8 files changed, 46 insertions, 25 deletions
diff --git a/src/gui/image/image.pri b/src/gui/image/image.pri
index 8d75fdd..c4eac95 100644
--- a/src/gui/image/image.pri
+++ b/src/gui/image/image.pri
@@ -93,12 +93,12 @@ SOURCES += \
     SOURCES += image/qpnghandler.cpp
 
     contains(QT_CONFIG, system-png) {
-        unix:LIBS_PRIVATE  += -lpng
-        win32:LIBS += libpng.lib
+        unix|win32-g++*:LIBS_PRIVATE  += -lpng
+        win32:!win32-g++*:LIBS += libpng.lib
     } else {
 	DEFINES *= QT_USE_BUNDLED_LIBPNG
         !isEqual(QT_ARCH, i386):!isEqual(QT_ARCH, x86_64):DEFINES += PNG_NO_ASSEMBLER_CODE
-        INCLUDEPATH  += ../3rdparty/libpng ../3rdparty/zlib
+        INCLUDEPATH += ../3rdparty/libpng
         SOURCES += ../3rdparty/libpng/png.c \
           ../3rdparty/libpng/pngerror.c \
           ../3rdparty/libpng/pngget.c \
@@ -114,6 +114,14 @@ SOURCES += \
           ../3rdparty/libpng/pngwrite.c \
           ../3rdparty/libpng/pngwtran.c \
           ../3rdparty/libpng/pngwutil.c
+
+        contains(QT_CONFIG, system-zlib) {
+            symbian:LIBS_PRIVATE += -llibz
+            else:if(unix|win32-g++*):LIBS_PRIVATE += -lz
+            else:LIBS += zdll.lib
+        } else {
+            INCLUDEPATH  += ../3rdparty/zlib
+        }
     }
 } else {
     DEFINES *= QT_NO_IMAGEFORMAT_PNG
diff --git a/src/gui/image/qbmphandler.cpp b/src/gui/image/qbmphandler.cpp
index 42e19b8..074b8f0 100644
--- a/src/gui/image/qbmphandler.cpp
+++ b/src/gui/image/qbmphandler.cpp
@@ -674,13 +674,15 @@ bool QBmpHandler::readHeader()
 
 bool QBmpHandler::canRead() const
 {
-    if (state == Ready) {
-        if (!canRead(device()))
-            return false;
+    if (state == Ready && !canRead(device()))
+        return false;
+
+    if (state != Error) {
         setFormat("bmp");
         return true;
     }
-    return state != Error;
+
+    return false;
 }
 
 bool QBmpHandler::canRead(QIODevice *device)
diff --git a/src/gui/image/qpixmap.cpp b/src/gui/image/qpixmap.cpp
index 20e4b50..fd2c139 100644
--- a/src/gui/image/qpixmap.cpp
+++ b/src/gui/image/qpixmap.cpp
@@ -1766,6 +1766,9 @@ QPixmap QPixmap::transformed(const QMatrix &matrix, Qt::TransformationMode mode)
     function returns the actual matrix used for transforming the
     pixmap.
 
+    \note When using the native X11 graphics system, the pixmap
+    becomes invalid when the QApplication instance is destroyed.
+
     \sa QBitmap, QImage, QImageReader, QImageWriter
 */
 
diff --git a/src/gui/image/qpixmap_x11.cpp b/src/gui/image/qpixmap_x11.cpp
index 6bebefc..e8dc5ae 100644
--- a/src/gui/image/qpixmap_x11.cpp
+++ b/src/gui/image/qpixmap_x11.cpp
@@ -1250,10 +1250,8 @@ void QX11PixmapData::release()
     pengine = 0;
 
     if (!X11) {
-#ifndef QT_NO_DEBUG
-        qWarning("~QX11PixmapData(): QPixmap objects must be destroyed before the QApplication"
-                 " object, otherwise the native pixmap object will be leaked.");
-#endif
+        // At this point, the X server will already have freed our resources,
+        // so there is nothing to do.
         return;
     }
 
diff --git a/src/gui/image/qpnghandler.cpp b/src/gui/image/qpnghandler.cpp
index dd31834..2cf8222 100644
--- a/src/gui/image/qpnghandler.cpp
+++ b/src/gui/image/qpnghandler.cpp
@@ -892,13 +892,15 @@ QPngHandler::~QPngHandler()
 
 bool QPngHandler::canRead() const
 {
-    if (d->state == QPngHandlerPrivate::Ready) {
-        if (!canRead(device()))
-            return false;
+    if (d->state == QPngHandlerPrivate::Ready && !canRead(device()))
+        return false;
+
+    if (d->state != QPngHandlerPrivate::Error) {
         setFormat("png");
         return true;
     }
-    return d->state != QPngHandlerPrivate::Error;
+
+    return false;
 }
 
 bool QPngHandler::canRead(QIODevice *device)
diff --git a/src/gui/image/qppmhandler.cpp b/src/gui/image/qppmhandler.cpp
index cbbbef4..a9e796c 100644
--- a/src/gui/image/qppmhandler.cpp
+++ b/src/gui/image/qppmhandler.cpp
@@ -409,13 +409,15 @@ bool QPpmHandler::readHeader()
 
 bool QPpmHandler::canRead() const
 {
-    if (state == Ready) {
-        if (!canRead(device(), &subType))
-            return false;
+    if (state == Ready && !canRead(device(), &subType))
+        return false;
+
+    if (state != Error) {
         setFormat(subType);
         return true;
     }
-    return state != Error;
+
+    return false;
 }
 
 bool QPpmHandler::canRead(QIODevice *device, QByteArray *subType)
diff --git a/src/gui/image/qxbmhandler.cpp b/src/gui/image/qxbmhandler.cpp
index 385340a..0dd4e99 100644
--- a/src/gui/image/qxbmhandler.cpp
+++ b/src/gui/image/qxbmhandler.cpp
@@ -261,13 +261,15 @@ bool QXbmHandler::readHeader()
 
 bool QXbmHandler::canRead() const
 {
-    if (state == Ready) {
-        if (!canRead(device()))
-            return false;
+    if (state == Ready && !canRead(device()))
+        return false;
+
+    if (state != Error) {
         setFormat("xbm");
         return true;
     }
-    return state != Error;
+
+    return false;
 }
 
 bool QXbmHandler::canRead(QIODevice *device)
diff --git a/src/gui/image/qxpmhandler.cpp b/src/gui/image/qxpmhandler.cpp
index a475cd0..b97afd3 100644
--- a/src/gui/image/qxpmhandler.cpp
+++ b/src/gui/image/qxpmhandler.cpp
@@ -1225,11 +1225,15 @@ bool QXpmHandler::readImage(QImage *image)
 
 bool QXpmHandler::canRead() const
 {
-    if (state == Ready && canRead(device())) {
+    if (state == Ready && !canRead(device()))
+        return false;
+
+    if (state != Error) {
         setFormat("xpm");
         return true;
     }
-    return state != Error;
+
+    return false;
 }
 
 bool QXpmHandler::canRead(QIODevice *device)