[LyX/master] Remove unnecessary `c_str`

[Yuriy Skalko]

commit 5999dd96e64c707339c7cd05b81956017080fbb3
Author: Yuriy Skalko <yuriy.skalko at gmail.com>
Date:   Thu Dec 10 14:32:55 2020 +0200

    Remove unnecessary `c_str`
---
 src/graphics/PreviewLoader.cpp |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/graphics/PreviewLoader.cpp b/src/graphics/PreviewLoader.cpp
index 63ddd43..d0590f6 100644
--- a/src/graphics/PreviewLoader.cpp
+++ b/src/graphics/PreviewLoader.cpp
@@ -380,8 +380,8 @@ PreviewLoader::Impl::Impl(PreviewLoader & p, Buffer const & b)
 {
 	font_scaling_factor_ = int(buffer_.fontScalingFactor());
 	if (theApp()) {
-		fg_color_ = convert(theApp()->hexName(foregroundColor()).c_str(), 16);
-		bg_color_ = convert(theApp()->hexName(backgroundColor()).c_str(), 16);
+		fg_color_ = convert(theApp()->hexName(foregroundColor()), 16);
+		bg_color_ = convert(theApp()->hexName(backgroundColor()), 16);
 	} else {
 		fg_color_ = 0x0;
 		bg_color_ = 0xffffff;
@@ -444,8 +444,8 @@ PreviewLoader::Impl::preview(string const & latex_snippet) const
 	int fg = 0x0;
 	int bg = 0xffffff;
 	if (theApp()) {
-		fg = convert(theApp()->hexName(foregroundColor()).c_str(), 16);
-		bg = convert(theApp()->hexName(backgroundColor()).c_str(), 16);
+		fg = convert(theApp()->hexName(foregroundColor()), 16);
+		bg = convert(theApp()->hexName(backgroundColor()), 16);
 	}
 	if (font_scaling_factor_ != fs || fg_color_ != fg || bg_color_ != bg) {
 		// Schedule refresh of all previews on zoom or color changes.