Fixed mac specific compiler errors and cleaned up Objective C code

Created new file src/gui/macutilities.mm, moved code from mainwindow.cpp and torrentcontentmodel.cpp that used the Objective C runtime into it and converted it to actual Objective C. Rewrote pixmapForExtension() so that it doesn't call into private Qt functions.

macxconf.pri

@@ -9,7 +9,7 @@ exists($$OUT_PWD/../conf.pri) {
     include(conf.pri)
 }
 
-LIBS += -framework Carbon -framework IOKit
+LIBS += -framework Carbon -framework IOKit -framework AppKit
 
 QT_LANG_PATH = ../dist/qt-translations
 DIST_PATH = ../dist/mac

src/base/CMakeLists.txt

@@ -141,5 +141,6 @@ endif ()
 if (APPLE)
     find_library(IOKit_LIBRARY IOKit)
     find_library(Carbon_LIBRARY Carbon)
-    target_link_libraries(qbt_base PRIVATE ${Carbon_LIBRARY} ${IOKit_LIBRARY})
+    find_library(AppKit_LIBRARY AppKit)
+    target_link_libraries(qbt_base PRIVATE ${Carbon_LIBRARY} ${IOKit_LIBRARY} ${AppKit_LIBRARY})
 endif (APPLE)

src/gui/CMakeLists.txt

@@ -118,6 +118,11 @@ transferlistwidget.cpp
 updownratiodlg.cpp
 )
 
+if (APPLE)
+    list(APPEND QBT_GUI_HEADERS macutilities.h)
+    list(APPEND QBT_GUI_SOURCES macutilities.mm)
+endif (APPLE)
+
 if (WIN32 OR APPLE)
     list(APPEND QBT_GUI_HEADERS programupdater.h)
     list(APPEND QBT_GUI_SOURCES programupdater.cpp)

src/gui/gui.pri

@@ -121,6 +121,11 @@ win32|macx {
     SOURCES += $$PWD/programupdater.cpp
 }
 
+macx {
+    HEADERS += $$PWD/macutilities.h
+    OBJECTIVE_SOURCES += $$PWD/macutilities.mm
+}
+
 FORMS += \
     $$PWD/mainwindow.ui \
     $$PWD/about.ui \

src/gui/macutilities.h

@@ -0,0 +1,39 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2017  Brian Kendall <brian@briankendall.net>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link this program with the OpenSSL project's "OpenSSL" library (or with
+ * modified versions of it that use the same license as the "OpenSSL" library),
+ * and distribute the linked executables. You must obey the GNU General Public
+ * License in all respects for all of the code used other than "OpenSSL".  If you
+ * modify file(s), you may extend this exception to your version of the file(s),
+ * but you are not obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ */
+
+#ifndef MACUTILITIES_H
+#define MACUTILITIES_H
+
+#include <QPixmap>
+#include <QSize>
+#include <objc/objc.h>
+
+QPixmap pixmapForExtension(const QString &ext, const QSize &size);
+void overrideDockClickHandler(bool (*dockClickHandler)(id, SEL, ...));
+
+#endif // MACUTILITIES_H

src/gui/macutilities.mm

@@ -0,0 +1,71 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2017  Brian Kendall <brian@briankendall.net>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link this program with the OpenSSL project's "OpenSSL" library (or with
+ * modified versions of it that use the same license as the "OpenSSL" library),
+ * and distribute the linked executables. You must obey the GNU General Public
+ * License in all respects for all of the code used other than "OpenSSL".  If you
+ * modify file(s), you may extend this exception to your version of the file(s),
+ * but you are not obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ */
+
+#include "macutilities.h"
+
+#include <QtMac>
+#include <objc/message.h>
+#import <Cocoa/Cocoa.h>
+
+QPixmap pixmapForExtension(const QString &ext, const QSize &size)
+{
+    @autoreleasepool {
+        NSImage *image = [[NSWorkspace sharedWorkspace] iconForFileType:ext.toNSString()];
+        if (image) {
+            NSRect rect = NSMakeRect(0, 0, size.width(), size.height());
+            CGImageRef cgImage = [image CGImageForProposedRect:&rect context:nil hints:nil];
+            return QtMac::fromCGImageRef(cgImage);
+        }
+
+        return QPixmap();
+    }
+}
+
+void overrideDockClickHandler(bool (*dockClickHandler)(id, SEL, ...))
+{
+    NSApplication *appInst = [NSApplication sharedApplication];
+
+    if (!appInst)
+        return;
+
+    Class delClass = [[appInst delegate] class];
+    SEL shouldHandle = sel_registerName("applicationShouldHandleReopen:hasVisibleWindows:");
+
+    if (class_getInstanceMethod(delClass, shouldHandle)) {
+        if (class_replaceMethod(delClass, shouldHandle, (IMP)dockClickHandler, "B@:"))
+            qDebug("Registered dock click handler (replaced original method)");
+        else
+            qWarning("Failed to replace method for dock click handler");
+    }
+    else {
+        if (class_addMethod(delClass, shouldHandle, (IMP)dockClickHandler, "B@:"))
+            qDebug("Registered dock click handler");
+        else
+            qWarning("Failed to register dock click handler");
+    }
+}

src/gui/mainwindow.cpp

@@ -31,8 +31,6 @@
 #include "mainwindow.h"
 
 #ifdef Q_OS_MAC
-#include <objc/objc.h>
-#include <objc/message.h>
 #include <QtMacExtras>
 #include <QtMac>
 #endif
@@ -107,7 +105,11 @@
 #include "hidabletabwidget.h"
 #include "ui_mainwindow.h"
 
-#ifdef Q_OS_MAC
+#if defined (Q_OS_MAC)
+#include "macutilities.h"
+#endif
+
+#if defined (Q_OS_MAC)
 void qt_mac_set_dock_menu(QMenu *menu);
 #endif
 
@@ -1294,29 +1296,9 @@ static bool dockClickHandler(id self, SEL cmd, ...)
 }
 
 void MainWindow::setupDockClickHandler()
-{
-    Class cls = objc_getClass("NSApplication");
-    objc_object *appInst = objc_msgSend(reinterpret_cast<objc_object *>(cls), sel_registerName("sharedApplication"));
-
-    if (!appInst)
-        return;
-
+{    
     dockMainWindowHandle = this;
-    objc_object* delegate = objc_msgSend(appInst, sel_registerName("delegate"));
-    Class delClass = reinterpret_cast<Class>(objc_msgSend(delegate, sel_registerName("class")));
-    SEL shouldHandle = sel_registerName("applicationShouldHandleReopen:hasVisibleWindows:");
-    if (class_getInstanceMethod(delClass, shouldHandle)) {
-        if (class_replaceMethod(delClass, shouldHandle, reinterpret_cast<IMP>(dockClickHandler), "B@:"))
-            qDebug("Registered dock click handler (replaced original method)");
-        else
-            qWarning("Failed to replace method for dock click handler");
-    }
-    else {
-        if (class_addMethod(delClass, shouldHandle, reinterpret_cast<IMP>(dockClickHandler), "B@:"))
-            qDebug("Registered dock click handler");
-        else
-            qWarning("Failed to register dock click handler");
-    }
+    overrideDockClickHandler(dockClickHandler);
 }
 
 #endif

src/gui/torrentcontentmodel.cpp

@@ -32,14 +32,12 @@
 #include <QFileIconProvider>
 #include <QFileInfo>
 #include <QIcon>
+#include <QMap>
 
 #if defined(Q_OS_WIN)
 #include <Windows.h>
 #include <Shellapi.h>
 #include <QtWin>
-#elif defined(Q_OS_MAC) 
-#include <objc/objc.h>
-#include <objc/message.h>
 #else
 #include <QMimeDatabase>
 #include <QMimeType>
@@ -52,13 +50,8 @@
 #include "torrentcontentmodelitem.h"
 #include "torrentcontentmodelfolder.h"
 #include "torrentcontentmodelfile.h"
-
-#ifdef Q_OS_MAC
-struct NSImage;
-// This function is a private QtGui library export on macOS
-// See src/gui/painting/qcoregraphics_p.h for more details
-// QtMac::fromCGImageRef takes a CGImageRef and thus requires a double conversion
-QPixmap qt_mac_toQPixmap(const NSImage *image, const QSizeF &size);
+#if defined(Q_OS_MAC) 
+#include "macutilities.h"
 #endif
 
 namespace
@@ -113,31 +106,23 @@ namespace
         {
             const QString ext = info.suffix();
             if (!ext.isEmpty()) {
-                const QPixmap pixmap = pixmapForExtension(ext, QSize(32, 32));
-                if (!pixmap.isNull())
-                    return QIcon(pixmap);
+                auto cacheIter = m_iconCache.find(ext);
+
+                if (cacheIter != m_iconCache.end())
+                    return *cacheIter;
+
+                QIcon icon = QIcon(pixmapForExtension(ext, QSize(32, 32)));
+                if (!icon.isNull()) {
+                    m_iconCache.insert(ext, icon);
+                    return icon;
+                }
             }
 
             return UnifiedFileIconProvider::icon(info);
         }
 
     private:
-        QPixmap pixmapForExtension(const QString &ext, const QSize &size) const
-        {
-            QMacAutoReleasePool pool;
-            objc_object *woskspaceCls = reinterpret_cast<objc_object *>(objc_getClass("NSWorkspace"));
-            SEL sharedWorkspaceSel = sel_registerName("sharedWorkspace");
-            SEL iconForFileTypeSel = sel_registerName("iconForFileType:");
-
-            objc_object *sharedWorkspace = objc_msgSend(woskspaceCls, sharedWorkspaceSel);
-            if (sharedWorkspace) {
-                objc_object *image = objc_msgSend(sharedWorkspace, iconForFileTypeSel, ext.toNSString());
-                if (image)
-                    return qt_mac_toQPixmap(reinterpret_cast<NSImage *>(image), size);
-            }
-
-            return QPixmap();
-        }
+        mutable QMap<QString, QIcon> m_iconCache;
     };
 #else
     /**