Clean up text drawer compression issues

qiskit/visualization/text.py

@@ -867,9 +867,7 @@ def should_compress(self, top_line, bot_line):
         for top, bot in zip(top_line, bot_line):
             if top in ["┴", "╨"] and bot in ["┬", "╥"]:
                 return False
-        for line in (bot_line, top_line):
-            no_spaces = line.replace(" ", "")
-            if len(no_spaces) > 0 and all(c.isalpha() or c.isnumeric() for c in no_spaces):
+            if (top.isalnum() and bot != " ") or (bot.isalnum() and top != " "):
                 return False
         return True
 
@@ -959,6 +957,8 @@ def merge_lines(top, bot, icod="top"):
                 ret += "╫"
             elif topc in "║╫╬" and botc in " ":
                 ret += "║"
+            elif topc in "│┼╪" and botc in " ":
+                ret += "│"
             elif topc == "└" and botc == "┌" and icod == "top":
                 ret += "├"
             elif topc == "┘" and botc == "┐":
@@ -1518,8 +1518,10 @@ def connect_with(self, wire_char):
                     wire_char = "║"
                     if index == 0 and len(affected_bits) > 1:
                         affected_bit.connect(wire_char, ["bot"])
-                    else:
+                    elif index == len(affected_bits) - 1:
                         affected_bit.connect(wire_char, ["top"])
+                    else:
+                        affected_bit.connect(wire_char, ["bot", "top"])
                 else:
                     if index == 0:
                         affected_bit.connect(wire_char, ["bot"])

releasenotes/notes/fix-text-drawer-compression-a80a5636957e8eec.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    There were two bugs in the ``text`` circuit drawer that were fixed.
+    These appeared when ``vertical_compression`` was set to ``medium``,
+    which is the default. The first would sometimes cause text to overwrite
+    other text or gates, and the second would sometimes cause the connections
+    between a gate and its controls to break.
+    See `#8588 <https://github.com/Qiskit/qiskit-terra/issues/8588>`__.

test/python/visualization/test_circuit_text_drawer.py

@@ -1683,7 +1683,7 @@ def test_control_gate_label_with_cond_1_high_cregbundle(self):
             str(_text_circuit_drawer(circ, vertical_compression="high", cregbundle=True)), expected
         )
 
-    def test_control_gate_label_with_cond_2_med(self):
+    def test_control_gate_label_with_cond_2_med_space(self):
         """Control gate has a label and a conditional (on label, compression=med)
         See https://github.com/Qiskit/qiskit-terra/issues/4361"""
         expected = "\n".join(
@@ -1692,8 +1692,7 @@ def test_control_gate_label_with_cond_2_med(self):
                 "q_0: |0>┤ my h ├",
                 "        └──┬───┘",
                 "q_1: |0>───■────",
-                "         my ch  ",
-                "           ║    ",
+                "         my║ch  ",
                 "   c: 0 ═══■════",
                 "          0x1   ",
             ]
@@ -1708,6 +1707,31 @@ def test_control_gate_label_with_cond_2_med(self):
 
         self.assertEqual(str(_text_circuit_drawer(circ, vertical_compression="medium")), expected)
 
+    def test_control_gate_label_with_cond_2_med(self):
+        """Control gate has a label and a conditional (on label, compression=med)
+        See https://github.com/Qiskit/qiskit-terra/issues/4361"""
+        expected = "\n".join(
+            [
+                "          ┌──────┐ ",
+                "q_0: |0>──┤ my h ├─",
+                "          └──┬───┘ ",
+                "q_1: |0>─────■─────",
+                "         my ctrl-h ",
+                "             ║     ",
+                "   c: 0 ═════■═════",
+                "            0x1    ",
+            ]
+        )
+
+        qr = QuantumRegister(2, "q")
+        cr = ClassicalRegister(1, "c")
+        circ = QuantumCircuit(qr, cr)
+        hgate = HGate(label="my h")
+        controlh = hgate.control(label="my ctrl-h").c_if(cr, 1)
+        circ.append(controlh, [1, 0])
+
+        self.assertEqual(str(_text_circuit_drawer(circ, vertical_compression="medium")), expected)
+
     def test_control_gate_label_with_cond_2_med_cregbundle(self):
         """Control gate has a label and a conditional (on label, compression=med) with cregbundle
         See https://github.com/Qiskit/qiskit-terra/issues/4361"""
@@ -2046,7 +2070,6 @@ def test_text_conditional_1(self):
                 "      └─╥─┘└─╥─┘",
                 "c0: 0 ══■════╬══",
                 "       0x1   ║  ",
-                "             ║  ",
                 "c1: 0 ═══════■══",
                 "            0x1 ",
             ]
@@ -2148,6 +2171,98 @@ def test_text_measure_with_spaces_bundle(self):
             expected,
         )
 
+    def test_text_barrier_med_compress_1(self):
+        """Medium vertical compression avoids connection break."""
+        circuit = QuantumCircuit(4)
+        circuit.cx(1, 3)
+        circuit.x(1)
+        circuit.barrier((2, 3), label="Bar 1")
+
+        expected = "\n".join(
+            [
+                "                    ",
+                "q_0: |0>────────────",
+                "              ┌───┐ ",
+                "q_1: |0>──■───┤ X ├─",
+                "          │   └───┘ ",
+                "          │   Bar 1 ",
+                "q_2: |0>──┼─────░───",
+                "        ┌─┴─┐   ░   ",
+                "q_3: |0>┤ X ├───░───",
+                "        └───┘   ░   ",
+            ]
+        )
+
+        self.assertEqual(
+            str(_text_circuit_drawer(circuit, vertical_compression="medium", cregbundle=False)),
+            expected,
+        )
+
+    def test_text_barrier_med_compress_2(self):
+        """Medium vertical compression avoids overprint."""
+        circuit = QuantumCircuit(4)
+        circuit.barrier((0, 1, 2), label="a")
+        circuit.cx(1, 3)
+        circuit.x(1)
+        circuit.barrier((2, 3), label="Bar 1")
+
+        expected = "\n".join(
+            [
+                "         a             ",
+                "q_0: |0>─░─────────────",
+                "         ░       ┌───┐ ",
+                "q_1: |0>─░───■───┤ X ├─",
+                "         ░   │   └───┘ ",
+                "         ░   │   Bar 1 ",
+                "q_2: |0>─░───┼─────░───",
+                "         ░ ┌─┴─┐   ░   ",
+                "q_3: |0>───┤ X ├───░───",
+                "           └───┘   ░   ",
+            ]
+        )
+
+        self.assertEqual(
+            str(_text_circuit_drawer(circuit, vertical_compression="medium", cregbundle=False)),
+            expected,
+        )
+
+    def test_text_barrier_med_compress_3(self):
+        """Medium vertical compression avoids conditional connection break."""
+        qr = QuantumRegister(1, "qr")
+        qc1 = ClassicalRegister(3, "cr")
+        qc2 = ClassicalRegister(1, "cr2")
+        circuit = QuantumCircuit(qr, qc1, qc2)
+        circuit.x(0).c_if(qc1, 3)
+        circuit.x(0).c_if(qc2[0], 1)
+
+        expected = "\n".join(
+            [
+                "        ┌───┐┌───┐",
+                " qr: |0>┤ X ├┤ X ├",
+                "        └─╥─┘└─╥─┘",
+                "cr_0: 0 ══■════╬══",
+                "          ║    ║  ",
+                "cr_2: 0 ══o════╬══",
+                "          ║    ║  ",
+                " cr2: 0 ══╬════■══",
+                "          ║       ",
+                "cr_1: 0 ══■═══════",
+                "         0x3      ",
+            ]
+        )
+
+        self.assertEqual(
+            str(
+                _text_circuit_drawer(
+                    circuit,
+                    vertical_compression="medium",
+                    wire_order=[0, 1, 3, 4, 2],
+                    cregbundle=False,
+                )
+            ),
+            expected,
+        )
+
 
 class TestTextConditional(QiskitTestCase):
     """Gates with conditionals"""