C# Signature:

[DllImport("gdi32.dll")]
static extern int SetMapMode(IntPtr hdc, int fnMapMode);

Constants:

//Mapping Modes
static int MM_TEXT = 1;
static int MM_LOMETRIC = 2;
static int MM_HIMETRIC = 3;
static int MM_LOENGLISH = 4;
static int MM_HIENGLISH = 5;
static int MM_TWIPS = 6;
static int MM_ISOTROPIC = 7;
static int MM_ANISOTROPIC = 8;

//Minimum and Maximum Mapping Mode values
static int MM_MIN = MM_TEXT;
static int MM_MAX = MM_ANISOTROPIC;
static int MM_MAX_FIXEDSCALE = MM_TWIPS;

User-Defined Types:

MapModes

Notes:

None.

Tips & Tricks:

Please add some!

Sample Code:

using System;

using System.Runtime.InteropServices; // For calling Windows API functions.

partial class Form1

{

    [DllImport("gdi32.dll")]
    static extern int SetMapMode(IntPtr hDC, int nMapMode);

    [DllImport("gdi32.dll")]
    static extern bool SetViewportOrgEx(IntPtr hDC, int x, int y, Point[] prevPoint);

    [DllImport("gdi32.dll")]
    static extern bool SetWindowOrgEx(IntPtr hDC, int x, int y, Point[] prevPoint);

    [DllImport("gdi32.dll")]
    static extern bool SetViewportExtEx(IntPtr hDC, int nExtentX, int nExtentY, Size[] prevSize);

    [DllImport("gdi32.dll")]
    static extern bool SetWindowExtEx(IntPtr hDC, int nExtentX, int nExtentY, Size[] prevSize);

    [DllImport("Gdi32.dll")]
    public static extern int CreatePen(int nPenStyle, int nWidth, int nColor);

    [DllImport("Gdi32.dll")]
    public static extern int GetStockObject(int nStockBrush);

    [DllImport("Gdi32.dll")]
    public static extern int SelectObject(IntPtr hDC, int hGdiObject);

    [DllImport("Gdi32.dll")]
    public static extern int DeleteObject(int hBitmap);

    [DllImport("Gdi32.dll")]
    public static extern int MoveToEx(IntPtr hDC, int x, int y, int nPreviousPoint);

    [DllImport("Gdi32.dll")]
    public static extern int LineTo(IntPtr hDC, int x, int y);

    [DllImport("Gdi32.dll")]
    public static extern int Rectangle(IntPtr hDC, int nLeft, int nTop, int nRight, int nBottom);

    [DllImport("Gdi32.dll")]
    public static extern bool DPtoLP(IntPtr hdc, [In, Out] Point[] lpPoints, int nCount);

    // Mapping modes.
    const int MM_TEXT = 1;
    const int MM_LOMETRIC = 2;
    const int MM_HIMETRIC = 3;
    const int MM_LOENGLISH = 4;
    const int MM_HIENGLISH = 5;
    const int MM_TWIPS = 6;
    const int MM_ISOTROPIC = 7;
    const int MM_ANISOTROPIC = 8;

    // Gdi stock objects.
    const int WHITE_BRUSH = 0;
    const int LTGRAY_BRUSH = 1;
    const int GRAY_BRUSH = 2;
    const int DKGRAY_BRUSH = 3;
    const int BLACK_BRUSH = 4;
    const int NULL_BRUSH = 5;
    const int HOLLOW_BRUSH = NULL_BRUSH;
    const int WHITE_PEN = 6;
    const int BLACK_PEN = 7;
    const int NULL_PEN = 8;
    const int OEM_FIXED_FONT = 10;
    const int ANSI_FIXED_FONT = 11;
    const int ANSI_VAR_FONT = 12;
    const int SYSTEM_FONT = 13;
    const int DEVICE_DEFAULT_FONT = 14;
    const int DEFAULT_PALETTE = 15;
    const int SYSTEM_FIXED_FONT = 16;

    // Pen styles.
    const int PS_SOLID = 0;
    const int PS_DASH = 1;
    const int PS_DOT = 2;
    const int PS_DASHDOT = 3;
    const int PS_DASHDOTDOT = 4;
    const int PS_NULL = 5;
    const int PS_INSIDEFRAME = 6;
    const int PS_USERSTYLE = 7;
    const int PS_ALTERNATE = 8;
    const int PS_STYLE_MASK = 0x0000000F;
    const int PS_ENDCAP_ROUND = 0x00000000;
    const int PS_ENDCAP_SQUARE = 0x00000100;
    const int PS_ENDCAP_FLAT = 0x00000200;
    const int PS_ENDCAP_MASK = 0x00000F00;
    const int PS_JOIN_ROUND = 0x00000000;
    const int PS_JOIN_BEVEL = 0x00001000;
    const int PS_JOIN_MITER = 0x00002000;
    const int PS_JOIN_MASK = 0x0000F000;
    const int PS_COSMETIC = 0x00000000;
    const int PS_GEOMETRIC = 0x00010000;
    const int PS_TYPE_MASK = 0x000F0000;

     ...
     ...
     ...

}

// ____________ Place the following code inside an event handler: ____________________________

Graphics dc = this.CreateGraphics();

Debug.Assert(dc != null);

GraphicsContainer graphicsContainer = dc.BeginContainer();

IntPtr hDC = dc.GetHdc();

Debug.Assert(hDC != null);

Point[] point = new Point[1];

Size[] size = new Size[1];

double fAspectRatio = (double)(this.ClientRectangle.Bottom) / (double)(this.ClientRectangle.Right);

SetMapMode(hDC, MM_ANISOTROPIC);

SetViewportOrgEx(

         hDC,
         0,
         this.ClientRectangle.Bottom,    // So that (0,0) is at the bottom left.
         point);

SetWindowOrgEx(

           hDC,
           0,
           0,
           point);

SetViewportExtEx(

         hDC,
         this.ClientRectangle.Right,
         -this.ClientRectangle.Bottom, // Negative so that y gets positive as you go up.
         size);

SetWindowExtEx(

           hDC,
1000,            (int)(1000 * fAspectRatio),
           size);

// Create a red pen and select it into the device context.

int hPen = CreatePen(PS_SOLID, 1, 0x000000FF);

int hOldPen = SelectObject(hDC, hPen);

// Draw a line.

MoveToEx(hDC, 10, 25, 0);

LineTo(hDC, 990, (int)(990 * fAspectRatio));

// Create a null brush and select it into the device context.

int hBrush = GetStockObject(NULL_BRUSH);

int hOldBrush = SelectObject(hDC, hBrush);

// Draw a rectangle.

Rectangle(hDC, 10, 25, 990, (int)(990 * fAspectRatio));

// Cleanup.

SelectObject(hDC, hOldPen);

SelectObject(hDC, hOldBrush);

DeleteObject(hPen);

dc.ReleaseHdc();

dc.EndContainer(graphicsContainer);

Alternative Managed API:

Do you know one? Please contribute it!