Windows 7 中有显示设置(控制面板 -> 显示)。它允许更改屏幕上文本和其他项目的大小。 我需要获得此设置才能根据设置值打开/关闭 C# 应用程序中的某些功能。 这可能吗?
graphics.DpiX 和 DeviceCap.LOGPIXELSX 在 Surface Pro 上的所有缩放级别上均返回 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()
{
using Graphics g = Graphics.FromHwnd(IntPtr.Zero);
IntPtr desktop = g.GetHdc();
int LogicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.VERTRES);
int PhysicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.DESKTOPVERTRES);
g.ReleaseHdc(desktop);
float ScreenScalingFactor = (float)PhysicalScreenHeight / (float)LogicalScreenHeight;
return ScreenScalingFactor; // 1.25 = 125%
}
此设置是屏幕 DPI,或每英寸点数。
像这样读:
float dpiX, dpiY;
Graphics graphics = this.CreateGraphics();
dpiX = graphics.DpiX;
dpiY = graphics.DpiY;
我认为目前 X 和 Y 值不可能不同。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,用户可以设置这些标准值以外的值。
请注意,除非您的应用程序被声明为支持 DPI,否则您观察到的值可能会受到 DPI 虚拟化的影响。
GetDeviceCaps
函数。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
}
及用法:
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,您无需将应用程序标记为支持 dpi。
这就是在 WPF 中执行此操作的方法。返回值采用 WPF 的逻辑单位,等于 1/96 英寸。因此,如果您的屏幕 DPI 设置为 96,您将得到的值为 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
(来源)
这是一个在 Windows 10 中运行良好的解决方案。不需要 DPI 感知或其他任何东西。
public static int GetWindowsScaling()
{
return (int)(100 * Screen.PrimaryScreen.Bounds.Width / SystemParameters.PrimaryScreenWidth);
}
使用 Farshid T 的答案作为基础,适用于除 125% 之外的所有缩放因子。我测试了大约 20 个不同的缩放因子,DPI 始终返回 96,但设置为 125% 时除外,它返回的 DPI 为 120。120 / 96 = 1.25。不确定为什么会出现这种情况,但此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
及用法:
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...
}
这是一个非常老的问题,但是从Windows 8.1开始,人们可以使用各种其他功能,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;
}
}
为了使其在 Windows 10 周年纪念日上正常工作,您需要将
app.manifest
添加到您的 C# 项目中:
<?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>
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;
}
如果是 WPF,请使用以下代码片段,
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;
}
Ric Gaudet 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;
}
我认为这应该为您提供您正在寻找的信息:
http://www.pinvoke.net/default.aspx/user32.getsystemmetrics
http://pinvoke.net/default.aspx/Enums.SystemMetric
编辑 - 哦抱歉,现在似乎有一种更简单的方法可以在不使用 pinvoke 的情况下获取此信息,
http://msdn.microsoft.com/en-us/library/system.windows.forms.systeminformation.aspx