implement action redo

data/layout.xml

@@ -709,6 +709,7 @@
           </button-custom>
         </node>
         <button id="btn-undo" width="50" height="100%" margin="0 5 0 0" text="Undo"/>
+        <button id="btn-redo" width="50" height="100%" margin="0 5 0 0" text="Redo"/>
         <!--
         <button-custom id="btn-layer" width="50" height="100%" margin="0 5 0 0" thickness="1" border-color="0 0 0 1" pad="6" align="center" justify="center">
           <icon width="100%" height="100%" icon="disk"/>

engine/action.cpp

@@ -7,6 +7,7 @@ ActionManager ActionManager::I;
 
 void ActionManager::add(Action *action)
 {
+    I.m_redos = std::stack<std::unique_ptr<Action>>();
     I.m_actions.emplace(action);
     I.m_memory += action->memory();
     //LOG("History: %.2f KB", I.m_memory / 1024.f);
@@ -15,6 +16,11 @@ void ActionManager::add(Action *action)
 
 void ActionManager::undo()
 {
+    if (I.m_actions.empty())
+        return;
+
+    I.m_redos.emplace(I.m_actions.top()->get_redo());
+
     I.m_actions.top()->undo();
     I.m_memory -= I.m_actions.top()->memory();
     I.m_actions.pop();
@@ -22,6 +28,20 @@ void ActionManager::undo()
     App::I.update_memory_usage(I.m_memory);
 }
 
+void ActionManager::redo()
+{
+    if (I.m_redos.empty())
+        return;
+
+    I.m_actions.emplace(I.m_redos.top()->get_redo());
+    I.m_memory += I.m_actions.top()->memory();
+
+    I.m_redos.top()->undo();
+    I.m_redos.pop();
+    //LOG("History: %.2f KB", I.m_memory / 1024.f);
+    App::I.update_memory_usage(I.m_memory);
+}
+
 void ActionManager::clear()
 {
     while (!I.m_actions.empty())

engine/action.h

@@ -5,6 +5,7 @@ class Action
 public:
     virtual void run() = 0;
     virtual void undo() = 0;
+    virtual Action* get_redo() = 0;
     virtual size_t memory() = 0;
     virtual ~Action(){};
 };
@@ -14,9 +15,11 @@ class ActionManager
 public:
     static ActionManager I;
     std::stack<std::unique_ptr<Action>> m_actions;
+    std::stack<std::unique_ptr<Action>> m_redos;
     size_t m_memory = 0;
     static void add(Action* action);
     static void undo();
+    static void redo();
     static void clear();
     static bool empty()
     {

engine/app_layout.cpp

@@ -55,8 +55,13 @@ void App::init_toolbar_main()
     if (auto* button = layout[main_id]->find<NodeButton>("btn-undo"))
     {
         button->on_click = [this, button](Node*) {
-            if (!ActionManager::empty())
-                ActionManager::undo();
+            ActionManager::undo();
+        };
+    }
+    if (auto* button = layout[main_id]->find<NodeButton>("btn-redo"))
+    {
+        button->on_click = [this, button](Node*) {
+            ActionManager::redo();
         };
     }
     if (auto* button = layout[main_id]->find<NodeButtonCustom>("btn-clean-memory"))

engine/canvas.cpp

@@ -160,6 +160,35 @@ void ui::Canvas::snap_history(const std::vector<int>& planes)
     action->clear_layer = true;
     ActionManager::add(action);
 }
+ui::ActionStroke* ui::Canvas::create_action(int layer)
+{
+    auto action = new ActionStroke;
+    for (int i = 0; i < 6; i++)
+    {
+        if (!m_layers[layer].m_dirty_face[i])
+            continue; // no stroke on this face, skip it
+
+        m_layers[layer].m_rtt[i].bindFramebuffer();
+
+        // save image before commit
+        glm::vec2 box_or = xy(m_layers[layer].m_dirty_box[i]);
+        glm::vec2 box_sz = zw(m_layers[layer].m_dirty_box[i]) - xy(m_layers[layer].m_dirty_box[i]);
+        action->m_image[i] = std::make_unique<uint8_t[]>(box_sz.x * box_sz.y * 4);
+        glReadPixels(box_or.x, box_or.y, box_sz.x, box_sz.y, GL_RGBA, GL_UNSIGNED_BYTE, action->m_image[i].get());
+
+        action->m_box[i] = m_layers[layer].m_dirty_box[i];
+        action->m_old_box[i] = m_layers[layer].m_dirty_box[i];
+        action->m_old_dirty[i] = m_layers[layer].m_dirty_face[i];
+
+        m_layers[layer].m_rtt[i].unbindFramebuffer();
+    }
+    // save history
+    action->m_layer_idx = layer;
+    action->m_canvas = this;
+    action->m_stroke = std::move(m_current_stroke);
+    action->clear_layer = true;
+    return action;
+}
 void ui::Canvas::stroke_end()
 {
     if (!m_current_stroke)

engine/canvas.h

@@ -131,6 +131,7 @@ public:
     void snapshot_save(std::string data_path);
     void snapshot_restore();
     void snap_history(const std::vector<int>& planes);
+    class ActionStroke* create_action(int layer);
     void clear_context();
     void import_equirectangular(std::string file_path);
     void import_equirectangular_thread(std::string file_path);
@@ -174,6 +175,11 @@ public:
     virtual void run() override
     {
         
+    }
+    virtual Action* get_redo()
+    {
+        auto redo = m_canvas->create_action(m_layer_idx);
+        return redo;
     }
     virtual void undo() override
     {