From 6e3eff356b427d2d2b13f1515516266892292d3d Mon Sep 17 00:00:00 2001
From: Philippe Teuwen <phil@teuwen.org>
Date: Sun, 1 Aug 2021 19:52:45 +0200
Subject: [PATCH] fix demod plot on first sample, remove spurious vertical line

---
 client/src/proxguiqt.cpp | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/client/src/proxguiqt.cpp b/client/src/proxguiqt.cpp
index 074e3b848..f45360c6e 100644
--- a/client/src/proxguiqt.cpp
+++ b/client/src/proxguiqt.cpp
@@ -443,9 +443,6 @@ void ProxWidget::resizeEvent(QResizeEvent *event) {
 //----------- Plotting
 
 int Plot::xCoordOf(int i, QRect r) {
-    if (i < 0) {
-        i = 0;
-    }
     return r.left() + (int)((i - GraphStart) * GraphPixelsPerPoint);
 }
 
@@ -536,25 +533,19 @@ void Plot::PlotDemod(uint8_t *buffer, size_t len, QRect plotRect, QRect annotati
     painter->setPen(getColor(graphNum));
     char str[5];
     int absVMax = (int)(100 * 1.05 + 1);
-    int x = xCoordOf(DemodStart, plotRect);
-    int y = 0;
-    if (DemodStart >= 0) {
-        y = yCoordOf((buffer[BitStart] * 200 - 100) * -1, plotRect, absVMax);
-    } else {
-        y = yCoordOf(0, plotRect, absVMax);
-    }
-    penPath.moveTo(x, y);
     delta_x = 0;
     int clk = first_delta_x;
     for (int i = BitStart; i < (int)len && xCoordOf(delta_x + DemodStart, plotRect) < plotRect.right(); i++) {
         for (int j = 0; j < (clk) && i < (int)len && xCoordOf(DemodStart + delta_x + j, plotRect) < plotRect.right() ; j++) {
-            x = xCoordOf(DemodStart + delta_x + j, plotRect);
+            int x = xCoordOf(DemodStart + delta_x + j, plotRect);
             int v = buffer[i] * 200 - 100;
 
-            y = yCoordOf(v, plotRect, absVMax);
-
-            penPath.lineTo(x, y);
-
+            int y = yCoordOf(v, plotRect, absVMax);
+            if ((i == BitStart) && (j == 0)) { // First point
+                penPath.moveTo(x, y);
+            } else {
+                penPath.lineTo(x, y);
+            }
             if (GraphPixelsPerPoint > 10) {
                 QRect f(QPoint(x - 3, y - 3), QPoint(x + 3, y + 3));
                 painter->fillRect(f, getColor(graphNum));