Work on a new spin animation

src/calibre/gui2/progress_indicator/QProgressIndicator.h

@@ -1,9 +1,87 @@
 #pragma once
 
 #include <QtWidgets/QWidget>
+#include <QObject>
 #include <QColor>
 #include <QHash>
 #include <QPainter>
+#include <QPropertyAnimation>
+#include <QParallelAnimationGroup>
+
+class SpinAnimator: public QObject {
+	Q_OBJECT
+	Q_PROPERTY(float arc_length READ get_arc_length WRITE set_arc_length)
+	Q_PROPERTY(int arc_rotation READ get_arc_rotation WRITE set_arc_rotation)
+	Q_PROPERTY(int overall_rotation READ get_overall_rotation WRITE set_overall_rotation)
+public:
+	SpinAnimator(QObject* parent = 0) :
+		QObject(parent),
+		m_arc_length(0),
+		m_arc_rotation(0),
+		m_overall_rotation(0),
+		m_has_pending_updates(false),
+		m_animation(this)
+	{
+		QPropertyAnimation *a;
+#define S(property, duration) a = new QPropertyAnimation(this, QByteArray(#property), this); a->setEasingCurve(QEasingCurve::InOutCubic); a->setDuration(duration); a->setLoopCount(-1); m_animation.addAnimation(a);
+		S(arc_length, 1400);
+		const float arc_length_max = 0.734f, arc_length_min = 0.01f;
+		a->setStartValue(arc_length_min);
+        a->setKeyValueAt(0.25, arc_length_min);
+        a->setKeyValueAt(0.5, arc_length_max);
+        a->setKeyValueAt(0.75, arc_length_max);
+        a->setEndValue(arc_length_min);
+
+		S(arc_rotation, 1400);
+        a->setStartValue(0);
+        a->setKeyValueAt(0.25, 0);
+        a->setKeyValueAt(0.5, 45);
+        a->setKeyValueAt(0.75, 45);
+        a->setEndValue(360);
+
+		S(overall_rotation, 2000);
+		a->setStartValue(0);
+		a->setEndValue(360);
+#undef S
+	}
+	~SpinAnimator() { m_animation.stop(); m_animation.clear(); }
+	void start() { m_animation.start(); }
+	void stop() { m_animation.stop(); }
+	bool is_running() { return m_animation.state() == QAbstractAnimation::Running; }
+	void draw(QPainter &painter, QRect bounds, const QColor &color) {
+		m_has_pending_updates = false;
+		painter.save();
+		painter.setRenderHint(QPainter::Antialiasing);
+        QRectF rect(bounds);
+		float thickness = std::max(3.f, std::min((float)rect.width() / 10.f, 24.f));
+		QPen pen(color);
+		pen.setWidthF(thickness);
+        float ht = thickness / 2 + 1;
+        rect.adjust(ht, ht, -ht, -ht);
+        pen.setCapStyle(Qt::RoundCap);
+		painter.setPen(pen);
+        int rotated_by = (m_overall_rotation + m_arc_rotation) * 16;
+		int arc_length = (int)(m_arc_length * 360 * 16);
+        painter.drawArc(rect, -rotated_by, -arc_length);
+		painter.restore();
+	}
+
+	float get_arc_length() const { return m_arc_length; }
+	int get_arc_rotation() const { return m_arc_rotation; }
+	int get_overall_rotation() const { return m_overall_rotation; }
+public slots:
+	void set_arc_length(float val) { m_arc_length = val; notify_of_update(); }
+	void set_arc_rotation(int val) { m_arc_rotation = val; notify_of_update(); }
+	void set_overall_rotation(int val) { m_overall_rotation = val; notify_of_update(); }
+signals:
+	void updated();
+private:
+	float m_arc_length;
+	int m_arc_rotation, m_overall_rotation;
+	bool m_has_pending_updates;
+	void notify_of_update() { if (!m_has_pending_updates) { m_has_pending_updates = true; emit updated(); } }
+	QParallelAnimationGroup m_animation;
+};
 
 /*!
     \class QProgressIndicator

src/calibre/gui2/progress_indicator/QProgressIndicator.sip

@@ -12,6 +12,29 @@ void set_no_activate_on_click(QWidget *widget);
 void draw_snake_spinner(QPainter &painter, QRect rect, int angle, const QColor & light, const QColor & dark);
 %End
 
+class SpinAnimator : QObject {
+
+%TypeHeaderCode
+#include <QProgressIndicator.h>
+%End
+
+public:
+    SpinAnimator(QWidget *parent /TransferThis/ = 0);
+	float get_arc_length() const ;
+	int get_arc_rotation() const ;
+	int get_overall_rotation() const ;
+	void draw(QPainter &painter, QRect bounds, const QColor &color);
+	void start();
+	void stop();
+	bool is_running();
+public slots:
+	void set_arc_length(float val) ;
+	void set_arc_rotation(int val) ;
+	void set_overall_rotation(int val) ;
+signals:
+	void updated();
+};
+
 class QProgressIndicator : QWidget {
 
 %TypeHeaderCode

src/calibre/gui2/progress_indicator/__init__.py

@@ -94,6 +94,31 @@ class WaitLayout(QStackedLayout):
         self.wp.msg = val
 
 
+def develop():
+    from PyQt5.Qt import QPalette, QPainter, QRect
+    from calibre.gui2 import Application
+    from calibre_extensions.progress_indicator import SpinAnimator
+
+    class Widget(QWidget):
+
+        def __init__(self):
+            QWidget.__init__(self)
+            self.a = SpinAnimator(self)
+            self.a.updated.connect(self.update)
+
+        def paintEvent(self, ev):
+            p = QPainter(self)
+            pal = self.palette()
+            self.a.draw(p, QRect(0, 0, 64, 64), pal.color(QPalette.ColorRole.WindowText))
+            p.end()
+
+    app = Application([])
+    w = Widget()
+    w.show()
+    w.a.start()
+    app.exec_()
+
+
 if __name__ == '__main__':
     from calibre.gui2 import Application
     app = Application([])