limit transition values set in the effect controls

effects/fields/doublefield.cpp

@@ -23,11 +23,13 @@ double DoubleField::GetDoubleAt(double timecode)
 void DoubleField::SetMinimum(double minimum)
 {
   min_ = minimum;
+  emit MinimumChanged(min_);
 }
 
 void DoubleField::SetMaximum(double maximum)
 {
   max_ = maximum;
+  emit MaximumChanged(max_);
 }
 
 void DoubleField::SetDefault(double d)
@@ -89,6 +91,8 @@ QWidget *DoubleField::CreateWidget(QWidget *existing)
   connect(ls, SIGNAL(valueChanged(double)), this, SLOT(UpdateFromWidget(double)));
   connect(ls, SIGNAL(clicked()), this, SIGNAL(Clicked()));
   connect(this, SIGNAL(EnabledChanged(bool)), ls, SLOT(setEnabled(bool)));
+  connect(this, SIGNAL(MaximumChanged(double)), ls, SLOT(SetMaximum(double)));
+  connect(this, SIGNAL(MinimumChanged(double)), ls, SLOT(SetMinimum(double)));
 
   return ls;
 }

effects/fields/doublefield.h

@@ -37,6 +37,9 @@ public:
 
   virtual QWidget* CreateWidget(QWidget *existing = nullptr) override;
   virtual void UpdateWidgetValue(QWidget* widget, double timecode) override;
+signals:
+  void MaximumChanged(double maximum);
+  void MinimumChanged(double maximum);
 private:
   double min_;
   double max_;

effects/transition.cpp

@@ -48,10 +48,12 @@ Transition::Transition(Clip *c, Clip *s, const EffectMeta* em) :
   EffectRow* length_row = new EffectRow(this, tr("Length"), false, false);
   length_field = new DoubleField(length_row, "length");
   length_field->SetDefault(30);
-  length_field->SetMinimum(0);
+  length_field->SetMinimum(1);
   length_field->SetDisplayType(LabelSlider::FrameNumber);
   length_field->SetFrameRate(parent_clip->sequence == nullptr ?
                                parent_clip->cached_frame_rate() : parent_clip->sequence->frame_rate);
+
+  connect(length_field, SIGNAL(Changed()), this, SLOT(UpdateMaximumLength()));
 }
 
 TransitionPtr Transition::copy(Clip *c, Clip *s) {
@@ -119,6 +121,42 @@ TransitionPtr Transition::CreateFromMeta(Clip* c, Clip* s, const EffectMeta* em)
   return nullptr;
 }
 
+void Transition::UpdateMaximumLength()
+{
+  // Get the maximum area this transition can occupy on the clip
+  long maximum_length = GetMaximumEmptySpaceOnClip(parent_clip);
+
+  // If this clip is a shared transition, get the maximum area this can occupy on the other clip too
+  if (secondary_clip != nullptr) {
+    long secondary_max_length = GetMaximumEmptySpaceOnClip(secondary_clip);
+
+    maximum_length = qMin(secondary_max_length, maximum_length);
+  }
+
+  length_field->SetMaximum(maximum_length);
+}
+
+long Transition::GetMaximumEmptySpaceOnClip(Clip *c)
+{
+  long maximum_transition_length = c->length();
+
+  Transition* opposite_transition;
+
+  // See if this clip has a transition on the opposite side that we need to account for
+  if (c->opening_transition.get() == this) {
+    opposite_transition = c->closing_transition.get();
+  } else {
+    opposite_transition = c->opening_transition.get();
+  }
+
+  // If is does, subtract the maximum length by the transition's length
+  if (opposite_transition != nullptr) {
+    maximum_transition_length -= opposite_transition->get_true_length();
+  }
+
+  return maximum_transition_length;
+}
+
 TransitionPtr Transition::Create(Clip* c, Clip* s, const EffectMeta* em, long length) {
   TransitionPtr t(CreateFromMeta(c, s, em));
   if (t != nullptr) {

effects/transition.h

@@ -62,6 +62,10 @@ public:
 
 private:
   DoubleField* length_field;
+
+private slots:
+  void UpdateMaximumLength();
+  long GetMaximumEmptySpaceOnClip(Clip* c);
 };
 
 #endif // TRANSITION_H

ui/effectui.cpp

@@ -143,8 +143,6 @@ void EffectUI::AddAdditionalEffect(Effect *e)
 
     for (int j=0;j<row->FieldCount();j++) {
 
-      EffectField* field = row->Field(j);
-
       // Attach existing field widget to this effect's field
       e->row(i)->Field(j)->CreateWidget(Widget(i, j));
 

ui/labelslider.h

@@ -61,30 +61,6 @@ public:
    */
   void SetDefault(double v);
 
-  /**
-   * @brief Set the minimum value
-   *
-   * If a minimum value is set, the value will never go below it. If the user manually sets a value lower than
-   * the minimum, it will automatically snap to the minimum.
-   *
-   * @param v
-   *
-   * Value to set as minimum
-   */
-  void SetMinimum(double v);
-
-  /**
-   * @brief Set the maximum value
-   *
-   * If a maximum value is set, the value will never go above it. If the user manually sets a value higher than
-   * the maximum, it will automatically snap to the maximum.
-   *
-   * @param v
-   *
-   * Value to set as maximum
-   */
-  void SetMaximum(double v);
-
   /**
    * @brief Returns the internal value as a double
    * @return The internal value. This will not respect the `display_type`, i.e. 100% will return as 1.0, 12dB will
@@ -145,6 +121,31 @@ public:
    * Defaults to 1
    */
   void SetDecimalPlaces(int places);
+public slots:
+  /**
+   * @brief Set the minimum value
+   *
+   * If a minimum value is set, the value will never go below it. If the user manually sets a value lower than
+   * the minimum, it will automatically snap to the minimum.
+   *
+   * @param v
+   *
+   * Value to set as minimum
+   */
+  void SetMinimum(double v);
+
+  /**
+   * @brief Set the maximum value
+   *
+   * If a maximum value is set, the value will never go above it. If the user manually sets a value higher than
+   * the maximum, it will automatically snap to the maximum.
+   *
+   * @param v
+   *
+   * Value to set as maximum
+   */
+  void SetMaximum(double v);
+
 protected:
   void mousePressEvent(QMouseEvent *ev);
   void mouseMoveEvent(QMouseEvent *ev);