Chunk updates

src/ESPUI.cpp

@@ -947,9 +947,8 @@ Initially this function used to send the control element data individually.
 Due to a change in the ESPAsyncWebserver library this had top be changed to be
 sent as one blob at the beginning. Therefore a new type is used as well
 */
-void ESPUIClass::jsonDom(AsyncWebSocketClient* client)
-{
-    String json;
+void ESPUIClass::jsonDom(AsyncWebSocketClient* client) {
+
     DynamicJsonDocument document(jsonInitialDocumentSize);
     document["type"] = (int)UI_INITIAL_GUI;
     document["sliderContinuous"] = sliderContinuous;
@@ -961,9 +960,38 @@ void ESPUIClass::jsonDom(AsyncWebSocketClient* client)
     titleItem["type"] = (int)UI_TITLE;
     titleItem["label"] = ui_title;
 
-    while (control != nullptr)
-    {
-        JsonObject item = items.createNestedObject();
+    while(1) {
+        control = prepareJSONChunk(client, control, &items);
+
+        String json;
+        serializeJson(document, json);
+    #if defined(DEBUG_ESPUI)
+        if (this->verbosity >= Verbosity::VerboseJSON) {
+            Serial.println("Sending elements --------->");
+            Serial.println(json);
+        }
+    #endif
+        if (client != nullptr) client->text(json);
+        else this->ws->textAll(json);
+
+        if(control == nullptr) break;
+
+        document.clear();
+        items.clear();
+        document["type"] = (int) UI_EXTEND_GUI;
+        items = document.createNestedArray("controls");
+    }
+}
+
+
+/* Prepare a chunk of elements as a single JSON string. If the allowed number of elements is greater than the total number
+this will represent the entire UI and this function will return null. If a control pointer is returned then the limit 
+was reached, the currently serialised must be sent, and then processing resumed to send the next chunk. */
+Control *ESPUIClass::prepareJSONChunk(AsyncWebSocketClient* client, Control* control, JsonArray *items) {
+    int elementcount = 0;
+
+    while (control != nullptr && elementcount < 10) {
+        JsonObject item = items->createNestedObject();
 
         item["id"] = String(control->id);
         item["type"] = (int)control->type;
@@ -972,46 +1000,25 @@ void ESPUIClass::jsonDom(AsyncWebSocketClient* client)
         item["color"] = (int)control->color;
         item["visible"] = (int)control->visible;
 
-        if (control->parentControl != Control::noParent)
-        {
+        if (control->parentControl != Control::noParent) {
             item["parentControl"] = String(control->parentControl);
         }
 
         // special case for selects: to preselect an option, you have to add
         // "selected" to <option>
-        if (control->type == ControlType::Option)
-        {
-            if (ESPUI.getControl(control->parentControl)->value == control->value)
-            {
+        if (control->type == ControlType::Option) {
+            if (ESPUI.getControl(control->parentControl)->value == control->value) {
                 item["selected"] = "selected";
             }
-            else
-            {
+            else {
                 item["selected"] = "";
             }
         }
 
         control = control->next;
+        elementcount++;
     }
-
-    // Send as one big bunch
-    serializeJson(document, json);
-
-#if defined(DEBUG_ESPUI)
-    if (this->verbosity >= Verbosity::VerboseJSON)
-    {
-        Serial.println(json);
-    }
-#endif
-
-    if (client != nullptr)
-    {
-        client->text(json);
-    }
-    else
-    {
-        this->ws->textAll(json);
-    }
+    return control;
 }
 
 void ESPUIClass::jsonReload()

src/ESPUI.h

@@ -77,11 +77,13 @@ enum ControlType : uint8_t
     UpdateAccel,
 
     InitialGui = 200,
-    Reload = 201
+    Reload = 201,
+    ExtendGUI = 210
 };
 
 #define UI_INITIAL_GUI ControlType::InitialGui
 #define UI_RELOAD ControlType::Reload
+#define UI_EXTEND_GUI ControlType::ExtendGUI
 
 #define UI_TITLE ControlType::Title
 #define UI_LABEL ControlType::Label
@@ -294,6 +296,8 @@ private:
     const char* basicAuthUsername = nullptr;
     const char* basicAuthPassword = nullptr;
     bool basicAuth = true;
+
+    Control *prepareJSONChunk(AsyncWebSocketClient* client, Control *control, JsonArray *items);
 };
 
 extern ESPUIClass ESPUI;