Added TransitionControl and plot rewinding.

New component overlays main view and handles middle clicks/drags
to performing rewinding. Also sports smooth transitioning back to
current projection whenever the mouse button is lifted.

Next up, the same kind of transitions in the displayed values.

1 files changed, 61 insertions, 0 deletions

diff --git a/transitioncontrol.cpp b/transitioncontrol.cpp
new file mode 100644
index 0000000..cf8f644
--- /dev/null
+++ b/transitioncontrol.cpp
@@ -0,0 +1,61 @@
+#include "transitioncontrol.h"
+
+#include <QObject>
+#include <QThread>
+
+#include "rewindworkerthread.h"
+
+// The mouse button used for interaction
+static const Qt::MouseButton MOUSE_BUTTON = Qt::MiddleButton;
+
+TransitionControl::TransitionControl()
+    : m_t(1.0)
+    , m_startPos(-1)
+{
+}
+
+void TransitionControl::setT(double t)
+{
+    if (t < 0.0 || t > 1.0) {
+        return;
+    }
+
+    m_t = t;
+    emit tChanged(m_t);
+}
+
+void TransitionControl::mousePressEvent(QMouseEvent *event)
+{
+    if (event->button() != MOUSE_BUTTON) {
+        return;
+    }
+
+    m_t = 1.0;
+    m_startPos = event->pos().x();
+}
+
+void TransitionControl::mouseMoveEvent(QMouseEvent *event)
+{
+    int x = event->pos().x();
+    if (!(event->buttons() & MOUSE_BUTTON) || x > m_startPos || x < 0) {
+        return;
+    }
+
+    m_t = double(x) / m_startPos;
+    emit tChanged(m_t);
+}
+
+void TransitionControl::mouseReleaseEvent(QMouseEvent *event)
+{
+    if (event->button() != MOUSE_BUTTON) {
+        return;
+    }
+
+    // Back to initial state
+    m_startPos = -1;
+
+    // We now have to smoothly go back to m_t == 1.0
+    m_rewindThread = new RewindWorkerThread(this);
+    connect(m_rewindThread, &QThread::finished, m_rewindThread, &QObject::deleteLater);
+    m_rewindThread->start();
+}