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僅顯示USB驅動器的QTreeView和QFileSystemModel

2014-12-02 106 views
0

我正在嘗試編寫一個對話框，允許用戶從系統中找到的任何已安裝的USB驅動器中進行選擇。在Windows中，我可以通過調用GetLogicalDriveStrings和GetDriveType來手動獲取這些信息，這樣我就可以創建一個簡單的列表。但用戶還需要能夠導航到任何一個USB驅動器，以選擇寫入文件的正確文件夾。我看了一下QFileSystemModel，但我沒有看到如何限制（過濾）它只顯示掛載的USB驅動器及其子文件夾/文件。有誰知道如何最好的使用Qt框架來完成這個想法嗎？僅顯示USB驅動器的QTreeView和QFileSystemModel

更新 - 24年12月3日：

docsteer，感謝您的建議。聽起來像是正確的方式去與此。我實現了建議的更改，並且在運行應用程序的大部分時間裏發生崩潰。它顯示了C :,並等待了一段時間，然後崩潰了一個255的錯誤代碼。我認爲有些東西我沒有正確地掛在這裏，但還沒有弄清楚。那些不會崩潰的時候，我仍然可以看到系統中可用驅動器的完整列表，包括我插入的兩個USB，而不是僅僅看到USB。如果我更改了filesystemmodeldialog.cpp中的第42行，以便通過「dir」而不是「usbModel」，則不會發生崩潰。您或任何人都可以在這裏看到可能導致崩潰的任何事情，以及爲什麼我創建的USBDriveFilterProxyModel能正確選擇來自所有已安裝驅動器的兩個USB的任何原因無法用於過濾視圖中的數據？我已經從我的小測試應用程序中提供了所有文件，包括從.ui文件生成的頭文件，以便如果有人想運行它來查看發生了什麼，他們可以。

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：

所以我發現，墜機發生在IconItemDelegate :: sizeHint（），在filesystemusbmodeldialog.cpp文件。運行到達第9行：

QFileInfo info = model->fileInfo(index);

並且在該點處逐步提供訪問衝突。我認爲這是因爲我使用USBDriveFilterProxyModel替換了FileFileSystemUsbModel對象作爲FileSystemUsbModelDialog構造函數中的QTreeView模型。因此，我假定在IconItemDelegate :: sizeHint（）中投射index.model（）是不正確的強制轉換，現在我需要在調用fileInfo（）之前獲取原始源模型。所以我改變sizeHint（）超載爲以下內容：

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，這並沒有奏效。後來我發現，似乎在說我需要調用setRootIndex（）在我看來，現在的代理到位模型的鏈接，所以我補充說，在我的FileSystemUsbModelDialog構造函數現在看起來是這樣的：

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); 
}

這沒有奏效。我回到我的IconItemUsbDelegate :: sizeHint（）並將其改回，認爲可能在視圖上設置根目錄是我真正需要做的，而且沒有運氣。

有什麼想法？

來源

2014-12-02 bmahf

回答

0

所以docsteer讓我在正確的軌道上，正如我在更新中所說的那樣，但正如我之前所說的，當我進入我的item委託的sizeHint（）方法時我崩潰了。每別人的建議，我把一些調試語句，找出哪些指數錄如下：

qDebug() << index.isValid(); 
qDebug() << "text = " << index.data(); 
qDebug() << "Row = " << index.row() << "Column = " << index.column();

，我發現該指數的內容是具體到我期望的代理模型遏制，而不是文件系統模型。仔細一看，我意識到我已經將與代理模型相關聯的索引傳遞給文件系統模型的castInfo（）方法。我改變了它，如下所示，以便我首先將索引的模型轉換爲代理模型類型的指針，然後從中獲取源（文件系統）模型指針並調用它的fileInfo（）方法。但現在我首先映射索引源索引和我是映射的結果傳遞到文件系統模型的fileInfo（）方法，它現在就像一個魅力：

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); 
}

感謝您的幫助。

來源

2014-12-10 13:46:10 bmahf

1

我會建議用QSortFilterProxyModel做這個。一個例子可能看起來像

.header

class USBDriveFilter : public QSortFilterProxyModel 
{ 
    Q_OBJECT; 
public: 
    USBDriveFilter(QObject *parent = 0); 
protected: 
    // Reimplemented from QSortFilterProxyModel 
    virtual bool filterAcceptsRow (int source_row, const QModelIndex & source_parent) const; 
};

的.cpp

bool USBDriveFilter::filterAcceptsRow(int sourceRow, 
     const QModelIndex &sourceParent) const 
{ 
    QModelIndex index0 = sourceModel()->index(sourceRow, 0, sourceParent); 
    // This is a naive example and just doesn't accept the drive if the name 
    // of the root node contains C: - you should extend it to check the letter 
    // against your known list of USB drives derived from the windows API 
    return (!sourceModel()->data(index0).toString().contains("C:")); 
}

要使用這個，你會做這樣的事情

QFileSystemModel *m = new QFileSystemModel(this); 
USBDriveFilter *filter = new USBDriveFilter(this); 
filter->setSourceModel(m); 
// Now use filter as your model to pass into your tree view.

來源

2014-12-02 22:20:46 docsteer

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