QIcon: Prefer high-quality images of Windows .ico files.

Refactor the code QPixmapIconEngine::addFile() using a convenience
class for reading all images.
Special-case .ico-files: Read images into a list and replace by
higher-quality ones.

Task-number: QTBUG-39287
Change-Id: I32ab6c77a276dc5d4d9a8f7b216c81149b8772b8
Reviewed-by: aavit <eirik.aavitsland@digia.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/plugins/imageformats/ico/qicohandler.cpp b/src/plugins/imageformats/ico/qicohandler.cpp
index 77bb727a51..505d6cc42b 100644
--- a/src/plugins/imageformats/ico/qicohandler.cpp
+++ b/src/plugins/imageformats/ico/qicohandler.cpp
@@ -517,6 +517,8 @@ void ICOReader::read16_24_32BMP(QImage & image)
     }
 }
 
+static const char icoOrigDepthKey[] = "_q_icoOrigDepth";
+
 QImage ICOReader::iconAt(int index)
 {
     QImage img;
@@ -535,7 +537,9 @@ QImage ICOReader::iconAt(int index)
 
             if (isPngImage) {
                 iod->seek(iconEntry.dwImageOffset);
-                return QImage::fromData(iod->read(iconEntry.dwBytesInRes), "png");
+                QImage image = QImage::fromData(iod->read(iconEntry.dwBytesInRes), "png");
+                image.setText(QLatin1String(icoOrigDepthKey), QString::number(iconEntry.wBitCount));
+                return image;
             }
 
             BMP_INFOHDR header;
@@ -598,6 +602,7 @@ QImage ICOReader::iconAt(int index)
                         }
                     }
                 }
+                img.setText(QLatin1String(icoOrigDepthKey), QString::number(iconEntry.wBitCount));
             }
         }
     }