Flicker Issues

[Jneiswin]

I am experimenting with making a game focused on crafting. At the moment, i have a 100x100 tileset with four sprites. Background, character, tree, tree stump.

It creates 8 trees and places them randomly on the form, move the character over the tree and press space to chop it down (change it to the stump image)

But every time you move the whole screen flickers. It MIGHT be just my computer, but I have a feeling it's the redraw. Not sure how to lower flickering.

Imports System.Drawing

Public Class Form1

    Dim G As Graphics
    Dim BBG As Graphics
    Dim sRect As Rectangle
    Dim dRect As Rectangle
    Dim bmap As Bitmap
    Dim BB As Bitmap
    Dim NumberOfTrees As Integer = 8
    Dim GuyY As Integer = 0
    Dim GuyX As Integer = 0
    Dim Trees As Integer
    Dim X2 As Integer = Nothing
    Dim Y2 As Integer = Nothing
    Dim XArray(NumberOfTrees - 1) As Integer
    Dim YArray(NumberOfTrees - 1) As Integer
    Dim Stumps(NumberOfTrees - 1) As Integer

    Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

        Select Case e.KeyCode
            Case Keys.W
                GuyY = GuyY - 50
            Case Keys.A
                GuyX = GuyX - 50
            Case Keys.S
                GuyY = GuyY + 50
            Case Keys.D
                GuyX = GuyX + 50
            Case Keys.Space
                ChopTree()
        End Select

        DrawAll()
        DrawTrees()

    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        bmap = New Bitmap(PictureBox1.Image)
        G = Me.CreateGraphics
        BB = New Bitmap(Me.Width, Me.Height)

        For Me.Trees = 0 To NumberOfTrees - 1
            Me.XArray(Me.Trees) = Int(Rnd() * 9) * 50
            Me.YArray(Me.Trees) = Int(Rnd() * 9) * 50
        Next

        DrawAll()
        DrawTrees()

    End Sub

    Private Sub ChopTree()

        For Me.Trees = 0 To NumberOfTrees - 1
            If GuyX = Me.XArray(Me.Trees) Then
                If GuyY = Me.YArray(Me.Trees) Then
                    Me.Stumps(Me.Trees) = 1
                End If
            End If
        Next

    End Sub

    Private Sub DrawAll()

        Dim X, Y As Integer

        For X = 0 To 9
            For Y = 0 To 9
                sRect = New Rectangle(0, 0, 50, 50)
                dRect = New Rectangle(X * 50, Y * 50, 50, 50)
                G.DrawImage(bmap, dRect, sRect, GraphicsUnit.Pixel)
            Next
        Next

        For Me.Trees = 0 To NumberOfTrees - 1

            If Me.Stumps(Me.Trees) = 0 Then
                sRect = New Rectangle(50, 0, 50, 50)
                G.DrawImage(bmap, Me.XArray(Me.Trees), Me.YArray(Me.Trees), sRect, GraphicsUnit.Pixel)
                G = (Graphics.FromImage(BB))
                BBG = Me.CreateGraphics
                BBG.DrawImage(BB, 0, 0, Me.Width, Me.Height)
            End If

            If Me.Stumps(Me.Trees) = 1 Then
                sRect = New Rectangle(0, 50, 50, 50)
                G.DrawImage(bmap, Me.XArray(Me.Trees), Me.YArray(Me.Trees), sRect, GraphicsUnit.Pixel)
                G = (Graphics.FromImage(BB))
                BBG = Me.CreateGraphics
                BBG.DrawImage(BB, 0, 0, Me.Width, Me.Height)
            End If
        Next

        bmap.MakeTransparent(Color.Fuchsia)
        sRect = New Rectangle(50, 50, 50, 50)
        G.DrawImage(bmap, GuyX, GuyY, sRect, GraphicsUnit.Pixel)

        G = (Graphics.FromImage(BB))
        BBG = Me.CreateGraphics
        BBG.DrawImage(BB, 0, 0, Me.Width, Me.Height)

    End Sub

    Private Sub Form1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint

        DrawAll()
        DrawTrees()

    End Sub

    Private Sub DrawTrees()


    End Sub

End Class

[Jacob Roman]

Try adding Me.Doublebuffer = True to the Form_Load statement. That should eliminate the flicker

[Jneiswin]

When I turn on double buffering, rather it be in the load, the drawall(), or anywhere, it makes the screen blank. It shows the graphics at first when the program loads, but then quickly disappears.

[Atheist]

Dont call Me.CreateGraphics, do all drawing from your paint eventhandler and use the Graphics instance supplied to you by the e.Graphics property.

[Jenner]

Yea, do something like this, first, delete "Dim G as Graphic", then change your "DrawAll" and "DrawTrees" to take the following:

Private Sub DrawAll(ByRef G As Graphics)
.....

Private Sub DrawTrees(ByRef G As Graphics)
.....

Finally, change the Draw override to:

    Private Sub Form1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint

        DrawAll(e.Graphics)
        DrawTrees(e.Graphics)

    End Sub

I'll warn you, it'll probably still be flickery if you get too fancy or too fast with it. GDI+ can only draw so fast. DoubleBuffer buys you some elbowroom in the mean time.

[Jneiswin]

I have started a new project to rewrite the code, leaving the original in tact to remind myself of how I did some things. I'm now drawing to a bitmap and setting a picture box's image to the bitmap. This has gotten rid of seeing the form draw each square, but it's not displaying the top leftmost "square"...

Imports System.Drawing

Public Class Form1

    Dim BackBuffer As Bitmap
    Dim G As Graphics
    Dim SRect As Rectangle
    Dim DRect As Rectangle
    Dim SImage As Bitmap

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        SImage = New Bitmap(picTemplate.Image)
        BackBuffer = New Bitmap(499, 499)
        G = picCanvas.CreateGraphics

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        For X = 0 To 9
            For Y = 0 To 9
                SRect = New Rectangle(0, 0, 50, 50)
                DRect = New Rectangle(X * 50, Y * 50, 50, 50)
                G.DrawImage(SImage, DRect, SRect, GraphicsUnit.Pixel)
                G = Graphics.FromImage(BackBuffer)
            Next
        Next

        picCanvas.Image = BackBuffer

    End Sub
End Class

Umm, any idea's on why?