#187 - Refactor new canvas ready for easy extension to do the actual drawing per analysis type

Author: dmh23

src/prototype_ui/canvas.py

@@ -1,6 +1,6 @@
 import sys
 from PyQt6.QtWidgets import QGraphicsScene, QGraphicsView, QGraphicsRectItem, QApplication, QGraphicsPixmapItem, \
-    QMainWindow, QLabel
+    QMainWindow, QLabel, QAbstractGraphicsShapeItem
 from PyQt6.QtGui import QBrush, QPen, QPixmap, QPainter
 from PyQt6.QtCore import Qt
 
@@ -9,41 +9,49 @@ class Canvas(QGraphicsView):
     def __init__(self, width: int, height: int, background_colour: Qt.GlobalColor):
         super().__init__(None)
         self._background_colour = background_colour
-        self._recreate_scene(width, height)
-        self._last_drawn_width = self.geometry().width()
-        self._last_drawn_height = self.geometry().height()
+        self._width = self.geometry().width()
+        self._height = self.geometry().height()
+        self._recreate_scene()
 
     def paintEvent(self, event):
-        width = self.geometry().width()
-        height = self.geometry().height()
-        if self._last_drawn_width != width or self._last_drawn_height != height:
-            self._recreate_scene(width, height)
-            self._last_drawn_width = width
-            self._last_drawn_height = height
+        new_width = self.geometry().width()
+        new_height = self.geometry().height()
+        if self._width != new_width or self._height != new_height:
+            self._width = new_width
+            self._height = new_height
+            self._recreate_scene()
 
         super().paintEvent(event)
 
-    def _recreate_scene(self, width: int, height: int):
-        print("REDRAW***", width, height)
-        pixmap = QPixmap(width, height)
-        pixmap.fill(self._background_colour)
+    def _recreate_scene(self):
+        # print("REDRAW***", self._width, self._height)
 
+        pixmap = QPixmap(self._width, self._height)
+        pixmap.fill(self._background_colour)
         painter = QPainter(pixmap)
-        painter.fillRect(0, 0, round(width / 2), round(height / 2), Qt.GlobalColor.green)
+        self._paint(painter)
         painter.end()
 
-        scene = QGraphicsScene(0, 0, width, height)
-        rect = QGraphicsRectItem(0, 0, width/3, height/3)
-        rect.setPos(width/10, height/10)
+        scene = QGraphicsScene(0, 0, self._width, self._height)
+        scene.addItem(QGraphicsPixmapItem(pixmap))
+        for i in self._get_scene_items():
+            scene.addItem(i)
+        self.setScene(scene)
+
+    # Hardcoded examples for now - these will be abstract shortly
+    def _paint(self, painter: QPainter):
+        painter.fillRect(0, 0, round(self._width / 2), round(self._height / 2), Qt.GlobalColor.darkYellow)
+
+    # Hardcoded examples for now - these will be abstract shortly
+    def _get_scene_items(self) -> list[QAbstractGraphicsShapeItem]:
+        rect = QGraphicsRectItem(0, 0, self._width / 3, self._height / 3)
+        rect.setPos(self._width / 10, self._height / 10)
         brush = QBrush(Qt.GlobalColor.red)
         rect.setBrush(brush)
         pen = QPen(Qt.GlobalColor.cyan)
         pen.setWidth(10)
         rect.setPen(pen)
 
-        scene.addItem(QGraphicsPixmapItem(pixmap))
-        scene.addItem(rect)
-
-        self.setScene(scene)
+        return [rect]