Implement initial structure and core functionality for Duck Preview application

duck_preview/rendering/video_widget.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+from PySide6.QtCore import Qt
+from PySide6.QtGui import QColor, QImage, QPainter
+from PySide6.QtMultimedia import QVideoFrame
+from PySide6.QtWidgets import QWidget
+
+
+class VideoWidget(QWidget):
+    def __init__(self, parent: QWidget | None = None) -> None:
+        super().__init__(parent)
+        self._frame: QImage | None = None
+        self.setAttribute(Qt.WA_OpaquePaintEvent)
+        self.setMinimumSize(320, 240)
+
+    def on_frame(self, frame: QVideoFrame) -> None:
+        image = frame.toImage()
+        if not image.isNull():
+            self._frame = image
+            self.update()
+
+    def paintEvent(self, event) -> None:  # noqa: N802
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.SmoothPixmapTransform)
+
+        if self._frame is not None:
+            painter.fillRect(self.rect(), QColor(0, 0, 0))
+            scaled = self._frame.scaled(
+                self.size(),
+                Qt.KeepAspectRatio,
+                Qt.SmoothTransformation,
+            )
+            x = (self.width() - scaled.width()) // 2
+            y = (self.height() - scaled.height()) // 2
+            painter.drawImage(x, y, scaled)
+        else:
+            painter.fillRect(self.rect(), QColor(20, 20, 20))
+            painter.setPen(QColor(100, 100, 100))
+            painter.drawText(self.rect(), Qt.AlignCenter, "No camera feed")