how can I apply a texture to a bitmap?

[MrPolite]

I'm asking too many of these questions anyways, I can't figure out how. I couldnt find anything on the internet either

[shutty]

Sorry I don't fully understand your question...

Do you mean that you want to use a bitmap texture as a brush?

if so look here or here

unfortunately the examples are not in VB but the GDI+ API's are largely the same across .NET languages.

[MrPolite]

Originally posted by shutty
Sorry I don't fully understand your question...

Do you mean that you want to use a bitmap texture as a brush?

if so look here or here

unfortunately the examples are not in VB but the GDI+ API's are largely the same across .NET languages.

no, I want to apply a texture to a bitmap, as I said I dont know how else to say it here, I'll show you an example:

[Lunatic3]

I guess you are writing 'Mr.Polite Photoshop' to replace 'Adobe Photoshop' . Great! We back you all. Good Luck

[MrPolite]

Originally posted by Lunatic3
I guess you are writing 'Mr.Polite Photoshop' to replace 'Adobe Photoshop' . Great! We back you all. Good Luck

ok I started working on this crappy program of mine again... I thought a little about this texture thing and I figured it out.
here's what I do: I convert the texture to grayscale. The whitemost pixels (highest r, g, or b value) will have the most transparency. The darkmost pixels will be the least transparent pixels when you are applying the texture:

' Modifies the ORIGINAL bitmap and also returns a reference to it
    Public Shared Function ApplyTexture(ByRef bmp As Bitmap, ByVal textureTransparency As Single) As Bitmap
        If bmp Is Nothing Then Throw New ArgumentNullException
        If textureTransparency < 0 OrElse textureTransparency > 1 Then
            Throw New ArgumentOutOfRangeException("textureTransparency must be between 0 and 1.")
        End If
 
        bmp = MakeImageGrayscale(bmp)
 
        Dim x, y As Integer
        Dim alpha As Integer
 
        For x = 0 To bmp.Width - 1
            For y = 0 To bmp.Height - 1
                Dim c As Color = bmp.GetPixel(x, y)
                ' c.R -> all of the RGB values are the same since the image is grayscale.
                alpha = CInt(c.R * textureTransparency)
                c = Color.FromArgb(alpha, c)
 
                bmp.SetPixel(x, y, c)
            Next
        Next
 
        Return bmp
    End Function
 
     Public Shared Function MakeImageGrayscale(ByVal bmp As Bitmap) As Bitmap
            Dim imageAttrib As ImageAttributes = GetGrayscaleAttr()
            Return ApplyImageAttribute(bmp, imageAttrib)
        End Function
 
 
 Public Shared Function GetGrayscaleAttr() As ImageAttributes
            Dim values()() As Single = {New Single() {0.5, 0.5, 0.5, 0, 0}, _
                                              New Single() {0.5, 0.5, 0.5, 0, 0}, _
                                              New Single() {0.5, 0.5, 0.5, 0, 0}, _
                                              New Single() {0, 0, 0, 1, 0}, _
                                              New Single() {0, 0, 0, 0, 1}}
            ' Use the matrix to initialize a new colorMatrix object
            Dim colMatrix As New ColorMatrix(values)
            Dim imageAttr As New ImageAttributes
            imageAttr.SetColorMatrix(colMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap)
 
            Return imageAttr
        End Function
 
    Public Shared Function ApplyImageAttribute(ByVal img As Bitmap, ByVal imageAttrib As ImageAttributes) As Bitmap
            Dim bmp As New Bitmap(img.Width, img.Height)
            Dim gr As Graphics = Graphics.FromImage(bmp)
            gr.DrawImage(img, New Rectangle(0, 0, img.Width, img.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel, imageAttrib)
            Return bmp
        End Function

I just copy pasted my code from my project... you can combine all those a3 functions for converting to grayscale if you want


edit: ahem, would it be more efficient if I converted the image to grayscale myself in that first forloop? or would applying an image attribute be faster?