Implement initial structure and core functionality for Duck Preview application

duck_preview/rendering/overlay.py

@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+from PySide6.QtCore import Qt
+from PySide6.QtGui import QColor, QFont, QFontMetrics, QPainter
+from PySide6.QtWidgets import QWidget
+
+
+class OverlayWidget(QWidget):
+    def __init__(self, parent: QWidget | None = None) -> None:
+        super().__init__(parent)
+        self.setAttribute(Qt.WA_TransparentForMouseEvents)
+        self.setAttribute(Qt.WA_NoSystemBackground)
+        self._visible = True
+        self._metrics: dict[str, float | int] = {}
+
+    def set_visible(self, visible: bool) -> None:
+        self._visible = visible
+        self.update()
+
+    def set_metrics(self, metrics: dict[str, float | int]) -> None:
+        self._metrics = metrics
+        self.update()
+
+    def paintEvent(self, event) -> None:  # noqa: N802
+        if not self._visible or not self._metrics:
+            return
+
+        lines = [
+            f"FPS:     {self._metrics.get('fps', 0):>7}",
+            f"Frame:   {self._metrics.get('frame_time_ms', 0):>7.1f} ms",
+            f"Frames:  {self._metrics.get('frame_count', 0):>7}",
+        ]
+
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.TextAntialiasing)
+
+        font = QFont("Consolas", 11)
+        painter.setFont(font)
+        fm = QFontMetrics(font)
+
+        text_width = max(fm.horizontalAdvance(line) for line in lines) + 24
+        text_height = len(lines) * (fm.height() + 6) + 12
+
+        painter.fillRect(8, 8, text_width, text_height, QColor(0, 0, 0, 160))
+
+        painter.setPen(QColor(0, 255, 0))
+        for i, line in enumerate(lines):
+            y = 22 + i * (fm.height() + 6)
+            painter.drawText(16, y, line)