Установка системы координат

void TransformAndDraw(int iTransform, HWND hWnd)
{
    HDC hDC;
    XFORM xForm;
    RECT rect;
 
    // Retrieve a DC handle for the application's window.
 
    hDC = GetDC(hWnd);
 
    // Set the mapping mode to LOENGLISH. This moves the
    // client area origin from the upper left corner of the
    // window to the lower left corner (this also reorients
    // the y-axis so that drawing operations occur in a true
    // Cartesian space). It guarantees portability so that
    // the object drawn retains its dimensions on any display.

    SetGraphicsMode(hDC, GM_ADVANCED);
    SetMapMode(hDC, MM_LOENGLISH);
 
    // Set the appropriate world transformation (based on the
    // user's menu selection).
 
    switch (iTransform)
    {
        case SCALE:        // Scale to 1/2 of the original size.
            xForm.eM11 = (FLOAT) 0.5;
            xForm.eM12 = (FLOAT) 0.0;
            xForm.eM21 = (FLOAT) 0.0;
            xForm.eM22 = (FLOAT) 0.5;
            xForm.eDx  = (FLOAT) 0.0;
            xForm.eDy  = (FLOAT) 0.0;
            SetWorldTransform(hDC, &xForm);
            break;
 
        case TRANSLATE:   // Translate right by 3/4 inch.
            xForm.eM11 = (FLOAT) 1.0;
            xForm.eM12 = (FLOAT) 0.0;
            xForm.eM21 = (FLOAT) 0.0;
            xForm.eM22 = (FLOAT) 1.0;
            xForm.eDx  = (FLOAT) 75.0;
            xForm.eDy  = (FLOAT) 0.0;
            SetWorldTransform(hDC, &xForm);
            break;
 
        case ROTATE:      // Rotate 30 degrees counterclockwise.
            xForm.eM11 = (FLOAT) 0.8660;
            xForm.eM12 = (FLOAT) 0.5000;
            xForm.eM21 = (FLOAT) -0.5000;
            xForm.eM22 = (FLOAT) 0.8660;
            xForm.eDx  = (FLOAT) 0.0;
            xForm.eDy  = (FLOAT) 0.0;
            SetWorldTransform(hDC, &xForm);
            break;
 
        case SHEAR:       // Shear along the x-axis with a
                          // proportionality constant of 1.0.
            xForm.eM11 = (FLOAT) 1.0;
            xForm.eM12 = (FLOAT) 1.0;
            xForm.eM21 = (FLOAT) 0.0;
            xForm.eM22 = (FLOAT) 1.0;
            xForm.eDx  = (FLOAT) 0.0;
            xForm.eDy  = (FLOAT) 0.0;
            SetWorldTransform(hDC, &xForm);
            break;
 
        case REFLECT:     // Reflect about a horizontal axis.
            xForm.eM11 = (FLOAT) 1.0;
            xForm.eM12 = (FLOAT) 0.0;
            xForm.eM21 = (FLOAT) 0.0;
            xForm.eM22 = (FLOAT) -1.0;
            xForm.eDx  = (FLOAT) 0.0;
            xForm.eDy  = (FLOAT) 0.0;
            SetWorldTransform(hDC, &xForm);
            break;
 
        case NORMAL:      // Set the unity transformation.
            xForm.eM11 = (FLOAT) 1.0;
            xForm.eM12 = (FLOAT) 0.0;
            xForm.eM21 = (FLOAT) 0.0;
            xForm.eM22 = (FLOAT) 1.0;
            xForm.eDx  = (FLOAT) 0.0;
            xForm.eDy  = (FLOAT) 0.0;
            SetWorldTransform(hDC, &xForm);
            break;
 
    }
 
    // Find the midpoint of the client area.
 
    GetClientRect(hWnd, (LPRECT) &rect);
    DPtoLP(hDC, (LPPOINT) &rect, 2);
 
    // Select a hollow brush.
 
    SelectObject(hDC, GetStockObject(HOLLOW_BRUSH));
 
    // Draw the exterior circle.
 
    Ellipse(hDC, (rect.right / 2 - 100), (rect.bottom / 2 + 100),
        (rect.right / 2 + 100), (rect.bottom / 2 - 100));
 
    // Draw the interior circle.
 
    Ellipse(hDC, (rect.right / 2 -94), (rect.bottom / 2 + 94),
        (rect.right / 2 + 94), (rect.bottom / 2 - 94));
 
    // Draw the key.
 
    Rectangle(hDC, (rect.right / 2 - 13), (rect.bottom / 2 + 113),
        (rect.right / 2 + 13), (rect.bottom / 2 + 50));
    Rectangle(hDC, (rect.right / 2 - 13), (rect.bottom / 2 + 96),
        (rect.right / 2 + 13), (rect.bottom / 2 + 50));
 
    // Draw the horizontal lines.
 
    MoveToEx(hDC, (rect.right/2 - 150), (rect.bottom / 2 + 0), NULL);
    LineTo(hDC, (rect.right / 2 - 16), (rect.bottom / 2 + 0));
 
    MoveToEx(hDC, (rect.right / 2 - 13), (rect.bottom / 2 + 0), NULL);
    LineTo(hDC, (rect.right / 2 + 13), (rect.bottom / 2 + 0));
 
    MoveToEx(hDC, (rect.right / 2 + 16), (rect.bottom / 2 + 0), NULL);
    LineTo(hDC, (rect.right / 2 + 150), (rect.bottom / 2 + 0));
 
    // Draw the vertical lines.
 
    MoveToEx(hDC, (rect.right/2 + 0), (rect.bottom / 2 - 150), NULL);
    LineTo(hDC, (rect.right / 2 + 0), (rect.bottom / 2 - 16));
 
    MoveToEx(hDC, (rect.right / 2 + 0), (rect.bottom / 2 - 13), NULL);
    LineTo(hDC, (rect.right / 2 + 0), (rect.bottom / 2 + 13));
 
    MoveToEx(hDC, (rect.right / 2 + 0), (rect.bottom / 2 + 16), NULL);
    LineTo(hDC, (rect.right / 2 + 0), (rect.bottom / 2 + 150));
 
    ReleaseDC(hWnd, hDC);
}