DPI aware and Rect

Question

I got a small problem which I can't seem to find the answer of. I have a application that gets certain processes and gets the window size of it. Only the problem is it takes a percentage of the actual screen size (which the user sees).

I want to make a screenshot of the application, but if I use the Rect of the window I get a smaller screen than it is, because the resolotion is 125%. This means my original resolution which gets outputted (1280 * 800) is smaller then my screen resolution (1600 * 1000) you can understand that this small hiccup makes my program unreliable. My question is how to fix this?

I've created a manifest which I set DPIAware to true. Also I disabled the Visual Studio hosting in the debug. But it doesn't help. I still get the same values and the same problem. Here is my code snippet for the actual screenshotting:

RECT Rect = new RECT();
System.Diagnostics.Process[] p = System.Diagnostics.Process.GetProcessesByName("Process");
ShowWindow(p[0].MainWindowHandle, 9);
SetForegroundWindow(p[0].MainWindowHandle);

if (GetWindowRect(p[0].MainWindowHandle, ref Rect))
{
    var bmp = new Bitmap(Rect.Width, Rect.Height);
    var graphics = Graphics.FromImage(bmp);
    graphics.CopyFromScreen(Rect.Left, Rect.Top, 0, 0, new Size(Rect.Width, Rect.Height), CopyPixelOperation.SourceCopy);
    bmp.Save(@"C:\Screenshots\temp1.png");
}

This gives me an screenshot of 1280 * 800, not enough to cover the whole process, which is 1600 * 1000. Everything is off because the screen coordinates are not right. If I multiply everything by 1,25 it will be alright but that is not a solution because I don't know what the DPI settings on other PC's are.

EDIT 3:

I'll post the full code with the RECT in it.

RECT Rect = new RECT();
System.Diagnostics.Process[] p = System.Diagnostics.Process.GetProcessesByName("LoLPatcherUx");
ShowWindow(p[0].MainWindowHandle, 9);
SetForegroundWindow(p[0].MainWindowHandle);

if (GetWindowRect(p[0].MainWindowHandle, ref Rect))
{
    int processH = Rect.Bottom - Rect.Top;
    int processW = Rect.Right - Rect.Left;

    float processWidth;
    float processHeight;                            

    SizeF dpi = GetCurrentDpi();
    // Calc the scale.
    SizeF scale = new SizeF()
    {
        Width = dpi.Width / 96f,
        Height = dpi.Height / 96f                                  
    };

    // Scale the rectangle.
    processWidth = Rect.Width * scale.Width;
    processHeight = Rect.Height * scale.Height;

    var bmp = new Bitmap(lolPatcherBreedte, lolPatcherHoogte);
    Graphics graphics = Graphics.FromImage(bmp);
    graphics.CopyFromScreen(Rect.Left, Rect.Top, 0, 0, new Size(processW, processH));

    bmp.Save(@"C:\Screenshots\temp1.png");
}

public struct RECT
{
    private int _Left;
    private int _Top;
    private int _Right;
    private int _Bottom;

    public RECT(RECT Rectangle)
        : this(Rectangle.Left, Rectangle.Top, Rectangle.Right, Rectangle.Bottom) { }

    public RECT(int Left, int Top, int Right, int Bottom)
    {
        _Left = Left;
        _Top = Top;
        _Right = Right;
        _Bottom = Bottom;
    }

    public int X
    {
        get { return _Left; }
        set { _Left = value; }
    }

    public int Y
    {
        get { return _Top; }
        set { _Top = value; }
    }

    public int Left
    {
        get { return _Left; }
        set { _Left = value; }
    }

    public int Top
    {
        get { return _Top; }
        set { _Top = value; }
    }

    public int Right
    {
        get { return _Right; }
        set { _Right = value; }
    }

    public int Bottom
    {
        get { return _Bottom; }
        set { _Bottom = value; }
    }

    public int Height
    {
        get { return _Bottom - _Top; }
        set { _Bottom = value + _Top; }
    }

    public int Width
    {
        get { return _Right - _Left; }
        set { _Right = value + _Left; }
    }

    public Point Location
    {
        get { return new Point(Left, Top); }
        set
        {
            _Left = value.X;
            _Top = value.Y;
        }
    }

    public Size Size
    {
        get { return new Size(Width, Height); }
        set
        {
            _Right = value.Width + _Left;
            _Bottom = value.Height + _Top;
        }
    }

    public static implicit operator Rectangle(RECT Rectangle)
    {
        return new Rectangle(Rectangle.Left, Rectangle.Top, Rectangle.Width, Rectangle.Height);
    }

    public static implicit operator RECT(Rectangle Rectangle)
    {
        return new RECT(Rectangle.Left, Rectangle.Top, Rectangle.Right, Rectangle.Bottom);
    }

    public static bool operator ==(RECT Rectangle1, RECT Rectangle2)
    {
        return Rectangle1.Equals(Rectangle2);
    }

    public static bool operator !=(RECT Rectangle1, RECT Rectangle2)
    {
        return !Rectangle1.Equals(Rectangle2);
    }

    public override string ToString()
    {
        return "{Left: " + _Left + "; " + "Top: " + _Top + "; Right: " + _Right + "; Bottom: " + _Bottom + "}";
    }

    public override int GetHashCode()
    {
        return ToString().GetHashCode();
    }

    public bool Equals(RECT Rectangle)
    {
        return Rectangle.Left == _Left && Rectangle.Top == _Top && Rectangle.Right == _Right && Rectangle.Bottom == _Bottom;
    }

    public override bool Equals(object Object)
    {
        if (Object is RECT)
        {
            return Equals((RECT)Object);
        }
        else if (Object is Rectangle)
        {
            return Equals(new RECT((Rectangle)Object));
        }

        return false;
    }
}

Answer 1

You can get the current DPI setting via the

• Graphics.DpiX and
• Graphics.DpiY

properties.

This way you should be able to calculate it correctly (it's how I do it in one of my projects).

Just get these by creating a dummy Form and a Graphics object from it (if your code is being executed outside of a Form's context):

public static SizeF GetCurrentDpi()
{
    using (Form form = new Form())
    using (Graphics g = form.CreateGraphics())
    {
        var result = new SizeF()
        {
            Width = g.DpiX,
            Height = g.DpiY
        };
        return result;
    }
}

Control.CreateGraphics Method

---

Usage:

if (GetWindowRect(p[0].MainWindowHandle, ref Rect))
{
    var bmp = new Bitmap(Rect.Width, Rect.Height);
    Graphics graphics = Graphics.FromImage(bmp);

    // Use the helper function to get the current dpi.
    SizeF dpi = GetCurrentDpi();

    // Calc the scale.
    SizeF scale = new SizeF()
    {
        Width = dpi.Width / 96f,
        Height = dpi.Height / 96f
    };

    // Scale the rectangle.
    Rect.Width *= scale.Width;
    Rect.Height *= scale.Height;

    graphics.CopyFromScreen(Rect.Left, Rect.Top, 0, 0, new Size(Rect.Width, Rect.Height), CopyPixelOperation.SourceCopy);
    bmp.Save(@"C:\Screenshots\temp1.png");
}

Demo:

class Program
{
    [DllImport("user32.dll", SetLastError = true)]
    static extern bool GetWindowRect(IntPtr hwnd, ref RECT lpRect);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool ShowWindow(IntPtr hWnd, ShowWindowCommands nCmdShow);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool SetForegroundWindow(IntPtr hWnd);

    static void Main(string[] args)
    {

        RECT rect = new RECT();
        Process[] processes = System.Diagnostics.Process.GetProcessesByName("iexplore");
        Process iexplore = processes.First();

        ShowWindow(iexplore.MainWindowHandle, ShowWindowCommands.Restore);
        SetForegroundWindow(iexplore.MainWindowHandle);
        var result = GetWindowRect(iexplore.MainWindowHandle, ref rect);

        RectangleF rectF = new RectangleF()
        {
            Location = new PointF(rect.Left, rect.Top),
            Size = new SizeF(rect.Right - rect.Left + 1, rect.Bottom - rect.Top + 1)
        };            

        var bmp = new Bitmap((int)rectF.Width, (int)rectF.Height);
        Graphics graphics = Graphics.FromImage(bmp);
        graphics.CopyFromScreen((int)rectF.Left, (int)rectF.Top, 0, 0, new Size((int)rectF.Width, (int)rectF.Height), CopyPixelOperation.SourceCopy);
        bmp.Save(@"C:\temp\screenshot1.jpg", ImageFormat.Jpeg);          
    }      
}

enum ShowWindowCommands
{
    Hide = 0,
    Normal = 1,
    ShowMinimized = 2,
    Maximize = 3,
    ShowMaximized = 3,
    ShowNoActivate = 4,
    Show = 5,
    Minimize = 6,
    ShowMinNoActive = 7,
    ShowNA = 8,
    Restore = 9,
    ShowDefault = 10,
    ForceMinimize = 11
}

[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
    public int Left;
    public int Top;
    public int Right;
    public int Bottom;
}