fully implemented setting keyframes and standard values in the NodeParamView

Widget now supports creating keyframe and standard values, supports dragging
from sliders (not creating an undo command for each drag), and everything is
undoable.

app/node/input.cpp

@@ -20,6 +20,10 @@
 
 #include "input.h"
 
+#include <QVector2D>
+#include <QVector3D>
+#include <QVector4D>
+
 #include "common/lerp.h"
 #include "node.h"
 #include "output.h"
@@ -81,6 +85,15 @@ Node *NodeInput::get_connected_node() const
   return nullptr;
 }
 
+bool NodeInput::type_can_be_interpolated(NodeParam::DataType type)
+{
+  return type == kFloat
+      || type == kVec2
+      || type == kVec3
+      || type == kVec4
+      || type == kColor;
+}
+
 QVariant NodeInput::get_value_at_time(const rational &time) const
 {
   if (is_using_standard_value()) {
@@ -103,7 +116,7 @@ QVariant NodeInput::get_value_at_time(const rational &time) const
     NodeKeyframePtr after = keyframes_.at(i+1);
 
     if (before->time() == time
-        || data_type() != kFloat // FIXME: Expand this to other types that can be interpolated
+        || !type_can_be_interpolated(data_type())
         || (before->time() < time && before->type() == NodeKeyframe::kHold)) {
 
       // Time == keyframe time, so value is precise
@@ -121,7 +134,25 @@ QVariant NodeInput::get_value_at_time(const rational &time) const
       } else {
         // To have arrived here, the keyframes must both be linear
         qreal period_progress = (time.toDouble() - before->time().toDouble()) / (after->time().toDouble() - before->time().toDouble());
-        qreal interpolated_value = lerp(before->value().toDouble(), after->value().toDouble(), period_progress);
+
+        QVariant interpolated_value;
+
+        switch (data_type()) {
+        case kFloat:
+          interpolated_value = lerp(before->value().toDouble(), after->value().toDouble(), period_progress);
+          break;
+        case kVec2:
+          interpolated_value = lerp(before->value().value<QVector2D>(), after->value().value<QVector2D>(), static_cast<float>(period_progress));
+          break;
+        case kVec3:
+          interpolated_value = lerp(before->value().value<QVector3D>(), after->value().value<QVector3D>(), static_cast<float>(period_progress));
+          break;
+        case kVec4:
+          interpolated_value = lerp(before->value().value<QVector4D>(), after->value().value<QVector4D>(), static_cast<float>(period_progress));
+          break;
+        default:
+          interpolated_value = before->value();
+        }
 
         return interpolated_value;
       }

app/node/input.h

@@ -179,6 +179,11 @@ signals:
   void KeyframeRemoved(NodeKeyframePtr key);
 
 private:
+  /**
+   * @brief Returns whether a data type can be interpolated or not
+   */
+  static bool type_can_be_interpolated(DataType type);
+
   /**
    * @brief We use Qt signals/slots for keyframe communication but store them as shared ptrs. This function converts
    * a raw ptr to a list index