get and set display name for XOpenDisplay()

src/robotjs.cc

@@ -2,6 +2,7 @@
 #include <nan.h>
 #include <v8.h>
 #include <vector>
+#include "string.h"
 #include "mouse.h"
 #include "deadbeef_rand.h"
 #include "keypress.h"
@@ -10,6 +11,7 @@
 #include "MMBitmap.h"
 #include "snprintf.h"
 #include "microsleep.h"
+#include "xdisplay.h"
 
 using namespace v8;
 
@@ -678,6 +680,26 @@ NAN_METHOD(getScreenSize)
 	info.GetReturnValue().Set(obj);
 }
 
+NAN_METHOD(getXDisplayName)
+{
+	NanScope();
+	NanReturnValue(NanNew<String>(getXDisplay()));
+}
+
+NAN_METHOD(setXDisplayName)
+{
+	NanScope();
+
+	//Convert arg to c-string
+	//NOTE: surely better way to go from v8::String to char* ?
+	std::string name =
+		std::string(*v8::String::Utf8Value(args[0]->ToString()));
+	char *display_name = strdup(name.c_str());
+
+	setXDisplay(display_name);
+	NanReturnUndefined();
+}
+
 NAN_METHOD(captureScreen) 
 {
 	size_t x;
@@ -850,6 +872,12 @@ NAN_MODULE_INIT(InitAll)
 
 	Nan::Set(target, Nan::New("getColor").ToLocalChecked(),
 		Nan::GetFunction(Nan::New<FunctionTemplate>(getColor)).ToLocalChecked());
+
+	Nan::Set(target, Nan::New("getXDisplayName").ToLocalChecked(),
+		Nan::GetFunction(Nan::New<FunctionTemplate>(getXDisplayName)).ToLocalChecked());
+
+	Nan::Set(target, Nan::New("setXDisplayName").ToLocalChecked(),
+		Nan::GetFunction(Nan::New<FunctionTemplate>(setXDisplayName)).ToLocalChecked());
 }
 
 NODE_MODULE(robotjs, InitAll)

src/xdisplay.c

@@ -4,11 +4,25 @@
 
 static Display *mainDisplay = NULL;
 static int registered = 0;
+static char *display_name = ":0.0";
+static int display_name_changed = 0;
 
 Display *XGetMainDisplay(void)
 {
+	/* Close the display if display_name has changed */
+	if (display_name_changed) {
+		XCloseMainDisplay();
+	}
+	display_name_changed = 0;
+
 	if (mainDisplay == NULL) {
-		mainDisplay = XOpenDisplay(NULL);
+		/* First try the user set display_name */
+		mainDisplay = XOpenDisplay(display_name);
+
+		/* Then try using environment variable DISPLAY */
+		if (mainDisplay == NULL) {
+			mainDisplay = XOpenDisplay(NULL);
+		}
 
 		if (mainDisplay == NULL) {
 			fputs("Could not open main display\n", stderr);
@@ -28,3 +42,13 @@ void XCloseMainDisplay(void)
 		mainDisplay = NULL;
 	}
 }
+
+char *getXDisplay(void)
+{
+	return display_name;
+}
+
+void setXDisplay(char *name) {
+	display_name = name;
+	display_name_changed = 1;
+}

src/xdisplay.h

@@ -14,4 +14,16 @@ Display *XGetMainDisplay(void);
 /* Closes the main display if it is open, or does nothing if not. */
 void XCloseMainDisplay(void);
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+char *getXDisplay(void);
+void setXDisplay(char *name);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* XDISPLAY_H */