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我正在尝试编写一个对话框，允许用户从系统中找到的任何已安装的USB驱动器中进行选择。在Windows中，我可以通过调用GetLogicalDriveStrings和GetDriveType来手动获取这些信息，这样我就可以创建一个简单的列表。但用户还需要能够导航到任何一个USB驱动器，以选择写入文件的正确文件夹。我看了一下QFileSystemModel，但我没有看到如何限制（过滤）它只显示挂载的USB驱动器及其子文件夹/文件。有谁知道如何最好的使用Qt框架来完成这个想法吗？仅显示USB驱动器的QTreeView和QFileSystemModel
更新 - 24年12月3日：
docsteer，感谢您的建议。听起来像是正确的方式去与此。我实现了建议的更改，并且在运行应用程序的大部分时间里发生崩溃。它显示了C :,并等待了一段时间，然后崩溃了一个255的错误代码。我认为有些东西我没有正确地挂在这里，但还没有弄清楚。那些不会崩溃的时候，我仍然可以看到系统中可用驱动器的完整列表，包括我插入的两个USB，而不是仅仅看到USB。如果我更改了filesystemmodeldialog.cpp中的第42行，以便通过“dir”而不是“usbModel”，则不会发生崩溃。您或任何人都可以在这里看到可能导致崩溃的任何事情，以及为什么我创建的USBDriveFilterProxyModel能正确选择来自所有已安装驱动器的两个USB的任何原因无法用于过滤视图中的数据？我已经从我的小测试应用程序中提供了所有文件，包括从.ui文件生成的头文件，以便如果有人想运行它来查看发生了什么，他们可以。
main.cpp中：
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
mainwindow.cpp：
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
class FileSystemModelDialog;
class QFileSystemModel;
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
void detectUsb();
private:
Ui::MainWindow *ui;
FileSystemModelDialog *treeView;
QFileSystemModel *fileSystemModel;
};
#endif // MAINWINDOW_H
mainwindow.cpp：
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "filesystemmodeldialog.h"
#include <QFileSystemModel>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
treeView = new FileSystemModelDialog(this);
setCentralWidget(treeView);
fileSystemModel = new QFileSystemModel;
}
MainWindow::~MainWindow()
{
delete ui;
}
filesystemmodeldialog.h：
#ifndef FILESYSTEMMODELDIALOG_H
#define FILESYSTEMMODELDIALOG_H
#include "ui_filesystemmodelwidget.h"
#include <QWidget>
#include <QFileSystemModel>
#include <QItemDelegate>
class USBDriveFilterProxyModel;
class IconItemDelegate : public QItemDelegate
{
public:
IconItemDelegate();
QSize sizeHint (const QStyleOptionViewItem & option, const QModelIndex & index) const;
};
class IconFileSystemModel : public QFileSystemModel
{
Q_OBJECT
public:
virtual QVariant data (const QModelIndex & index, int role = Qt::DisplayRole) const;
};
class FileSystemModelDialog : public QWidget
{
Q_OBJECT
public:
explicit FileSystemModelDialog(QWidget *parent);
~FileSystemModelDialog();
private:
Ui::FileSystemModelWidget *ui;
IconFileSystemModel *dir;
USBDriveFilterProxyModel *usbModel;
Q_SIGNALS:
void signalFileSelected(QString);
};
#endif // FILESYSTEMMODELDIALOG_H
filesystemmodeldialog.cpp：
#include "filesystemmodeldialog.h"
#include "usbdrivefilter.h"
IconItemDelegate::IconItemDelegate(){}
QSize IconItemDelegate::sizeHint (const QStyleOptionViewItem & /*option*/, const QModelIndex & index) const
{
const QFileSystemModel *model = reinterpret_cast<const QFileSystemModel *>(index.model());
QFileInfo info = model->fileInfo(index);
if(info.isDir())
{
return QSize(40,40);
}
else
{
return QSize(64,64);
}
}
QVariant IconFileSystemModel::data (const QModelIndex & index, int role) const
{
// will do more, but for now, just paints to view
return QFileSystemModel::data(index, role);
}
FileSystemModelDialog::FileSystemModelDialog(QWidget *parent) :
QWidget(parent),
ui(new Ui::FileSystemModelWidget)
{
ui->setupUi(this);
dir = new IconFileSystemModel();
dir->setRootPath("\\");
dir->setFilter(QDir::AllDirs | QDir::NoDotAndDotDot);
usbModel = new USBDriveFilterProxyModel(this);
usbModel->setSourceModel(dir);
usbModel->setDynamicSortFilter(true);
IconItemDelegate *iconItemDelegate = new IconItemDelegate();
ui->treeView->setModel(usbModel);
// hide unneeded hierachy info columns
ui->treeView->hideColumn(1);
ui->treeView->hideColumn(2);
ui->treeView->hideColumn(3);
ui->treeView->setItemDelegate(iconItemDelegate);
}
FileSystemModelDialog::~FileSystemModelDialog()
{
delete dir;
}
usbdrivefilter.h：
#ifndef USBDRIVEFILTER_H
#define USBDRIVEFILTER_H
#include <QSortFilterProxyModel>
#include <QModelIndex>
#include <QString>
class USBDriveFilterProxyModel : public QSortFilterProxyModel
{
Q_OBJECT
public:
explicit USBDriveFilterProxyModel(QObject *parent = 0);
protected:
virtual bool filterAcceptsRow(
int source_row, const QModelIndex &source_parent) const;
private:
void getMountedRemovables();
private:
QList<QString> removables;
};
#endif // USBDRIVEFILTER_H
usbdrivefilter.cpp：
#include "usbdrivefilter.h"
#include <windows.h>
USBDriveFilterProxyModel::USBDriveFilterProxyModel(QObject *parent) :
QSortFilterProxyModel(parent)
{
getMountedRemovables();
// will eventually also register for changes to mounted removables
// but need to get passed my current issue of not displaying only USBs.
}
bool USBDriveFilterProxyModel::filterAcceptsRow(int sourceRow,
const QModelIndex &sourceParent) const
{
QModelIndex index0 = sourceModel()->index(sourceRow, 0, sourceParent);
// Since drive string can have more than just "<DriveLetter>:", need
// to check each entry in the usb list for whether it is contained in
// the current drive string.
for (int i = 0; i < removables.size(); i++)
{
if (sourceModel()->data(index0).toString().contains(removables[i]))
{
return true;
}
}
return false;
}
void USBDriveFilterProxyModel::getMountedRemovables()
{
DWORD test = GetLogicalDrives();
DWORD mask = 1;
UINT type = 0;
WCHAR wdrive[] = L"C:\\"; // use as a drive letter template
for (int i = 0; i < 32; i++)
{
if (test & mask)
{
wdrive[0] = (char)('A' + i); // change letter in template
type = GetDriveType(wdrive);
switch (type) {
case DRIVE_REMOVABLE:
{
QString qdrive = QString((char)('A' + i)) + ":";
removables.append(qdrive);
break;
}
default: break;
}
}
mask = mask << 1;
}
}
ui_filesystemmodelwidget.h：
#ifndef UI_FILESYSTEMMODELWIDGET_H
#define UI_FILESYSTEMMODELWIDGET_H
#include <QtWidgets/QApplication>
#include <QtWidgets/QHeaderView>
#include <QtWidgets/QTreeView>
QT_BEGIN_NAMESPACE
class Ui_FileSystemModelWidget
{
public:
QTreeView *treeView;
void setupUi(QWidget *FileSystemModelWidget)
{
if (FileSystemModelWidget->objectName().isEmpty())
FileSystemModelWidget->setObjectName(QStringLiteral("FileSystemModelWidget"));
FileSystemModelWidget->resize(670, 755);
treeView = new QTreeView(FileSystemModelWidget);
treeView->setGeometry(QRect(0, 0, 670, 531));
treeView->setObjectName(QStringLiteral("treeView"));
treeView->setAutoFillBackground(true);
treeView->setStyleSheet(QLatin1String(" QScrollBar:vertical {\n"
" width: 61px;\n"
" background-color: rgb(227, 227, 227);\n"
" }\n"
" QScrollBar::handle:vertical {\n"
" min-height: 50px;\n"
" }\n"
"\n"
"QTreeView, QListView {\n"
" alternate-background-color: rgb(226, 226, 226);\n"
" font-size: 16px;\n"
" show-decoration-selected: 1;\n"
" }\n"
"\n"
" QTreeView::item, QListView::item {\n"
" height: 22px;\n"
" border: 1px solid transparent;\n"
" border-top-color: transparent;\n"
" border-bottom-color: transparent;\n"
" }\n"
"\n"
" QTreeView::item:selected, QListView::item::selected {\n"
" border: 1px solid #567dbc;\n"
" background-color: rgb(85, 170, 255);\n"
" }\n"
"\n"
"\n"
" QTreeView::branch:has-siblings:!adjoins-item {\n"
" border-image: url(:/new/prefix1/images/vline.png) 0;\n"
" }\n"
"\n"
" QTreeView::branch:has-siblings:adjoins-item {\n"
" border-image: url(:/new/prefix1/images/branch-more.png) 0;\n"
" }\n"
"\n"
" QTreeView::branch:!has-children:!has-siblings:adjoins-item {\n"
" border-image: url"
"(:/new/prefix1/images/branch-end.png) 0;\n"
" }\n"
"\n"
" QTreeView::branch:has-children:!has-siblings:closed,\n"
" QTreeView::branch:closed:has-children:has-siblings {\n"
" border-image: none;\n"
" image: url(:/new/prefix1/images/branch-closed.png);\n"
" }\n"
"\n"
" QTreeView::branch:open:has-children:!has-siblings,\n"
" QTreeView::branch:open:has-children:has-siblings {\n"
" border-image: none;\n"
" image: url(:/new/prefix1/images/branch-open.png);\n"
" }\n"
""));
treeView->setFrameShape(QFrame::Box);
treeView->setFrameShadow(QFrame::Plain);
treeView->setHorizontalScrollMode(QAbstractItemView::ScrollPerItem);
treeView->setExpandsOnDoubleClick(true);
treeView->header()->setVisible(false);
treeView->header()->setStretchLastSection(true);
retranslateUi(FileSystemModelWidget);
QMetaObject::connectSlotsByName(FileSystemModelWidget);
} // setupUi
void retranslateUi(QWidget *FileSystemModelWidget)
{
FileSystemModelWidget->setWindowTitle(QApplication::translate("FileSystemModelWidget", "Form", 0));
} // retranslateUi
};
namespace Ui {
class FileSystemModelWidget: public Ui_FileSystemModelWidget {};
} // namespace Ui
QT_END_NAMESPACE
#endif // UI_FILESYSTEMMODELWIDGET_H
更新 - 24年12月4日：
所以我发现，坠机发生在IconItemDelegate :: sizeHint（），在filesystemusbmodeldialog.cpp文件。运行到达第9行：
QFileInfo info = model->fileInfo(index);
并且在该点处逐步提供访问冲突。我认为这是因为我使用USBDriveFilterProxyModel替换了FileFileSystemUsbModel对象作为FileSystemUsbModelDialog构造函数中的QTreeView模型。因此，我假定在IconItemDelegate :: sizeHint（）中投射index.model（）是不正确的强制转换，现在我需要在调用fileInfo（）之前获取原始源模型。所以我改变sizeHint（）超载为以下内容：
QSize IconItemUsbDelegate::sizeHint (const QStyleOptionViewItem & /*option*/, const QModelIndex & index) const
{
const USBDriveFilterProxyModel *model = reinterpret_cast<const USBDriveFilterProxyModel *>(index.model());
const QFileSystemModel *fsmodel = reinterpret_cast<const QFileSystemModel *>(model->sourceModel());
QFileInfo info = fsmodel->fileInfo(index);
if(info.isDir())
{
return QSize(40,40);
}
else
{
return QSize(64,64);
}
}
但是，这并没有奏效。后来我发现，似乎在说我需要调用setRootIndex（）在我看来，现在的代理到位模型的链接，所以我补充说，在我的FileSystemUsbModelDialog构造函数现在看起来是这样的：
FileSystemUsbModelDialog::FileSystemUsbModelDialog(QWidget *parent) :
QWidget(parent),
ui(new Ui::FileSystemUsbModelWidget)
{
ui->setupUi(this);
dir = new IconFileSystemUsbModel();
dir->setRootPath("\\");
dir->setFilter(QDir::AllDirs | QDir::NoDotAndDotDot);
usbModel = new USBDriveFilterProxyModel(this);
usbModel->setSourceModel(dir);
usbModel->setDynamicSortFilter(false);
IconItemUsbDelegate *iconItemDelegate = new IconItemUsbDelegate();
ui->treeView->setModel(usbModel);
ui->treeView->setRootIndex(usbModel->mapFromSource(dir->setRootPath("\\")));
// hide unneeded hierachy info columns
ui->treeView->hideColumn(1);
ui->treeView->hideColumn(2);
ui->treeView->hideColumn(3);
ui->treeView->setItemDelegate(iconItemDelegate);
}
这没有奏效。我回到我的IconItemUsbDelegate :: sizeHint（）并将其改回，认为可能在视图上设置根目录是我真正需要做的，而且没有运气。
有什么想法？