From a72b3f0c89bbacdd056be3338e164adf027c514b Mon Sep 17 00:00:00 2001
From: Fen Dweller <chemicalcrux@gmail.com>
Date: Mon, 22 Jun 2020 13:16:50 -0400
Subject: [PATCH] Improve drawing of the horizontal axis

---
 macrovision.js | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/macrovision.js b/macrovision.js
index e20dd933..b41f63e5 100644
--- a/macrovision.js
+++ b/macrovision.js
@@ -484,8 +484,9 @@ function drawHorizontalScale(ifDirty = false) {
         x += offset / heightPer.toNumber("meters") * pixelsPer;
         total = math.subtract(total, math.unit(offset, "meters"));
 
-        for (; x >= 50; x -= pixelsPer) {
-            drawTick(ctx, x, 50, total);
+        for (; x >= 50 - pixelsPer; x -= pixelsPer) {
+            // negate it so that the left side is negative
+            drawTick(ctx, x, 50, math.multiply(-1, total));
             total = math.add(total, heightPer);
         }
     }
@@ -553,12 +554,12 @@ function drawHorizontalScale(ifDirty = false) {
     
 
     ctx.beginPath();
-    ctx.moveTo(50, 50);
-    ctx.lineTo(ctx.canvas.clientWidth-50, 50);
+    ctx.moveTo(0, 50);
+    ctx.lineTo(ctx.canvas.clientWidth, 50);
     ctx.stroke();
     ctx.beginPath();
-    ctx.moveTo(50,  ctx.canvas.clientHeight - 50);
-    ctx.lineTo(ctx.canvas.clientWidth - 50, ctx.canvas.clientHeight - 50);
+    ctx.moveTo(0,  ctx.canvas.clientHeight - 50);
+    ctx.lineTo(ctx.canvas.clientWidth , ctx.canvas.clientHeight - 50);
     ctx.stroke();
 
     drawTicks(ctx, pixelsPer, heightPer);