diff options
Diffstat (limited to 'src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx')
| -rw-r--r-- | src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx index b89d18881..52e3f5287 100644 --- a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx +++ b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx @@ -656,6 +656,30 @@ Fl_WinAPI_Screen_Driver::read_win_rectangle(uchar *p, // I - Pixel buffer or NU return rgb; } +/** Returns the current desktop scaling factor (1.75 for example) + */ +float Fl_WinAPI_Screen_Driver::desktop_scaling_factor() { + // Compute the global desktop scaling factor: 1, 1.25, 1.5, 1.75, etc... + // This factor can be set in Windows 10 by + // "Change the size of text, apps and other items" in display settings. + // We don't cache this value because it can change while the app is running. + HDC hdc = GetDC(NULL); + int hr = GetDeviceCaps(hdc, HORZRES); // pixels visible to the app +#ifndef DESKTOPHORZRES +#define DESKTOPHORZRES 118 + /* As of 27 august 2016, the DESKTOPHORZRES flag for GetDeviceCaps() + has disappeared from Microsoft online doc, but is quoted in numerous coding examples + e.g., https://social.msdn.microsoft.com/Forums/en-US/6acc3b21-23a4-4a00-90b4-968a43e1ccc8/capture-screen-with-high-dpi?forum=vbgeneral + It is necessary for the computation of the scaling factor at runtime as done here. + */ +#endif + int dhr = GetDeviceCaps(hdc, DESKTOPHORZRES); // true number of pixels on display + ReleaseDC(NULL, hdc); + float scaling = dhr/float(hr); + scaling = int(scaling * 100 + 0.5)/100.; // round to 2 digits after decimal point + return scaling; +} + // // End of "$Id$". //
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