Improvements

graphrenderer.cpp

@@ -6,40 +6,72 @@
 #include <QPainter>
 #include <QPalette>
 
-QPixmap GraphRenderer::render(const QSize &size, const frame_t *frameBegin, const frame_t *frameEnd, const QPalette &palette)
+QPixmap GraphRenderer::render(const QSize &size, const frame_t *begin, const frame_t *end, const QPalette &palette)
 {
     QPixmap pixmap{size};
 
-    QPainter painter;
-    painter.begin(&pixmap);
+    {
+        QPainter painter;
+        painter.begin(&pixmap);
 
-    painter.fillRect(pixmap.rect(), palette.base());
+        painter.setPen({});
+        painter.setBrush(palette.base());
+        painter.drawRect(pixmap.rect());
 
-    painter.setBrush(palette.base());
+        painter.setPen(QPen{palette.color(QPalette::Text)});
+        painter.setBrush(palette.text());
+        render(pixmap.rect(), begin, end, painter);
 
-    painter.drawRect(pixmap.rect());
+        painter.end();
+    }
 
-    render(pixmap.rect(), frameBegin, frameEnd, painter, palette);
-    painter.end();
     return pixmap;
 }
 
-void GraphRenderer::render(const QRect &rect, const frame_t *frameBegin, const frame_t *frameEnd, QPainter &painter, const QPalette &palette)
+void GraphRenderer::render(const QRect &rect, const frame_t *begin, const frame_t *end, QPainter &painter)
 {
-    if (frameEnd == frameBegin)
+    if (end == begin)
         return;
 
-    painter.setPen(QPen{palette.color(QPalette::Text)});
-    painter.setBrush(palette.text());
+    std::pair<frame_t, frame_t> arr[rect.width()];
 
-    const auto framesPerPixel = std::distance(frameBegin, frameEnd) / rect.width();
+    reduceSamples(begin, end, arr, arr+rect.width());
 
-    for (int x = 0; x < rect.width(); x++)
+    render(rect.topLeft(), rect.height(), arr, arr+rect.width(), painter);
+}
+
+void GraphRenderer::render(const QPoint &pos, int height, std::pair<frame_t, frame_t> *begin, std::pair<frame_t, frame_t> *end, QPainter &painter)
+{
+    int x = pos.x();
+    for (auto iter = begin; iter != end; iter++)
     {
-        const frame_t *begin = frameBegin + (x * framesPerPixel);
+        const frame_t &min = iter->first;
+        const frame_t &max = iter->second;
+
+        painter.drawLine(x, pos.y() + (height / 2) - (min[0] * (height / 2)),
+                         x, pos.y() + (height / 2) + (max[0] * (height / 2)));
+        x++;
+    }
+}
+
+void GraphRenderer::reduceSamples(const frame_t *inputBegin, const frame_t *inputEnd, std::pair<frame_t, frame_t> *outputBegin, std::pair<frame_t, frame_t> *outputEnd)
+{
+    const auto inputLength = std::distance(inputBegin, inputEnd);
+    const auto outputLength = std::distance(outputBegin, outputEnd);
+
+    const auto framesPerPixel = inputLength / outputLength;
+
+    for (int i = 0; i < outputLength; i++)
+    {
+        frame_t &min = outputBegin[i].first;
+        frame_t &max = outputBegin[i].second;
+
+        min = {1.f, 1.f};
+        max = {-1.f, -1.f};
+
+        const frame_t *begin = inputBegin + (i * framesPerPixel);
         const frame_t *end = begin + framesPerPixel;
 
-        frame_t min{1.f, 1.f}, max{-1.f, -1.f};
         for (auto iter = begin; iter != end; iter++)
         {
             if ((*iter)[0] < min[0])
@@ -51,8 +83,5 @@ void GraphRenderer::render(const QRect &rect, const frame_t *frameBegin, const f
             if ((*iter)[1] > max[1])
                 max[1] = (*iter)[1];
         }
-
-        painter.drawLine(rect.x() + x, rect.y() + (rect.height() / 2) - (min[0] * (rect.height() / 2)),
-                         rect.x() + x, rect.y() + (rect.height() / 2) + (max[0] * (rect.height() / 2)));
     }
 }