Draft implementation of Following mechanism for Image processing

ImGuiVisitor.cpp

@@ -473,9 +473,16 @@ void ImGuiVisitor::visit (Source& s)
             ImGui::OpenPopup( "MenuImageProcessing" );
         if (ImGui::BeginPopup( "MenuImageProcessing" ))
         {
+            if (s.processingshader_link_.connected()) {
+                if (ImGui::MenuItem( "Unfollow" )){
+                    s.processingshader_link_.disconnect();
+                }
+            }
+            else {
                 if (ImGui::MenuItem("Reset" )){
                     ImageProcessingShader defaultvalues;
                     s.processingShader()->copy(defaultvalues);
+                    s.processingshader_link_.disconnect();
                     std::ostringstream oss;
                     oss << s.name() << ": " << "Reset Filter";
                     Action::manager().store(oss.str());
@@ -493,12 +500,42 @@ void ImGuiVisitor::visit (Source& s)
                     oss << s.name() << ": " << "Change Filter";
                     Action::manager().store(oss.str());
                 }
+                ImGui::Separator();
+                if (ImGui::BeginMenu("Follow"))
+                {
+                    for (auto mpit = Mixer::manager().session()->begin();
+                         mpit != Mixer::manager().session()->end(); mpit++ )
+                    {
+                        std::string label = (*mpit)->name();
+                        if ( (*mpit)->id() != s.id() &&
+                             (*mpit)->imageProcessingEnabled() &&
+                             !(*mpit)->processingshader_link_.connected()) {
+                            if (ImGui::MenuItem( label.c_str() )){
+                                s.processingshader_link_.connect(*mpit);
+                                s.touch();
+                            }
+                        }
+                    }
+                    ImGui::EndMenu();
+                }
+            }
 
             ImGui::EndPopup();
         }
 
         // full panel for image processing
         ImGui::SetCursorPos( ImVec2( pos.x, pos.y + preview_height)); // ...come back
+
+        if (s.processingshader_link_.connected()) {
+            ImGuiToolkit::Icon(6, 2);
+            ImGui::SameLine(0, 10);
+            ImGui::Text("Filters");
+            Source *target = s.processingshader_link_.source();
+            ImGui::Text("Following");
+            if ( ImGui::Button(target->name().c_str(), ImVec2(IMGUI_RIGHT_ALIGN, 0)) )
+                Mixer::manager().setCurrentSource(target);
+        }
+        else
             s.processingShader()->accept(*this);
     }
 

Source.cpp

@@ -12,7 +12,6 @@
 #include "ImageShader.h"
 #include "ImageProcessingShader.h"
 #include "SystemToolkit.h"
-#include "SessionVisitor.h"
 #include "Log.h"
 #include "MixingGroup.h"
 
@@ -234,6 +233,10 @@ Source::Source() : initialized_(false), symbol_(nullptr), active_(true), locked_
 
 Source::~Source()
 {
+    // inform links that they lost their target
+    while ( !links_.empty() )
+        links_.front()->disconnect();
+
     // inform clones that they lost their origin
     for (auto it = clones_.begin(); it != clones_.end(); it++)
         (*it)->detach();
@@ -649,6 +652,15 @@ void Source::update(float dt)
         need_update_ = false;
     }
 
+    if (processingshader_link_.connected() && imageProcessingEnabled()) {
+        Source *ref_source = processingshader_link_.source();
+        if (ref_source!=nullptr) {
+            if (ref_source->imageProcessingEnabled())
+                processingshader_->copy( *ref_source->processingShader() );
+            else
+                processingshader_link_.disconnect();
+        }
+    }
 }
 
 FrameBuffer *Source::frame() const
@@ -749,6 +761,7 @@ void Source::clearMixingGroup()
     overlay_mixinggroup_->visible_ = false;
 }
 
+
 CloneSource *Source::clone()
 {
     CloneSource *s = new CloneSource(this);

Source.h

@@ -15,7 +15,6 @@ class MaskShader;
 class ImageProcessingShader;
 class FrameBuffer;
 class FrameBufferSurface;
-class Session;
 class Frame;
 class Handles;
 class Symbol;
@@ -26,6 +25,7 @@ typedef std::list<CloneSource *> CloneList;
 
 class Source
 {
+    friend class SourceLink;
     friend class CloneSource;
     friend class View;
     friend class MixingView;
@@ -198,6 +198,8 @@ public:
     // class-dependent icon
     virtual glm::ivec2 icon () const { return glm::ivec2(12, 11); }
 
+    SourceLink processingshader_link_;
+
 protected:
     // name
     std::string name_;
@@ -263,6 +265,9 @@ protected:
     // clones
     CloneList clones_;
 
+    // links
+    SourceLinkList links_;
+
     // Mixing
     MixingGroup *mixinggroup_;
     Switch *overlay_mixinggroup_;

SourceList.cpp

@@ -4,6 +4,8 @@
 #include <glm/gtx/rotate_vector.hpp>
 
 #include "Source.h"
+#include "Session.h"
+
 #include "SourceList.h"
 
 // utility to sort Sources by depth
@@ -118,3 +120,64 @@ SourceList join (const SourceList &first, const SourceList &second)
     return l;
 }
 
+
+void SourceLink::connect(uint64_t id, Session *se)
+{
+    if (connected())
+        disconnect();
+
+    id_ = id;
+    host_ = se;
+}
+
+void SourceLink::connect(Source *s)
+{
+    if (connected())
+        disconnect();
+
+    target_ = s;
+    id_ = s->id();
+    target_->links_.push_back(this);
+    // TODO veryfy circular dependency recursively ?
+}
+
+void SourceLink::disconnect()
+{
+    if (target_)
+        target_->links_.remove(this);
+
+    id_ = 0;
+    target_ = nullptr;
+    host_ = nullptr;
+}
+
+SourceLink::~SourceLink()
+{
+    disconnect();
+}
+
+Source *SourceLink::source()
+{
+    // no link to pointer yet?
+    if ( target_ == nullptr ) {
+        // to find a source, we need a host and an id
+        if ( id_ > 0 && host_ != nullptr) {
+            // find target in session
+            SourceList::iterator it = host_->find(id_);
+            // found: keep pointer
+            if (it != host_->end()) {
+                target_ = *it;
+                target_->links_.push_back(this);
+            }
+            // not found: invalidate link
+            else
+                disconnect();
+        }
+        // no host: invalidate link
+        else
+            disconnect();
+    }
+
+    return target_;
+}
+

SourceList.h

@@ -5,6 +5,7 @@
 #include <glm/glm.hpp>
 
 class Source;
+class Session;
 
 typedef std::list<Source *> SourceList;
 
@@ -25,4 +26,24 @@ SourceListCompare compare (const SourceList &first, const SourceList &second);
 typedef std::list<uint64_t> SourceIdList;
 SourceIdList ids (const SourceList &list);
 
+class SourceLink {
+
+public:
+    SourceLink(): host_(nullptr), target_(nullptr), id_(0) { }
+    ~SourceLink();
+
+    void connect(uint64_t id, Session *se);
+    void connect(Source *s);
+    void disconnect();
+    bool connected() { return id_ > 0; }
+
+    Source *source();
+
+protected:
+    Session *host_;
+    Source *target_;
+    uint64_t id_;
+};
+typedef std::list<SourceLink*> SourceLinkList;
+
 #endif // SOURCELIST_H