draw to image

beeref/widgets/color_gamut.py

@@ -17,6 +17,7 @@
 import math
 
 from PyQt6 import QtWidgets, QtGui, QtCore
+from PyQt6.QtCore import Qt
 
 
 logger = logging.getLogger(__name__)
@@ -27,22 +28,24 @@ class GamutWidget(QtWidgets.QWidget):
     def __init__(self, parent, item):
         super().__init__(parent)
         self.item = item
+        self.image = None
+        self.radius = 250
 
     def minimumSizeHint(self):
-        return QtCore.QSize(100, 100)
+        return QtCore.QSize(200, 200)
 
-    def paintEvent(self, event):
-        painter = QtGui.QPainter(self)
+    def draw_gamut_image(self):
+        self.image = QtGui.QImage(
+            QtCore.QSize(2 * self.radius, 2 * self.radius),
+            QtGui.QImage.Format.Format_ARGB32)
+        self.image.fill(QtGui.QColor(0, 0, 0, 0))
+
+        painter = QtGui.QPainter(self.image)
         painter.setRenderHint(QtGui.QPainter.RenderHint.Antialiasing)
-        painter.setClipRegion(event.region())
         painter.setBrush(QtGui.QBrush(QtGui.QColor(0, 0, 0)))
-        painter.setPen(QtCore.Qt.PenStyle.NoPen)
-
-        # Paint the circle, always centered
-        center = QtCore.QPoint(int(self.size().width() / 2),
-                               int(self.size().height() / 2))
-        radius = int(min(self.size().width(), self.size().height()) / 2)
-        painter.drawEllipse(center, radius, radius)
+        painter.setPen(Qt.PenStyle.NoPen)
+        center = QtCore.QPoint(self.radius, self.radius)
+        painter.drawEllipse(center, self.radius, self.radius)
 
         threshold = max(1, int(len(self.item.color_gamut) / 1000))
         print(threshold)
@@ -52,15 +55,27 @@ def paintEvent(self, event):
         for (hue, saturation), value in self.item.color_gamut.items():
             if value < threshold:
                 continue
-            hypotenuse = saturation / 255 * radius
+            hypotenuse = saturation / 255 * self.radius
             h = math.radians(hue)
             x = int(math.sin(h) * hypotenuse) + center.x()
             y = int(math.cos(h) * hypotenuse) + center.y()
             color = QtGui.QColor()
             color.setHsv(hue, saturation, 255)
             painter.setBrush(QtGui.QBrush(color))
-            painter.drawEllipse(x, y, 3, 3)
+            painter.drawEllipse(QtCore.QPoint(x, y), 3, 3)
 
+    def paintEvent(self, event):
+        painter = QtGui.QPainter(self)
+        painter.setRenderHint(painter.RenderHint.SmoothPixmapTransform)
+        if not self.image:
+            # Draw gamut onto image instead of directly onto the painter
+            # because it's too slow to redraw it on every paint event
+            # (when resizing the widget for example).
+            self.draw_gamut_image()
+        size = min(self.size().width(), self.size().height())
+        x = max((self.size().width() - size) / 2, 0)
+        y = max((self.size().height() - size) / 2, 0)
+        painter.drawImage(QtCore.QRectF(x, y, size, size), self.image)
 
 
 class GamutDialog(QtWidgets.QDialog):