Fix multiple usability issues in the texture region editor

- Correctly display atlas textures when used by other objects.
- Make region handles easier to hit in ninepatchable objects.
- Correctly initialize and restore various visual properties.
- Improve code quality.

editor/editor_themes.cpp

@@ -1507,6 +1507,11 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	style_theme_preview_bg_tab->set_expand_margin(SIDE_BOTTOM, 2 * EDSCALE);
 	theme->set_stylebox("ThemeEditorPreviewBG", "EditorStyles", style_theme_preview_bg_tab);
 
+	Ref<StyleBoxFlat> style_texture_region_bg = style_tree_bg->duplicate();
+	style_texture_region_bg->set_content_margin_all(0);
+	theme->set_stylebox("TextureRegionPreviewBG", "EditorStyles", style_texture_region_bg);
+	theme->set_stylebox("TextureRegionPreviewFG", "EditorStyles", make_empty_stylebox(0, 0, 0, 0));
+
 	// Separators
 	theme->set_stylebox("separator", "HSeparator", make_line_stylebox(separator_color, MAX(Math::round(EDSCALE), border_width)));
 	theme->set_stylebox("separator", "VSeparator", make_line_stylebox(separator_color, MAX(Math::round(EDSCALE), border_width), 0, 0, true));

editor/plugins/texture_region_editor_plugin.h

@@ -42,6 +42,7 @@
 
 class AtlasTexture;
 class OptionButton;
+class PanelContainer;
 class ViewPanner;
 
 class TextureRegionEditor : public AcceptDialog {
@@ -66,16 +67,18 @@ class TextureRegionEditor : public AcceptDialog {
 	SpinBox *sb_off_x = nullptr;
 	SpinBox *sb_sep_y = nullptr;
 	SpinBox *sb_sep_x = nullptr;
-	Panel *edit_draw = nullptr;
+
+	PanelContainer *texture_preview = nullptr;
+	Panel *texture_overlay = nullptr;
 
 	VScrollBar *vscroll = nullptr;
 	HScrollBar *hscroll = nullptr;
 
 	Vector2 draw_ofs;
-	float draw_zoom = 0.0;
+	float draw_zoom = 1.0;
 	bool updating_scroll = false;
 
-	int snap_mode = 0;
+	SnapMode snap_mode = SNAP_NONE;
 	Vector2 snap_offset;
 	Vector2 snap_step;
 	Vector2 snap_separation;
@@ -83,28 +86,28 @@ class TextureRegionEditor : public AcceptDialog {
 	Sprite2D *node_sprite_2d = nullptr;
 	Sprite3D *node_sprite_3d = nullptr;
 	NinePatchRect *node_ninepatch = nullptr;
-	Ref<StyleBoxTexture> obj_styleBox;
-	Ref<AtlasTexture> atlas_tex;
-
-	Ref<CanvasTexture> preview_tex;
+	Ref<StyleBoxTexture> res_stylebox;
+	Ref<AtlasTexture> res_atlas_texture;
 
 	Rect2 rect;
 	Rect2 rect_prev;
 	float prev_margin = 0.0f;
-	int edited_margin = 0;
+	int edited_margin = -1;
 	HashMap<RID, List<Rect2>> cache_map;
 	List<Rect2> autoslice_cache;
-	bool autoslice_is_dirty = false;
+	bool autoslice_is_dirty = true;
 
 	bool drag = false;
 	bool creating = false;
 	Vector2 drag_from;
-	int drag_index = 0;
+	int drag_index = -1;
 	bool request_center = false;
 
 	Ref<ViewPanner> panner;
 	void _pan_callback(Vector2 p_scroll_vec, Ref<InputEvent> p_event);
 	void _zoom_callback(float p_zoom_factor, Vector2 p_origin, Ref<InputEvent> p_event);
+	void _scroll_changed(float);
+	Transform2D _get_offset_transform() const;
 
 	void _set_snap_mode(int p_mode);
 	void _set_snap_off_x(float p_val);
@@ -113,35 +116,39 @@ class TextureRegionEditor : public AcceptDialog {
 	void _set_snap_step_y(float p_val);
 	void _set_snap_sep_x(float p_val);
 	void _set_snap_sep_y(float p_val);
+
 	void _zoom_on_position(float p_zoom, Point2 p_position = Point2());
 	void _zoom_in();
 	void _zoom_reset();
 	void _zoom_out();
-	void apply_rect(const Rect2 &p_rect);
+
+	void _apply_rect(const Rect2 &p_rect);
 	void _update_rect();
 	void _update_autoslice();
 
+	Ref<Texture2D> _get_edited_object_texture() const;
+	Rect2 _get_edited_object_region() const;
 	void _texture_changed();
+	void _node_removed(Node *p_node);
+
+	void _edit_region();
+	void _clear_edited_object();
+
+	void _draw_margin_line(Vector2 p_from, Vector2 p_to);
 
 protected:
 	void _notification(int p_what);
-	void _node_removed(Object *p_obj);
 	static void _bind_methods();
 
+	void _texture_preview_draw();
+	void _texture_overlay_draw();
+	void _texture_overlay_input(const Ref<InputEvent> &p_input);
+
 	Vector2 snap_point(Vector2 p_target) const;
 
 public:
-	void _edit_region();
-	void _region_draw();
-	void _region_input(const Ref<InputEvent> &p_input);
-	void _scroll_changed(float);
-	bool is_stylebox();
-	bool is_atlas_texture();
-	bool is_ninepatch();
-	Sprite2D *get_sprite_2d();
-	Sprite3D *get_sprite_3d();
-
 	void edit(Object *p_obj);
+
 	TextureRegionEditor();
 };
 

scene/resources/atlas_texture.cpp

@@ -245,11 +245,16 @@ bool AtlasTexture::is_pixel_opaque(int p_x, int p_y) const {
 }
 
 Ref<Image> AtlasTexture::get_image() const {
-	if (!atlas.is_valid() || !atlas->get_image().is_valid()) {
+	if (atlas.is_null() || region.size.x <= 0 || region.size.y <= 0) {
 		return Ref<Image>();
 	}
 
-	return atlas->get_image()->get_region(region);
+	Ref<Image> atlas_image = atlas->get_image();
+	if (atlas_image.is_null()) {
+		return Ref<Image>();
+	}
+
+	return atlas_image->get_region(region);
 }
 
 AtlasTexture::AtlasTexture() {}