ui: fixes so that the ui demo works on linux too

* Implement os.resource_abs_path/1 .
* Implement glfw.get_window_size and glfw.get_framebuffer_size .

vlib/glfw/glfw.v

@@ -101,7 +101,7 @@ pub fn init_glfw() {
 	C.glfwWindowHint(C.GLFW_OPENGL_PROFILE, C.GLFW_OPENGL_CORE_PROFILE)
 }
 
-pub fn (w &Window) destroy() {
+pub fn (w &glfw.Window) destroy() {
 	C.glfwDestroyWindow(w.data)
 }
 
@@ -118,7 +118,7 @@ pub fn window_hint(key, val int) {
 	C.glfwWindowHint(key, val)
 }
 
-pub fn create_window(c WinCfg) &Window {
+pub fn create_window(c WinCfg) &glfw.Window {
 	if c.borderless {
 		window_hint(C.GLFW_RESIZABLE, 0)
 		window_hint(C.GLFW_DECORATED, 0)
@@ -133,18 +133,18 @@ pub fn create_window(c WinCfg) &Window {
 	}
 	println('create window wnd=$cwindow ptr==$c.ptr')
 	C.glfwSetWindowUserPointer(cwindow, c.ptr)
-	window := &Window {
+	window := &glfw.Window {
 		data: cwindow,
 		title: c.title,
 	}
 	return window
 }
 
-pub fn (w &Window) set_title(title string) {
+pub fn (w &glfw.Window) set_title(title string) {
 	C.glfwSetWindowTitle(w.data, title.str)
 }
 
-pub fn (w &Window) make_context_current() {
+pub fn (w &glfw.Window) make_context_current() {
 	C.glfwMakeContextCurrent(w.data)
 }
 
@@ -164,31 +164,31 @@ pub fn set_should_close(w voidptr, close bool) {
 	C.glfwSetWindowShouldClose(w, close)
 }
 
-pub fn (w &Window) should_close() bool {
+pub fn (w &glfw.Window) should_close() bool {
 	return C.glfwWindowShouldClose(w.data)
 }
 
-pub fn (w &Window) swap_buffers() {
+pub fn (w &glfw.Window) swap_buffers() {
 	C.glfwSwapBuffers(w.data)
 }
 
-pub fn (w mut Window) onmousemove(cb voidptr) {
+pub fn (w mut glfw.Window) onmousemove(cb voidptr) {
 	C.glfwSetCursorPosCallback(w.data, cb)
 }
 
-pub fn (w mut Window) set_mouse_button_callback(cb voidptr) {
+pub fn (w mut glfw.Window) set_mouse_button_callback(cb voidptr) {
 	C.glfwSetMouseButtonCallback(w.data, cb)
 }
 
-pub fn (w mut Window) on_click(cb voidptr) {
+pub fn (w mut glfw.Window) on_click(cb voidptr) {
 	C.glfwSetMouseButtonCallback(w.data, cb)
 }
 
-pub fn (w &Window) set_scroll_callback(cb voidptr) {
+pub fn (w &glfw.Window) set_scroll_callback(cb voidptr) {
 	C.glfwSetScrollCallback(w.data, cb)
 }
 
-pub fn (w &Window) on_scroll(cb voidptr) {
+pub fn (w &glfw.Window) on_scroll(cb voidptr) {
 	C.glfwSetScrollCallback(w.data, cb)
 }
 
@@ -196,11 +196,11 @@ pub fn post_empty_event() {
 	C.glfwPostEmptyEvent()
 }
 
-pub fn (w mut Window) onkeydown(cb voidptr) {
+pub fn (w mut glfw.Window) onkeydown(cb voidptr) {
 	C.glfwSetKeyCallback(w.data, cb)
 }
 
-pub fn (w mut Window) onchar(cb voidptr) {
+pub fn (w mut glfw.Window) onchar(cb voidptr) {
 	C.glfwSetCharModsCallback(w.data, cb)
 }
 
@@ -212,11 +212,11 @@ pub fn key_pressed(wnd voidptr, key int) bool {
 	return int(C.glfwGetKey(wnd, key)) == C.GLFW_PRESS
 }
 
-pub fn (w &Window) get_clipboard_text() string {
+pub fn (w &glfw.Window) get_clipboard_text() string {
 	return string(byteptr(C.glfwGetClipboardString(w.data)))
 }
 
-pub fn (w &Window) set_clipboard_text(s string) {
+pub fn (w &glfw.Window) set_clipboard_text(s string) {
 	C.glfwSetClipboardString(w.data, s.str)
 }
 
@@ -227,7 +227,7 @@ pub fn get_cursor_pos(glfw_window voidptr) (f64, f64) {
 	return x,y
 }
 
-pub fn (w &Window) get_cursor_pos() Pos {
+pub fn (w &glfw.Window) get_cursor_pos() Pos {
 	x := f64(0)
 	y := f64(0)
 	C.glfwGetCursorPos(w.data, &x, &y)
@@ -247,16 +247,16 @@ pub fn set_cursor(c Cursor) {
 	C.glfwSetCursor(0, C.GLFW_IBEAM_CURSOR)
 }
 
-pub fn (w &Window) set_cursor(c Cursor) {
+pub fn (w &glfw.Window) set_cursor(c Cursor) {
 	C.glfwSetCursor(w.data, C.GLFW_IBEAM_CURSOR)
 
 }
 
-pub fn (w &Window) user_ptr() voidptr {
+pub fn (w &glfw.Window) user_ptr() voidptr {
 	return C.glfwGetWindowUserPointer(w.data)
 }
 
-pub fn (w &Window) set_user_ptr(ptr voidptr) {
+pub fn (w &glfw.Window) set_user_ptr(ptr voidptr) {
 	C.glfwSetWindowUserPointer(w.data, ptr)
 }
 
@@ -273,6 +273,23 @@ pub fn get_monitor_size() Size {
 	return Size{mode.width, mode.height}
 }
 
+fn C.glfwGetWindowSize(window &glfw.Window, width &int, height &int) // screen coordinates
+fn C.glfwGetFramebufferSize(window &glfw.Window, width &int, height &int) // pixels
+
+// get_window_size in screen coordinates
+pub fn (w &glfw.Window) get_window_size() Size {
+	res := Size{ 0, 0 }
+	C.glfwGetWindowSize( w.data, &res.width, &res.height )
+	return res
+}
+
+// get_framebuffer_size in pixels
+pub fn (w &glfw.Window) get_framebuffer_size() Size {
+	res := Size{ 0, 0 }
+	C.glfwGetFramebufferSize( w.data, &res.width, &res.height )
+	return res
+}
+
 pub fn (size Size) str() string {
 	return '{$size.width, $size.height}'
 }