Winform App different Win 7 versus Win 8 - winforms

Question

I am having an interesting problem with a standard data driven Winform application.
The application was originally developed on Windows 7 and Visual Studio 2010. I then built a new development machine with Windows 8, and also Visual Studio 2010. I released a new version of the Winform application, built on the Windows 8 machine. No sourcecode changes, same .NET 4.0 framework target. Client PCs running the Winform app on Windows 7 now experience form rendering issues. Controls seems to be crunched a bit on Windows 7, visually changing the form, and in some cases, rendering functionality broken (controls off screen due to rendering issues).
I have since upgraded to VS2012, and targeting .NET 4.5. Same issue(s) still exist.
Is there something I need to do so I get consistent forms rendering between Windows 7 and Windows 8?

Answer 1

I had similar issue. To fix it I check current DPI setting and scale dimensions horizontally and vertically where is needed. This helper class gives horizontal and vertical scale: HDpiScale, VDpiScale.
Usage:
MyControl.Height = (int) (MyControl.Height * util.VDpiScale);
MyControl.Width = (int) (MyControl.Width * util.HDpiScale);
It makes difference only if font size is x1.25
public class PresentationUtils : IPresentationUtils
{
private double vDpiScale = -1;
private double hDpiScale = -1;
public double HDpiScale
{
get
{
if (hDpiScale < 0)
SetDpiScales();
return hDpiScale;
}
}
public double VDpiScale
{
get
{
if (vDpiScale < 0)
SetDpiScales();
return vDpiScale;
}
}
private void SetDpiScales()
{
vDpiScale = 1;
hDpiScale = 1;
IntPtr dc = GetDC(IntPtr.Zero);
try
{
int hPixels = GetDeviceCaps(dc, (int) DeviceCap.LOGPIXELSX);
int vPixels = GetDeviceCaps(dc, (int) DeviceCap.LOGPIXELSY);
vDpiScale = vPixels/96.0;
hDpiScale = hPixels/96.0;
}
finally
{
ReleaseDC(IntPtr.Zero, dc);
}
}
[DllImport("gdi32.dll")]
public static extern int GetDeviceCaps(IntPtr hdc, int nIndex);
[DllImport("user32.dll", SetLastError = true)]
public static extern IntPtr GetDC(IntPtr hWnd);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool ReleaseDC(IntPtr hWnd, IntPtr hDC);
}
public enum DeviceCap
{
/// <summary>
/// Logical pixels inch in X
/// </summary>
LOGPIXELSX = 88,
/// <summary>
/// Logical pixels inch in Y
/// </summary>
LOGPIXELSY = 90,
}