Implement signal multi-selection

This way they can be added with fewer clicks.
The latest Imgui version is required for this, as multi-selection has
only recently been implemented in imgui:
ocornut/imgui#6518

Fixes #193

While we are at it, this patch also implements clipping of the list with
an ImGuiListClipper.
This is possible, because all rows have the same height in the table.
With this change, scrolling through a large list (100k+ rows) is
significantly smoother.

Signed-off-by: Magnus Groß <magnus.gross@kdab.com>

src/ui/cmake/Dependencies.cmake

@@ -3,7 +3,7 @@ include(FetchContent)
 FetchContent_Declare(
     imgui
     GIT_REPOSITORY  https://github.com/ocornut/imgui.git
-    GIT_TAG         v1.90.8 # latest as of 2024-07-01
+    GIT_TAG         v1.91.0 # latest as of 2024-08-15
     SYSTEM
 )
 

src/ui/components/SignalSelector.hpp

@@ -344,10 +344,12 @@ class SignalSelector {
         }
     }
 
-    void drawElement(const SignalData& entry, int idx, FlowGraph* fg) {
+    void drawElement(const SignalData& entry, int idx, FlowGraph* fg, ImGuiSelectionBasicStorage& selection) {
         ImGui::TableNextRow();
         ImGui::TableNextColumn();
-        ImGui::TextUnformatted(entry.device.c_str());
+        const bool itemSelected = selection.Contains(static_cast<ImGuiID>(idx));
+        ImGui::SetNextItemSelectionUserData(idx);
+        ImGui::Selectable(entry.device.c_str(), itemSelected, ImGuiSelectableFlags_SpanAllColumns | ImGuiSelectableFlags_AllowOverlap);
         ImGui::TableNextColumn();
         ImGui::TextUnformatted(entry.signalName.c_str());
         ImGui::TableNextColumn();
@@ -358,11 +360,6 @@ class SignalSelector {
         ImGui::TextUnformatted(entry.frontend.c_str());
         ImGui::TableNextColumn();
         ImGui::Text(entry.comment.c_str());
-        ImGui::TableNextColumn();
-        if (ImGui::Button(("+##" + std::to_string(idx)).c_str())) {
-            const auto uri = opencmw::URI<>::UriFactory().scheme(entry.protocol).hostName(entry.hostname).port(static_cast<uint16_t>(entry.port)).path(entry.serviceName).addQueryParameter("channelNameFilter", entry.signalName).build();
-            fg->addRemoteSource(uri.str());
-        }
     }
 
     void drawSignalSelector(FlowGraph* fg) {
@@ -381,7 +378,6 @@ class SignalSelector {
             } else {
                 m_selectedFilters.addLabel({item->title, item, colorForCategory(item->category)});
             }
-
             filtersChanged = true;
         }
 
@@ -409,26 +405,58 @@ class SignalSelector {
             while (loadMoreItems()) {
             }
         }
-
         ImGui::Separator();
         ImGui::SetNextWindowSize(ImGui::GetContentRegionAvail(), ImGuiCond_Once);
-        IMW::Child signals("Signals", ImVec2(0, 0), 0, 0);
-
-        if (auto table = DigitizerUi::IMW::Table("Signals", 7, static_cast<ImGuiTableFlags>(ImGuiTableFlags_BordersInnerV), ImVec2(0.0f, 0.0f), 0.0f)) {
-            ImGui::TableHeader("SignalsHeader");
-            ImGui::TableSetupColumn("Device");
-            ImGui::TableSetupColumn("Name");
-            ImGui::TableSetupColumn("Quantity");
-            ImGui::TableSetupColumn("Unit");
-            ImGui::TableSetupColumn("DAQ-M");
-            ImGui::TableSetupColumn("Comment");
-            ImGui::TableSetupColumn("Add Signal");
-            ImGui::TableHeadersRow();
-            {
-                std::for_each(m_filteredItems.begin(), m_filteredItems.end(), [this, fg, idx = 0](const auto& e) mutable { drawElement(*e, idx++, fg); });
+        static ImGuiSelectionBasicStorage selection;
+        {
+            IMW::Child signals("Signals", ImVec2(0, -ImGui::GetTextLineHeightWithSpacing()), 0, 0);
+            if (auto table = DigitizerUi::IMW::Table("Signals", 6, static_cast<ImGuiTableFlags>(ImGuiTableFlags_BordersInnerV), ImVec2(0.0f, 0.0f), 0.0f)) {
+                // allow multi-selection
+                ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_ClearOnEscape | ImGuiMultiSelectFlags_BoxSelect1d | ImGuiMultiSelectFlags_ClearOnClickVoid;
+                auto*                 ms_io = ImGui::BeginMultiSelect(flags, selection.Size, m_filteredItems.size());
+                selection.ApplyRequests(ms_io);
+
+                ImGui::TableHeader("SignalsHeader");
+                ImGui::TableSetupColumn("Device");
+                ImGui::TableSetupColumn("Name");
+                ImGui::TableSetupColumn("Quantity");
+                ImGui::TableSetupColumn("Unit");
+                ImGui::TableSetupColumn("DAQ-M");
+                ImGui::TableSetupColumn("Comment");
+                ImGui::TableHeadersRow();
+
+                // clip list for better performance
+                ImGuiListClipper clipper;
+                clipper.Begin(m_filteredItems.size());
+                if (ms_io->RangeSrcItem != -1) {
+                    clipper.IncludeItemByIndex(static_cast<int>(ms_io->RangeSrcItem)); // do not clip RangeSrcItem
+                }
+
+                while (clipper.Step()) {
+                    for (auto n = clipper.DisplayStart; n < clipper.DisplayEnd; ++n) {
+                        drawElement(*m_filteredItems[n], n, fg, selection);
+                    }
+                }
+
+                ms_io = ImGui::EndMultiSelect();
+                selection.ApplyRequests(ms_io);
             }
         }
 
+        if (ImGui::Button("Add Signal")) {
+            std::vector<SignalData> entries;
+            void*                   it = nullptr;
+            ImGuiID                 id = 0;
+            while (selection.GetNextSelectedItem(&it, &id)) {
+                entries.push_back(*m_filteredItems[id]);
+            }
+
+            for (const auto& e : entries) {
+                const auto uri = opencmw::URI<>::UriFactory().scheme(e.protocol).hostName(e.hostname).port(static_cast<uint16_t>(e.port)).path(e.serviceName).addQueryParameter("channelNameFilter", e.signalName).build();
+                fg->addRemoteSource(uri.str());
+            }
+        }
+        ImGui::SameLine();
         if (ImGui::Button("Refresh")) {
             m_signalList.update();
         }