FFT Graph: Only update the view when visible to the user. Cleaned up the Graph class

src/gui/graph.cpp

@@ -3,105 +3,82 @@
 #include <QSGGeometryNode>
 #include <cmath>
 
-namespace GUI{
+namespace GUI {
 
-Graph::Graph():haveNewData(false)
-{
-setFlag(ItemHasContents);
-lastCreated = this;
+Graph *Graph::lastCreated = nullptr;
+
+Graph::Graph(QQuickItem *parent) : QQuickItem(parent), haveNewData(false) {
+    setFlag(ItemHasContents);
+    lastCreated = this;
+    startTimer(15);
 }
 
-Graph * Graph::lastCreated = nullptr;
+Graph::~Graph() {
+    if (lastCreated == this) {
+        lastCreated = nullptr;
+    }
+}
 
-float mins = 1;
-int counter = 1;
+void Graph::showData(float *data, int size) {
+    setImplicitWidth(size * 2);
+    this->data.assign(data, data + size);
+    haveNewData.store(true);
+}
 
-QSGNode * Graph::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *){
+void Graph::setLineColor(const QColor &c) {
+    lineColor = c;
+    update();
+    lineColorChanged();
+}
+
+QSGNode *Graph::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *transformNode) {
+    Q_UNUSED(transformNode)
     QSGNode *node = nullptr;
     QSGGeometryNode *lineNode = nullptr;
     QSGGeometry *lineGeometry = nullptr;
     if (!oldNode) {
-        node  = new QSGNode;
-        {
-            lineNode = new QSGGeometryNode;
-            lineGeometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), size);
-            lineGeometry->setLineWidth(1);
-            lineGeometry->setDrawingMode(QSGGeometry::DrawLineStrip);
-            lineNode->setGeometry(lineGeometry);
-            lineNode->setFlag(QSGNode::OwnsGeometry);
-
-
-            QSGFlatColorMaterial *material = new QSGFlatColorMaterial;
-            material->setColor(lineColor);
-            lineNode->setMaterial(material);
-            lineNode->setFlag(QSGNode::OwnsMaterial);
-        }
-
-        /*{
-            pointNode = new QSGGeometryNode;
-            pointGeometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 4);
-            pointGeometry->setLineWidth(1);
-            pointGeometry->setDrawingMode(QSGGeometry::DrawTriangleStrip);
-            pointNode->setGeometry(pointGeometry);
-            pointNode->setFlag(QSGNode::OwnsGeometry);
-
-            QSGFlatColorMaterial * material = new QSGFlatColorMaterial;
-            material->setColor(backgroundColor);
-            pointNode->setMaterial(material);
-            pointNode->setFlag(QSGNode::OwnsMaterial);
-        }
-        node->appendChildNode(pointNode);*/
+        node = new QSGNode;
+
+        lineNode = new QSGGeometryNode;
+        lineGeometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), static_cast<int>(data.size()));
+        lineGeometry->setLineWidth(1);
+        lineGeometry->setDrawingMode(QSGGeometry::DrawLineStrip);
+        lineNode->setGeometry(lineGeometry);
+        lineNode->setFlag(QSGNode::OwnsGeometry);
+
+        auto *material = new QSGFlatColorMaterial;
+        material->setColor(lineColor);
+        lineNode->setMaterial(material);
+        lineNode->setFlag(QSGNode::OwnsMaterial);
+
         node->appendChildNode(lineNode);
     } else {
-        node = static_cast<QSGNode *>(oldNode);
+        node = oldNode;
 
         lineNode = static_cast<QSGGeometryNode *>(node->childAtIndex(0));
         lineGeometry = lineNode->geometry();
-        lineGeometry->allocate(size);
-        static_cast<QSGFlatColorMaterial*>(lineNode->material())->setColor(lineColor);
-
-        /*pointNode = static_cast<QSGGeometryNode *>(node->childAtIndex(0));
-        pointGeometry = pointNode->geometry();
-        pointGeometry->allocate(4);
-        static_cast<QSGFlatColorMaterial*>(pointNode->material())->setColor(backgroundColor);*/
+        lineGeometry->allocate(static_cast<int>(data.size()));
+        static_cast<QSGFlatColorMaterial *>(lineNode->material())->setColor(lineColor);
     }
 
     QSGGeometry::Point2D *vertices = lineGeometry->vertexDataAsPoint2D();
 
-    /*if(haveNewData.load()){
-        float min = 999999;
-        float max = 0;
-        for(int i = 0 ; i< size; ++i){
-            data[i] = (std::log10(data[i]));
-            min = std::min(min,data[i]);
-            max = std::max(max,data[i]);
-        }
-        for(int i = 0 ; i< size; ++i){
-            data[i]-=min;
-            data[i]/=(max-min);
-            data[i] = std::pow(data[i],2);
-        }
-
-        if(min > 0)
-        mins += min;
-        ++counter;
-    }
-
-    float scale = 0.1;
-    float curMin = mins/counter;
-    qDebug() << ' '<<mins << ' ' << curMin <<' '<<counter;
-*/
-    for(int i = 0 ; i< size; ++i){
-        vertices->x = i*2;
-        //vertices->y = height() - 50 - 20* (std::log10(data[i]));
-        vertices->y = height() - 2*data[i];
+    for (int i = 0; i < static_cast<int>(data.size()); ++i) {
+        vertices->x = i * 2;
+        vertices->y = height() - 2 * data[i];
         ++vertices;
     }
 
     haveNewData = false;
     lineNode->markDirty(QSGNode::DirtyGeometry);
     return node;
+}
 
+void Graph::timerEvent(QTimerEvent *event) {
+    Q_UNUSED(event)
+    if (visibleForUser && haveNewData) {
+        update();
+    }
 }
 
 } // namespace GUI

src/gui/graph.h

@@ -2,39 +2,40 @@
 #define GRAPH_H
 
 #include <QQuickItem>
+#include <atomic>
+#include <utility>
+#include <vector>
 
-namespace GUI{
+namespace GUI {
 
-class Graph : public QQuickItem
-{
+class Graph : public QQuickItem {
     Q_OBJECT
-    float data[2048];
-    int size = 0;
-    QColor lineColor = QColor(0,0,0);
+    std::vector<float> data;
+    QColor lineColor = QColor(0, 0, 0);
     Q_PROPERTY(QColor lineColor READ getLineColor WRITE setLineColor NOTIFY lineColorChanged)
-    static Graph * lastCreated;
+    Q_PROPERTY(bool visibleForUser MEMBER visibleForUser NOTIFY visibleForUserChanged)
+    bool visibleForUser = true;
+    static Graph *lastCreated;
     std::atomic_bool haveNewData;
+
 public:
-    Graph();
-    ~Graph(){
-        if(lastCreated==this)
-            lastCreated = nullptr;
-    }
-    static Graph * getLast(){return lastCreated;}
-    void showData(float* data, int size){
-        setImplicitWidth(size * 2);
-        this->size = std::min(2048,size);
-        memcpy(this->data,data,this->size*sizeof (float));
-        haveNewData.store(true);
-    }
-    void setLineColor(QColor c){lineColor=c;update();lineColorChanged();}
-    QColor getLineColor(){return lineColor;}
+    explicit Graph(QQuickItem *parent = nullptr);
+    ~Graph() override;
+    Q_DISABLE_COPY_MOVE(Graph)
+
+    static Graph *getLast() { return lastCreated; }
+
+    void showData(float *data, int size);
+
+    void setLineColor(const QColor &c);
+    QColor getLineColor() { return lineColor; }
 
 protected:
-    virtual QSGNode * updatePaintNode(QSGNode *, UpdatePaintNodeData *)override;
+    QSGNode *updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *transformNode) override;
+    void timerEvent(QTimerEvent *event) override;
 signals:
-  void lineColorChanged();
-public slots:
+    void lineColorChanged();
+    void visibleForUserChanged();
 };
 
 } // namespace GUI

src/main.cpp

@@ -329,11 +329,8 @@ int main(int argc, char *argv[]) {
 
     QTimer timer;
     timer.setInterval(15);
-    QObject::connect(&timer,&QTimer::timeout,[&](){
-        if(Audio::AudioCaptureManager::get().isCapturing()){
-            if(Graph::getLast()) {
-                Graph::getLast()->update();
-            }
+    QObject::connect(&timer, &QTimer::timeout, [&]() {
+        if (Audio::AudioCaptureManager::get().isCapturing()) {
             if(Oscillogram::getLast()) {
                 Oscillogram::getLast()->update();
             }

src/qml/FFTGraphView.qml

@@ -4,6 +4,7 @@ import QtQuick.Controls 2.5
 import custom.licht 1.0
 
 Item {
+    property alias visibleForUser: graph.visibleForUser
     Label{
         id: label
         anchors.top: parent.top

src/qml/main.qml

@@ -232,7 +232,9 @@ ApplicationWindow {
                 onMoveToOwnWindow: ledWindow.moveToWindow(SwipeView.index);
             }
 
-            FFTGraphView{}
+            FFTGraphView{
+                visibleForUser: SwipeView.isCurrentItem
+            }
 
             Oscillogram{
             }