Imports System
Imports System.Runtime.InteropServices
Imports System.Drawing
Imports System.ComponentModel
Imports System.Windows.Forms
Public Class MainClass
Shared Sub Main(ByVal args As String())
Dim myform As Form = New Form1()
Application.Run(myform)
End Sub
End Class
Public Class Form1
Public Structure Rect
Public left As Integer
Public top As Integer
Public right As Integer
Public bottom As Integer
End Structure
Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
Const WM_SIZING As Long = &H214
Const WMSZ_LEFT As Integer = 1
Const WMSZ_RIGHT As Integer = 2
Const WMSZ_TOP As Integer = 3
Const WMSZ_TOPLEFT As Integer = 4
Const WMSZ_TOPRIGHT As Integer = 5
Const WMSZ_BOTTOM As Integer = 6
Const WMSZ_BOTTOMLEFT As Integer = 7
Const WMSZ_BOTTOMRIGHT As Integer = 8
Static fixed_aspect_ratio As Double = 0
Dim new_aspect_ratio As Double
If m.Msg = WM_SIZING And m.HWnd.Equals(Me.Handle) Then
Dim r As Rect
r = DirectCast( _
Marshal.PtrToStructure(m.LParam, GetType(Rect)), _
Rect)
Dim width As Double = r.right - r.left
Dim height As Double = r.bottom - r.top
new_aspect_ratio = height / width
If fixed_aspect_ratio = 0 Then
fixed_aspect_ratio = new_aspect_ratio
End If
If fixed_aspect_ratio <> new_aspect_ratio Then
If m.WParam.ToInt32 = WMSZ_TOPLEFT Or _
m.WParam.ToInt32 = WMSZ_TOPRIGHT Or _
m.WParam.ToInt32 = WMSZ_BOTTOMLEFT Or _
m.WParam.ToInt32 = WMSZ_BOTTOMRIGHT _
Then
If new_aspect_ratio > fixed_aspect_ratio Then
width = height / fixed_aspect_ratio
Else
height = width * fixed_aspect_ratio
End If
ElseIf m.WParam.ToInt32 = WMSZ_LEFT Or _
m.WParam.ToInt32 = WMSZ_RIGHT _
Then
height = width * fixed_aspect_ratio
ElseIf m.WParam.ToInt32 = WMSZ_TOP Or _
m.WParam.ToInt32 = WMSZ_BOTTOM _
Then
width = height / fixed_aspect_ratio
End If
If m.WParam.ToInt32 = WMSZ_TOP Or _
m.WParam.ToInt32 = WMSZ_TOPLEFT Or _
m.WParam.ToInt32 = WMSZ_TOPRIGHT _
Then
r.top = r.bottom - CInt(height)
Else
r.bottom = r.top + CInt(height)
End If
If m.WParam.ToInt32 = WMSZ_LEFT Or _
m.WParam.ToInt32 = WMSZ_TOPLEFT Or _
m.WParam.ToInt32 = WMSZ_BOTTOMLEFT _
Then
r.left = r.right - CInt(width)
Else
r.right = r.left + CInt(width)
End If
Marshal.StructureToPtr(r, m.LParam, True)
End If
End If
MyBase.WndProc(m)
End Sub
End Class
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Public Class Form1
Inherits System.Windows.Forms.Form
'Form overrides dispose to clean up the component list.
<System.Diagnostics.DebuggerNonUserCode()> _
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing AndAlso components IsNot Nothing Then
components.Dispose()
End If
MyBase.Dispose(disposing)
End Sub
'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer
'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> _
Private Sub InitializeComponent()
Me.SuspendLayout()
'
'Form1
'
Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
Me.ClientSize = New System.Drawing.Size(292, 273)
Me.Name = "Form1"
Me.Text = "FixedAspectRatio"
Me.ResumeLayout(False)
End Sub
End Class
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