From 52e18ff80028afc515fb4681b0691afddf654fc9 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 6 May 2016 08:49:35 +0530
Subject: [PATCH] Use constScanLine()

---
 src/calibre/utils/imageops/imageops.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/calibre/utils/imageops/imageops.cpp b/src/calibre/utils/imageops/imageops.cpp
index da58cffb94..165cada01f 100644
--- a/src/calibre/utils/imageops/imageops.cpp
+++ b/src/calibre/utils/imageops/imageops.cpp
@@ -117,7 +117,8 @@ QImage grayscale(const QImage &image) {
 QImage convolve(QImage &img, int matrix_size, float *matrix) {
     int i, x, y, w, h, matrix_x, matrix_y;
     int edge = matrix_size/2;
-    QRgb *dest, *src, *s, **scanblock;
+    QRgb *dest, *s, **scanblock;
+    const QRgb *src = NULL;
     float *m, *normalize_matrix, normalize, r, g, b;
 
     if(!(matrix_size % 2))
@@ -147,7 +148,7 @@ QImage convolve(QImage &img, int matrix_size, float *matrix) {
     // apply
 
     for(y=0; y < h; ++y){
-        src = (QRgb *)img.scanLine(y);
+        src = reinterpret_cast<const QRgb*>(img.constScanLine(y));
         dest = (QRgb *)buffer.scanLine(y);
         // Read in scanlines to pixel neighborhood. If the scanline is outside
         // the image use the top or bottom edge.