Add animation panel action planner

src/app_core/document_animation.h

@@ -25,6 +25,20 @@ enum class DocumentAnimationOperation {
     set_onion_size,
 };
 
+enum class DocumentAnimationPanelAction {
+    goto_frame,
+    next_frame,
+    previous_frame,
+    playback_step,
+    toggle_playback,
+};
+
+struct DocumentAnimationPanelState {
+    int total_duration = 1;
+    int current_frame = 0;
+    bool playback_active = false;
+};
+
 struct DocumentAnimationOperationPlan {
     DocumentAnimationOperation operation = DocumentAnimationOperation::goto_frame;
     int frame_count = 1;
@@ -380,6 +394,32 @@ public:
     return pp::foundation::Result<DocumentAnimationOperationPlan>::success(plan);
 }
 
+[[nodiscard]] inline pp::foundation::Result<DocumentAnimationOperationPlan> plan_animation_panel_action(
+    DocumentAnimationPanelAction action,
+    const DocumentAnimationPanelState& state,
+    int target_frame = 0)
+{
+    switch (action) {
+    case DocumentAnimationPanelAction::goto_frame:
+        return plan_animation_goto_frame(state.total_duration, target_frame);
+
+    case DocumentAnimationPanelAction::next_frame:
+        return plan_animation_step_frame(state.total_duration, state.current_frame, 1);
+
+    case DocumentAnimationPanelAction::previous_frame:
+        return plan_animation_step_frame(state.total_duration, state.current_frame, -1);
+
+    case DocumentAnimationPanelAction::playback_step:
+        return plan_animation_playback_step(state.total_duration, state.current_frame, 1);
+
+    case DocumentAnimationPanelAction::toggle_playback:
+        return plan_animation_playback_toggle(state.playback_active);
+    }
+
+    return pp::foundation::Result<DocumentAnimationOperationPlan>::failure(
+        pp::foundation::Status::invalid_argument("unknown animation panel action"));
+}
+
 [[nodiscard]] inline pp::foundation::Status validate_animation_operation_plan(
     const DocumentAnimationOperationPlan& plan) noexcept
 {