Use native code to draw wait spinner

src/calibre/gui2/progress_indicator/__init__.py

@@ -4,97 +4,20 @@
 
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-import numbers
 from PyQt5.Qt import (
-    Qt, QWidget, QSizePolicy, QSize, QRect, QConicalGradient, QPen, QBrush,
-    QPainter, QTimer, QVBoxLayout, QLabel, QStackedWidget, QDialog, QStackedLayout
+    QDialog, QLabel, QSizePolicy, QStackedLayout, QStackedWidget, Qt, QVBoxLayout,
+    QWidget
 )
 
+from calibre.constants import plugins
 
-def draw_snake_spinner(painter, rect, angle, light, dark):
-    painter.setRenderHint(QPainter.Antialiasing)
-
-    if rect.width() > rect.height():
-        delta = (rect.width() - rect.height()) // 2
-        rect = rect.adjusted(delta, 0, -delta, 0)
-    elif rect.height() > rect.width():
-        delta = (rect.height() - rect.width()) // 2
-        rect = rect.adjusted(0, delta, 0, -delta)
-    disc_width = max(3, min(rect.width() // 10, 8))
-
-    drawing_rect = QRect(rect.x() + disc_width, rect.y() + disc_width, rect.width() - 2 * disc_width, rect.height() - 2 *disc_width)
-
-    gap = 60  # degrees
-    gradient = QConicalGradient(drawing_rect.center(), angle - gap // 2)
-    gradient.setColorAt((360 - gap//2)/360.0, light)
-    gradient.setColorAt(0, dark)
-
-    pen = QPen(QBrush(gradient), disc_width)
-    pen.setCapStyle(Qt.RoundCap)
-    painter.setPen(pen)
-    painter.drawArc(drawing_rect, angle * 16, (360 - gap) * 16)
+pi, err = plugins['progress_indicator']
+if err:
+    raise RuntimeError('Failed to import the progress_indicator plugin with error: {}'.format(err))
 
 
-class ProgressSpinner(QWidget):
-
-    def __init__(self, parent=None, size=64, interval=10):
-        QWidget.__init__(self, parent)
-        self.setSizePolicy(QSizePolicy(
-            QSizePolicy.GrowFlag | QSizePolicy.ShrinkFlag, QSizePolicy.GrowFlag | QSizePolicy.ShrinkFlag))
-        self._size_hint = QSize(size, size)
-        self.timer = t = QTimer(self)
-        t.setInterval(interval)
-        self.timer.timeout.connect(self.tick)
-        self.loading_angle = 0
-        pal = self.palette()
-        self.dark = pal.color(pal.Text)
-        self.light = pal.color(pal.Window)
-        self.errored_out = False
-
-    def heightForWidth(self, w):
-        return w
-
-    def start(self):
-        self.loading_angle = 0
-        self.timer.start()
-        self.update()
-    startAnimation = start
-
-    def stop(self):
-        self.timer.stop()
-        self.loading_angle = 0
-        self.update()
-    stopAnimation = stop
-
-    def isAnimated(self):
-        return self.timer.isActive()
-
-    def sizeHint(self):
-        return self._size_hint
-
-    def setSizeHint(self, val):
-        if isinstance(val, numbers.Integral):
-            val = QSize(val, val)
-        self._size_hint = val
-        self.update()
-    setDisplaySize = setSizeHint
-
-    def tick(self):
-        self.loading_angle -= 2
-        self.loading_angle %= 360
-        self.update()
-
-    def paintEvent(self, ev):
-        if not self.errored_out:
-            try:
-                draw_snake_spinner(QPainter(self), self.rect(), self.loading_angle, self.light, self.dark)
-            except Exception:
-                import traceback
-                traceback.print_exc()
-                self.errored_out = True
-
-
-ProgressIndicator = ProgressSpinner
+ProgressIndicator = pi.QProgressIndicator
+draw_snake_spinner = pi.draw_snake_spinner
 
 
 class WaitPanel(QWidget):
@@ -103,7 +26,7 @@ class WaitPanel(QWidget):
         QWidget.__init__(self, parent)
         self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
         self.l = l = QVBoxLayout(self)
-        self.spinner = ProgressIndicator(parent=self, size=size, interval=interval)
+        self.spinner = ProgressIndicator(self, size, interval)
         self.start, self.stop = self.spinner.start, self.spinner.stop
         l.addStretch(), l.addWidget(self.spinner, 0, Qt.AlignCenter)
         self.la = QLabel(msg)
@@ -182,7 +105,7 @@ if __name__ == '__main__':
     app = Application([])
     d = QDialog()
     d.resize(64, 64)
-    w = ProgressSpinner(d)
+    w = ProgressIndicator(d)
     l = QVBoxLayout(d)
     l.addWidget(w)
     w.start()