From e556c25047a887d41c97ef9df7941ba585ba852b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Sandve=20Aln=C3=A6s?= <martin.alnes@gmail.com>
Date: Mon, 29 Jan 2018 10:38:33 +0100
Subject: [PATCH] Avoid looping over unused rows and columns in SetCellStyle.

The recent improvement to SetCellStyle still loops
over all the rows before the area, moving the area checks
into the loop is more concise and faster.

Since the loop now covers the correct area by construction,
the inner loop check checkCellInArea is no longer needed.
---
 styles.go | 25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/styles.go b/styles.go
index 8cee5ff..7321c18 100644
--- a/styles.go
+++ b/styles.go
@@ -2307,6 +2307,7 @@ func (f *File) SetCellStyle(sheet, hcell, vcell string, styleID int) {
 	vyAxis := vrow - 1
 	vxAxis := TitleToNumber(vcol)
 
+	// Correct the coordinate area, such correct C1:B3 to B1:C3.
 	if vxAxis < hxAxis {
 		hcell, vcell = vcell, hcell
 		vxAxis, hxAxis = hxAxis, vxAxis
@@ -2317,32 +2318,14 @@ func (f *File) SetCellStyle(sheet, hcell, vcell string, styleID int) {
 		vyAxis, hyAxis = hyAxis, vyAxis
 	}
 
-	// Correct the coordinate area, such correct C1:B3 to B1:C3.
-	hcell = ToAlphaString(hxAxis) + strconv.Itoa(hyAxis+1)
-	vcell = ToAlphaString(vxAxis) + strconv.Itoa(vyAxis+1)
-
 	xlsx := f.workSheetReader(sheet)
 
 	completeRow(xlsx, vyAxis+1, vxAxis+1)
 	completeCol(xlsx, vyAxis+1, vxAxis+1)
 
-	for r, row := range xlsx.SheetData.Row {
-		if r < hyAxis {
-			continue
-		} else if r > vyAxis {
-			break
-		}
-
-		for k, c := range row.C {
-			if k < hxAxis {
-				continue
-			} else if k > vxAxis {
-				break
-			}
-
-			if checkCellInArea(c.R, hcell+":"+vcell) {
-				xlsx.SheetData.Row[r].C[k].S = styleID
-			}
+	for r := hyAxis; r <= vyAxis; r++ {
+		for k := hxAxis; k <= vxAxis; k++ {
+			xlsx.SheetData.Row[r].C[k].S = styleID
 		}
 	}
 }