From Gossip@caterpillar

Qt3 Gossip: QCheckListItem 類別

QCheckListItem類別是QListViewItem的子類別，它可以顯示三種不同的Item，如下所示：
QCheckListItem::RadioButton
QCheckListItem::CheckBox
QCheckListItem::Controller

其中RadioButton的父節點必須是一個Controller，否則RadioButton的互斥效果就會失效。

下面這個程式綜合QListView、QListViewItem與QCheckListItem來展示，並示範如何在按下某個項目後，更換Item的資料夾圖示。

首先請編輯checklists.h：
  • checkists.h
#ifndef QCHECK_LIST
#define QCHECK_LIST

#include <qlistview.h>
#include <qpixmap.h>

class ListView : public QListView {
    Q_OBJECT

public:
    ListView();

protected:
    QListViewItem *folder, *subfolder;
    QPixmap close, open;
    bool subfolderOn;

protected slots:
    void clicked1(QListViewItem*);
    void clicked2(QListViewItem*);
};

#endif


然後是checklists.cpp：
  • checklists.cpp
#include "checklists.h"
#include <qiconset.h>

ListView::ListView()
        : close("folder.xpm"), open("folder_open.xpm") {
    QCheckListItem *chklistitem1, *chklistitem2;

    setCaption("QListView");
    addColumn(QIconSet(close), "Folders");
    addColumn("Type");
    setColumnWidth(0, 230);

    folder = new QListViewItem(this, " parent folder", "QListViewItem");
    folder->setPixmap(0, open);
    folder->setOpen(true);

    subfolder = new QListViewItem(folder, " subfolder", "QListViewItem");
    subfolder->setPixmap(0, close);
    subfolderOn = false;

    chklistitem1 = new QCheckListItem(folder,
                       "click me", QCheckListItem::CheckBox);
    chklistitem1->setText(1, "Check Box");

    chklistitem1 = new QCheckListItem(folder, "child");
    chklistitem1->setText(1, "Controller");
    chklistitem1->setOpen(true);

    chklistitem2 = new QCheckListItem(chklistitem1,
                       "grand child 1", QCheckListItem::RadioButton);
    chklistitem2->setText(1, "Radio Button");
    chklistitem2 = new QCheckListItem(chklistitem1,
                       "grand child 2", QCheckListItem::RadioButton);
    chklistitem2->setText(1, "Radio Button");
   
    setTreeStepSize(30); // 與父節點的距離，default是20pixel
    setSorting(0, false);
    sort();

    connect(this, SIGNAL(clicked(QListViewItem*)),
            this, SLOT(clicked1(QListViewItem*)));
    connect(this, SIGNAL(doubleClicked(QListViewItem*)),
            this, SLOT(clicked2(QListViewItem*)));
}

void ListView::clicked1(QListViewItem *item) {
    if(item == subfolder) {
        subfolderOn = !subfolderOn;
        item->setPixmap(0, subfolderOn ? open : close );
    }
}

void ListView::clicked2(QListViewItem *item) {
    if(item == folder)
        item->setPixmap(0, item->isOpen() ? open : close);
}

最後是main.cpp：
  • main.cpp
#include "checklists.h"
#include <qapplication.h>

int main(int argc, char **argv) {
    QApplication app(argc, argv);

    ListView *piv = new ListView();
    app.setMainWidget(piv);
    piv->show();

    return app.exec();
}


基本上這個程式在邏輯與配置上並不難，主要在於判斷發生Signals時，是哪一個Item發出的就可以了，這使用if(item == subfolder)或if(item == folder)來判斷。

以下是程式的執行結果畫面：