From b009ed0cc87a3b16e5c4554f07875177366d1dba Mon Sep 17 00:00:00 2001 From: Sergey Borovkov Date: Sat, 27 Oct 2012 18:17:05 +0400 Subject: Save grayscale palleted images to grayscale png While Qt does not support grayscale images explicitly it makes sense to save palleted images to grayscale png when possible for better compression and compatibility as opening and saving grayscale images now converts them to palleted Change-Id: Iab7c5a5a9d24b9352f5a7bafe04824a97d2463d9 Reviewed-by: aavit --- src/gui/image/qpnghandler.cpp | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/src/gui/image/qpnghandler.cpp b/src/gui/image/qpnghandler.cpp index 8434282178..bedf881a9a 100644 --- a/src/gui/image/qpnghandler.cpp +++ b/src/gui/image/qpnghandler.cpp @@ -102,7 +102,6 @@ QT_BEGIN_NAMESPACE All PNG files load to the minimal QImage equivalent. All QImage formats output to reasonably efficient PNG equivalents. - Never to grayscale. */ class QPngHandlerPrivate @@ -834,8 +833,12 @@ bool Q_INTERNAL_WIN_NO_THROW QPNGImageWriter::writeImage(const QImage& image, vo int color_type = 0; - if (image.colorCount()) - color_type = PNG_COLOR_TYPE_PALETTE; + if (image.colorCount()) { + if (image.isGrayscale()) + color_type = PNG_COLOR_TYPE_GRAY; + else + color_type = PNG_COLOR_TYPE_PALETTE; + } else if (image.hasAlphaChannel()) color_type = PNG_COLOR_TYPE_RGB_ALPHA; else @@ -852,7 +855,7 @@ bool Q_INTERNAL_WIN_NO_THROW QPNGImageWriter::writeImage(const QImage& image, vo if (image.format() == QImage::Format_MonoLSB) png_set_packswap(png_ptr); - if (image.colorCount()) { + if (color_type == PNG_COLOR_TYPE_PALETTE) { // Paletted int num_palette = qMin(256, image.colorCount()); png_color palette[256]; -- cgit v1.2.3