Question

Windows 7中有显示设置（控制面板 - ＆gt;显示）。它允许更改屏幕上文本和其他项目的大小。我需要让这个设置能够根据设置值打开/关闭我的C＃应用程序中的某些功能。这可能吗？

Answer 1

在所有缩放级别中，graphics.DpiX和DeviceCap.LOGPIXELSX都在Surface Pro上返回96。

相反，我设法以这种方式计算比例因子：

[DllImport("gdi32.dll")]
static extern int GetDeviceCaps(IntPtr hdc, int nIndex);
public enum DeviceCap
{
    VERTRES = 10,
    DESKTOPVERTRES = 117,

    // http://pinvoke.net/default.aspx/gdi32/GetDeviceCaps.html
}  


private float getScalingFactor()
{
    Graphics g = Graphics.FromHwnd(IntPtr.Zero);
    IntPtr desktop = g.GetHdc();
    int LogicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.VERTRES);
    int PhysicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.DESKTOPVERTRES); 

    float ScreenScalingFactor = (float)PhysicalScreenHeight / (float)LogicalScreenHeight;

    return ScreenScalingFactor; // 1.25 = 125%
}

Answer 2

此设置是屏幕DPI或每英寸点数。

如此阅读：

float dpiX, dpiY;
Graphics graphics = this.CreateGraphics();
dpiX = graphics.DpiX;
dpiY = graphics.DpiY;

我认为目前X和Y值不同是不可能的。值96对应于100％字体缩放（较小），120对应于125％缩放（中），144对应于150％缩放（较大）。但是，用户可以设置除这些标准值之外的值。

请注意，除非您的应用程序被声明为DPI识别，否则您观察到的值可能会受到DPI虚拟化的影响。

Answer 3

我认为最简单的方法是使用GetDeviceCaps功能。来自pinvoke.net：

[DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
public static extern int GetDeviceCaps(IntPtr hDC, int nIndex);

public enum DeviceCap
{
  /// <summary>
  /// Logical pixels inch in X
  /// </summary>
  LOGPIXELSX = 88,
  /// <summary>
  /// Logical pixels inch in Y
  /// </summary>
  LOGPIXELSY = 90

  // Other constants may be founded on pinvoke.net
}

用法：

Graphics g = Graphics.FromHwnd(IntPtr.Zero);            
IntPtr desktop = g.GetHdc();

int Xdpi = GetDeviceCaps(desktop, (int)DeviceCap.LOGPIXELSX);
int Ydpi = GetDeviceCaps(desktop, (int)DeviceCap.LOGPIXELSY);

在这种方法中，您无需将应用标记为dpi识别。

Answer 4

这是你在WPF中的方法。返回值以WPF的逻辑单位表示，等于1/96英寸。因此，如果屏幕DPI设置为96，则值为1.

Matrix m =
PresentationSource.FromVisual(Application.Current.MainWindow).CompositionTarget.TransformToDevice;
double dx = m.M11; // notice it's divided by 96 already
double dy = m.M22; // notice it's divided by 96 already

（source）

Answer 5

如果是WPF，请使用以下代码段

PresentationSource source = PresentationSource.FromVisual(this);

        double dpiX, dpiY;
        if (source != null)
        {
            dpiX = 96.0 * source.CompositionTarget.TransformToDevice.M11;
            dpiY = 96.0 * source.CompositionTarget.TransformToDevice.M22;
        }

Answer 6

我在控制台应用程序中使用这种方式：

float dpiX, dpiY;
using (Graphics graphics = Graphics.FromHwnd(IntPtr.Zero))
{
    dpiX = graphics.DpiX;
    dpiY = graphics.DpiY;
}

Answer 7

使用Farshid T作为基础的答案适用于每个比例因子，除了125％。我测试了大约20个不同的缩放因子，DPI总是返回96，除非设置为125％，返回DPI为120. 120/96 = 1.25。不知道为什么会这样，但是这个代码似乎适用于任何比例设置。

    [DllImport("gdi32.dll")]
    static extern int GetDeviceCaps(IntPtr hdc, int nIndex);
    public enum DeviceCap
    {
        VERTRES = 10,
        DESKTOPVERTRES = 117,
        LOGPIXELSY = 90,

        // http://pinvoke.net/default.aspx/gdi32/GetDeviceCaps.html

和用法：

        Graphics g = Graphics.FromHwnd(IntPtr.Zero);
        IntPtr desktop = g.GetHdc();
        int LogicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.VERTRES);
        int PhysicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.DESKTOPVERTRES);
        int logpixelsy = GetDeviceCaps(desktop, (int)DeviceCap.LOGPIXELSY);
        float screenScalingFactor = (float)PhysicalScreenHeight / (float)LogicalScreenHeight;
        float dpiScalingFactor = (float)logpixelsy / (float)96;

        if (screenScalingFactor > 1 ||
            dpiScalingFactor > 1)
        {
            // do something nice for people who can't see very well...
        }

Answer 8

这是一个非常古老的问题，但是从Windows 8.1开始，人们可以使用其他各种功能，例如GetDpiForWindow

在C＃中：

[DllImport("user32.dll")]
static extern int GetDpiForWindow(IntPtr hWnd);

public float GetDisplayScaleFactor(IntPtr windowHandle)
{
    try
    {
        return GetDpiForWindow(windowHandle) / 96f;
    }
    catch
    {
        // Or fallback to GDI solutions above
        return 1;
    }
}

为了在Windows 10周年纪念日正常运行，您需要在C＃项目中添加app.manifest：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<assembly xmlns="urn:schemas-microsoft-com:asm.v1"
          manifestVersion="1.0">
  <application xmlns="urn:schemas-microsoft-com:asm.v3">
    <windowsSettings>
      <!-- The combination of below two tags have the following effect : 
      1) Per-Monitor for >= Windows 10 Anniversary Update
      2) System < Windows 10 Anniversary Update -->
      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitor</dpiAwareness>
      <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">True/PM</dpiAware>
    </windowsSettings>
  </application>

</assembly>

Answer 9

这是一个在Windows 10中运行良好的解决方案。不需要DPI意识或其他任何内容。

public static int GetWindowsScaling()
{
    return (int)(100 * Screen.PrimaryScreen.Bounds.Width / SystemParameters.PrimaryScreenWidth);
}

Answer 10

我认为这应该为您提供所需的信息：

http://www.pinvoke.net/default.aspx/user32.getsystemmetrics

http://pinvoke.net/default.aspx/Enums.SystemMetric

编辑 - 哦对不起看起来现在有一种更简单的方法可以在没有pinvoke的情况下获取此信息，

http://msdn.microsoft.com/en-us/library/system.windows.forms.systeminformation.aspx

Answer 11

Ric Gaudet的答案的更完整版本：

[DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
public static extern int GetDeviceCaps(IntPtr hDC, int nIndex);

public enum DeviceCap
{
    VERTRES = 10,
    DESKTOPVERTRES = 117
}

static double GetWindowsScreenScalingFactor(bool percentage = true)
{
    //Create Graphics object from the current windows handle
    Graphics GraphicsObject = Graphics.FromHwnd(IntPtr.Zero);
    //Get Handle to the device context associated with this Graphics object
    IntPtr DeviceContextHandle = GraphicsObject.GetHdc();
    //Call GetDeviceCaps with the Handle to retrieve the Screen Height
    int LogicalScreenHeight = GetDeviceCaps(DeviceContextHandle, (int)DeviceCap.VERTRES);
    int PhysicalScreenHeight = GetDeviceCaps(DeviceContextHandle, (int)DeviceCap.DESKTOPVERTRES);
    //Divide the Screen Heights to get the scaling factor and round it to two decimals
    double ScreenScalingFactor = Math.Round((double)PhysicalScreenHeight / (double)LogicalScreenHeight, 2);
    //If requested as percentage - convert it
    if (percentage)
    {
        ScreenScalingFactor *= 100.0;
    }
    //Release the Handle and Dispose of the GraphicsObject object
    GraphicsObject.ReleaseHdc(DeviceContextHandle);
    GraphicsObject.Dispose();
    //Return the Scaling Factor
    return ScreenScalingFactor;
}

如何获取Windows显示设置？

11 个答案: