From 44b01751e6300736a58d0f0aaf34a7b95557580f Mon Sep 17 00:00:00 2001
From: Hugo Locurcio <hugo.locurcio@hugo.pro>
Date: Fri, 16 Jul 2021 06:03:09 +0200
Subject: [PATCH] Prevent accidental drags by adding drag distance threshold

Co-authored-by: fox <12120644+foxydevloper@users.noreply.github.com>
---
 editor/plugins/canvas_item_editor_plugin.cpp | 45 ++++++++++++++------
 editor/plugins/canvas_item_editor_plugin.h   |  2 +
 editor/plugins/spatial_editor_plugin.cpp     |  4 +-
 editor/plugins/spatial_editor_plugin.h       |  1 +
 4 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/editor/plugins/canvas_item_editor_plugin.cpp b/editor/plugins/canvas_item_editor_plugin.cpp
index a74812fcf1e..b6bea0a7e06 100644
--- a/editor/plugins/canvas_item_editor_plugin.cpp
+++ b/editor/plugins/canvas_item_editor_plugin.cpp
@@ -2491,20 +2491,8 @@ bool CanvasItemEditor::_gui_input_select(const Ref<InputEvent> &p_event) {
 				// Start dragging
 				if (still_selected) {
 					// Drag the node(s) if requested
-					List<CanvasItem *> selection2 = _get_edited_canvas_items();
-
-					drag_selection.clear();
-					for (int i = 0; i < selection2.size(); i++) {
-						if (_is_node_movable(selection2[i], true)) {
-							drag_selection.push_back(selection2[i]);
-						}
-					}
-
-					if (selection2.size() > 0) {
-						drag_type = DRAG_MOVE;
-						drag_from = click;
-						_save_canvas_item_state(drag_selection);
-					}
+					drag_start_origin = click;
+					drag_type = DRAG_QUEUED;
 				}
 				// Select the item
 				return true;
@@ -2512,6 +2500,35 @@ bool CanvasItemEditor::_gui_input_select(const Ref<InputEvent> &p_event) {
 		}
 	}
 
+	if (drag_type == DRAG_QUEUED) {
+		if (b.is_valid() && !b->is_pressed()) {
+			drag_type = DRAG_NONE;
+			return true;
+		}
+		if (m.is_valid()) {
+			Point2 click = transform.affine_inverse().xform(m->get_position());
+			// Scale movement threshold with zoom (which itself is set relative to the editor scale).
+			bool movement_threshold_passed = drag_start_origin.distance_to(click) > (8 * MAX(1, EDSCALE)) / zoom;
+			if (m.is_valid() && movement_threshold_passed) {
+				List<CanvasItem *> selection2 = _get_edited_canvas_items();
+
+				drag_selection.clear();
+				for (int i = 0; i < selection2.size(); i++) {
+					if (_is_node_movable(selection2[i], true)) {
+						drag_selection.push_back(selection2[i]);
+					}
+				}
+
+				if (selection2.size() > 0) {
+					drag_type = DRAG_MOVE;
+					drag_from = click;
+					_save_canvas_item_state(drag_selection);
+				}
+				return true;
+			}
+		}
+	}
+
 	if (drag_type == DRAG_BOX_SELECTION) {
 		if (b.is_valid() && !b->is_pressed() && b->get_button_index() == BUTTON_LEFT) {
 			// Confirms box selection
diff --git a/editor/plugins/canvas_item_editor_plugin.h b/editor/plugins/canvas_item_editor_plugin.h
index 380a1c1a603..dec90a8fa38 100644
--- a/editor/plugins/canvas_item_editor_plugin.h
+++ b/editor/plugins/canvas_item_editor_plugin.h
@@ -211,6 +211,7 @@ private:
 		DRAG_ANCHOR_BOTTOM_RIGHT,
 		DRAG_ANCHOR_BOTTOM_LEFT,
 		DRAG_ANCHOR_ALL,
+		DRAG_QUEUED,
 		DRAG_MOVE,
 		DRAG_SCALE_X,
 		DRAG_SCALE_Y,
@@ -390,6 +391,7 @@ private:
 	Control *top_ruler;
 	Control *left_ruler;
 
+	Point2 drag_start_origin;
 	DragType drag_type;
 	Point2 drag_from;
 	Point2 drag_to;
diff --git a/editor/plugins/spatial_editor_plugin.cpp b/editor/plugins/spatial_editor_plugin.cpp
index aec3310758c..abee01551b3 100644
--- a/editor/plugins/spatial_editor_plugin.cpp
+++ b/editor/plugins/spatial_editor_plugin.cpp
@@ -1206,6 +1206,7 @@ void SpatialEditorViewport::_sinput(const Ref<InputEvent> &p_event) {
 					}
 
 					_edit.mouse_pos = b->get_position();
+					_edit.original_mouse_pos = b->get_position();
 					_edit.snap = spatial_editor->is_snap_enabled();
 					_edit.mode = TRANSFORM_NONE;
 
@@ -1412,7 +1413,8 @@ void SpatialEditorViewport::_sinput(const Ref<InputEvent> &p_event) {
 			} else if (nav_scheme == NAVIGATION_MODO && m->get_alt()) {
 				nav_mode = NAVIGATION_ORBIT;
 			} else {
-				if (clicked) {
+				const bool movement_threshold_passed = _edit.original_mouse_pos.distance_to(_edit.mouse_pos) > 8 * EDSCALE;
+				if (clicked && movement_threshold_passed) {
 					if (!clicked_includes_current) {
 						_select_clicked(clicked_wants_append, true);
 						// Processing was deferred.
diff --git a/editor/plugins/spatial_editor_plugin.h b/editor/plugins/spatial_editor_plugin.h
index 8d680cb0105..b9fc25d8632 100644
--- a/editor/plugins/spatial_editor_plugin.h
+++ b/editor/plugins/spatial_editor_plugin.h
@@ -357,6 +357,7 @@ private:
 		Vector3 orig_gizmo_pos;
 		int edited_gizmo;
 		Point2 mouse_pos;
+		Point2 original_mouse_pos;
 		bool snap;
 		Ref<EditorSpatialGizmo> gizmo;
 		int gizmo_handle;