Fix display of sidetext gates with conditions (Qiskit#7673)

* First testing

* Fix display of sidetext gates with conditions in text

* Add comment

* Start it up again

* Add mpl and latex tests

* Add cu1 and rzz tests

* Start it up again

* Break out RZZ and CU1

* Restart

Author: enavarro51

qiskit/visualization/text.py

@@ -430,6 +430,7 @@ class Bullet(DirectOnQuWire):
 
     def __init__(self, top_connect="", bot_connect="", conditional=False, label=None, bottom=False):
         super().__init__("■")
+        self.conditional = conditional
         self.top_connect = top_connect
         self.bot_connect = "║" if conditional else bot_connect
         if label and bottom:
@@ -451,6 +452,7 @@ class OpenBullet(DirectOnQuWire):
 
     def __init__(self, top_connect="", bot_connect="", conditional=False, label=None, bottom=False):
         super().__init__("o")
+        self.conditional = conditional
         self.top_connect = top_connect
         self.bot_connect = "║" if conditional else bot_connect
         if label and bottom:
@@ -1033,6 +1035,10 @@ def _set_ctrl_state(self, node, conditional, ctrl_text, bottom):
         ctrl_qubits = node.qargs[:num_ctrl_qubits]
         cstate = f"{op.ctrl_state:b}".rjust(num_ctrl_qubits, "0")[::-1]
         for i in range(len(ctrl_qubits)):
+            # For sidetext gate alignment, need to set every Bullet with
+            # conditional on if there's a condition.
+            if op.condition is not None:
+                conditional = True
             if cstate[i] == "1":
                 gates.append(Bullet(conditional=conditional, label=ctrl_text, bottom=bottom))
             else:
@@ -1502,3 +1508,5 @@ def connect_with(self, wire_char):
             if label:
                 for affected_bit in affected_bits:
                     affected_bit.right_fill = len(label) + len(affected_bit.mid)
+                    if isinstance(affected_bit, (Bullet, OpenBullet)) and affected_bit.conditional:
+                        affected_bit.left_fill = len(label) + len(affected_bit.mid)

releasenotes/notes/fix-phase-gate-condition-text-display-3e1595ad508d225c.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes a problem in the ``text`` circuit drawer when gates that
+    use side text, such as the ``CPhaseGate`` and ``RZZGate``, when
+    displayed with conditions would not display properly.

test/ipynb/mpl/circuit/references/sidetext_condition.png

@@ -35,6 +35,7 @@
     ZGate,
     SGate,
     U1Gate,
+    CPhaseGate,
 )
 from qiskit.circuit.library import MCXVChain
 from qiskit.extensions import HamiltonianGate
@@ -863,6 +864,14 @@ def test_conditions_with_bits_reverse(self):
             circuit, cregbundle=False, reverse_bits=True, filename="cond_bits_reverse.png"
         )
 
+    def test_sidetext_with_condition(self):
+        """Test that sidetext gates align properly with conditions"""
+        qr = QuantumRegister(2, "q")
+        cr = ClassicalRegister(2, "c")
+        circuit = QuantumCircuit(qr, cr)
+        circuit.append(CPhaseGate(pi / 2), [qr[0], qr[1]]).c_if(cr[1], 1)
+        self.circuit_drawer(circuit, cregbundle=False, filename="sidetext_condition.png")
+
     def test_fold_with_conditions(self):
         """Test that gates with conditions draw correctly when folding"""
         qr = QuantumRegister(3)

test/ipynb/mpl/circuit/test_circuit_matplotlib_drawer.py

@@ -0,0 +1,14 @@
+\documentclass[border=2px]{standalone}
+
+\usepackage[braket, qm]{qcircuit}
+\usepackage{graphicx}
+
+\begin{document}
+\scalebox{1.0}{
+\Qcircuit @C=1.0em @R=0.8em @!R { \\
+	 	\nghost{{q}_{0} :  } & \lstick{{q}_{0} :  } & \ctrl{1} & \dstick{\hspace{2.0em}\mathrm{P}\,(\mathrm{\frac{\pi}{2}})} \qw & \qw & \qw & \qw & \qw\\
+	 	\nghost{{q}_{1} :  } & \lstick{{q}_{1} :  } & \control \qw & \qw & \qw & \qw & \qw & \qw\\
+	 	\nghost{{c}_{0} :  } & \lstick{{c}_{0} :  } & \cw & \cw & \cw & \cw & \cw & \cw\\
+	 	\nghost{{c}_{1} :  } & \lstick{{c}_{1} :  } & \control \cw^(0.0){^{\mathtt{}}} \cwx[-2] & \cw & \cw & \cw & \cw & \cw\\
+\\ }}
+\end{document}

test/python/visualization/references/test_latex_sidetext_condition.tex

@@ -22,7 +22,7 @@
 from qiskit.visualization import circuit_drawer
 from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister, transpile
 from qiskit.test.mock import FakeTenerife
-from qiskit.circuit.library import XGate, MCXGate, RZZGate, SwapGate, DCXGate
+from qiskit.circuit.library import XGate, MCXGate, RZZGate, SwapGate, DCXGate, CPhaseGate
 from qiskit.extensions import HamiltonianGate
 from qiskit.circuit import Parameter, Qubit, Clbit
 from qiskit.circuit.library import IQP
@@ -645,6 +645,16 @@ def test_conditions_with_bits_reverse(self):
         )
         self.assertEqualToReference(filename)
 
+    def test_sidetext_with_condition(self):
+        """Test that sidetext gates align properly with a condition"""
+        filename = self._get_resource_path("test_latex_sidetext_condition.tex")
+        qr = QuantumRegister(2, "q")
+        cr = ClassicalRegister(2, "c")
+        circuit = QuantumCircuit(qr, cr)
+        circuit.append(CPhaseGate(pi / 2), [qr[0], qr[1]]).c_if(cr[1], 1)
+        circuit_drawer(circuit, cregbundle=False, filename=filename, output="latex_source")
+        self.assertEqualToReference(filename)
+
 
 if __name__ == "__main__":
     unittest.main(verbosity=2)

test/python/visualization/test_circuit_latex.py

@@ -635,6 +635,81 @@ def test_text_cp(self):
         circuit.append(CPhaseGate(pi / 2), [qr[2], qr[0]])
         self.assertEqual(str(_text_circuit_drawer(circuit)), expected)
 
+    def test_text_cu1_condition(self):
+        """Test cu1 with condition"""
+        expected = "\n".join(
+            [
+                "                      ",
+                "q_0: ────────■────────",
+                "             │U1(π/2) ",
+                "q_1: ────────■────────",
+                "             ║        ",
+                "q_2: ────────╫────────",
+                "             ║        ",
+                "c_0: ════════╬════════",
+                "             ║        ",
+                "c_1: ════════■════════",
+                "                      ",
+                "c_2: ═════════════════",
+                "                      ",
+            ]
+        )
+        qr = QuantumRegister(3, "q")
+        cr = ClassicalRegister(3, "c")
+        circuit = QuantumCircuit(qr, cr)
+        circuit.append(CU1Gate(pi / 2), [qr[0], qr[1]]).c_if(cr[1], 1)
+        self.assertEqual(str(_text_circuit_drawer(circuit, initial_state=False)), expected)
+
+    def test_text_rzz_condition(self):
+        """Test rzz with condition"""
+        expected = "\n".join(
+            [
+                "                      ",
+                "q_0: ────────■────────",
+                "             │ZZ(π/2) ",
+                "q_1: ────────■────────",
+                "             ║        ",
+                "q_2: ────────╫────────",
+                "             ║        ",
+                "c_0: ════════╬════════",
+                "             ║        ",
+                "c_1: ════════■════════",
+                "                      ",
+                "c_2: ═════════════════",
+                "                      ",
+            ]
+        )
+        qr = QuantumRegister(3, "q")
+        cr = ClassicalRegister(3, "c")
+        circuit = QuantumCircuit(qr, cr)
+        circuit.append(RZZGate(pi / 2), [qr[0], qr[1]]).c_if(cr[1], 1)
+        self.assertEqual(str(_text_circuit_drawer(circuit, initial_state=False)), expected)
+
+    def test_text_cp_condition(self):
+        """Test cp with condition"""
+        expected = "\n".join(
+            [
+                "                    ",
+                "q_0: ───────■───────",
+                "            │P(π/2) ",
+                "q_1: ───────■───────",
+                "            ║       ",
+                "q_2: ───────╫───────",
+                "            ║       ",
+                "c_0: ═══════╬═══════",
+                "            ║       ",
+                "c_1: ═══════■═══════",
+                "                    ",
+                "c_2: ═══════════════",
+                "                    ",
+            ]
+        )
+        qr = QuantumRegister(3, "q")
+        cr = ClassicalRegister(3, "c")
+        circuit = QuantumCircuit(qr, cr)
+        circuit.append(CPhaseGate(pi / 2), [qr[0], qr[1]]).c_if(cr[1], 1)
+        self.assertEqual(str(_text_circuit_drawer(circuit, initial_state=False)), expected)
+
     def test_text_cu1_reverse_bits(self):
         """cu1 drawing with reverse_bits"""
         expected = "\n".join(