add Linux high DPI support and only windows use scaled()

robotgo.go

@@ -221,7 +221,7 @@ func GetMouseColor() string {
 	return GetPixelColor(x, y)
 }
 
-// SysScale get the sys scale (x11 todo)
+// SysScale get the sys scale
 func SysScale() float64 {
 	s := C.sys_scale()
 	return float64(s)
@@ -229,7 +229,12 @@ func SysScale() float64 {
 
 // Scaled get the screen scaled size
 func Scaled(x int) int {
-	return int(float64(x) * ScaleF())
+	return Scaled0(x, ScaleF())
+}
+
+// Scaled0 return int(x * f)
+func Scaled0(x int, f float64) int {
+	return int(float64(x) * f)
 }
 
 // GetScreenSize get the screen size
@@ -247,15 +252,16 @@ func GetScreenRect(displayId ...int) Rect {
 	}
 
 	rect := C.getScreenRect(C.int32_t(display))
+	x, y, w, h := int(rect.origin.x), int(rect.origin.y),
+		int(rect.size.w), int(rect.size.h)
+
+	if runtime.GOOS == "windows" {
+		f := ScaleF()
+		x, y, w, h = Scaled0(x, f), Scaled0(y, f), Scaled0(w, f), Scaled0(h, f)
+	}
 	return Rect{
-		Point{
-			X: Scaled(int(rect.origin.x)),
-			Y: Scaled(int(rect.origin.y)),
-		},
-		Size{
-			W: Scaled(int(rect.size.w)),
-			H: Scaled(int(rect.size.h)),
-		},
+		Point{X: x, Y: y},
+		Size{W: w, H: h},
 	}
 }
 

robotgo_mac.go

@@ -15,5 +15,9 @@ package robotgo
 
 // ScaleF get the system scale val
 func ScaleF() float64 {
-	return SysScale()
+	f := SysScale()
+	if f == 0.0 {
+		f = 1.0
+	}
+	return f
 }

robotgo_win.go

@@ -54,7 +54,11 @@ func SetFocus(hwnd win.HWND) win.HWND {
 
 // ScaleF get the system scale val
 func ScaleF() float64 {
-	return float64(GetMainDPI()) / 96.0
+	f := float64(GetMainDPI()) / 96.0
+	if f == 0.0 {
+		f = 1.0
+	}
+	return f
 }
 
 // GetMainDPI get the display dpi

window/win_sys.h

@@ -9,6 +9,11 @@
 // except according to those terms.
 
 // #include "../base/os.h"
+#if defined(USE_X11)
+	// #include <X11/Xlib.h>
+	// #include <X11/Xatom.h>
+	#include <X11/Xresource.h>
+#endif
 
 Bounds get_client(uintptr pid, uintptr isHwnd);
 
@@ -38,21 +43,34 @@ double sys_scale() {
 		
 		return pixelWidth / targetWidth;
 	#elif defined(USE_X11)
+		double xres;
+		Display *dpy;
 
-		// double xres;
-		// Display *dpy;
+		char *displayname = NULL;
+		int scr = 0; /* Screen number */
 
-		// char *displayname = NULL;
-		// int scr = 0; /* Screen number */
+		dpy = XOpenDisplay(displayname);
+		xres = ((((double) DisplayWidth(dpy, scr)) * 25.4) /
+			((double) DisplayWidthMM(dpy, scr)));
 
-		// dpy = XOpenDisplay (displayname);
-		// xres = ((((double) DisplayWidth(dpy, scr)) * 25.4) /
-		// 	((double) DisplayWidthMM(dpy, scr)));
+		// https://github.com/glfw/glfw/issues/1019#issuecomment-302772498
+		char *rms = XResourceManagerString(dpy);
+		if (rms) {
+			XrmDatabase db;
+			XrmValue value;
+			char *type = NULL;
 
-   		// XCloseDisplay (dpy);
+			XrmInitialize(); /* Need to initialize the DB before calling Xrm* functions */
+			db = XrmGetStringDatabase(rms);
+			if (XrmGetResource(db, "Xft.dpi", "String", &type, &value) == True) {
+				if (value.addr) {
+					xres = atof(value.addr);
+				}
+			}
+		}
+		XCloseDisplay (dpy);
 
-		// return xres / 96.0;
-		return 1.0;
+		return xres / 96.0;
    	#elif defined(IS_WINDOWS)
    		double s = scaleX() / 96.0;
    		return s;