Avoid accidental graph edits on click

src/mini_eq/window_graph.py

@@ -45,6 +45,8 @@
 GRAPH_PLOT_TOP = 26.0
 GRAPH_PLOT_BOTTOM = 34.0
 SELECTED_BAND_PLACEHOLDER_FREQUENCY_HZ = 1000.0
+GRAPH_DRAG_EDIT_THRESHOLD_PX = 3.0
+GRAPH_POINT_HIT_RADIUS_PX = 32.0
 
 
 def rounded_rectangle_path(cr, x: float, y: float, width: float, height: float, radius: float) -> None:
@@ -352,6 +354,7 @@ def on_graph_pressed(self, gesture: Gtk.GestureClick, _press_count: int, x: floa
         self.select_band(target)
 
     def on_graph_drag_begin(self, gesture: Gtk.GestureDrag, start_x: float, start_y: float) -> None:
+        self.clear_graph_drag_state()
         width = self.graph_area.get_allocated_width()
         height = self.graph_area.get_allocated_height()
         if width <= 0 or height <= 0:
@@ -366,6 +369,8 @@ def on_graph_drag_begin(self, gesture: Gtk.GestureDrag, start_x: float, start_y:
 
         best_index = -1
         min_dist = float("inf")
+        best_point_x = 0.0
+        best_point_y = 0.0
 
         for index in active:
             band = self.controller.bands[index]
@@ -380,19 +385,31 @@ def on_graph_drag_begin(self, gesture: Gtk.GestureDrag, start_x: float, start_y:
             if dist < min_dist:
                 min_dist = dist
                 best_index = index
+                best_point_x = bx
+                best_point_y = by
 
-        if min_dist < 32.0:
+        if min_dist < GRAPH_POINT_HIT_RADIUS_PX:
             self.drag_band_index = best_index
             self.drag_start_q = self.controller.bands[best_index].q
+            self.drag_start_point_x = best_point_x
+            self.drag_start_point_y = best_point_y
             self.select_band(best_index)
-        else:
-            self.drag_band_index = None
-            self.drag_start_q = None
+
+    def clear_graph_drag_state(self) -> None:
+        self.drag_band_index = None
+        self.drag_start_q = None
+        self.drag_start_point_x = None
+        self.drag_start_point_y = None
+
+    def graph_drag_edit_threshold(self) -> float:
+        return GRAPH_DRAG_EDIT_THRESHOLD_PX
 
     def on_graph_drag_update(self, gesture: Gtk.GestureDrag, offset_x: float, offset_y: float) -> None:
         drag_index = getattr(self, "drag_band_index", None)
         if drag_index is None:
             return
+        if math.hypot(offset_x, offset_y) < self.graph_drag_edit_threshold():
+            return
 
         width = self.graph_area.get_allocated_width()
         height = self.graph_area.get_allocated_height()
@@ -422,13 +439,15 @@ def on_graph_drag_update(self, gesture: Gtk.GestureDrag, offset_x: float, offset
             changed_q = self.controller.set_band_q(drag_index, new_q, apply=False)
         else:
             # No shift -> Frequency and Gain adjustment
-            curr_x = start_x + offset_x
+            drag_start_point_x = getattr(self, "drag_start_point_x", None)
+            curr_x = (drag_start_point_x if drag_start_point_x is not None else start_x) + offset_x
             freq = self.x_to_frequency(curr_x, width_f, left, right)
             changed_f = self.controller.set_band_frequency(drag_index, freq, apply=False)
 
             # Gain adjustment (only for gain-capable filters)
             if band.filter_type in {FILTER_TYPES["Bell"], FILTER_TYPES["Hi-shelf"], FILTER_TYPES["Lo-shelf"]}:
-                curr_y = start_y + offset_y
+                drag_start_point_y = getattr(self, "drag_start_point_y", None)
+                curr_y = (drag_start_point_y if drag_start_point_y is not None else start_y) + offset_y
                 target_db = self.y_to_db(curr_y, height_f, top, bottom)
 
                 # To make the point stay under the mouse on the combined curve, we calculate
@@ -474,7 +493,7 @@ def on_graph_drag_update(self, gesture: Gtk.GestureDrag, offset_x: float, offset
             self.schedule_curve_metadata_refresh()
 
     def on_graph_drag_end(self, _gesture: Gtk.GestureDrag, _offset_x: float, _offset_y: float) -> None:
-        self.drag_band_index = None
+        self.clear_graph_drag_state()
 
     def on_preamp_changed(self, scale: Gtk.Scale) -> None:
         value = scale.get_value()

tests/test_mini_eq_window_graph.py

@@ -160,6 +160,8 @@ def __init__(self, bands: list[core.EqBand]) -> None:
         self.updating_ui = False
         self.drag_band_index = None
         self.drag_start_q = None
+        self.drag_start_point_x = None
+        self.drag_start_point_y = None
         self.engine_updates: list[int] = []
         self.ui_updates: list[object] = []
 
@@ -447,18 +449,79 @@ def x_to_frequency(x: float, width: float, left: float, right: float) -> float:
     assert window.selected_band_index == 1
 
 
+def test_graph_zero_offset_drag_selects_without_modifying_band() -> None:
+    window = GraphInteractionWindow(
+        [
+            core.EqBand(core.FILTER_TYPES["Bell"], 1000.0, gain_db=3.0),
+        ]
+    )
+    start_x, start_y = window.band_point(0)
+
+    window.on_graph_drag_begin(FakeGraphDragGesture(start_x, start_y), start_x, start_y)
+    window.on_graph_drag_update(FakeGraphDragGesture(start_x, start_y), 0.0, 0.0)
+
+    assert window.selected_band_index == 0
+    assert window.controller.frequency_updates == []
+    assert window.controller.gain_updates == []
+    assert window.controller.q_updates == []
+    assert window.engine_updates == []
+    assert window.ui_updates == []
+
+
+def test_graph_drag_waits_for_edit_threshold_before_modifying_band() -> None:
+    window = GraphInteractionWindow(
+        [
+            core.EqBand(core.FILTER_TYPES["Bell"], 1000.0, gain_db=3.0),
+        ]
+    )
+    window.graph_drag_edit_threshold = lambda: 8.0
+    start_x, start_y = window.band_point(0)
+
+    window.on_graph_drag_begin(FakeGraphDragGesture(start_x, start_y), start_x, start_y)
+    window.on_graph_drag_update(FakeGraphDragGesture(start_x, start_y), 4.0, 3.0)
+
+    assert window.controller.frequency_updates == []
+    assert window.controller.gain_updates == []
+    assert window.engine_updates == []
+
+
+def test_graph_drag_uses_band_point_as_anchor_to_avoid_click_jump() -> None:
+    window = GraphInteractionWindow(
+        [
+            core.EqBand(core.FILTER_TYPES["Hi-pass"], 1000.0, gain_db=3.0),
+        ]
+    )
+    window.graph_drag_edit_threshold = lambda: 4.0
+    point_x, point_y = window.band_point(0)
+    captured_x: list[float] = []
+
+    def x_to_frequency(x: float, _width: float, _left: float, _right: float) -> float:
+        captured_x.append(x)
+        return 1200.0
+
+    window.x_to_frequency = x_to_frequency
+
+    window.on_graph_drag_begin(FakeGraphDragGesture(point_x + 20.0, point_y), point_x + 20.0, point_y)
+    window.on_graph_drag_update(FakeGraphDragGesture(point_x + 20.0, point_y), 10.0, 0.0)
+
+    assert captured_x == [pytest.approx(point_x + 10.0)]
+    assert window.controller.frequency_updates == [(0, 1200.0)]
+    assert window.controller.gain_updates == []
+
+
 def test_graph_drag_preserves_solo_context_when_calculating_other_response() -> None:
     window = GraphInteractionWindow(
         [
             core.EqBand(core.FILTER_TYPES["Bell"], 1000.0, gain_db=6.0, solo=True),
             core.EqBand(core.FILTER_TYPES["Bell"], 1000.0, gain_db=6.0),
         ]
     )
+    window.graph_drag_edit_threshold = lambda: 4.0
     start_x, start_y = window.band_point(0)
     window.drag_band_index = 0
     window.drag_start_q = window.controller.bands[0].q
 
-    window.on_graph_drag_update(FakeGraphDragGesture(start_x, start_y), 0.0, 0.0)
+    window.on_graph_drag_update(FakeGraphDragGesture(start_x, start_y), 12.0, 0.0)
 
     assert window.controller.gain_updates
     assert window.controller.bands[0].gain_db == pytest.approx(6.0)