 2002 Prentice Hall. All rights reserved. 1 Chapter 16 – Graphics and Multimedia Outline 只教 16.3 16.1Introduction 16.2 Graphics Contexts and Graphics.

 2002 Prentice Hall. All rights reserved. 1 Chapter 16 – Graphics and Multimedia Outline 只教 16.3 16.1Introduction 16.2 Graphics Contexts and Graphics Objects 16.3 Color Control 16.4 Font Control 16.5 Drawing Lines, Rectangles and Ovals 16.6 Drawing Arcs 16.7 Drawing Polygons and Polylines 16.8 Advanced Graphics Capabilities 16.9 Introduction to Multimedia 16.10 Loading, Displaying and Scaling Images 16.11 Animating a Series of Images 16.12 Windows Media Player 16.13 Microsoft Agent 16.3 Color Control

 2002 Prentice Hall. All rights reserved. 2 16.1Introduction GDI+ –extension of the Graphical Device Interface –System.Drawing and System.Drawing.Drawing2D Class Graphics –Various methods for drawing on a Control –Requires a Pen (shape outlines) or Brush (solid objects) Structure Color Font and FontFamily classes

 2002 Prentice Hall. All rights reserved. 4 16.1Introduction GDI+’s coordinate system –Upper-left corner of component has coordinates (0, 0) –Coordinate pairs Allow positioning of text and shapes Horizontal coordinate (x-coordinate) –Distance to the right from upper-left corner Vertical coordinate (y-coordinate) –Distance down from upper-left corner –Coordinate units measured in pixels –Used with structures Rectangle and Point

 2002 Prentice Hall. All rights reserved. 6 16.2 Graphics Contexts and Graphics Objects Graphics context –Represents drawing surface –Managed using a Graphics object Overridable OnPaint method –Inherited by every Form –Performs most graphics operations –Takes PaintEventArgs object as argument Graphics property contains Graphics object –Triggers Control ’s Paint event

 2002 Prentice Hall. All rights reserved. 7 16.2 Graphics Contexts and Graphics Objects Paint event handler versus overriding OnPaint –Painting as an event-driven process –Calling method Invalidate instead of OnPaint Passing Rectangle argument to Invalidate Graphics contexts for Control s –Each Control has its own graphics context Method CreateGraphics

 2002 Prentice Hall. All rights reserved. 8 16.3 Color Control Structure Color –ARGB values Alpha, red, green and blue values, respectively Each value represented as a Byte A, R, G, B properties Alpha value determines intensity –0 = transparent, 255 = opaque color –Alpha blending of RGB value and background color FromArgb method –Shared Color constants Color names representing RGB values (A = 255) FromName method

 2002 Prentice Hall. All rights reserved. 11 16.3 Color Control Pen objects –Used to draw lines –Constructors allow specification of color and drawing width –Pens collection ( System.Drawing ) contains predefined Pen s Brush objects –Used to color interiors of shapes –Abstract class –Various derived classes for fill styles –Upcoming example: Color value and alpha demonstration

 2002 Prentice Hall. All rights reserved. Outline 13 ShowColors.vb 1 ' Fig. 16.6: ShowColors.vb 2 ' Using different colors in Visual Basic. 3 4 Public Class FrmColorForm 5 Inherits System.Windows.Forms.Form 6 7 ' input text boxes 8 Friend WithEvents txtColorName As TextBox 9 Friend WithEvents txtGreenBox As TextBox 10 Friend WithEvents txtRedBox As TextBox 11 Friend WithEvents txtAlphaBox As TextBox 12 Friend WithEvents txtBlueBox As TextBox 13 14 ' set color command buttons 15 Friend WithEvents cmdColorName As Button 16 Friend WithEvents cmdColorValue As Button 17 18 ' color labels 19 Friend WithEvents lblBlue As Label 20 Friend WithEvents lblGreen As Label 21 Friend WithEvents lblRed As Label 22 Friend WithEvents lblAlpha As Label 23 24 ' group boxes 25 Friend WithEvents nameBox As GroupBox 26 Friend WithEvents colorValueGroup As GroupBox 27 28 ' Visual Studio.NET generated code 29 30 ' color for back rectangle 31 Private mBehindColor As Color = Color.Wheat 32 33 ' color for front rectangle 34 Private mFrontColor As Color = Color.FromArgb(100, 0, 0, 255) 35

 2002 Prentice Hall. All rights reserved. Outline 14 ShowColors.vb 36 ' overrides Form OnPaint method 37 Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs) 38 Dim graphicsObject As Graphics = e.Graphics ' get graphics 39 40 Dim textBrush As SolidBrush = _ 41 New SolidBrush(Color.Black) ' create text brush 42 43 Dim brush As SolidBrush = _ 44 New SolidBrush(Color.White) ' create solid brush 45 46 ' draw white background 47 graphicsObject.FillRectangle(brush, 4, 4, 275, 180) 48 49 ' display name of behindColor 50 graphicsObject.DrawString(mBehindColor.Name, Me.Font, _ 51 textBrush, 40, 5) 52 53 ' set brush color and display back rectangle 54 brush.Color = mBehindColor 55 56 graphicsObject.FillRectangle(brush, 45, 20, 150, 120) 57 58 ' display Argb values of front color 59 graphicsObject.DrawString("Alpha: " & mFrontColor.A & _ 60 " Red: " & mFrontColor.R & " Green: " & mFrontColor.G _ 61 & " Blue: " & mFrontColor.B, Me.Font, textBrush, _ 62 55, 165) 63 64 ' set brush color and display front rectangle 65 brush.Color = mFrontColor 66 67 graphicsObject.FillRectangle(brush, 65, 35, 170, 130) 68 End Sub ' OnPaint 69 Creates a black and white SolidBrush for drawing on the form Gets a reference to PaintEventArgs e ’s Graphics object and assigns it to Graphics object graphicsObject Graphics method FillRectangle draws a solid white rectangle with the Brush supplied as a parameter Assigns the ColormBehindColor value to the Brush ’s Color property and displays a rectangle

 2002 Prentice Hall. All rights reserved. Outline 15 ShowColors.vb 70 ' handle cmdColorValue click event 71 Private Sub cmdColorValue_Click(ByVal sender As _ 72 System.Object, ByVal e As System.EventArgs) _ 73 Handles cmdColorValue.Click 74 75 ' obtain new front color from text boxes 76 mFrontColor = Color.FromArgb(txtAlphaBox.Text, _ 77 txtRedBox.Text, txtGreenBox.Text, txtBlueBox.Text) 78 79 Invalidate() ' refresh Form 80 End Sub ' cmdColorValue_Click 81 82 Private Sub cmdColorName_Click(ByVal sender As _ 83 System.Object, ByVal e As System.EventArgs) _ 84 Handles cmdColorName.Click 85 86 ' set behindColor to color specified in text box 87 mBehindColor = Color.FromName(txtColorName.Text) 88 89 Invalidate() ' refresh Form 90 End Sub ' cmdColorName_Click 91 92 End Class ' FrmColorForm

 2002 Prentice Hall. All rights reserved. Outline 17 ShowColorsComple x.vb 1 ' Fig. 16.7: ShowColorsComplex.vb 2 ' Change the background and text colors of a form. 3 4 Imports System.Windows.Forms 5 6 Public Class FrmColorDialogTest 7 Inherits System.Windows.Forms.Form 8 9 Friend WithEvents cmdBackgroundButton As Button 10 Friend WithEvents cmdTextButton As Button 11 12 ' Visual Studio.NET generated code 13 14 ' change text color 15 Private Sub cmdTextButton_Click (ByVal sender As System.Object, _ 16 ByVal e As System.EventArgs) Handles cmdTextButton.Click 17 18 ' create ColorDialog object 19 Dim colorBox As ColorDialog = New ColorDialog() 20 Dim result As DialogResult 21 22 ' get chosen color 23 result = colorBox.ShowDialog() 24 25 If result = DialogResult.Cancel Then 26 Return 27 End If 28 29 ' assign forecolor to result of dialog 30 cmdBackgroundButton.ForeColor = colorBox.Color 31 cmdTextButton.ForeColor = colorBox.Color 32 End Sub ' cmdTextButton_Click 33 Define Button cmdTextButton’s event handler Creates new ColorDialog named colorBox and invokes ShowDialog method to display the window Sets the text color of both buttons to the selected color

 2002 Prentice Hall. All rights reserved. Outline 18 ShowColorsComple x.vb 34 ' change background color 35 Private Sub cmdBackgroundButton_Click( _ 36 ByVal sender As System.Object, _ 37 ByVal e As System.EventArgs) _ 38 Handles cmdBackgroundButton.Click 39 40 ' create ColorDialog object 41 Dim colorBox As ColorDialog = New ColorDialog() 42 Dim result As DialogResult 43 44 ' show ColorDialog and get result 45 colorBox.FullOpen = True 46 result = colorBox.ShowDialog() 47 48 If result = DialogResult.Cancel Then 49 Return 50 End If 51 52 ' set background color 53 Me.BackColor = colorBox.Color 54 End Sub ' cmdBackgroundButton_Click 55 56 End Class ' FrmColorDialogTest Defines the event handler for button cmdBackgroundButton Sets the dialog’s FullOpen property to True

 2002 Prentice Hall. All rights reserved. 20 16.4 Font Control Font s –After a Font is created, its properties cannot be modified –Programmers must create a new Font object to be different Font constructors –Must require a font name as an argument –They usually require the font size as an argument –And usually require the font style Font metrics –Height –Descent (the amount that characters dip below the baseline) –Ascent (the amount that characters rise above the baseline) –Leading (difference between ascent of one line and descent of the previous line)

 2002 Prentice Hall. All rights reserved. Outline 22 UsingFonts.vb 1 ' Fig. 16.9: UsingFonts.vb 2 ' Demonstrating various font settings. 3 4 Public Class FrmFonts 5 Inherits System.Windows.Forms.Form 6 7 ' Visual Studio.NET generated code 8 9 ' demonstrate various font and style settings 10 Protected Overrides Sub OnPaint( _ 11 ByVal paintEvent As PaintEventArgs) 12 13 Dim graphicsObject As Graphics = paintEvent.Graphics 14 Dim brush As SolidBrush = New SolidBrush(Color.DarkBlue) 15 16 ' arial, 12 pt bold 17 Dim style As FontStyle = FontStyle.Bold 18 Dim arial As Font = New Font( _ 19 New FontFamily("Arial"), 12, style) 20 21 ' times new roman, 12 pt regular 22 style = FontStyle.Regular 23 Dim timesNewRoman As Font = New Font( _ 24 "Times New Roman", 12, style) 25 26 ' courier new, 16 pt bold and italic 27 style = FontStyle.Bold Or FontStyle.Italic 28 Dim courierNew As Font = New Font("Courier New", _ 29 16, style) 30 31 ' tahoma, 18 pt strikeout 32 style = FontStyle.Strikeout 33 Dim tahoma As Font = New Font("Tahoma", 18, style) 34 Font constructor initializes Font objectsCreates a DarkBlue SolidBrush object ( brush ), causing all strings drawn with that brush to appear in DarkBlue

 2002 Prentice Hall. All rights reserved. Outline 23 UsingFonts.vb 35 graphicsObject.DrawString(arial.Name & " 12 point bold.", _ 36 arial, brush, 10, 10) 37 38 graphicsObject.DrawString(timesNewRoman.Name & _ 39 " 12 point plain.", timesNewRoman, brush, 10, 30) 40 41 graphicsObject.DrawString(courierNew.Name & _ 42 " 16 point bold and italic.", courierNew, brush, 10, 54 ) 43 44 graphicsObject.DrawString(tahoma.Name & _ 45 " 18 point strikeout.", tahoma, brush, 10, 75) 46 End Sub ' OnPaint 47 48 End Class ' FrmFonts

 2002 Prentice Hall. All rights reserved. Outline 26 UsingFontMetrics.vb 1 ' Fig. 16.12: UsingFontMetrics.vb 2 ' Displaying font metric information. 3 4 Imports System 5 Imports System.Drawing 6 Imports System.Drawing.Text 7 8 Public Class FrmFontMetrics 9 Inherits System.Windows.Forms.Form 10 11 ' Visual Studio.NET generated code 12 13 Protected Overrides Sub OnPaint( _ 14 ByVal paintEvent As PaintEventArgs) 15 16 Dim graphicsObject As Graphics = paintEvent.Graphics 17 Dim brush As SolidBrush = New SolidBrush(Color.Red) 18 Dim pen As Pen = New Pen(brush, Convert.ToSingle(2.5)) 19 20 ' Arial font metrics 21 Dim arial As Font = New Font("Arial", 12) 22 Dim family As FontFamily = arial.FontFamily 23 Dim sanSerif As Font = New Font("Microsoft Sans Serif", _ 24 14, FontStyle.Italic) 25 26 pen.Color = brush.Color 27 brush.Color = Color.DarkBlue 28 29 ' display Arial font metrics 30 graphicsObject.DrawString("Current Font: " & arial.ToString, _ 31 arial, brush, 10, 10) 32 33 graphicsObject.DrawString("Ascent: " & _ 34 family.GetCellAscent(FontStyle.Regular), arial, brush, _ 35 10, 30) 36 Creates Font arial and sets it to 12 point Arial font Uses class Font property FontFamily to obtain objects arial’s FontFamily object

 2002 Prentice Hall. All rights reserved. Outline 27 UsingFontMetrics.vb 37 graphicsObject.DrawString("Descent: " & _ 38 family.GetCellDescent(FontStyle.Regular), arial, brush, _ 39 10, 50) 40 41 graphicsObject.DrawString("Height: " & _ 42 family.GetEmHeight(FontStyle.Regular), _ 43 arial, brush, 10, 70) 44 45 graphicsObject.DrawString("Leading: " & _ 46 family.GetLineSpacing(FontStyle.Regular), arial, brush, _ 47 10, 90) 48 49 ' display Sans Serif font metrics 50 family = sanSerif.FontFamily 51 52 graphicsObject.DrawString("Current Font: " & _ 53 sanSerif.ToString(), sanSerif, brush, 10, 130) 54 55 graphicsObject.DrawString("Ascent: " & _ 56 family.GetCellAscent(FontStyle.Italic), _ 57 sanSerif, brush, 10, 150) 58 59 graphicsObject.DrawString("Descent: " & _ 60 family.GetCellDescent(FontStyle.Italic), sanSerif, _ 61 brush, 10, 170) 62 63 graphicsObject.DrawString("Height: " & family.GetEmHeight _ 64 (FontStyle.Italic), sanSerif, brush, 10, 190) 65 66 graphicsObject.DrawString("Leading: " & _ 67 family.GetLineSpacing(FontStyle.Italic), sanSerif, _ 68 brush, 10, 210) 69 End Sub ' OnPaint 70 71 End Class ' FrmFontMetrics Uses methods of class FontFamily to return integers specifying the ascent, descent, height and leading of the font

 2002 Prentice Hall. All rights reserved. 29 16.5 Drawing Lines, Rectangles and Ovals Drawing shape outlines –Versions that take a Pen and four Integer s are used Drawing solid shapes –Versions that take a Brush and four Integer s Integer arguments –First two represent the coordinates of the upper-left corner of the shape or its enclosing area –Last two indicate the shape’s width and height

 2002 Prentice Hall. All rights reserved. Outline 31 LinesRectanglesO vals.vb 1 ' Fig. 16.14: LinesRectanglesOvals.vb 2 ' Demonstrating lines, rectangles, and ovals. 3 4 Public Class FrmDrawing 5 Inherits System.Windows.Forms.Form 6 7 ' Visual Studio.NET generated code 8 9 ' display ovals lines, and rectangles 10 Protected Overrides Sub OnPaint( _ 11 ByVal paintEvent As PaintEventArgs) 12 13 ' get graphics object 14 Dim g As Graphics = paintEvent.Graphics 15 Dim brush As SolidBrush = New SolidBrush(Color.Blue) 16 Dim pen As Pen = New Pen(Color.AliceBlue) 17 18 ' create filled rectangle 19 g.FillRectangle(brush, 90, 30, 150, 90) 20 21 ' draw lines to connect rectangles 22 g.DrawLine(pen, 90, 30, 110, 40) 23 g.DrawLine(pen, 90, 120, 110, 130) 24 g.DrawLine(pen, 240, 30, 260, 40) 25 g.DrawLine(pen, 240, 120, 260, 130) 26 27 ' draw top rectangle 28 g.DrawRectangle(pen, 110, 40, 150, 90) 29 30 ' set brush to red 31 brush.Color = Color.Red 32 33 ' draw base Ellipse 34 g.FillEllipse(brush, 280, 75, 100, 50) 35 Method DrawLine takes a Pen and two pairs of Integer s, specifying the start and endpoint of the line Methods DrawRectangle and FillRectangle draw rectangles on the screen

 2002 Prentice Hall. All rights reserved. Outline 32 LinesRectanglesO vals.vb 36 ' draw connecting lines 37 g.DrawLine(pen, 380, 55, 380, 100) 38 g.DrawLine(pen, 280, 55, 280, 100) 39 40 ' draw Ellipse outline 41 g.DrawEllipse(pen, 280, 30, 100, 50) 42 End Sub ' OnPaint 43 44 End Class ' FrmDrawing

 2002 Prentice Hall. All rights reserved. 34 16.6 Drawing Arcs Arcs –Arcs are portions of ellipses –Measured in degrees, beginning at the starting angle and continuing for a specified number of degrees, the arc angle –An arc is said to sweep (traverse) its arc angle, beginning from its starting angle –Measuring Sweep in a clockwise direction, measured in positive degrees Sweep in a counterclockwise direction, measured in negative degrees –Graphics methods used to draw arcs DrawArc, DrawPie, and FillPie

 2002 Prentice Hall. All rights reserved. Outline 37 DrawArcs.vb 1 ' Fig. 16.18: DrawArcs.vb 2 ' Drawing various arcs on a form. 3 4 Public Class FrmArcTest 5 Inherits System.Windows.Forms.Form 6 7 ' Visual Studio.NET generated code 8 9 Protected Overrides Sub OnPaint( _ 10 ByVal paintEvent As PaintEventArgs) 11 12 ' get graphics object 13 Dim graphicsObject As Graphics = paintEvent.Graphics 14 Dim rectangle1 As Rectangle = New Rectangle(15, 35, 80, 80) 15 Dim brush1 As SolidBrush = New SolidBrush(Color.FireBrick) 16 Dim pen1 As Pen = New Pen(brush1, 1) 17 Dim brush2 As SolidBrush = New SolidBrush(Color.DarkBlue) 18 Dim pen2 As Pen = New Pen(brush2, 1) 19 20 ' start at 0 and sweep 360 degrees 21 graphicsObject.DrawRectangle(pen1, rectangle1) 22 graphicsObject.DrawArc(pen2, rectangle1, 0, 360) 23 24 ' start at 0 and sweep 110 degrees 25 rectangle1.Location = New Point(100, 35) 26 graphicsObject.DrawRectangle(pen1, rectangle1) 27 graphicsObject.DrawArc(pen2, rectangle1, 0, 110) 28 29 ' start at 0 and sweep -270 degrees 30 rectangle1.Location = New Point(185, 35) 31 graphicsObject.DrawRectangle(pen1, rectangle1) 32 graphicsObject.DrawArc(pen2, rectangle1, 0, -270) 33 Creates the objects needed to draw various arcsDraws a rectangle and then an arc inside the rectangle Changes the location of the Rectangle by setting its Location property to a new Point

 2002 Prentice Hall. All rights reserved. Outline 38 DrawArcs.vb 34 ' start at 0 and sweep 360 degrees 35 rectangle1.Location = New Point(15, 120) 36 rectangle1.Size = New Size(80, 40) 37 graphicsObject.DrawRectangle(pen1, rectangle1) 38 graphicsObject.FillPie(brush2, rectangle1, 0, 360) 39 40 ' start at 270 and sweep -90 degrees 41 rectangle1.Location = New Point(100, 120) 42 graphicsObject.DrawRectangle(pen1, rectangle1) 43 graphicsObject.FillPie(brush2, rectangle1, 270, -90) 44 45 ' start at 0 and sweep -270 degrees 46 rectangle1.Location = New Point(185, 120) 47 graphicsObject.DrawRectangle(pen1, rectangle1) 48 graphicsObject.FillPie(brush2, rectangle1, 0, -270) 49 End Sub ' OnPaint 50 51 End Class ' FrmArcTest Sets the Size property to a new Size object

 2002 Prentice Hall. All rights reserved. Outline 41 DrawPolygons.vb 1 ' Fig. 16.20: DrawPolygons.vb 2 ' Demonstrating polygons. 3 4 Public Class FrmPolygon 5 Inherits System.Windows.Forms.Form 6 7 ' polygon type options 8 Friend WithEvents filledPolygonRadio As RadioButton 9 Friend WithEvents lineRadio As RadioButton 10 Friend WithEvents polygonRadio As RadioButton 11 12 ' command buttons 13 Friend WithEvents cmdClear As Button 14 Friend WithEvents cmdNewColor As Button 15 16 Friend WithEvents drawWindow As Panel 17 Friend WithEvents typeGroup As GroupBox 18 19 ' Visual Studio.NET generated code 20 21 ' contains list of polygon points 22 Private mPoints As ArrayList = New ArrayList() 23 24 ' initialize default pen and brush 25 Dim mPen As Pen = New Pen(Color.DarkBlue) 26 Dim mBrush As SolidBrush = New SolidBrush(Color.DarkBlue) 27 28 ' draw panel mouse down event handler 29 Private Sub drawWindow_MouseDown(ByVal sender _ 30 As Object, ByVal e As _ 31 System.Windows.Forms.MouseEventArgs) _ 32 Handles drawWindow.MouseDown 33 Declares the Pen and Brush used to color our shapes Declaring ArrayList mPoints as a container for our Point objects allows the user to specify a variable number of points

 2002 Prentice Hall. All rights reserved. Outline 42 DrawPolygons.vb 34 ' Add mouse position to vertex list 35 mPoints.Add(New Point(e.X, e.Y)) 36 drawWindow.Invalidate() ' refresh panel 37 End Sub ' drawWindow_MouseDown 38 39 ' draw panel paint event handler 40 Private Sub drawWindow_Paint(ByVal sender As Object, _ 41 ByVal e As System.Windows.Forms.PaintEventArgs) _ 42 Handles drawWindow.Paint 43 44 ' get graphics object for panel 45 Dim graphicsObject As Graphics = e.Graphics 46 47 ' if arraylist has 2 or more points, display shape 48 If mPoints.Count > 1 Then 49 50 ' get array for use in drawing functions 51 Dim pointArray() As Point = _ 52 mPoints.ToArray(mPoints(0).GetType()) 53 54 If polygonRadio.Checked Then ' draw polygon 55 graphicsObject.DrawPolygon(mPen, pointArray) 56 57 ElseIf lineRadio.Checked Then ' draw lines 58 graphicsObject.DrawLines(mPen, pointArray) 59 60 ElseIf filledPolygonRadio.Checked Then ' draw filled 61 graphicsObject.FillPolygon(mBrush, pointArray) 62 End If 63 64 End If 65 66 End Sub ' drawWindow_Paint 67 Extracts an Array from the ArrayList via method ToArray

 2002 Prentice Hall. All rights reserved. Outline 43 DrawPolygons.vb 68 ' handle cmdClear click event 69 Private Sub cmdClear_Click(ByVal sender As System.Object, _ 70 ByVal e As System.EventArgs) Handles cmdClear.Click 71 72 mPoints = New ArrayList() ' remove points 73 74 drawWindow.Invalidate() ' refresh panel 75 End Sub ' cmdClear_Click 76 77 ' handle polygon radio button CheckedChange event 78 Private Sub polygonRadio_CheckedChanged(ByVal sender As _ 79 System.Object, ByVal e As System.EventArgs) _ 80 Handles polygonRadio.CheckedChanged 81 82 drawWindow.Invalidate() ' refresh panel 83 End Sub ' polygonRadio_CheckedChanged 84 85 ' handle line radio button CheckChanged event 86 Private Sub lineRadio_CheckedChanged(ByVal sender As _ 87 System.Object, ByVal e As System.EventArgs) _ 88 Handles lineRadio.CheckedChanged 89 90 drawWindow.Invalidate() ' refresh panel 91 End Sub ' lineRadio_CheckedChanged 92 93 ' handle filled polygon radio button CheckChanged event 94 Private Sub filledPolygonRadio_CheckedChanged(ByVal sender _ 95 As System.Object, ByVal e As System.EventArgs) _ 96 Handles filledPolygonRadio.CheckedChanged 97 98 drawWindow.Invalidate() ' refresh panel 99 End Sub ' filledPolygonRadio_CheckedChanged 100

 2002 Prentice Hall. All rights reserved. Outline 44 DrawPolygons.vb 101 ' handle cmdNewColor click event 102 Private Sub cmdNewColor_Click(ByVal sender As _ 103 System.Object, ByVal e As System.EventArgs) _ 104 Handles cmdNewColor.Click 105 106 ' create new color dialog 107 Dim colorBox As ColorDialog = New ColorDialog() 108 109 ' show dialog and obtain result 110 Dim result As DialogResult = colorBox.ShowDialog() 111 112 ' return if user cancels 113 If result = DialogResult.Cancel Then 114 Return 115 End If 116 117 mPen.Color = colorBox.Color ' set pen to new color 118 mBrush.Color = colorBox.Color ' set brush 119 drawWindow.Invalidate() ' refresh panel 120 End Sub ' cmdNewColor_Click 121 122 End Class ' FrmPolygon

 2002 Prentice Hall. All rights reserved. 46 16.8 Advanced Graphics Capabilities Visual Basic offers many additional graphics capabilities Examples –Brush hierarchy also includes: HatchBrush, LinearGradientBrush, PathGradientBrush and TextureBrush –Additional graphics features Dashed lines, thick lines, filling shapes with patterns, etc –General path A shape constructed from straight lines and complex curves

 2002 Prentice Hall. All rights reserved. Outline 47 DrawShapes.vb 1 ' Fig. 16.21: DrawShapes.vb 2 ' Drawing various shapes on a form. 3 4 Imports System.Drawing.Drawing2D 5 6 Public Class FrmDrawShapes 7 Inherits System.Windows.Forms.Form 8 9 ' Visual Studio.NET generated code 10 11 ' draw various shapes on form 12 Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs) 13 14 ' references to object we will use 15 Dim graphicsObject As Graphics = e.Graphics 16 17 ' ellipse rectangle and gradient brush 18 Dim drawArea1 As Rectangle = New Rectangle(5, 35, 30, 100) 19 Dim linearBrush As LinearGradientBrush = _ 20 New LinearGradientBrush(drawArea1, Color.Blue, _ 21 Color.Yellow, LinearGradientMode.ForwardDiagonal) 22 23 ' pen and location for red outline rectangle 24 Dim thickRedPen As Pen = New Pen(Color.Red, 10) 25 Dim drawArea2 As Rectangle = New Rectangle(80, 30, 65, 100) 26 27 ' bitmap texture 28 Dim textureBitmap As Bitmap = New Bitmap(10, 10) 29 Dim graphicsObject2 As Graphics = _ 30 Graphics.FromImage(textureBitmap) ' get bitmap graphics 31 32 ' brush and pen used throughout program 33 Dim solidColorBrush As SolidBrush = _ 34 New SolidBrush(Color.Red) 35 Dim coloredPen As Pen = New Pen(solidColorBrush) Creates LinearGradientBrush object Brush Creates a Pen object pen, and passes arguments Color.Red and Integer 10, indicating that we want pen to draw red lines that are 10 pixels wide Creates a new Bitmap image, which is initially empty

 2002 Prentice Hall. All rights reserved. Outline 48 DrawShapes.vb 36 37 ' draw ellipse filled with a blue-yellow gradient 38 graphicsObject.FillEllipse(linearBrush, 5, 30, 65, 100) 39 40 ' draw thick rectangle outline in red 41 graphicsObject.DrawRectangle(thickRedPen, drawArea2) 42 43 ' fill textureBitmap with yellow 44 solidColorBrush.Color = Color.Yellow 45 graphicsObject2.FillRectangle(solidColorBrush, 0, 0, 10, 10) 46 47 ' draw small black rectangle in textureBitmap 48 coloredPen.Color = Color.Black 49 graphicsObject2.DrawRectangle(coloredPen, 1, 1, 6, 6) 50 51 ' draw small blue rectangle in textureBitmap 52 solidColorBrush.Color = Color.Blue 53 graphicsObject2.FillRectangle(solidColorBrush, 1, 1, 3, 3) 54 55 ' draw small red square in textureBitmap 56 solidColorBrush.Color = Color.Red 57 graphicsObject2.FillRectangle(solidColorBrush, 4, 4, 3, 3) 58 59 ' create textured brush and display textured rectangle 60 Dim texturedBrush As TextureBrush = _ 61 New TextureBrush(textureBitmap) 62 63 graphicsObject.FillRectangle( _ 64 texturedBrush, 155, 30, 75, 100) 65 66 ' draw pie-shaped arc in white 67 coloredPen.Color = Color.White 68 coloredPen.Width = 6 69 graphicsObject.DrawPie( _ 70 coloredPen, 240, 30, 75, 100, 0, 270) Uses Graphics method FillEllipse to draw an ellipse with brush, the color gradually changes from blue to yellow

 2002 Prentice Hall. All rights reserved. Outline 49 DrawShapes.vb 71 72 ' draw lines in green and yellow 73 coloredPen.Color = Color.Green 74 coloredPen.Width = 5 75 graphicsObject.DrawLine(coloredPen, 395, 30, 320, 150) 76 77 ' draw a rounded, dashed yellow line 78 coloredPen.Color = Color.Yellow 79 coloredPen.DashCap = LineCap.Round 80 coloredPen.DashStyle = DashStyle.Dash 81 graphicsObject.DrawLine(coloredPen, 320, 30, 395, 150) 82 End Sub ' OnPaint 83 84 End Class ' FrmDrawShapes

 2002 Prentice Hall. All rights reserved. Outline 50 DrawStars.vb 1 ' Fig. 16.22: DrawStars.vb 2 ' Using paths to draw stars on a form. 3 4 Imports System.Drawing.Drawing2D 5 6 Public Class FrmDrawStars 7 Inherits System.Windows.Forms.Form 8 9 ' Visual Studio.NET generated code 10 11 ' create path and draw stars along it 12 Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs) 13 Dim graphicsObject As Graphics = e.Graphics 14 Dim i As Integer 15 Dim random As Random = New Random() 16 Dim brush As SolidBrush = _ 17 New SolidBrush(Color.DarkMagenta) 18 19 ' x and y points of path 20 Dim xPoints As Integer() = _ 21 {55, 67, 109, 73, 83, 55, 27, 37, 1, 43} 22 Dim yPoints As Integer() = _ 23 {0, 36, 36, 54, 96, 72, 96, 54, 36, 36} 24 25 ' create graphics path for star 26 Dim star As GraphicsPath = New GraphicsPath() 27 28 ' translate origin to (150, 150) 29 graphicsObject.TranslateTransform(150, 150) 30 31 ' create star from series of points 32 For i = 0 To 8 Step 2 33 star.AddLine(xPoints(i), yPoints(i), _ 34 xPoints(i + 1), yPoints(i + 1)) 35 Next Defines two Integer arrays, representing the x- and y-coordinates of the points in the star Defines GraphicsPath object star Sets the origin of the Graphics object

 2002 Prentice Hall. All rights reserved. Outline 51 DrawStars.vb 36 37 ' close shape 38 star.CloseFigure() 39 40 ' rotate origin and draw stars in random colors 41 For i = 1 To 18 42 graphicsObject.RotateTransform(20) 43 44 brush.Color = Color.FromArgb(random.Next(200, 255), _ 45 random.Next(255), random.Next(255), random.Next(255)) 46 47 graphicsObject.FillPath(brush, star) 48 Next 49 50 End Sub ' OnPaint 51 52 End Class ' FrmDrawStars Uses GraphicsPath method CloseFigure to complete the shapeDraws the star 18 times, rotating it around the origin Uses Graphics method RotateTransform to move to the next position on the form Graphics method FillPath draws a filled version of the star with the Brush created earlier

 2002 Prentice Hall. All rights reserved. 52 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

 2002 Prentice Hall. All rights reserved. Outline 54 DisplayLogo.vb 1 ' Fig. 16.23: DisplayLogo.vb 2 ' Displaying and resizing an image. 3 4 Public Class FrmDisplayLogo 5 Inherits System.Windows.Forms.Form 6 7 ' width controls 8 Friend WithEvents txtWidth As TextBox 9 Friend WithEvents lblWidth As Label 10 11 ' height controls 12 Friend WithEvents lblHeight As Label 13 Friend WithEvents txtHeight As TextBox 14 15 Private mGraphicsObject As Graphics 16 Private mImage As Image 17 18 ' sets member variables on form load 19 Private Sub FrmDisplayLogo_Load(ByVal sender As _ 20 System.Object, ByVal e As System.EventArgs) _ 21 Handles MyBase.Load 22 23 ' get Form's graphics object 24 mGraphicsObject = Me.CreateGraphics 25 26 ' load image 27 mImage = Image.FromFile("images/Logo.gif") 28 29 End Sub ' FrmDisplayLogo_Load 30 31 ' Visual Studio.NET generated code 32 Declares Image reference mImage Uses Form method CreateGraphics to create a Graphics object associated with the Form The Shared Image method FromFile retrieves an image stored on disk and assigns it to mImage

 2002 Prentice Hall. All rights reserved. Outline 55 DisplayLogo.vb 33 Private Sub cmdSetButton_Click (ByVal sender As System.Object, _ 34 ByVal e As System.EventArgs) Handles cmdSetButton.Click 35 36 ' get user input 37 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 problem 41 If (width > 375 OrElse height > 225) Then 42 MessageBox.Show("Height or Width too large") 43 44 Return 45 End If 46 mGraphicsObject.Clear(Me.BackColor) ' clear Windows Form 47 48 ' draw image 49 mGraphicsObject.DrawImage(mImage, 5, 5, width, height) 50 End Sub ' cmdSetButton_Click 51 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

 2002 Prentice Hall. All rights reserved. 57 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

 2002 Prentice Hall. All rights reserved. Outline 58 LogoAnimator.vb 1 ' Fig. 16.24: LogoAnimator.vb 2 ' Program that animates a series of images. 3 4 Public Class FrmLogoAnimator 5 Inherits System.Windows.Forms.Form 6 7 Private mImages As ArrayList = New ArrayList() 8 Private mCount As Integer = 1 9 10 Public Sub New() 11 MyBase.New() 12 13 ' This call is required by Windows Form Designer. 14 InitializeComponent() 15 16 ' load all images 17 Dim i As Integer 18 19 For i = 0 To 29 20 mImages.Add(Image.FromFile("images/deitel" & i _ 21 & ".gif")) 22 Next 23 24 ' load first image 25 logoPictureBox.Image = CType(mImages(0), Image) 26 27 ' set PictureBox to be same size as Image 28 logoPictureBox.Size = logoPictureBox.Image.Size 29 End Sub ' New 30 31 Friend WithEvents timer As System.Windows.Forms.Timer 32 33 Friend WithEvents logoPictureBox As _ 34 System.Windows.Forms.PictureBox 35 Load each of 30 images and place then in an ArrayList Places the first image in the PictureBox ArrayList method Add allows is to add objects to the ArrayList Modifies the size of the PictureBox so that it is equal to the size of the Image it is displaying

 2002 Prentice Hall. All rights reserved. Outline 59 LogoAnimator.vb 36 ' Visual Studio.NET generated code 37 38 Private Sub timer_Tick(ByVal sender As System.Object, _ 39 ByVal e As System.EventArgs) Handles timer.tick 40 41 ' increment counter 42 mCount = (mCount + 1) Mod 30 43 44 ' load next image 45 logoPictureBox.Image = CType(mImages(mCount), Image) 46 End Sub ' Timer_Tick 47 48 End Class ' FrmLogoAnimator The event handler for timer’s Tick event displays the next mage from the ArrayList

 2002 Prentice Hall. All rights reserved. Outline 60 Chesspiece.vb 1 ' Fig. 16.25 : Chesspiece.vb 2 ' Storage class for chess piece attributes. 3 4 Public Class CChessPiece 5 6 ' define chess-piece type constants 7 Public Enum Types 8 KING 9 QUEEN 10 BISHOP 11 KNIGHT 12 ROOK 13 PAWN 14 End Enum 15 16 Private mCurrentType As Integer ' this object's type 17 Private mPieceImage As Bitmap ' this object's image 18 19 ' default display location 20 Private mLocationRectangle As Rectangle = _ 21 New Rectangle(0, 0, 75, 75) 22 23 ' construct piece 24 Public Sub New(ByVal type As Integer, _ 25 ByVal xLocation As Integer, ByVal yLocation As Integer, _ 26 ByVal sourceImage As Bitmap) 27 28 mCurrentType = type ' set current type 29 mLocationRectangle.X = xLocation ' set current x location 30 mLocationRectangle.Y = yLocation ' set current y location 31 32 ' obtain pieceImage from section of sourceImage 33 mPieceImage = sourceImage.Clone(New Rectangle(type * 75, _ 34 0, 75, 75), Drawing.Imaging.PixelFormat.DontCare) 35 End Sub ' constructor Define a public enumeration of constants that identify each chess-piece type Rectangle object mLocationRectangle identifies the image location on the chess board Extract a subimage that contains only the current piece’s bitmap data

 2002 Prentice Hall. All rights reserved. Outline 61 Chesspiece.vb 36 37 ' draw this piece 38 Public Sub Draw(ByVal graphicsObect As Graphics) 39 graphicsObect.DrawImage(mPieceImage, mLocationRectangle) 40 End Sub ' Draw 41 42 ' obtain this piece's location rectangle 43 Public Readonly Property LocationRectangle As Rectangle 44 Get 45 Return mLocationRectangle 46 End Get 47 End Property ' LocationRectangle 48 49 ' set this piece's location 50 Public Sub SetLocation(ByVal xLocation As Integer, _ 51 ByVal yLocation As Integer) 52 53 mLocationRectangle.X = xLocation 54 mLocationRectangle.Y = yLocation 55 End Sub ' SetLocation 56 57 End Class ' CChesspiece Method Draw causes the CChessPiece to draw mPieceImage in mLocationRectangle on the passed Graphics object

 2002 Prentice Hall. All rights reserved. Outline 62 ChessGame.vb 1 ' Fig. 16.26: ChessGame.vb 2 ' Chess Game graphics code. 3 4 Imports System.Drawing.Drawing2D 5 6 Public Class FrmChessSurface 7 Inherits System.Windows.Forms.Form 8 9 ' display box 10 Friend WithEvents pieceBox As PictureBox 11 12 ' game menu 13 Friend WithEvents gameMenu As MainMenu 14 Friend WithEvents gameItem As MenuItem 15 Friend WithEvents newGame As MenuItem 16 17 ' Visual Studio.NET generated code 18 19 ' ArrayList for board tile images 20 Dim mChessTile As ArrayList = New ArrayList() 21 22 ' ArrayList for chess pieces 23 Dim mChessPieces As ArrayList = New ArrayList() 24 25 ' define index for selected piece 26 Dim mSelectedIndex As Integer = -1 27 Dim mBoard As Integer(,) = New Integer(7,7) {} ' board array 28 29 ' define chess tile size in pixels 30 Private Const TILESIZE As Integer = 75 31 Class FrmChessSurface defines the game and graphics code for our chess game ArrayListmChessTile stores the board tile images ArrayListmChessPieces stores all active CChessPiece objects IntegermSelectedIndex identifies the index in mChessPieces of the currently selected pieces Integer TILESIZE is a constant defining the size of each tile in pixels

 2002 Prentice Hall. All rights reserved. Outline 63 ChessGame.vb 32 ' load tile bitmaps and reset game 33 Private Sub FrmChessSurface_Load(ByVal sender _ 34 As System.Object, ByVal e As System.EventArgs) _ 35 Handles MyBase.Load 36 37 ' load chess board tiles 38 mChessTile.Add(Bitmap.FromFile("lightTile1.png")) 39 mChessTile.Add(Bitmap.FromFile("lightTile2.png")) 40 mChessTile.Add(Bitmap.FromFile("darkTile1.png")) 41 mChessTile.Add(Bitmap.FromFile("darkTile2.png")) 42 43 ResetBoard() ' initialize board 44 Invalidate() ' refresh form 45 End Sub ' FrmChessSurface_Load 46 47 ' initialize pieces to start positions and rebuild board 48 Private Sub ResetBoard() 49 Dim column As Integer = 0 50 Dim row As Integer = 0 51 Dim current As Integer 52 Dim piece As CChessPiece 53 Dim random As Random = New Random() 54 Dim light As Boolean = False 55 Dim type As Integer 56 57 ' ensure empty arraylist 58 mChessPieces = New ArrayList() 59 60 ' load whitepieces image 61 Dim whitePieces As Bitmap = _ 62 Bitmap.FromFile("whitePieces.png") 63 64 ' load blackpieces image 65 Dim blackPieces As Bitmap = _ 66 Bitmap.FromFile("blackPieces.png") The FrmChessSurface load event loads each tile image into mChessTile Method ResetBoard assigns mChessPieces to a new ArrayList

 2002 Prentice Hall. All rights reserved. Outline 64 ChessGame.vb 67 68 ' set whitepieces drawn first 69 Dim selected As Bitmap = whitePieces 70 71 ' traverse board rows in outer loop 72 For row = 0 To mBoard.GetUpperBound(0) 73 74 ' if at bottom rows, set to black piece images 75 If row > 5 Then 76 selected = blackPieces 77 End If 78 79 ' traverse board columns in inner loop 80 For column = 0 To mBoard.GetUpperBound(1) 81 82 ' if first or last row, organize pieces 83 If (row = 0 OrElse row = 7) Then 84 85 Select Case column 86 87 Case 0, 7 ' set current piece to rook 88 current = CChessPiece.Types.ROOK 89 90 Case 1, 6 ' set current piece to knight 91 current = CChessPiece.Types.KNIGHT 92 93 Case 2, 5 ' set current piece to bishop 94 current = CChessPiece.Types.BISHOP 95 96 Case 3 ' set current piece to king 97 current = CChessPiece.Types.KING 98 99 Case 4 ' set current piece to queen 100 current = CChessPiece.Types.QUEEN 101 End Select Loops through 64 positions on the chess board, setting the tile color and piece for each tile Causes the currently selected image to switch to the blackPieces after the fifth row

 2002 Prentice Hall. All rights reserved. Outline 65 ChessGame.vb 102 103 ' create current piece at start position 104 piece = New CChessPiece(current, _ 105 column * TILESIZE, row * TILESIZE, selected) 106 107 ' add piece to ArrayList 108 mChessPieces.Add(piece) 109 End If 110 111 ' if second or seventh row, organize pawns 112 If (row = 1 OrElse row = 6) Then 113 piece = New CChessPiece(CChessPiece.Types.PAWN, _ 114 column * TILESIZE, row * TILESIZE, selected) 115 116 mChessPieces.Add(piece) 117 End If 118 119 ' determine board piece type 120 type = random.Next(0, 2) 121 122 If light Then ' set light tile 123 mBoard(row, column) = type 124 light = False 125 Else ' set dark tile 126 mBoard(row, column) = type + 2 127 light = True 128 End If 129 130 Next ' next column 131 132 ' account for new row tile color switch 133 light = Not light 134 Next ' next row 135 136 End Sub ' ResetBoard Add a new pawn at the current location if the current row is second or seventh Assigns the current board-tile color as an index in the mBoard array

 2002 Prentice Hall. All rights reserved. Outline 66 ChessGame.vb 137 138 ' display board in form OnPaint event 139 Protected Overrides Sub OnPaint(ByVal paintEvent _ 140 As PaintEventArgs) 141 142 ' obtain graphics object 143 Dim graphicsObject As Graphics = paintEvent.Graphics 144 Dim row, column As Integer 145 146 For row = 0 To mBoard.GetUpperBound(0) 147 148 For column = 0 To mBoard.GetUpperBound(1) 149 150 ' draw image specified in board array 151 graphicsObject.DrawImage( _ 152 CType(mChessTile(mBoard(row, column)), _ 153 Image), New Point(TILESIZE * column, _ 154 TILESIZE * row)) 155 Next 156 157 Next 158 159 End Sub ' OnPaint 160 161 ' return index of piece that intersects point 162 ' optionally exclude a value 163 Private Function CheckBounds(ByVal point As Point, _ 164 Optional ByVal exclude As Integer = -1) As Integer 165 166 Dim rectangle As Rectangle ' current bounding rectangle 167 Dim i As Integer 168 Method OnPaint overrides class Form’s OnPaint method and draws the tiles according to their values in the board array Method CheckBounds is a collision-detection helper method

 2002 Prentice Hall. All rights reserved. Outline 67 ChessGame.vb 169 For i = 0 To mChessPieces.Count - 1 170 171 ' get piece rectangle 172 rectangle = Getpiece(i).LocationRectangle() 173 174 ' check if rectangle contains point 175 If (rectangle.Contains(point) AndAlso i <> exclude) Then 176 Return i 177 End If 178 179 Next 180 181 Return -1 182 End Function ' CheckBounds 183 184 ' handle pieceBox pain event 185 Private Sub pieceBox_Paint(ByVal sender As System.Object, _ 186 ByVal e As System.Windows.Forms.PaintEventArgs) _ 187 Handles pieceBox.Paint 188 189 Dim i As Integer 190 191 ' draw all pieces 192 For i = 0 To mChessPieces.Count - 1 193 Getpiece(i).Draw(e.Graphics) 194 Next 195 196 End Sub ' pieceBox_Paint 197

 2002 Prentice Hall. All rights reserved. Outline 68 ChessGame.vb 198 ' on MouseDown event, select chess piece 199 Private Sub pieceBox_MouseDown(ByVal sender As System.Object, _ 200 ByVal e As System.Windows.Forms.MouseEventArgs) _ 201 Handles pieceBox.MouseDown 202 203 ' determine selected piece 204 mSelectedIndex = CheckBounds(New Point(e.X, e.Y)) 205 End Sub ' pieceBox_MouseDown 206 207 ' if piece is selected, move it 208 Private Sub pieceBox_MouseMove(ByVal sender As System.Object, _ 209 ByVal e As System.Windows.Forms.MouseEventArgs) _ 210 Handles pieceBox.MouseMove 211 212 If mSelectedIndex > -1 Then 213 214 Dim region As Rectangle = New Rectangle(e.X - _ 215 TILESIZE * 2, e.Y - TILESIZE * 2, TILESIZE * 4, _ 216 TILESIZE * 4) 217 218 ' set piece center to mouse 219 Getpiece(mSelectedIndex).SetLocation(e.X - _ 220 TILESIZE / 2, e.Y - TILESIZE / 2) 221 222 ' refresh immediate area 223 pieceBox.Invalidate(region) 224 End If 225 226 End Sub ' pieceBox_MouseMove 227 The MouseDown event handler calls method CheckBounds with the location of the user’s click to determine whether the user selected a piece The MouseMove event handler moves the currently selected piece with the mouse Define a refresh a region of the Panel that spans two tiles in every from the mouse

 2002 Prentice Hall. All rights reserved. Outline 69 ChessGame.vb 228 ' on mouse up, deselect chess piece and remove taken piece 229 Private Sub pieceBox_MouseUp(ByVal sender As _ 230 System.Object, ByVal e As _ 231 System.Windows.Forms.MouseEventArgs) _ 232 Handles pieceBox.MouseUp 233 234 Dim remove As Integer = -1 235 236 If mSelectedIndex > -1 Then ' if chess piece was selected 237 238 Dim current As Point = New Point(e.X, e.Y) 239 Dim newPoint As Point = New Point(current.X - _ 240 current.X Mod TILESIZE, current.Y - _ 241 current.Y Mod TILESIZE) 242 243 ' check bounds with point, exclude selected piece 244 remove = CheckBounds(current, mSelectedIndex) 245 246 ' snap piece into center of closest square 247 Getpiece(mSelectedIndex).SetLocation(newPoint.X, _ 248 newPoint.Y) 249 250 mSelectedIndex = -1 ' deselect piece 251 252 ' remove taken piece 253 If remove > -1 Then 254 mChessPieces.RemoveAt(remove) 255 End If 256 257 End If 258 259 ' refresh pieceBox to ensure artifact removal 260 pieceBox.Invalidate() 261 End Sub ' pieceBox_MouseUp 262 Define the MouseUp event handler Checks whether any piece is beneath the current mouse location Determine the closest valid chess tile and “snap” the selected piece to that location Panel is Invalidated in order to display the new piece location and remove any artifacts created during the move

 2002 Prentice Hall. All rights reserved. Outline 70 ChessGame.vb 263 ' helper function to convert ArrayList object as CChesspiece 264 Private Function Getpiece(ByVal i As Integer) _ 265 As CChessPiece 266 267 Return CType(mChessPieces(i), CChessPiece) 268 End Function ' Getpiece 269 270 ' handle NewGame menu option click 271 Private Sub NewGame_Click(ByVal sender As Object, _ 272 ByVal e As System.EventArgs) Handles NewGame.Click 273 274 ResetBoard() ' re-initialize board 275 Invalidate() ' refresh form 276 End Sub ' NewGame_Click 277 278 End Class ' FrmChessSurface Define helper function GetPiece that simplifies the conversion from Objects in the ArrayListmChessPieces to CChessPiece types

 2002 Prentice Hall. All rights reserved. 74 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)

 2002 Prentice Hall. All rights reserved. Outline 75 MediaPlayerTest. vb 1 ' Fig 16.27: MediaPlayerTest.vb 2 ' Demonstrates the Windows Media Player control 3 4 Public Class FrmMediaPlayer 5 Inherits System.Windows.Forms.Form 6 7 ' action menus 8 Friend WithEvents applicationMenu As MainMenu 9 Friend WithEvents fileItem As MenuItem 10 Friend WithEvents openItem As MenuItem 11 Friend WithEvents exitItem As MenuItem 12 Friend WithEvents aboutItem As MenuItem 13 Friend WithEvents aboutMessageItem As MenuItem 14 15 ' media player control 16 Friend WithEvents player As AxMediaPlayer.AxMediaPlayer 17 Friend WithEvents openMediaFileDialog As OpenFileDialog 18 19 ' Visual Studio.NET generated code 20 21 ' open new media file in Windows Media Player 22 Private Sub openItem_Click(ByVal sender As System.Object, _ 23 ByVal e As System.EventArgs) Handles openItem.Click 24 25 openMediaFileDialog.ShowDialog() 26 27 player.FileName = openMediaFileDialog.FileName 28 29 ' adjust the size of the Media Player control and the 30 ' Form according to the size of the image 31 player.Size = New Size( _ 32 player.ImageSourceWidth, player.ImageSourceHeight) 33 34 Me.Size = New Size(player.Size.Width + 20, _ 35 player.Size.Height + 60) 36 End Sub ' openItem_Click Adjust the size of the player and the application to reflect the size of the media contained in the file

 2002 Prentice Hall. All rights reserved. Outline 76 MediaPlayerTest. vb 37 38 ' exit application 39 Private Sub exitItem_Click(ByVal sender As System.Object, _ 40 ByVal e As System.EventArgs) Handles exitItem.Click 41 42 Application.Exit() 43 End Sub ' exitItem_Click 44 45 ' show the About box for Windows Media Player 46 Private Sub aboutMessageItem_Click(ByVal sender As _ 47 System.Object, ByVal e As System.EventArgs) _ 48 Handles aboutMessageItem.Click 49 50 player.AboutBox() 51 End Sub ' aboutMessageItem_Click 52 53 End Class ' FrmMediaPlayer The event handler that executes when the user chooses About Windows Media Player from the About menu calls the AboutBox method of the player

 2002 Prentice Hall. All rights reserved. 79 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 Agent technology enables users to interact with applications Web pages through speech When the user speaks into a microphone the control uses a speech recognition engine that translates vocal sound into a language that computer understands A text speech engine is an application that translates typed words into audio sound that users hear through headphones or speakers connected to a computer

 2002 Prentice Hall. All rights reserved. Outline 89 Agent.vb 1 ' Fig. 16.37: Agent.vb 2 ' Demonstrating Microsoft Agent. 3 4 Imports System.IO 5 Imports System.Collections 6 Imports System.Windows.Forms 7 8 Public Class FrmAgent 9 Inherits System.Windows.Forms.Form 10 11 ' options 12 Friend WithEvents characterCombo As ComboBox 13 Friend WithEvents actionsCombo As ComboBox 14 15 Friend WithEvents GroupBox1 As GroupBox 16 Friend WithEvents cmdSpeak As Button 17 Friend WithEvents mainAgent As AxAgentObjects.AxAgent 18 19 ' input boxes 20 Friend WithEvents txtLocation As TextBox 21 Friend WithEvents txtSpeech As TextBox 22 23 ' current agent object 24 Private mSpeaker As AgentObjects.IAgentCtlCharacter 25 26 ' Visual Studio.NET generated code 27 28 ' keyDown event handler for locationTextBox 29 Private Sub txtLocation_KeyDown(ByVal sender As _ 30 Object, ByVal e As System.Windows.Forms.KeyEventArgs)_ 31 Handles txtLocation.KeyDown 32 33 If e.KeyCode = Keys.Enter Then 34 Create an object named mSpeaker

 2002 Prentice Hall. All rights reserved. Outline 90 Agent.vb 35 ' set character location to text box value 36 Dim location As String = txtLocation.Text 37 38 ' initialize characters 39 Try 40 41 ' load characters into agent object 42 mainAgent.Characters.Load( _ 43 "Genie", location & "Genie.acs") 44 45 mainAgent.Characters.Load( _ 46 "Merlin", location & "Merlin.acs") 47 48 mainAgent.Characters.Load( _ 49 "Peedy", location & "Peedy.acs") 50 51 mainAgent.Characters.Load( _ 52 "Robby", location & "Robby.acs") 53 54 ' disable TextBox location and enable other controls 55 txtLocation.Enabled = False 56 txtSpeech.Enabled = True 57 cmdSpeak.Enabled = True 58 characterCombo.Enabled = True 59 actionsCombo.Enabled = True 60 61 ' set current character to Genie and show 62 mSpeaker = mainAgent.Characters("Genie") 63 GetAnimationNames() ' obtain animation name list 64 mSpeaker.Show(0) 65 66 Catch fileNotFound As FileNotFoundException 67 MessageBox.Show("Invalid character location", _ 68 "Error", MessageBoxButtons.OK, _ 69 MessageBoxIcon.Error) 70 End Try Disable txtLocation and enable the rest of the controls Set Genie as a default character

 2002 Prentice Hall. All rights reserved. Outline 91 Agent.vb 71 72 End If 73 74 End Sub ' txtLocation_KeyDown 75 76 ' speak button event handler 77 Private Sub cmdSpeak_Click(ByVal sender As System.Object, _ 78 ByVal e As System.EventArgs) Handles cmdSpeak.Click 79 80 ' if TextBox is empty, have character ask 81 ' user to type words into TextBox, otherwise 82 ' have character say words in TextBox 83 If txtSpeech.Text = "" Then 84 mSpeaker.Speak( _ 85 "Please type the words you want me to speak", "") 86 Else 87 mSpeaker.Speak(txtSpeech.Text, "") 88 End If 89 90 End Sub ' cmdSpeak_Click 91 92 ' click event for agent 93 Private Sub mainAgent_ClickEvent(ByVal sender As Object _ 94 Object, ByVal e As AxAgentObjects._AgentEvents_ClickEvent)_ 95 Handles mainAgent.ClickEvent 96 97 mSpeaker.Play("Confused") 98 mSpeaker.Speak("Why are you poking me?", "") 99 mSpeaker.Play("RestPose") 100 End Sub ' mainAgent_ClickEvent 101 When the user clicks the character, event handler mainAgent_ClickEvent executes First, mSpeaker method Play plays animation

 2002 Prentice Hall. All rights reserved. Outline 92 Agent.vb 102 ' comboBox changed event, switch active agent 103 Private Sub characterCombo_SelectedIndexChanged(ByVal _ 104 sender As System.Object, ByVal e As System.EventArgs) _ 105 Handles characterCombo.SelectedIndexChanged 106 107 ChangeCharacter(characterCombo.Text) 108 End Sub ' characterCombo_SelectedIndexChanged 109 110 ' hide current character and show new 111 Private Sub ChangeCharacter(ByVal name As String) 112 mSpeaker.Hide(0) 113 mSpeaker = mainAgent.Characters(name) 114 GetAnimationNames() ' regenerate animation name list 115 mSpeaker.Show(0) 116 End Sub ' ChangeCharacter 117 118 ' get animation names and store in arraylist 119 Private Sub GetAnimationNames() 120 121 ' ensure thread safety 122 SyncLock (Me) 123 124 ' get animation names 125 Dim enumerator As IEnumerator = _ 126 mainAgent.Characters.Character( _ 127 mSpeaker.Name).AnimationNames.GetEnumerator() 128 129 Dim voiceString As String 130 131 ' clear cboActions combo box 132 actionsCombo.Items.Clear() 133 mSpeaker.Commands.RemoveAll() 134 Method GetAnimationNames fills the actionsCombo ComboBox with the current character’s animation listing and defines the valid commands Assigns the newly selected character to mSpeaker Generates the character’s animation names and commands Method Show displays the character

 2002 Prentice Hall. All rights reserved. Outline 93 Agent.vb 135 ' copy enumeration to ArrayList 136 While enumerator.MoveNext() 137 138 ' remove underscores in speech string 139 voiceString = Convert.ToString(enumerator.Current) 140 voiceString = voiceString.Replace("_", "underscore") 141 142 actionsCombo.Items.Add(enumerator.Current) 143 144 ' add all animations as voice enabled commands 145 mSpeaker.Commands.Add(Convert.ToString( _ 146 enumerator.Current,, voiceString, True, False) 147 End While 148 149 ' add custom command 150 mSpeaker.Commands.Add("MoveToMouse", "MoveToMouse", _ 151 "MoveToMouse", True, True) 152 End SyncLock 153 154 End Sub ' GetAnimationNames 155 156 ' user selects new action 157 Private Sub actionsCombo_SelectedIndexChanged(ByVal sender _ 158 As System.Object, ByVal e As System.EventArgs) _ 159 Handles actionsCombo.SelectedIndexChanged 160 161 mSpeaker.Stop() 162 mSpeaker.Play(actionsCombo.Text) 163 mSpeaker.Play("RestPose") 164 End Sub ' actionsCombo_SelectedIndexChanged 165 Iterate through all items in the animation name enumerator Removes any underscore characters and replaces them with String “underscore” The Add method of the Commands property adds a new command to the current character Creates a new command named MoveToMouse that is visible in the Commands pop-up window

 2002 Prentice Hall. All rights reserved. Outline 94 Agent.vb 166 ' handles agent commands 167 Private Sub mainAgent_Command(ByVal sender As System.Object, _ 168 ByVal e As AxAgentObjects._AgentEvents_CommandEvent) _ 169 Handles mainAgent.Command 170 171 ' get UserInput object 172 Dim command As AgentObjects.IAgentCtlUserInput = _ 173 CType(e.userInput, AgentObjects.IAgentCtlUserInput) 174 175 ' change character if user speaks character name 176 If (command.Voice = "Peedy" OrElse _ 177 command.Voice = "Robby" OrElse _ 178 command.Voice = "Merlin" OrElse _ 179 command.Voice = "Genie") Then 180 ChangeCharacter(command.Voice) 181 182 Return 183 End If 184 185 ' send agent to mouse 186 If command.Name = "MoveToMouse" Then 187 mSpeaker.MoveTo(Convert.ToInt16( _ 188 Cursor.Position.X - 60), Convert.ToInt16( _ 189 Cursor.Position.Y - 60)) 190 191 Return 192 End If 193 194 ' play new animation 195 mSpeaker.Stop() 196 mSpeaker.Play(command.Name) 197 198 End Sub ' mainAgent_Command 199 200 End Class ' FrmAgent Uses method ChangeCharacter to change the current Agent character if the user speaks a character name Moves the character to the current mouse location if the user invokes the MoveToMouse command

 2002 Prentice Hall. All rights reserved. 1 Chapter 16 – Graphics and Multimedia Outline 只教 16.3 16.1Introduction 16.2 Graphics Contexts and Graphics.

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 2002 Prentice Hall. All rights reserved. 1 Chapter 16 – Graphics and Multimedia Outline 只教 16.3 16.1Introduction 16.2 Graphics Contexts and Graphics.

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Presentation on theme: " 2002 Prentice Hall. All rights reserved. 1 Chapter 16 – Graphics and Multimedia Outline 只教 16.3 16.1Introduction 16.2 Graphics Contexts and Graphics."— Presentation transcript:

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