fix: sub-pixel and off-by-one errors in bounded_move_shapes clamping

anylabeling/views/labeling/widgets/canvas.py

@@ -632,14 +632,12 @@ def bounded_move_shapes(self, shapes, pos):
             return False  # No need to move
         o1 = pos + self.offsets[0]
         if self.out_off_pixmap(o1):
-            pos -= QtCore.QPointF(
-                float(min(0, int(o1.x()))), float(min(0, int(o1.y())))
-            )
+            pos -= QtCore.QPointF(min(0.0, o1.x()), min(0.0, o1.y()))
         o2 = pos + self.offsets[1]
         if self.out_off_pixmap(o2):
             pos += QtCore.QPointF(
-                float(min(0, int(self.pixmap.width() - o2.x()))),
-                float(min(0, int(self.pixmap.height() - o2.y()))),
+                min(0.0, (self.pixmap.width() - 1) - o2.x()),
+                min(0.0, (self.pixmap.height() - 1) - o2.y()),
             )
         # XXX: The next line tracks the new position of the cursor
         # relative to the shape, but also results in making it

tests/test_canvas_bounded_move.py

@@ -0,0 +1,83 @@
+"""Regression tests for Canvas.bounded_move_shapes edge-clamping.
+
+Covers two bugs in the same lines, found while fixing #237/#238/#240/#241:
+  1. QPoint/QPointF TypeError when a selected shape is dragged past the
+     pixmap border (fixed in #241).
+  2. int() truncation silently dropping sub-pixel corrections, and a
+     related off-by-one against out_off_pixmap's (w-1, h-1) bound, both
+     of which could leave a shape slightly outside the pixmap after the
+     "correction" ran.
+
+Run:
+    QT_QPA_PLATFORM=offscreen python -m unittest tests.test_canvas_bounded_move -v
+"""
+import os
+import unittest
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+
+from PyQt6 import QtCore, QtGui
+from PyQt6.QtWidgets import QApplication
+
+_APP = QApplication.instance() or QApplication([])
+
+from anylabeling.views.labeling.shape import Shape
+from anylabeling.views.labeling.widgets.canvas import Canvas
+
+
+class TestBoundedMoveShapes(unittest.TestCase):
+    def _make_canvas(self, w=100, h=100):
+        canvas = Canvas(parent=None)
+        canvas.pixmap = QtGui.QPixmap(w, h)
+        return canvas
+
+    def test_does_not_raise_typeerror_at_left_edge(self):
+        canvas = self._make_canvas()
+        shape = Shape(shape_type="polygon")
+        shape.add_point(QtCore.QPointF(5, 5))
+        shape.add_point(QtCore.QPointF(15, 5))
+        shape.add_point(QtCore.QPointF(5, 15))
+        canvas.offsets = (QtCore.QPointF(-5, -5), QtCore.QPointF(5, 5))
+        canvas.prev_point = QtCore.QPointF(3, 5)
+        canvas.bounded_move_shapes([shape], QtCore.QPointF(3, 5))  # must not raise
+
+    def test_sub_pixel_overflow_at_left_top_is_corrected(self):
+        canvas = self._make_canvas()
+        shape = Shape(shape_type="polygon")
+        shape.add_point(QtCore.QPointF(5.3, 5.3))
+        canvas.offsets = (QtCore.QPointF(-5.6, -5.6), QtCore.QPointF(5.6, 5.6))
+        canvas.prev_point = QtCore.QPointF(5.3, 5.3)
+        pos = QtCore.QPointF(5.3, 5.3)
+        self.assertTrue(canvas.out_off_pixmap(pos + canvas.offsets[0]))
+
+        canvas.bounded_move_shapes([shape], pos)
+
+        o1_after = canvas.prev_point + canvas.offsets[0]
+        self.assertFalse(
+            canvas.out_off_pixmap(o1_after),
+            "sub-pixel overflow at the left/top edge must be corrected",
+        )
+
+    def test_sub_pixel_overflow_at_right_bottom_is_corrected(self):
+        canvas = self._make_canvas()
+        shape = Shape(shape_type="polygon")
+        shape.add_point(QtCore.QPointF(94.0, 94.0))
+        canvas.offsets = (QtCore.QPointF(-2.0, -2.0), QtCore.QPointF(5.3, 5.3))
+        canvas.prev_point = QtCore.QPointF(94.0, 94.0)
+        pos = QtCore.QPointF(94.0, 94.0)
+        self.assertTrue(canvas.out_off_pixmap(pos + canvas.offsets[1]))
+
+        canvas.bounded_move_shapes([shape], pos)
+
+        o2_after = canvas.prev_point + canvas.offsets[1]
+        self.assertFalse(
+            canvas.out_off_pixmap(o2_after),
+            "sub-pixel overflow at the right/bottom edge must be corrected",
+        )
+        # Corrected position should land exactly on the boundary out_off_pixmap
+        # itself uses (w - 1), not one past it.
+        self.assertAlmostEqual(o2_after.x(), canvas.pixmap.width() - 1)
+
+
+if __name__ == "__main__":
+    unittest.main()