save timelapse stream to file

src/canvas.h

@@ -8,6 +8,7 @@
 #include "canvas_actions.h"
 #include "canvas_modes.h"
 #include <stack>
+#include "mp4enc.h"
 
 #if __WEB__
 #define CANVAS_RES 512
@@ -33,7 +34,8 @@ struct PPIDocVersion
     // version 1: initial
     // version 2: added blend mode, alpha and visibility
     // version 3: added animation frames
-    int minor = 3;
+    // version 4: (released in 0.2.3) add info struct
+    int minor = 4;
 };
 
 struct PPISoftVersion
@@ -92,6 +94,7 @@ public:
     bool m_dirty = false;
     bool m_commit_delayed = false;
     bool m_dirty_stroke = false;
+    std::unique_ptr<MP4Encoder> m_encoder;
     std::chrono::time_point<std::chrono::steady_clock> m_disrty_stroke_time;
     std::stack<CameraData> m_camera_stack;
 
@@ -251,4 +254,5 @@ public:
     void pop_camera();
     CameraData get_camera();
     void set_camera(const CameraData& c);
+    void timelapse_reset_encoder() noexcept;
 };