Add the Pivot Assist widget

Part of #525

editor/src/messages/layout/layout_message_handler.rs

@@ -125,6 +125,12 @@ impl<F: Fn(&MessageDiscriminant) -> Vec<KeysGroup>> MessageHandler<LayoutMessage
 						let callback_message = (optional_input.on_update.callback)(optional_input);
 						responses.push_back(callback_message);
 					}
+					Widget::PivotAssist(pivot_assist) => {
+						let update_value = value.as_str().expect("RadioInput update was not of type: u64");
+						pivot_assist.position = update_value.into();
+						let callback_message = (pivot_assist.on_update.callback)(pivot_assist);
+						responses.push_back(callback_message);
+					}
 					Widget::PopoverButton(_) => {}
 					Widget::RadioInput(radio_input) => {
 						let update_value = value.as_u64().expect("RadioInput update was not of type: u64");

editor/src/messages/layout/utility_types/layout_widget.rs

@@ -1,3 +1,4 @@
+use super::widgets::assist_widgets::*;
 use super::widgets::button_widgets::*;
 use super::widgets::input_widgets::*;
 use super::widgets::label_widgets::*;
@@ -278,6 +279,7 @@ pub enum Widget {
 	InvisibleStandinInput(InvisibleStandinInput),
 	NumberInput(NumberInput),
 	OptionalInput(OptionalInput),
+	PivotAssist(PivotAssist),
 	PopoverButton(PopoverButton),
 	RadioInput(RadioInput),
 	Separator(Separator),

editor/src/messages/layout/utility_types/widgets/assist_widgets.rs

@@ -0,0 +1,48 @@
+use derivative::*;
+use serde::{Deserialize, Serialize};
+
+use crate::messages::layout::utility_types::layout_widget::WidgetCallback;
+
+#[derive(Clone, Default, Derivative, Serialize, Deserialize)]
+#[derivative(Debug, PartialEq)]
+pub struct PivotAssist {
+	pub position: PivotPosition,
+
+	// Callbacks
+	#[serde(skip)]
+	#[derivative(Debug = "ignore", PartialEq = "ignore")]
+	pub on_update: WidgetCallback<PivotAssist>,
+}
+
+#[derive(Clone, Serialize, Deserialize, Debug, Default, PartialEq, Eq)]
+pub enum PivotPosition {
+	#[default]
+	None,
+	TopLeft,
+	TopCenter,
+	TopRight,
+	CenterLeft,
+	Center,
+	CenterRight,
+	BottomLeft,
+	BottomCenter,
+	BottomRight,
+}
+
+impl From<&str> for PivotPosition {
+	fn from(input: &str) -> Self {
+		match input {
+			"None" => PivotPosition::None,
+			"TopLeft" => PivotPosition::TopLeft,
+			"TopCenter" => PivotPosition::TopCenter,
+			"TopRight" => PivotPosition::TopRight,
+			"CenterLeft" => PivotPosition::CenterLeft,
+			"Center" => PivotPosition::Center,
+			"CenterRight" => PivotPosition::CenterRight,
+			"BottomLeft" => PivotPosition::BottomLeft,
+			"BottomCenter" => PivotPosition::BottomCenter,
+			"BottomRight" => PivotPosition::BottomRight,
+			_ => panic!("Failed parsing unrecognized PivotPosition enum value '{}'", input),
+		}
+	}
+}

editor/src/messages/layout/utility_types/widgets/mod.rs

@@ -1,3 +1,4 @@
+pub mod assist_widgets;
 pub mod button_widgets;
 pub mod input_widgets;
 pub mod label_widgets;

editor/src/messages/portfolio/document/transform_layer/transform_layer_message_handler.rs

@@ -62,7 +62,7 @@ impl<'a> MessageHandler<TransformLayerMessage, TransformData<'a>> for TransformL
 				}
 
 				// Don't allow grab with no selected layers
-				if selected_layers.len() == 0 {
+				if selected_layers.is_empty() {
 					return;
 				}
 
@@ -78,7 +78,7 @@ impl<'a> MessageHandler<TransformLayerMessage, TransformData<'a>> for TransformL
 				}
 
 				// Don't allow rotate with no selected layers
-				if selected_layers.len() == 0 {
+				if selected_layers.is_empty() {
 					return;
 				}
 
@@ -94,7 +94,7 @@ impl<'a> MessageHandler<TransformLayerMessage, TransformData<'a>> for TransformL
 				}
 
 				// Don't allow scale with no selected layers
-				if selected_layers.len() == 0 {
+				if selected_layers.is_empty() {
 					return;
 				}
 

editor/src/messages/tool/common_functionality/transformation_cage.rs

@@ -107,7 +107,7 @@ impl SelectedEdges {
 				_ => size,
 			};
 			let delta_size = new_size - size;
-			min = min - delta_size * min_pivot;
+			min -= delta_size * min_pivot;
 			max = min + new_size;
 		}
 

editor/src/messages/tool/tool_messages/select_tool.rs

@@ -4,6 +4,7 @@ use crate::messages::frontend::utility_types::MouseCursorIcon;
 use crate::messages::input_mapper::utility_types::input_keyboard::{Key, KeysGroup, MouseMotion};
 use crate::messages::input_mapper::utility_types::input_mouse::ViewportPosition;
 use crate::messages::layout::utility_types::layout_widget::{Layout, LayoutGroup, PropertyHolder, Widget, WidgetCallback, WidgetHolder, WidgetLayout};
+use crate::messages::layout::utility_types::widgets::assist_widgets::{PivotAssist, PivotPosition};
 use crate::messages::layout::utility_types::widgets::button_widgets::{IconButton, PopoverButton};
 use crate::messages::layout::utility_types::widgets::label_widgets::{Separator, SeparatorDirection, SeparatorType};
 use crate::messages::portfolio::document::utility_types::misc::{AlignAggregate, AlignAxis, FlipAxis};
@@ -245,6 +246,19 @@ impl PropertyHolder for SelectTool {
 					text: "The contents of this popover menu are coming soon".into(),
 					..Default::default()
 				})),
+				WidgetHolder::new(Widget::Separator(Separator {
+					direction: SeparatorDirection::Horizontal,
+					separator_type: SeparatorType::Section,
+				})),
+				// We'd like this widget to hide and show itself whenever the transformation cage is active or inactive (i.e. when no layers are selected)
+				WidgetHolder::new(Widget::PivotAssist(PivotAssist {
+					position: PivotPosition::Center,
+					on_update: WidgetCallback::new(|pivot_assist: &PivotAssist| {
+						// TODO: Make this actually do something
+						log::debug!("Changed pivot to {:?}", pivot_assist.position);
+						Message::NoOp
+					}),
+				})),
 			],
 		}]))
 	}