clipboard: use a nicer error when X11/Xlib.h is missing

vlib/clipboard/x11/clipboard.c.v

@@ -9,39 +9,60 @@ import math
 #flag -lX11
 #flag freebsd -I/usr/local/include
 #flag freebsd -L/usr/local/lib -lX11
-#include <X11/Xlib.h>
+#include <X11/Xlib.h> # Please install a package with the X11 development headers, for example: `apt-get install libx11-dev`
-
 // X11
 [typedef]
-struct C.Display
+struct C.Display {
+}
 
 [typedef]
-struct C.Atom
+struct C.Atom {
+}
 
 [typedef]
-struct C.Window
+struct C.Window {
+}
 
 fn C.XInitThreads() int
+
 fn C.XCloseDisplay(d &Display)
+
 fn C.XFlush(d &Display)
+
 fn C.XDestroyWindow(d &Display, w C.Window)
+
 fn C.XNextEvent(d C.Display, e &XEvent)
+
 fn C.XSetSelectionOwner(d &Display, a C.Atom, w C.Window, time int)
+
 fn C.XGetSelectionOwner(d &Display, a C.Atom) C.Window
+
 fn C.XChangeProperty(d &Display, requestor C.Window, property C.Atom, typ C.Atom, format int, mode int, data voidptr, nelements int) int
+
 fn C.XSendEvent(d &Display, requestor C.Window, propogate int, mask i64, event &XEvent)
+
 fn C.XInternAtom(d &Display, typ byteptr, only_if_exists int) C.Atom
-fn C.XCreateSimpleWindow(d &Display, root C.Window, x int, y int, width u32, height u32, border_width u32,
+
-	border u64, background u64) C.Window
+fn C.XCreateSimpleWindow(d &Display, root C.Window, x int, y int, width u32, height u32, border_width u32, border u64, background u64) C.Window
+
 fn C.XOpenDisplay(name byteptr) &C.Display
+
 fn C.XConvertSelection(d &Display, selection C.Atom, target C.Atom, property C.Atom, requestor Window, time int) int
+
 fn C.XSync(d &Display, discard int) int
+
 fn C.XGetWindowProperty(d &Display, w Window, property C.Atom, offset i64, length i64, delete int, req_type C.Atom, actual_type_return &C.Atom, actual_format_return &int, nitems &u64, bytes_after_return &u64, prop_return &byteptr) int
+
 fn C.XDeleteProperty(d &Display, w Window, property C.Atom) int
+
 fn C.DefaultScreen() int
+
 fn C.RootWindow() voidptr
+
 fn C.BlackPixel() voidptr
+
 fn C.WhitePixel() voidptr
+
 fn C.XFree()
 
 fn todo_del() {}
@@ -49,7 +70,7 @@ fn todo_del(){}
 [typedef]
 struct C.XSelectionRequestEvent {
 mut:
-	display &C.Display	/* Display the event was read from */
+	display   &C.Display // Display the event was read from
 	owner     C.Window
 	requestor C.Window
 	selection C.Atom
@@ -62,7 +83,7 @@ struct C.XSelectionRequestEvent{
 struct C.XSelectionEvent {
 mut:
 	@type     int
-	display &C.Display	/* Display the event was read from */
+	display   &C.Display // Display the event was read from
 	requestor C.Window
 	selection C.Atom
 	target    C.Atom
@@ -94,10 +115,12 @@ union C.XEvent{
 }
 
 const (
-	atom_names = ["TARGETS", "CLIPBOARD", "PRIMARY", "SECONDARY", "TEXT", "UTF8_STRING", "text/plain", "text/html"]
+	atom_names = ['TARGETS', 'CLIPBOARD', 'PRIMARY', 'SECONDARY', 'TEXT', 'UTF8_STRING', 'text/plain',
+		'text/html',
+	]
 )
-//UNSUPPORTED TYPES: MULTIPLE, INCR, TIMESTAMP, image/bmp, image/jpeg, image/tiff, image/png
 
+// UNSUPPORTED TYPES: MULTIPLE, INCR, TIMESTAMP, image/bmp, image/jpeg, image/tiff, image/png
 // all the atom types we need
 // currently we only support text
 // in the future, maybe we can extend this
@@ -142,20 +165,22 @@ pub fn new_clipboard() &Clipboard {
 // We can initialize multiple clipboard instances and use them separately
 fn new_x11_clipboard(selection AtomType) &Clipboard {
 	if selection !in [.clipboard, .primary, .secondary] {
-		panic("Wrong AtomType. Must be one of .primary, .secondary or .clipboard.")
+		panic('Wrong AtomType. Must be one of .primary, .secondary or .clipboard.')
 	}
-
 	// init x11 thread support
 	status := C.XInitThreads()
 	if status == 0 {
-		println("WARN: this system does not support threads; clipboard will cause the program to lock.")
+		println('WARN: this system does not support threads; clipboard will cause the program to lock.')
 	}
 
 	display := new_display()
 
 	if display == C.NULL {
-		println("ERROR: No X Server running. Clipboard cannot be used.")
+		println('ERROR: No X Server running. Clipboard cannot be used.')
-		return &Clipboard{ display: 0 mutex: sync.new_mutex() }
+		return &Clipboard{
+			display: 0
+			mutex: sync.new_mutex()
+		}
 	}
 
 	mut cb := &Clipboard{
@@ -187,7 +212,7 @@ fn (mut cb Clipboard) clear(){
 	C.XSetSelectionOwner(cb.display, cb.selection, C.Window(C.None), C.CurrentTime)
 	C.XFlush(cb.display)
 	cb.is_owner = false
-	cb.text = ""
+	cb.text = ''
 	cb.mutex.unlock()
 }
 
@@ -201,7 +226,9 @@ fn (cb &Clipboard) take_ownership(){
 }
 
 pub fn (mut cb Clipboard) set_text(text string) bool {
-	if cb.window == C.Window(C.None) {return false}
+	if cb.window == C.Window(C.None) {
+		return false
+	}
 	cb.mutex.m_lock()
 	cb.text = text
 	cb.is_owner = true
@@ -214,19 +241,24 @@ pub fn (mut cb Clipboard) set_text(text string) bool {
 }
 
 fn (mut cb Clipboard) get_text() string {
-	if cb.window == C.Window(C.None) {return ""}
+	if cb.window == C.Window(C.None) {
+		return ''
+	}
 	if cb.is_owner {
 		return cb.text
 	}
 	cb.got_text = false
 
 	// Request a list of possible conversions, if we're pasting.
-	C.XConvertSelection(cb.display, cb.selection, cb.get_atom(.targets), cb.selection, cb.window, C.CurrentTime)
+	C.XConvertSelection(cb.display, cb.selection, cb.get_atom(.targets), cb.selection,
+		cb.window, C.CurrentTime)
 
 	// wait for the text to arrive
 	mut retries := 5
 	for {
-		if cb.got_text || retries == 0 {break}
+		if cb.got_text || retries == 0 {
+			break
+		}
 		time.usleep(50000)
 		retries--
 	}
@@ -238,10 +270,12 @@ fn (mut cb Clipboard) get_text() string {
 fn (mut cb Clipboard) transmit_selection(xse &C.XSelectionEvent) bool {
 	if xse.target == cb.get_atom(.targets) {
 		targets := cb.get_supported_targets()
-		C.XChangeProperty(xse.display, xse.requestor, xse.property, cb.get_atom(.xa_atom), 32, C.PropModeReplace, targets.data, targets.len)
+		C.XChangeProperty(xse.display, xse.requestor, xse.property, cb.get_atom(.xa_atom),
-	} else if cb.is_supported_target(xse.target) && cb.is_owner && cb.text != "" {
+			32, C.PropModeReplace, targets.data, targets.len)
+	} else if cb.is_supported_target(xse.target) && cb.is_owner && cb.text != '' {
 		cb.mutex.m_lock()
-		C.XChangeProperty(xse.display, xse.requestor, xse.property, xse.target, 8, C.PropModeReplace, cb.text.str, cb.text.len)
+		C.XChangeProperty(xse.display, xse.requestor, xse.property, xse.target, 8, C.PropModeReplace,
+			cb.text.str, cb.text.len)
 		cb.mutex.unlock()
 	} else {
 		return false
@@ -256,7 +290,7 @@ fn (mut cb Clipboard) start_listener(){
 	for {
 		C.XNextEvent(cb.display, &event)
 		if unsafe { event.@type == 0 } {
-			println("error")
+			println('error')
 			continue
 		}
 		match unsafe { event.@type } {
@@ -267,16 +301,20 @@ fn (mut cb Clipboard) start_listener(){
 				}
 			}
 			C.SelectionClear {
-				if unsafe { event.xselectionclear.window == cb.window } && unsafe { event.xselectionclear.selection == cb.selection } {
+				if unsafe { event.xselectionclear.window == cb.window } && unsafe { event.xselectionclear.selection ==
+					cb.selection }
+				{
 					cb.mutex.m_lock()
 					cb.is_owner = false
-					cb.text = ""
+					cb.text = ''
 					cb.mutex.unlock()
 				}
 			}
 			C.SelectionRequest {
 				if unsafe { event.xselectionrequest.selection == cb.selection } {
-					mut xsre := &C.XSelectionRequestEvent{ display: 0 }
+					mut xsre := &C.XSelectionRequestEvent{
+						display: 0
+					}
 					xsre = unsafe { &event.xselectionrequest }
 
 					mut xse := C.XSelectionEvent{
@@ -296,20 +334,25 @@ fn (mut cb Clipboard) start_listener(){
 				}
 			}
 			C.SelectionNotify {
-				if unsafe { event.xselection.selection == cb.selection && event.xselection.property != C.Atom(C.None) } {
+				if unsafe { event.xselection.selection == cb.selection &&
+					event.xselection.property != C.Atom(C.None) }
+				{
 					if unsafe { event.xselection.target == cb.get_atom(.targets) && !sent_request } {
 						sent_request = true
 						prop := read_property(cb.display, cb.window, cb.selection)
 						to_be_requested = cb.pick_target(prop)
 						if to_be_requested != C.Atom(0) {
-							C.XConvertSelection(cb.display, cb.selection, to_be_requested, cb.selection, cb.window, C.CurrentTime)
+							C.XConvertSelection(cb.display, cb.selection, to_be_requested,
+								cb.selection, cb.window, C.CurrentTime)
 						}
 					} else if unsafe { event.xselection.target == to_be_requested } {
 						sent_request = false
 						to_be_requested = C.Atom(0)
 						cb.mutex.m_lock()
-						prop := unsafe{ read_property(event.xselection.display, event.xselection.requestor, event.xselection.property) }
+						prop := unsafe { read_property(event.xselection.display, event.xselection.requestor,
-						unsafe{ C.XDeleteProperty(event.xselection.display, event.xselection.requestor, event.xselection.property) }
+							event.xselection.property) }
+						unsafe { C.XDeleteProperty(event.xselection.display, event.xselection.requestor,
+							event.xselection.property) }
 						if cb.is_supported_target(prop.actual_type) {
 							cb.got_text = true
 							unsafe {
@@ -326,10 +369,7 @@ fn (mut cb Clipboard) start_listener(){
 	}
 }
 
-
-
 // Helpers
-
 // Initialize all the atoms we need
 fn (mut cb Clipboard) intern_atoms() {
 	cb.atoms << C.Atom(4) // XA_ATOM
@@ -354,9 +394,12 @@ fn read_property(d &C.Display, w C.Window, p C.Atom) Property {
 		if ret != 0 {
 			C.XFree(ret)
 		}
-		C.XGetWindowProperty(d, w, p, 0, read_bytes, 0, C.AnyPropertyType, &actual_type, &actual_format, &nitems, &bytes_after, &ret)
+		C.XGetWindowProperty(d, w, p, 0, read_bytes, 0, C.AnyPropertyType, &actual_type,
+			&actual_format, &nitems, &bytes_after, &ret)
 		read_bytes *= 2
-		if bytes_after == 0 {break}
+		if bytes_after == 0 {
+			break
+		}
 	}
 	return Property{actual_type, actual_format, nitems, ret}
 }
@@ -365,16 +408,16 @@ fn read_property(d &C.Display, w C.Window, p C.Atom) Property {
 fn (cb &Clipboard) pick_target(prop Property) C.Atom {
 	// The list of targets is a list of atoms, so it should have type XA_ATOM
 	// but it may have the type TARGETS instead.
-	if (prop.actual_type != cb.get_atom(.xa_atom) && prop.actual_type != cb.get_atom(.targets)) || prop.actual_format != 32
+	if (prop.actual_type != cb.get_atom(.xa_atom) &&
+		prop.actual_type != cb.get_atom(.targets)) ||
+		prop.actual_format != 32
 	{
 		// This would be really broken. Targets have to be an atom list
 		// and applications should support this. Nevertheless, some
 		// seem broken (MATLAB 7, for instance), so ask for STRING
 		// next instead as the lowest common denominator
 		return cb.get_atom(.xa_string)
-	}
+	} else {
-	else
-	{
 		atom_list := &C.Atom(prop.data)
 
 		mut to_be_requested := C.Atom(0)
@@ -417,7 +460,9 @@ fn (cb &Clipboard) is_supported_target(target C.Atom) bool {
 
 fn (cb &Clipboard) get_target_index(target C.Atom) int {
 	for i, atom in cb.get_supported_targets() {
-		if atom == target {return i}
+		if atom == target {
+			return i
+		}
 	}
 	return -1
 }
@@ -432,8 +477,8 @@ fn new_atom(value int) &C.Atom {
 
 fn create_xwindow(display &C.Display) C.Window {
 	n := C.DefaultScreen(display)
-	return C.XCreateSimpleWindow(display, C.RootWindow(display, n), 0, 0, 1, 1,
+	return C.XCreateSimpleWindow(display, C.RootWindow(display, n), 0, 0, 1, 1, 0, C.BlackPixel(display,
-		0, C.BlackPixel(display, n), C.WhitePixel(display, n))
+		n), C.WhitePixel(display, n))
 }
 
 fn new_display() &C.Display {