– Two-dimensional collision detection is the detection of an

overlap between two shapes

• Chess Board– Defined by alternating light and dark tiles across a row in

the pattern where the color that starts each row is equal to the color of last tile of previous row

• Artifacts– An artifact is any unintended visual abnormality in a

graphical program

Places the first image in the PictureBox

Modifies the size of the PictureBox so that it is equal to the size of the Image it is displaying

Load each of 30 images and place then in an ArrayList

The event handler for timer’s Tick event displays the next mage from the ArrayList.Timer interval = 50 ms

16.12 Windows Media Player

• Windows Media player – Enables an application to play video and sound in

many multimedia formats• Motion Pictures Experts Group (MPEG)• Audio-Video Interleave (AVI)• Windows wave-file format (WAV)• Musical Instrument Digital Interface (MIDI)

– To use the Windows Media Player control, programmers must add the control to the Toolbox. This is accomplished as following:

1. Go to ToolBox Choose Items...

2. Click on the COM Components tab and scroll down near the bottom of the List. Look for Windows Media Player.

3. When you have found Windows Media Player, check the box beside it and click on Ok.

16.12 Windows Media Player

4. The windows media player control should now be in your Toolbox

5. Drag the control over a form and size it as needed.

16.12 Windows Media Player

16.13 Microsoft Agent

• Microsoft Agent– Microsoft Agent is a technology used to add interactive animated

characters to Windows applications or Web pages• Microsoft Agent control provides programmers with access to four

predefined characters: Genie (a genie), Merlin (a wizard), Peedy (a parrot), and Robby (a robot).

• Microsoft provides basic information on Agent technology at its Web site:

www.microsoft.com/msagent

• This section introduces the basic capabilities of the Microsoft Agent control. For complete details on downloading this control, visit:

http://www.microsoft.com/msagent/downloads/user.aspx

• The following example, Peedy’s Pizza Palace, was developed by Microsoft to illustrate the capabilities of the Microsoft Agent control.

• You can view this example at: http://www.microsoft.com/msagent/sdk/samples/html/peedypza.htm

16.13 Microsoft Agent

Fig. 16.28 Peedy introducing himself when the window opens.

• To use MS Agent, you have to add to your ToolBox:

1. Go to ToolBox Choose Items... 2. Click on the COM Components tab and scroll down near the bottom of the List. Check MS Agent Control.

3. Drag it to your form

• Before running any code, you first must download and install the control, speech recognition engine, text to speech engine and the character definitions from the Microsoft Agent Web site listed previously.

16.13 Microsoft Agent

In addition to the Microsoft Agent object myAgent (of type AxAgent) that managesall the characters, we also need an object (of type IAgentCtlCharacter) to representthe current character. We create this object, named mSpkr,