From e7a49c2c212d022df6cda4739b8c3e391fd3594a Mon Sep 17 00:00:00 2001
From: Mike Jensen <mike.jensen@goteleport.com>
Date: Thu, 4 May 2023 12:52:28 -0600
Subject: [PATCH] Improvements to how the X Axis is rendered

This provides two improvements to how the X Axis is rendered:
* The calculation for where a tick should exist has been improved.  It now will ensure a tick is always at both the start of the axis and the end of the axis.  This makes it clear exactly what data span is captured in the graph.
* The second improvement is how the label on the last tick is written.  It used to often get partially cut off, and with the change to ensure a tick is always at the end this could be seen more easily.  Now the last tick has it's label written to the left so that it can be fully displayed.
---
 painter.go | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/painter.go b/painter.go
index 18496fd..450afdf 100644
--- a/painter.go
+++ b/painter.go
@@ -615,6 +615,17 @@ func (p *Painter) TextFit(body string, x, y, width int, textAligns ...string) ch
 	return output
 }
 
+func isTick(totalRange int, numTicks int, index int) bool {
+	step := float64(totalRange-1) / float64(numTicks-1)
+	for i := 0; i < numTicks; i++ {
+		value := float64(i) * step
+		if int(value + 0.5) == index {
+			return true
+		}
+	}
+	return false
+}
+
 func (p *Painter) Ticks(opt TicksOption) *Painter {
 	if opt.Count <= 0 || opt.Length <= 0 {
 		return p
@@ -638,7 +649,7 @@ func (p *Painter) Ticks(opt TicksOption) *Painter {
 		if index < first {
 			continue
 		}
-		if (index-first)%unit != 0 {
+		if ! isTick(len(values), unit, index) {
 			continue
 		}
 		if isVertical {
@@ -674,15 +685,13 @@ func (p *Painter) MultiText(opt MultiTextOption) *Painter {
 	}
 	count := len(opt.TextList)
 	positionCenter := true
-	showIndex := opt.Unit / 2
+	tickLimit := true
 	if containsString([]string{
 		PositionLeft,
 		PositionTop,
 	}, opt.Position) {
 		positionCenter = false
 		count--
-		// 非居中
-		showIndex = 0
 	}
 	width := p.Width()
 	height := p.Height()
@@ -690,6 +699,7 @@ func (p *Painter) MultiText(opt MultiTextOption) *Painter {
 	isVertical := opt.Orient == OrientVertical
 	if isVertical {
 		values = autoDivide(height, count)
+		tickLimit = false
 	} else {
 		values = autoDivide(width, count)
 	}
@@ -699,7 +709,7 @@ func (p *Painter) MultiText(opt MultiTextOption) *Painter {
 		if index < opt.First {
 			continue
 		}
-		if opt.Unit != 0 && (index-opt.First)%opt.Unit != showIndex {
+		if opt.Unit != 0 && tickLimit && ! isTick(len(opt.TextList)-opt.First, opt.Unit, index-opt.First) {
 			continue
 		}
 		if isTextRotation {
@@ -724,7 +734,11 @@ func (p *Painter) MultiText(opt MultiTextOption) *Painter {
 				x = 0
 			}
 		} else {
-			x = start - box.Width()>>1
+			if index == len(opt.TextList) - 1 {
+				x = start - box.Width()
+			} else {
+				x = start - box.Width()>>1
+			}
 		}
 		x += offset.Left
 		y += offset.Top
@@ -749,7 +763,6 @@ func (p *Painter) Grid(opt GridOption) *Painter {
 			x1 := 0
 			y1 := 0
 			if isVertical {
-
 				x0 = v
 				x1 = v
 				y1 = height