Εquilibrium

Resize a bitmap

This function resizes a bitmap to fit given dimensions without stretching the bitmap

Imports System.IO 
Imports System.Drawing 
Imports System.Drawing.Imaging 

Public Module Bitmap 
    Public Function Resize(ByVal Bitmap As System.Drawing.Bitmap, ByVal MaxWidth As Integer, ByVal MaxHeight As Integer) As System.Drawing.Bitmap 
        If Bitmap Is Nothing Then Throw New Exception("No bitmap supplied for resize") 
        If MaxWidth <= 0 Then Throw New Exception("Invalid MaxWidth supplied for resizing bitmap") 
        If MaxHeight <= 0 Then Throw New Exception("Invalid MaxHeight supplied for resizing bitmap") 

        Dim TargetWidth, TargetHeight As Integer 

        TargetWidth = Bitmap.Width 
        TargetHeight = Bitmap.Height 

        If Bitmap.Width > MaxWidth Then 
            TargetWidth = MaxWidth 
            TargetHeight = Bitmap.Height * MaxWidth / Bitmap.Width 
            If TargetHeight > MaxHeight Then 
                TargetHeight = MaxHeight 
                TargetWidth = TargetWidth * MaxHeight / TargetHeight 
            End If 
        End If 
        If Bitmap.Height > MaxHeight Then 
            TargetHeight = MaxHeight 
            TargetWidth = Bitmap.Width * MaxHeight / Bitmap.Height 
            If TargetWidth > MaxWidth Then 
                TargetWidth = MaxWidth 
                TargetHeight = TargetHeight * MaxWidth / TargetWidth 
            End If 
        End If 

        Return New System.Drawing.Bitmap(Bitmap, TargetWidth, TargetHeight) 
    End Function 
End Module