Moving items in the graph

src/bedit_gui/application.py

@@ -46,7 +46,7 @@ def main() -> int:
 
     settings = ApplicationSettings()
     document = Document(app)
-    window = MainWindow()
+    window = MainWindow(settings.snap_to_grid_size)
     window.ui.actionAbout.triggered.connect(lambda: QMessageBox.about(window, "About BEdit", f"BEdit {BEDIT_VERSION}"))
     window.ui.actionAbout_QT.triggered.connect(app.aboutQt)
 

src/bedit_gui/commands/graph_position_command.py

@@ -0,0 +1,21 @@
+from PySide6.QtGui import QUndoCommand
+
+from bedit_core.models import ComponentID
+
+
+class MoveGraphComponentCommand(QUndoCommand):
+    def __init__(self, document: object, graph_id: ComponentID, component_id: ComponentID, position: tuple[int, int]) -> None:
+        super().__init__("Move graph component")
+        self.document = document
+        self.graph_id = graph_id
+        self.component_id = component_id
+        database = document._graph_database(False)
+        graph = database.graphs.get(graph_id) if database is not None else None
+        self.old_position = graph.component_positions.get(component_id) if graph is not None else None
+        self.new_position = position
+
+    def redo(self) -> None:
+        self.document._set_graph_component_position(self.graph_id, self.component_id, self.new_position)
+
+    def undo(self) -> None:
+        self.document._set_graph_component_position(self.graph_id, self.component_id, self.old_position)

src/bedit_gui/controllers/document_tree_controller.py

@@ -62,10 +62,12 @@ class DocumentTreeController(QObject):
         window.equation_editor.equation_text_change_requested.connect(self.document.update_component_equation_text)
         document.model_changed.connect(self._on_document_changed)
         document.icon_changed.connect(self._on_icon_changed)
+        document.graph_component_position_changed.connect(self._on_graph_component_position_changed)
         document.equation_text_changed.connect(self._on_equation_text_changed)
         self.model.rename_document_requested.connect(self.document.rename)
         self.model.rename_component_requested.connect(self.document.rename_component)
         window.ui.actionDelete.triggered.connect(self.delete_selected_component)
+        window.graph_editor.component_move_requested.connect(self.document.move_graph_component)
 
         # Add deselection with esc to this widget
         window.ui.actionEscape.setShortcutContext(Qt.ShortcutContext.WidgetWithChildrenShortcut)
@@ -142,6 +144,11 @@ class DocumentTreeController(QObject):
         if graph_component is not None and isinstance(graph_component.implementation, GraphImplementation) and component_id in graph_component.implementation.graph.components:
             self._show_component(graph_component)
 
+    def _on_graph_component_position_changed(self, graph_id: ComponentID, component_id: ComponentID, position: tuple[int, int] | None) -> None:
+        graph_component = self.window.graph_editor.component()
+        if graph_component is not None and self.document.component_id(graph_component) == graph_id:
+            self.window.graph_editor.set_component_position(component_id, position)
+
     def _collect_components(self, components: dict[ComponentID, Component]) -> None:
         for component_id, component in components.items():
             self._components[component_id] = component

src/bedit_gui/controllers/settings_controller.py

@@ -18,10 +18,13 @@ class SettingsDialogLike(Protocol):
     @property
     def log_level(self) -> int: ...
 
+    @property
+    def snap_to_grid_size(self) -> int: ...
+
     def exec(self) -> int: ...
 
 
-SettingsDialogFactory = Callable[[int, MainWindow], SettingsDialogLike]
+SettingsDialogFactory = Callable[[int, int, MainWindow], SettingsDialogLike]
 
 
 class SettingsController(QObject):
@@ -41,10 +44,12 @@ class SettingsController(QObject):
         window.ui.actionSettings.triggered.connect(self.open_settings)
 
     def open_settings(self) -> None:
-        dialog = self.dialog_factory(self.settings.log_level, self.window)
+        dialog = self.dialog_factory(self.settings.log_level, self.settings.snap_to_grid_size, self.window)
         if dialog.exec() != QDialog.DialogCode.Accepted:
             return
 
         self.settings.log_level = dialog.log_level
+        self.settings.snap_to_grid_size = dialog.snap_to_grid_size
+        self.window.graph_editor.set_snap_to_grid_size(dialog.snap_to_grid_size)
         set_log_level(dialog.log_level)
         logger.info("Application settings updated")

src/bedit_gui/documents/document.py

@@ -10,13 +10,14 @@ from bedit_core.models import ID, Component, ComponentID, GraphImplementation, P
 from bedit_core.models import Document as CoreDocument
 from bedit_gui.commands.change_icon_command import ChangeIconCommand
 from bedit_gui.commands.equation_text_command import ChangeEquationTextCommand
+from bedit_gui.commands.graph_position_command import MoveGraphComponentCommand
 from bedit_gui.commands.port_commands import AddPortCommand, ChangePortCommand, RemovePortCommand
 from bedit_gui.commands.param_commands import AddParamCommand, ChangeParamCommand, RemoveParamCommand
 from bedit_gui.commands.rename_component_command import RenameComponentCommand
 from bedit_gui.commands.rename_document_command import RenameDocumentCommand
 from bedit_gui.commands.simulation_database_command import ChangeSimulationDatabaseCommand
 from bedit_gui.commands.component_command import AddEmptyEquationComponent, AddEmptyGraphComponent, DeleteComponent, PasteComponents
-from bedit_gui.models import GraphDatabase, Icon, IconDatabase, Simulation, SimulationDatabase
+from bedit_gui.models import Graph, GraphDatabase, Icon, IconDatabase, Simulation, SimulationDatabase
 from bedit_gui.services import document_files
 
 
@@ -29,6 +30,7 @@ class Document(QObject):
     icon_changed = Signal(object, object)
     equation_text_changed = Signal(object, str)
     simulation_database_changed = Signal(object)
+    graph_component_position_changed = Signal(object, object, object)
 
     def __init__(self, parent: QObject | None = None) -> None:
         super().__init__(parent)
@@ -122,12 +124,44 @@ class Document(QObject):
         return self.stored_component_icon(component_id) or Icon()
 
     def graph_database(self) -> GraphDatabase:
+        database = self._graph_database(False)
+        return deepcopy(database) if database is not None else GraphDatabase()
+
+    def move_graph_component(self, graph_component: Component, component_id: ComponentID, position: tuple[int, int]) -> None:
+        graph_id = self.component_id(graph_component)
+        database = self._graph_database(False)
+        graph = database.graphs.get(graph_id) if database is not None else None
+        if graph is None or graph.component_positions.get(component_id) != position:
+            self.undo_stack.push(MoveGraphComponentCommand(self, graph_id, component_id, position))
+
+    def _set_graph_component_position(self, graph_id: ComponentID, component_id: ComponentID, position: tuple[int, int] | None) -> None:
+        if position is None:
+            database = self._graph_database(False)
+            graph = database.graphs.get(graph_id) if database is not None else None
+            if graph is not None:
+                graph.component_positions.pop(component_id, None)
+        else:
+            database = self._graph_database(True)
+            graph = database.graphs.setdefault(graph_id, Graph())
+            graph.component_positions[component_id] = position
+        self.graph_component_position_changed.emit(graph_id, component_id, position)
+
+    def _graph_database(self, create: bool) -> GraphDatabase | None:
         metadata = self.model.metadata
         value = metadata.get("graph_database") if metadata is not None else None
         if isinstance(value, dict):
             value = GraphDatabase.from_data(value)
             metadata["graph_database"] = value
-        return deepcopy(value) if isinstance(value, GraphDatabase) else GraphDatabase()
+        if isinstance(value, GraphDatabase):
+            return value
+        if not create:
+            return None
+        if metadata is None:
+            metadata = {}
+            self.model.metadata = metadata
+        database = GraphDatabase()
+        metadata["graph_database"] = database
+        return database
 
     def change_icon(self, component_id: ComponentID, icon: Icon) -> None:
         self.undo_stack.push(ChangeIconCommand(self, component_id, icon))

src/bedit_gui/services/application_settings.py

@@ -10,6 +10,8 @@ class ApplicationSettings:
 
     LOG_LEVEL_KEY = "logging/level"
     DEFAULT_LOG_LEVEL = logging.INFO
+    SNAP_TO_GRID_SIZE_KEY = "graph/snap_to_grid_size"
+    DEFAULT_SNAP_TO_GRID_SIZE = 4
 
     def __init__(self, settings: QSettings | None = None) -> None:
         self._settings = settings if settings is not None else QSettings()
@@ -26,6 +28,16 @@ class ApplicationSettings:
     def log_level(self, level: int) -> None:
         self._settings.setValue(self.LOG_LEVEL_KEY, level)
 
+    @property
+    def snap_to_grid_size(self) -> int:
+        return max(1, self._settings.value(self.SNAP_TO_GRID_SIZE_KEY, self.DEFAULT_SNAP_TO_GRID_SIZE, type=int))
+
+    @snap_to_grid_size.setter
+    def snap_to_grid_size(self, size: int) -> None:
+        if size < 1:
+            raise ValueError("snap-to-grid size must be positive")
+        self._settings.setValue(self.SNAP_TO_GRID_SIZE_KEY, size)
+
 class SimulationApplicationSettings:
     """Typed access to persistent BEsim application settings."""
 

src/bedit_gui/ui/forms/settings_dialog.ui

@@ -55,7 +55,27 @@
          </property>
         </widget>
        </item>
+       <item row="1" column="0">
+        <widget class="QLabel" name="labelSnapToGridSize">
+         <property name="text">
+          <string>Snap-to-grid size:</string>
+         </property>
+        </widget>
+       </item>
        <item row="1" column="1">
+        <widget class="QSpinBox" name="snapToGridSize">
+         <property name="minimum">
+          <number>1</number>
+         </property>
+         <property name="maximum">
+          <number>256</number>
+         </property>
+         <property name="value">
+          <number>4</number>
+         </property>
+        </widget>
+       </item>
+       <item row="2" column="1">
         <spacer name="verticalSpacer">
          <property name="orientation">
           <enum>Qt::Orientation::Vertical</enum>

src/bedit_gui/views/dialogs/settings_dialog.py

@@ -20,6 +20,7 @@ class SettingsDialog(QDialog):
     def __init__(
         self,
         log_level: int,
+        snap_to_grid_size: int,
         parent: QWidget | None = None,
     ) -> None:
         super().__init__(parent)
@@ -35,7 +36,12 @@ class SettingsDialog(QDialog):
         self.ui.logLevel.setCurrentIndex(
             selected if selected >= 0 else self.LOG_LEVELS.index(logging.INFO)
         )
+        self.ui.snapToGridSize.setValue(snap_to_grid_size)
 
     @property
     def log_level(self) -> int:
         return int(self.ui.logLevel.currentData())
+
+    @property
+    def snap_to_grid_size(self) -> int:
+        return self.ui.snapToGridSize.value()

src/bedit_gui/views/graph_editor_widget.py

@@ -2,28 +2,29 @@ from __future__ import annotations
 
 from math import hypot
 
-from PySide6.QtCore import QEvent, QObject, QPointF, QRectF, QSize, QTimer, Qt
+from PySide6.QtCore import QEvent, QObject, QPointF, QRectF, QSize, QTimer, Qt, Signal
 from PySide6.QtGui import QColor, QPainter, QPainterPath, QPen, QWheelEvent
-from PySide6.QtWidgets import QGraphicsItem, QGraphicsPathItem, QGraphicsPixmapItem, QGraphicsScene, QGraphicsView, QWidget
+from PySide6.QtWidgets import QGraphicsItem, QGraphicsPathItem, QGraphicsPixmapItem, QGraphicsScene, QGraphicsSceneMouseEvent, QGraphicsView, QWidget
 
-from bedit_core.models import BondCausality, BondConnection, Component, ComponentID, GraphImplementation, SignalConnection
+from bedit_core.models import BondCausality, BondConnection, Component, ComponentID, ConnectionID, GraphImplementation, SignalConnection
 from bedit_gui.models import Graph, Icon
 from bedit_gui.ui.generated.ui_graph_editor_widget import Ui_graphEditorWidget
 from bedit_gui.utils.icon import get_pixmap_bounding_box, render_icon
 
-GRID_SPACING = 32
+GRID_SPACING = 64
 SCENE_SIZE = 10000
 MIN_ZOOM = 0.2
 MAX_ZOOM = 4.0
 ZOOM_STEP = 1.15
 ZOOM_TO_FIT_PADDING = 32.0
-COMPONENT_ICON_SIZE = QSize(96, 96)
+COMPONENT_ICON_SIZE = QSize(128, 128)
 FALLBACK_COMPONENT_SPACING = 128
-CONNECTION_WIDTH = 2.0
+CONNECTION_WIDTH = 4.0
-CONNECTION_BOUNDING_BOX_SPACING = 8.0
+CONNECTION_BOUNDING_BOX_SPACING = 16.0
-ARROW_LENGTH = 14.0
+CONNECTION_STRAIGHTEN_TOLERANCE = 8.0
-ARROW_HALF_WIDTH = 7.0
+ARROW_LENGTH = 32.0
-CAUSALITY_TICK_HALF_LENGTH = 8.0
+ARROW_HALF_WIDTH = 16.0
+CAUSALITY_TICK_HALF_LENGTH = 16.0
 
 
 class GraphGraphicsScene(QGraphicsScene):
@@ -34,15 +35,16 @@ class GraphGraphicsScene(QGraphicsScene):
         pen = QPen(QColor(205, 205, 205), 0, Qt.PenStyle.DotLine)
         painter.setPen(pen)
 
+        scene_rect = self.sceneRect()
         left = int(rect.left()) - int(rect.left()) % GRID_SPACING
         top = int(rect.top()) - int(rect.top()) % GRID_SPACING
         x = left
         while x <= rect.right():
-            painter.drawLine(x, rect.top(), x, rect.bottom())
+            painter.drawLine(x, scene_rect.top(), x, scene_rect.bottom())
             x += GRID_SPACING
         y = top
         while y <= rect.bottom():
-            painter.drawLine(rect.left(), y, rect.right(), y)
+            painter.drawLine(scene_rect.left(), y, scene_rect.right(), y)
             y += GRID_SPACING
 
 
@@ -102,13 +104,54 @@ class GraphConnectionItem(QGraphicsPathItem):
         path.lineTo(endpoint.x() + perpendicular_x, endpoint.y() + perpendicular_y)
 
 
+class GraphComponentItem(QGraphicsPixmapItem):
+    def __init__(self, component_id: ComponentID, pixmap, editor: GraphEditorWidget) -> None:
+        super().__init__(pixmap)
+        self.component_id = component_id
+        self.editor = editor
+        self._drag_start = QPointF()
+        self._dragging = False
+        self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemIsSelectable)
+        self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemIsMovable)
+        self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemSendsGeometryChanges)
+
+    def itemChange(self, change: QGraphicsItem.GraphicsItemChange, value: object) -> object:
+        if change == QGraphicsItem.GraphicsItemChange.ItemPositionChange and self._dragging and isinstance(value, QPointF):
+            grid_size = self.editor.snap_to_grid_size
+            value = QPointF(round(value.x() / grid_size) * grid_size, round(value.y() / grid_size) * grid_size)
+        result = super().itemChange(change, value)
+        if change == QGraphicsItem.GraphicsItemChange.ItemPositionHasChanged:
+            self.editor.refresh_connections()
+        return result
+
+    def mousePressEvent(self, event: QGraphicsSceneMouseEvent) -> None:
+        self._drag_start = QPointF(self.pos())
+        self._dragging = True
+        super().mousePressEvent(event)
+
+    def mouseReleaseEvent(self, event: QGraphicsSceneMouseEvent) -> None:
+        super().mouseReleaseEvent(event)
+        self._dragging = False
+        position = (round(self.pos().x()), round(self.pos().y()))
+        self.setPos(*position)
+        if self.pos() != self._drag_start:
+            self.editor.finish_component_move(self.component_id, position)
+
+
 class GraphEditorWidget(QWidget):
-    def __init__(self, parent: QWidget | None = None) -> None:
+    component_move_requested = Signal(object, object, object)
+
+    def __init__(self, parent: QWidget | None = None, snap_to_grid_size: int = 4) -> None:
         super().__init__(parent)
 
         self.ui = Ui_graphEditorWidget()
         self.ui.setupUi(self)
         self._component: Component | None = None
+        self._graph = Graph()
+        self._component_items: dict[ComponentID, GraphComponentItem] = {}
+        self._component_bounds: dict[ComponentID, QRectF] = {}
+        self._connection_items: dict[ConnectionID, GraphConnectionItem] = {}
+        self.set_snap_to_grid_size(snap_to_grid_size)
         self.scene = GraphGraphicsScene(self)
         self.scene.setSceneRect(-SCENE_SIZE / 2, -SCENE_SIZE / 2, SCENE_SIZE, SCENE_SIZE)
         self.ui.graphicsView.setScene(self.scene)
@@ -117,65 +160,120 @@ class GraphEditorWidget(QWidget):
         self.ui.actionZoomToFit.triggered.connect(self.zoom_to_fit)
         self.ui.graphicsView.centerOn(0, 0)
 
+    @property
+    def snap_to_grid_size(self) -> int:
+        return self._snap_to_grid_size
+
+    def set_snap_to_grid_size(self, size: int) -> None:
+        if size < 1:
+            raise ValueError("snap-to-grid size must be positive")
+        self._snap_to_grid_size = size
+
     def set_component(self, component: Component | None, graph: Graph | None = None, icons: dict[ComponentID, Icon] | None = None) -> None:
         if component is not None and not isinstance(component.implementation, GraphImplementation):
             raise TypeError("GraphEditorWidget only supports components with a graph implementation")
         component_changed = component is not self._component
         self._component = component
+        self._graph = graph or Graph()
+        self._component_items = {}
+        self._component_bounds = {}
+        self._connection_items = {}
         self.scene.clear()
         if component is None:
             return
 
-        graph = graph or Graph()
+        graph = self._graph
         icons = icons or {}
         positions = {component_id: graph.component_positions.get(component_id, (index * FALLBACK_COMPONENT_SPACING, 0)) for index, component_id in enumerate(component.implementation.graph.components)}
-        port_owners = {port_id: component_id for component_id, child in component.implementation.graph.components.items() for port_id in child.interface.ports}
-        component_items: dict[ComponentID, QGraphicsPixmapItem] = {}
-        component_bounds: dict[ComponentID, QRectF] = {}
-
         for component_id, child in component.implementation.graph.components.items():
             icon = icons.get(component_id, Icon())
             pixmap = render_icon(icon, child.interface.ports, COMPONENT_ICON_SIZE).pixmap(COMPONENT_ICON_SIZE)
-            item = QGraphicsPixmapItem(pixmap)
+            item = GraphComponentItem(component_id, pixmap, self)
             item.setOffset(-pixmap.width() / 2, -pixmap.height() / 2)
             item.setPos(*positions[component_id])
             item.setToolTip(child.name)
-            item.setFlag(QGraphicsItem.GraphicsItemFlag.ItemIsSelectable)
-            component_items[component_id] = item
             bounds = get_pixmap_bounding_box(pixmap)
-            component_bounds[component_id] = bounds.translated(item.pos().x() - pixmap.width() / 2, item.pos().y() - pixmap.height() / 2)
+            self._component_items[component_id] = item
+            self._component_bounds[component_id] = bounds.translated(-pixmap.width() / 2, -pixmap.height() / 2)
+            self.scene.addItem(item)
 
         for connection_id, connection in component.implementation.graph.connections.items():
             if not isinstance(connection, (SignalConnection, BondConnection)):
                 continue
-            source_component = port_owners.get(connection.source)
-            target_component = port_owners.get(connection.target)
-            if source_component is None or target_component is None:
-                continue
-            visual_connection = graph.connections.get(connection_id)
-            points = list(visual_connection.points) if visual_connection is not None else []
-            if len(points) < 2:
-                points = [positions[source_component], positions[target_component]]
-            else:
-                points = [positions[source_component], *points[1:-1], positions[target_component]]
-            points = self._clip_connection(points, component_bounds[source_component], component_bounds[target_component])
             tick_at_source = None
             if isinstance(connection, BondConnection):
                 if connection.causality is BondCausality.EFFORT_OUT:
                     tick_at_source = False
                 elif connection.causality is BondCausality.FLOW_OUT:
                     tick_at_source = True
-            connection_item = GraphConnectionItem(points, half_arrow=isinstance(connection, BondConnection), tick_at_source=tick_at_source)
+            connection_item = GraphConnectionItem([(0, 0), (1, 0)], half_arrow=isinstance(connection, BondConnection), tick_at_source=tick_at_source)
             connection_item.setData(0, str(connection_id))
+            self._connection_items[connection_id] = connection_item
             self.scene.addItem(connection_item)
-
+        self.refresh_connections()
-        for item in component_items.values():
-            self.scene.addItem(item)
         if component_changed:
             QTimer.singleShot(0, self.ui.actionZoomToFit.trigger)
 
+    def refresh_connections(self) -> None:
+        component = self._component
+        if component is None or not self._connection_items:
+            return
+        port_owners = {port_id: component_id for component_id, child in component.implementation.graph.components.items() for port_id in child.interface.ports}
+        for connection_id, item in self._connection_items.items():
+            connection = component.implementation.graph.connections[connection_id]
+            source_component = port_owners.get(connection.source)
+            target_component = port_owners.get(connection.target)
+            if source_component is None or target_component is None:
+                continue
+            source_position = self._item_position(source_component)
+            target_position = self._item_position(target_component)
+            visual_connection = self._graph.connections.get(connection_id)
+            points = list(visual_connection.points) if visual_connection is not None else []
+            points = [source_position, target_position] if len(points) < 2 else [source_position, *points[1:-1], target_position]
+            points = self._straighten_direct_connection(points)
+            source_bounds = self._component_bounds[source_component].translated(*source_position)
+            target_bounds = self._component_bounds[target_component].translated(*target_position)
+            points = self._clip_connection(points, source_bounds, target_bounds)
+            tick_at_source = None
+            if isinstance(connection, BondConnection):
+                tick_at_source = False if connection.causality is BondCausality.EFFORT_OUT else True if connection.causality is BondCausality.FLOW_OUT else None
+            item.setPath(item._connection_path(points, isinstance(connection, BondConnection), tick_at_source))
+
+    def finish_component_move(self, component_id: ComponentID, position: tuple[int, int]) -> None:
+        if self._component is not None:
+            self.component_move_requested.emit(self._component, component_id, position)
+
+    def set_component_position(self, component_id: ComponentID, position: tuple[int, int] | None) -> None:
+        item = self._component_items.get(component_id)
+        if item is None:
+            return
+        if position is None:
+            index = list(self._component_items).index(component_id)
+            position = (index * FALLBACK_COMPONENT_SPACING, 0)
+        item.setPos(*position)
+        self.refresh_connections()
+
+    def _item_position(self, component_id: ComponentID) -> tuple[float, float]:
+        position = self._component_items[component_id].pos()
+        return position.x(), position.y()
+
     @staticmethod
-    def _clip_connection(points: list[tuple[int, int]], source_bounds: QRectF, target_bounds: QRectF) -> list[tuple[float, float]]:
+    def _straighten_direct_connection(points: list[tuple[float, float]]) -> list[tuple[float, float]]:
+        if len(points) != 2:
+            return points
+        source, target = points
+        dx = target[0] - source[0]
+        dy = target[1] - source[1]
+        if abs(dx) <= CONNECTION_STRAIGHTEN_TOLERANCE and abs(dx) < abs(dy):
+            x = (source[0] + target[0]) / 2
+            return [(x, source[1]), (x, target[1])]
+        if abs(dy) <= CONNECTION_STRAIGHTEN_TOLERANCE and abs(dy) < abs(dx):
+            y = (source[1] + target[1]) / 2
+            return [(source[0], y), (target[0], y)]
+        return points
+
+    @staticmethod
+    def _clip_connection(points: list[tuple[float, float]], source_bounds: QRectF, target_bounds: QRectF) -> list[tuple[float, float]]:
         source = points[0]
         target = points[-1]
         source_direction = next((point for point in points[1:] if point != source), None)
@@ -183,20 +281,19 @@ class GraphEditorWidget(QWidget):
         if source_direction is None or target_direction is None:
             return points
         clipped = list(points)
-        clipped[0] = GraphEditorWidget._bounding_box_edge(source_bounds, source_direction)
+        clipped[0] = GraphEditorWidget._bounding_box_edge(source_bounds, source, source_direction)
-        clipped[-1] = GraphEditorWidget._bounding_box_edge(target_bounds, target_direction)
+        clipped[-1] = GraphEditorWidget._bounding_box_edge(target_bounds, target, target_direction)
         return clipped
 
     @staticmethod
-    def _bounding_box_edge(bounds: QRectF, toward: tuple[int, int]) -> tuple[float, float]:
+    def _bounding_box_edge(bounds: QRectF, origin: tuple[float, float], toward: tuple[float, float]) -> tuple[float, float]:
         bounds = bounds.adjusted(-CONNECTION_BOUNDING_BOX_SPACING, -CONNECTION_BOUNDING_BOX_SPACING, CONNECTION_BOUNDING_BOX_SPACING, CONNECTION_BOUNDING_BOX_SPACING)
-        center = bounds.center()
+        dx = toward[0] - origin[0]
-        dx = toward[0] - center.x()
+        dy = toward[1] - origin[1]
-        dy = toward[1] - center.y()
+        horizontal_scale = (bounds.right() - origin[0]) / dx if dx > 0 else (bounds.left() - origin[0]) / dx if dx < 0 else float("inf")
-        horizontal_scale = bounds.width() / 2 / abs(dx) if dx else float("inf")
+        vertical_scale = (bounds.bottom() - origin[1]) / dy if dy > 0 else (bounds.top() - origin[1]) / dy if dy < 0 else float("inf")
-        vertical_scale = bounds.height() / 2 / abs(dy) if dy else float("inf")
         scale = min(horizontal_scale, vertical_scale)
-        return center.x() + dx * scale, center.y() + dy * scale
+        return origin[0] + dx * scale, origin[1] + dy * scale
 
     def component(self) -> Component | None:
         return self._component

src/bedit_gui/views/main_window.py

@@ -7,7 +7,7 @@ from bedit_gui.views.graph_editor_widget import GraphEditorWidget
 
 
 class MainWindow(QMainWindow):
-    def __init__(self) -> None:
+    def __init__(self, snap_to_grid_size: int = 4) -> None:
         super().__init__()
 
         self.ui = Ui_MainWindow()
@@ -18,7 +18,7 @@ class MainWindow(QMainWindow):
         self.equation_editor = EquationEditorWidget(self.ui.centralwidget)
         self.equation_editor.hide()
         central_layout.addWidget(self.equation_editor)
-        self.graph_editor = GraphEditorWidget(self.ui.centralwidget)
+        self.graph_editor = GraphEditorWidget(self.ui.centralwidget, snap_to_grid_size)
         self.graph_editor.hide()
         central_layout.addWidget(self.graph_editor)
 

untitled.bedit.json

@@ -438,8 +438,8 @@
                 -32,
                 -32
               ],
-              "width": 64,
+              "width": 64.0,
-              "height": 64,
+              "height": 64.0,
               "color": "#000000ff",
               "bold": true,
               "italic": false,
@@ -596,32 +596,32 @@
           "shapes": {},
           "component_positions": {
             "43b3aee6-0b38-429b-9c6d-d38fc097297f": [
-              128,
+              64,
-              -256
+              -384
             ],
             "9ee2f42b-5ed1-446d-8790-c2a1df6b61d3": [
-              -128,
+              64,
               -128
             ],
             "5a8b2e8d-489f-467b-8282-7e344dfad576": [
-              128,
+              320,
-              -64
+              -128
             ],
             "2804f2f1-6123-4a53-aff1-87a3a8202711": [
-              -320,
+              -192,
               -128
             ],
             "9f392c28-6bef-4b10-9305-93e250747007": [
-              128,
+              64,
-              160
+              128
             ],
             "77701f68-b14c-4b98-8929-c5fba0261962": [
-              352,
+              320,
-              96
+              128
             ],
             "033b930e-bf79-403a-8b0b-a159f3c81ce9": [
-              352,
+              -192,
-              224
+              128
             ]
           },
           "connections": {