Fix Control rect coordinate system inconsistency

Fix get_rect, get_global_rect and get_screen_rect to take Controls scale into
account.
Simplify get_screen_position and get_screen_rect

2 files changed, 15 insertions, 21 deletions

diff --git a/doc/classes/Control.xml b/doc/classes/Control.xml
index 91e9b65a8a..435885aefa 100644
--- a/doc/classes/Control.xml
+++ b/doc/classes/Control.xml
@@ -383,7 +383,9 @@
 		<method name="get_global_rect" qualifiers="const">
 			<return type="Rect2" />
 			<description>
-				Returns the position and size of the control relative to the [CanvasLayer]. See [member global_position] and [member size].
+				Returns the position and size of the control relative to the containing canvas. See [member global_position] and [member size].
+				[b]Note:[/b] If the node itself or any parent [CanvasItem] between the node and the canvas have a non default rotation or skew, the resulting size is likely not meaningful.
+				[b]Note:[/b] Setting [member Viewport.gui_snap_controls_to_pixels] to [code]true[/code] can lead to rounding inaccuracies between the displayed control and the returned [Rect2].
 			</description>
 		</method>
 		<method name="get_minimum_size" qualifiers="const">
@@ -414,7 +416,9 @@
 		<method name="get_rect" qualifiers="const">
 			<return type="Rect2" />
 			<description>
-				Returns the position and size of the control relative to the top-left corner of the parent Control. See [member position] and [member size].
+				Returns the position and size of the control in the coordinate system of the containing node. See [member position], [member scale] and [member size].
+				[b]Note:[/b] If [member rotation] is not the default rotation, the resulting size is not meaningful.
+				[b]Note:[/b] Setting [member Viewport.gui_snap_controls_to_pixels] to [code]true[/code] can lead to rounding inaccuracies between the displayed control and the returned [Rect2].
 			</description>
 		</method>
 		<method name="get_screen_position" qualifiers="const">
@@ -1041,7 +1045,7 @@
 			By default, the node's pivot is its top-left corner. When you change its [member rotation] or [member scale], it will rotate or scale around this pivot. Set this property to [member size] / 2 to pivot around the Control's center.
 		</member>
 		<member name="position" type="Vector2" setter="_set_position" getter="get_position" default="Vector2(0, 0)">
-			The node's position, relative to its parent. It corresponds to the rectangle's top-left corner. The property is not affected by [member pivot_offset].
+			The node's position, relative to its containing node. It corresponds to the rectangle's top-left corner. The property is not affected by [member pivot_offset].
 		</member>
 		<member name="rotation" type="float" setter="set_rotation" getter="get_rotation" default="0.0">
 			The node's rotation around its pivot, in radians. See [member pivot_offset] to change the pivot's position.
@@ -1055,7 +1059,7 @@
 			The [Node] which must be a parent of the focused [Control] for the shortcut to be activated. If [code]null[/code], the shortcut can be activated when any control is focused (a global shortcut). This allows shortcuts to be accepted only when the user has a certain area of the GUI focused.
 		</member>
 		<member name="size" type="Vector2" setter="_set_size" getter="get_size" default="Vector2(0, 0)">
-			The size of the node's bounding rectangle, in pixels. [Container] nodes update this property automatically.
+			The size of the node's bounding rectangle, in the node's coordinate system. [Container] nodes update this property automatically.
 		</member>
 		<member name="size_flags_horizontal" type="int" setter="set_h_size_flags" getter="get_h_size_flags" default="1">
 			Tells the parent [Container] nodes how they should resize and place the node on the X axis. Use one of the [enum SizeFlags] constants to change the flags. See the constants to learn what each does.
diff --git a/scene/gui/control.cpp b/scene/gui/control.cpp
index 064c4b597f..46777ff62b 100644
--- a/scene/gui/control.cpp
+++ b/scene/gui/control.cpp
@@ -1360,13 +1360,7 @@ Point2 Control::get_global_position() const {
 
 Point2 Control::get_screen_position() const {
 	ERR_FAIL_COND_V(!is_inside_tree(), Point2());
-	Point2 global_pos = get_global_transform_with_canvas().get_origin();
-	Window *w = Object::cast_to<Window>(get_viewport());
-	if (w && !w->is_embedding_subwindows()) {
-		global_pos += w->get_position();
-	}
-
-	return global_pos;
+	return get_screen_transform().get_origin();
 }
 
 void Control::_set_size(const Size2 &p_size) {
@@ -1416,24 +1410,20 @@ void Control::set_rect(const Rect2 &p_rect) {
 }
 
 Rect2 Control::get_rect() const {
-	return Rect2(get_position(), get_size());
+	Transform2D xform = get_transform();
+	return Rect2(xform.get_origin(), xform.get_scale() * get_size());
 }
 
 Rect2 Control::get_global_rect() const {
-	return Rect2(get_global_position(), get_size());
+	Transform2D xform = get_global_transform();
+	return Rect2(xform.get_origin(), xform.get_scale() * get_size());
 }
 
 Rect2 Control::get_screen_rect() const {
 	ERR_FAIL_COND_V(!is_inside_tree(), Rect2());
 
-	Rect2 r(get_global_position(), get_size());
-
-	Window *w = Object::cast_to<Window>(get_viewport());
-	if (w && !w->is_embedding_subwindows()) {
-		r.position += w->get_position();
-	}
-
-	return r;
+	Transform2D xform = get_screen_transform();
+	return Rect2(xform.get_origin(), xform.get_scale() * get_size());
 }
 
 Rect2 Control::get_window_rect() const {