Add native QCustomPlot renderer and shared plot adapters

python/set_devices/qt_ports/plot_layers.py

@@ -0,0 +1,46 @@
+"""Queued redraws and cached static layers for Qt plots (Qt 5/6)."""
+try:
+    from PySide6.QtCore import QTimer, Qt
+    from PySide6.QtGui import QPixmap, QPainter
+except ImportError:
+    from PySide2.QtCore import QTimer, Qt
+    from PySide2.QtGui import QPixmap, QPainter
+
+class PlotLayers:
+    def init_plot_layers(self):
+        self._static_revision = 0
+        self._static_plot_layer = None
+        self._redraw_timer = QTimer(self)
+        self._redraw_timer.setSingleShot(True)
+        self._redraw_timer.timeout.connect(self._flush_plot_update)
+
+    def update(self, *args):
+        if not hasattr(self, '_redraw_timer'):
+            return super().update(*args)
+        self._static_revision += 1
+        self.update_overlay()
+
+    def update_overlay(self):
+        if not hasattr(self, '_redraw_timer'):
+            return super().update()
+        if not self._redraw_timer.isActive():
+            self._redraw_timer.start(0)
+
+    def _flush_plot_update(self):
+        super().update()
+
+    def paint_static_layer(self, painter, draw):
+        ratio = self.devicePixelRatioF()
+        key = (self._static_revision, self.width(), self.height(), ratio,
+               tuple(self.plot_rect().getRect()))
+        if self._static_plot_layer is None or self._static_plot_layer[0] != key:
+            image = QPixmap(round(self.width()*ratio), round(self.height()*ratio))
+            image.setDevicePixelRatio(ratio)
+            image.fill(Qt.GlobalColor.transparent)
+            layer = QPainter(image)
+            try:
+                draw(layer)
+            finally:
+                layer.end()
+            self._static_plot_layer = key, image
+        painter.drawPixmap(0, 0, self._static_plot_layer[1])