DX: Full Screen GUI Development 1

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Full Screen GUI Development

Pt 1 ?The Basics

By Jim (Machaira) Perry

 

 

In this article we抣l look at developing a GUI for full-screen DirectX games. The code accompanying this article may be used as a base for developing your own GUI class. It will necessarily be simplistic, but may give you an idea of how to go about writing your own GUI code.

 

This article assumes a working knowledge of DirectX 7 and VB classes.

 

Download this tutorial (in Word format) and the sample projects in a zip file (336 KB)

 

When you think of a GUI you think in terms of windows, so the base class will handle most normal window properties and draw the bitmap used to represent the window. A bitmap for a simple window could look like the following.

 

 

This window has no Control Box or minimize, maximize, and close buttons. It抯 about as simple as you can get. See the window.bmp file.

 

Several example of more complex GUI抯 are below:

Figure 1 - Quake III Arena GUI

Figure 2 - Unreal Tournament GUI

 

Our GUI class won抰 quite be up to the task of handling something like this, but it抣l eventually be pretty useful.

 

Below is a first try at a base window class (see the WindowSample1 project):

 

ClsWindow Class

 

Option Explicit

 

Private objBitmap As DirectDrawSurface7

 

Private iX As Integer

Private iY As Integer

Private iWidth As Integer

Private iHeight As Integer

 

'Center the window against the parent window

'For a base window the parent is the screen

Private bCenterX As Boolean

Private bCenterY As Boolean

 

'Used for centering purposes

Private iParentWidth As Integer

Private iParentHeight As Integer

Private iParentX As Integer

Private iParentY As Integer

 

Public Property Let X(ByVal iData As Integer)

    iX = iData

End Property

 

Public Property Get X() As Integer

    X = iX

End Property

 

Public Property Let Y(ByVal iData As Integer)

    iY = iData

End Property

 

Public Property Get Y() As Integer

    Y = iY

End Property

 

'Only Property Get for Width and Height properties

'since they are set by the dimensions of the bitmap

Public Property Get Width() As Integer

    Width = iWidth

End Property

 

Public Property Get Height() As Integer

    Height = iHeight

End Property

 

Public Property Let CenterX(ByVal bData As Boolean)

    bCenterX = bData

    iX = ((iParentWidth / 2) + iParentX) - (iWidth / 2)

End Property

 

Public Property Get CenterX() As Boolean

    CenterX = bCenterX

End Property

 

Public Property Let CenterY(ByVal bData As Boolean)

    bCenterY = bData

    iY = ((iParentHeight / 2) + iParentY) - (iHeight / 2)

End Property

 

Public Property Get CenterY() As Boolean

    CenterY = bCenterY

End Property

 

Public Property Let ParentWidth(ByVal iData As Integer)

    iParentWidth = iData

End Property

 

Public Property Get ParentWidth() As Integer

    ParentWidth = iParentWidth

End Property

 

Public Property Let ParentHeight(ByVal iData As Integer)

    iParentHeight = iData

End Property

 

Public Property Get ParentHeight() As Integer

    ParentHeight = iParentHeight

End Property

 

Public Property Let ParentX(ByVal iData As Integer)

    iParentX = iData

End Property

 

Public Property Get ParentX() As Integer

    ParentX = iParentX

End Property

 

Public Property Let ParentY(ByVal iData As Integer)

    iParentY = iData

End Property

 

Public Property Get ParentY() As Integer

    ParentY = iParentY

End Property

 

Public Property Let ObjectSurface(ByVal objSurface As DirectDrawSurface7)

   

    Dim ddsd As DDSURFACEDESC2

   

    Set objBitmap = objSurface

   

    objBitmap.GetSurfaceDesc ddsd

   

    iHeight = ddsd.lHeight

    iWidth = ddsd.lWidth

   

End Property

 

Public Function DrawObject(objSurface As DirectDrawSurface7)

   

    Dim rectObject As RECT

    Dim rectBitmap As RECT

   

    On Error GoTo DrawObjectErr

   

    rectBitmap.Left = iX

    rectBitmap.Right = iX + iWidth

    rectBitmap.Top = iY

    rectBitmap.Bottom = iY + iHeight

            

    objSurface.Blt rectBitmap, objBitmap, rectObject, DDBLT_WAIT

 

    Exit Function

   

DrawObjectErr:

    Exit Function

End Function

 

Take a look at the InitDD function in the modDirectDraw module. The following code creates the window object:

 

    Window.ObjectSurface = objDD.CreateSurfaceFromFile(App.Path & "\window.bmp", ddsdSurf2)

    Window.ParentX = 0

    Window.ParentY = 0

    Window.ParentHeight = 600

    Window.ParentWidth = 800

    Window.CenterX = True

    Window.CenterY = True

 

This will simply draw a bitmap of a window centered on the screen. It doesn抰 handle input and contains no controls. Although this is a good start it doesn抰 really offer us much. Some other things are necessary. The ability to put controls on the window is one of them. Since controls are only windows themselves with some additional properties, we can use the clsWindow class to represent them with some modifications.

 

We want the base window to know about the controls it contains. A collection is a simple way to allow this. Add the following to the Declarations section of the clsWindow class (see the WindowSample2 project):

 

Private colChildren As New Collection

 

This collection will hold references to the controls that the window that contains them. We need a function to allow us to add controls to the class. The following function will handle that:

 

Public Sub AddChild(clsChild As clsWindow)

    colChildren.Add clsChild

End Sub

 

Since there are many types of controls we抣l need a way to tell what kind of control we抮e placing on the window. Add the following to the Declarations section as well:

 

Private iObjectType As eObjectType

Private iObjectState As eObjectState

 

and add the following to the modMain module:

 

Public Enum eObjectState

    iEnabled

    iDisabled

    iPressed

    iChecked

    iUnchecked

    iChecked_iDisabled

End Enum

 

Public Enum eObjectType

    Btn

    ChkBox

End Enum

 

These enums will represent the type of control and the state of that control. These enums will grow as new control types and states are added to them. For now a button and a checkbox are enough to demonstrate their usage.

 

Now we need objects of the new window types. Add the following to the modDirectDraw module:

 

Public OKButton As New clsWindow

Public Check As New clsWindow

 

These will represent the new controls. This will require us to update the InitDD function as well. Add the following to the function:

 

    Dim ddsdSurf3 As DDSURFACEDESC2

    Dim ddsdSurf4 As DDSURFACEDESC2

 

    OKButton.ObjectSurface = objDD.CreateSurfaceFromFile(App.Path & "\ok.bmp", ddsdSurf3)

    OKButton.ObjectType = Btn

    OKButton.ObjectState = iEnabled

    OKButton.ParentHeight = Window.Height

    OKButton.ParentWidth = Window.Width

    OKButton.ParentX = Window.X

    OKButton.ParentY = Window.Y

    OKButton.CenterX = True

    OKButton.CenterY = True

   

    Window.AddChild OKButton

       

    Check.ObjectSurface = objDD.CreateSurfaceFromFile(App.Path & "\check.bmp", ddsdSurf4)

    Check.ObjectType = ChkBox

    Check.ObjectState = iUnchecked

    Check.ParentHeight = Window.Height

    Check.ParentWidth = Window.Width

    Check.ParentX = Window.X

    Check.ParentY = Window.Y

    Check.X = 200

    Check.Y = 200

   

    Window.AddChild Check

Take a look at the ok.bmp and check.bmp files. These are the bitmaps that are used for the controls. Notice that there are several versions of the control in the file. They represent the various states that the control can have. For the button bitmap they are iEnabled, iPressed, and iDisabled. The checkbox has iUnchecked, iChecked, iDisabled, and iChecked_iDisabled. The iEnabled enum could have been used instead of the iUnchecked, but I felt it wouldn抰 have described the state of the control as well. Notice also that we抮e centering the button inside the window, but setting the X and Y coordinates of the checkbox. We抳e also added the text 揙K?to the bitmap for the button, but this could have been left out. This will be done later when we add text support to the class. This will also allow us to add text to the checkbox and the window.

 

Change the Property Let ObjectSurface to the following:

 

    Dim ddsd As DDSURFACEDESC2

   

    Set objBitmap = objSurface

   

    objBitmap.GetSurfaceDesc ddsd

   

    iWidth = ddsd.lWidth

    Select Case iObjectType

        Case Btn

            iHeight = ddsd.lHeight / 3

        Case ChkBox

            iHeight = ddsd.lHeight / 4

        Case BaseWindow

            iHeight = ddsd.lHeight

    End Select

 

This will handle the new types of controls. This could also have been done by adding Property Let statements to the class and setting the Width and Height properties in the InitDD function.

 

Now we need to handle clicking on the controls. Add the following to the clsWindow class:

 

Public Sub MouseDown(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Single, ByVal Y As Single)

   

    Dim iLp As Integer

   

    If X >= iX And X <= iX + iWidth And Y >= iY And Y <= iY + iHeight Then

       

        For iLp = 1 To colChildren.Count

            colChildren(iLp).MouseDown Button, Shift, X, Y

        Next iLp

 

        If Not (iObjectState = iDisabled) Then

            Select Case iObjectType

                Case ChkBox

                    If iObjectState = iChecked Then

                        iObjectState = iUnchecked

                    Else

                        iObjectState = iChecked

                    End If

                Case Btn

                    iObjectState = iPressed

            End Select

        End If

    End If

   

End Sub

 

Public Sub MouseUp(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Single, ByVal Y As Single)

   

    Dim iLp As Integer

   

    If Not (iObjectState = iDisabled) Then

        If iObjectState = iPressed And iObjectType = Btn Then iObjectState = iEnabled

    End If

   

    For iLp = 1 To colChildren.Count

        colChildren(iLp).MouseUp Button, Shift, X, Y

    Next iLp

   

End Sub

 

and add the following to the frmMain form抯 code:

 

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)

    Window.MouseDown Button, Shift, X, Y

End Sub

 

Private Sub Form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)

    Window.MouseUp Button, Shift, X, Y

End Sub

 

Notice that we only have to call the mouse events for the base window. The class handles calling the events for the controls it contains.

 

So what are we missing? Oh yes, we need to know how to draw the controls. Replace the DrawObject function with the following:

 

Public Function DrawObject(objSurface As DirectDrawSurface7)

   

    Dim clsWindow As clsWindow

    Dim iLp As Integer

    Dim ddsd As DDSURFACEDESC2

    Dim rectBitmap As RECT

    Dim rectObject As RECT

   

    On Error GoTo DrawObjectErr

   

    rectBitmap.Left = iX

    rectBitmap.Right = iX + iWidth

    rectBitmap.Top = iY

    rectBitmap.Bottom = iY + iHeight

   

    Select Case iObjectType

        Case Btn

           

            rectObject.Left = 0

            rectObject.Right = iWidth

            rectObject.Top = 0

            rectObject.Bottom = iHeight

            

            Select Case iObjectState

                Case iDisabled

                    rectObject.Top = iHeight * 2

                    rectObject.Bottom = iHeight * 3

                Case iPressed

                    rectObject.Top = iHeight

                    rectObject.Bottom = iHeight * 2

            End Select

           

        Case ChkBox

           

            rectObject.Left = 0

            rectObject.Right = iWidth

            rectObject.Top = 0

            rectObject.Bottom = iHeight

           

            Select Case iObjectState

                Case iDisabled

                    rectObject.Top = iHeight * 2

                    rectObject.Bottom = iHeight * 3

                Case iChecked

                    rectObject.Top = iHeight

                    rectObject.Bottom = iHeight * 2

                Case iChecked_iDisabled

                    rectObject.Top = iHeight * 3

                    rectObject.Bottom = iHeight * 4

            End Select

       

        Case BaseWindow

            'Nothing needed here since we use the base rectangle

    End Select

   

    objSurface.Blt rectBitmap, objBitmap, rectObject, DDBLT_WAIT

   

    For iLp = 1 To colChildren.Count

        colChildren(iLp).DrawObject objSurface

    Next iLp

   

    Exit Function

   

DrawObjectErr:

    Exit Function

   

End Function

 

What抯 Next?

 

The first part of this series is an intro into creating a relatively full-fledged GUI for your game. The next article will deal with some more advanced pieces ?more controls and adding additional properties for the controls, including text properties. If there is anything specific you would like to see, please e-mail me or post on the board for the site where you found this article (if applicable).

 

Feel free to modify this code as you see fit. Hopefully you抣l find a use for it, even though it抯 still in it抯 infant form.

 

See you next time!

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