c++ - QT如何实现自己的内存查看器

Question

最近我正在为我自己的硬件编写一个调试器。我想添加一个内存查看器小部件，如 eclipse 或 qt creator 或其他 IDE。但是，我不知道要使用哪种小部件。比如tableWidget，有没有设置成这样:

Answer 1

最好的选择是创建一个自定义小部件，因为该任务是私有(private)的，并且没有任何小部件适合该任务。

为此我们将从QAbstractScrollArea继承，从这个类继承QTableView、QListView、QListWidget和QTableWidget。它旨在显示 QScrollArea 内的数据。另外documentation这个类告诉我们如何创建自定义类。

When inheriting QAbstractScrollArea, you need to do the following:

• Control the scroll bars by setting their range, value, page step, andtracking their movements.
• Draw the contents of the area in theviewport according to the values of the scroll bars.
• Handle eventsreceived by the viewport in viewportEvent()
• notably resize events.Use viewport->update() to update the contents of the viewport insteadof update() as all painting operations take place on the viewport.

根据该引用，我创建了以下小部件:

内存查看器.h

#ifndef MEMORYVIEWER_H
#define MEMORYVIEWER_H

#include <QAbstractScrollArea>
#include <QBuffer>

class MemoryViewer : public QAbstractScrollArea
{
    Q_OBJECT
public:
    MemoryViewer(QWidget *parent = 0);
    ~MemoryViewer();

    void setData(const QByteArray &ba);
    bool setData(QIODevice &device);

protected:
    void paintEvent(QPaintEvent *);
    void resizeEvent(QResizeEvent *);

private:
    void adjustContent();
    void init();

    int addressWidth();
    int hexWidth();
    int asciiWidth();

    QByteArray data(qint64 pos=0, qint64 count=-1);

    int nBlockAddress;
    int mBytesPerLine;

    int pxWidth;
    int pxHeight;

    qint64 startPos;
    qint64 endPos;

    int nRowsVisible;

    QBuffer buffer;
    QIODevice *ioDevice;
    qint64 size;

    QByteArray dataVisible;
    QByteArray dataHex;
};

#endif // MEMORYVIEWER_H

内存查看器.cpp

#include "memoryviewer.h"

#include <QPainter>
#include <QScrollBar>

MemoryViewer::MemoryViewer(QWidget *parent):QAbstractScrollArea(parent)
{
    ioDevice = new QBuffer(this);
    init();
    connect(verticalScrollBar(), &QScrollBar::valueChanged, this, &MemoryViewer::adjustContent);
    connect(horizontalScrollBar(), &QScrollBar::valueChanged, this, &MemoryViewer::adjustContent);
}

MemoryViewer::~MemoryViewer()
{

}


void MemoryViewer::init()
{
    nBlockAddress = 2;
    mBytesPerLine = 16;

    pxWidth = fontMetrics().width(QChar('0'));
    pxHeight = fontMetrics().height();

}

int MemoryViewer::addressWidth()
{
    return  (nBlockAddress*4+ nBlockAddress -1)*pxWidth;
}

int MemoryViewer::hexWidth()
{
    return (mBytesPerLine*3+1)*pxWidth;
}

int MemoryViewer::asciiWidth()
{
    return (mBytesPerLine*2 +1)*pxWidth;
}

QByteArray MemoryViewer::data(qint64 pos, qint64 count)
{
    QByteArray buffer;

    if (pos >= size)
        return buffer;

    if (count < 0)
        count = size;
    else
        if ((pos + count) > size)
            count = size - pos;

    if(ioDevice->open(QIODevice::ReadOnly)){
        ioDevice->seek(pos);
        buffer = ioDevice->read(count);
        ioDevice->close();
    }
    return buffer;
}

void MemoryViewer::setData(const QByteArray &ba)
{
    buffer.setData(ba);
    setData(buffer);

}

bool MemoryViewer::setData(QIODevice &device)
{
    ioDevice = &device;
    bool ok = ioDevice->open(QIODevice::ReadOnly);
    if(ok){
        size = ioDevice->size();
        ioDevice->close();
    }
    else{
        QBuffer *buf = new QBuffer(this);
        ioDevice = buf;
    }
    init();
    adjustContent();
    return ok;
}

void MemoryViewer::resizeEvent(QResizeEvent *)
{
    adjustContent();
}


void MemoryViewer::paintEvent(QPaintEvent *)
{
    QPainter painter(viewport());

    int offsetX = horizontalScrollBar()->value();

    int y = pxHeight;
    QString address;

    painter.setPen(viewport()->palette().color(QPalette::WindowText));

    for(int row = 0; row <= dataVisible.size()/mBytesPerLine;  row++){
        QString str = QString("%1").arg(startPos + mBytesPerLine*row, nBlockAddress*4, 16, QChar('0')).toUpper();
        int i = 0;
        address = "";
        while(i < nBlockAddress){
            address += str.mid(i*4, 4) + ":";
            i++;
        }
        address.remove(address.size()-1, 1);

        painter.drawText(pxWidth/2 -offsetX , y, address);
        y+=pxHeight;
    }

    int x;
    int lx = addressWidth() +pxWidth;
    painter.drawLine(lx-offsetX, 0, lx-offsetX, height());
    lx += pxWidth/2;
    y = pxHeight;

    //hex data
    x = lx-offsetX+3*pxWidth;
    int w = 3*pxWidth;
    for(int col =0; col < mBytesPerLine/2; col++){
        painter.fillRect(x-pxWidth/2, 0, w, height(), viewport()->palette().color(QPalette::AlternateBase));
        x+= 6*pxWidth;
    }

    int bPos = 0;
    for(int row=0; row < nRowsVisible; row++){
        x = lx-offsetX;
        for(int col =0; (col < mBytesPerLine) && (bPos < dataHex.size()) ; col++){
            QString str = dataHex.mid(bPos*2,2).toUpper();
            painter.drawText(x, y, str);
            x += 3*pxWidth;
            bPos += 1;
        }
        y+= pxHeight;
    }

    lx = addressWidth() + hexWidth();
    painter.drawLine(lx-offsetX, 0, lx-offsetX, height());

    lx += pxWidth/2;

    bPos = 0;
    y = pxHeight ;
    int ch;
    for(int row=0; row < nRowsVisible; row++){
        x = lx-offsetX;
        for(int col =0; (col < mBytesPerLine) && (bPos < dataVisible.size()) ; col++){
            ch  = (uchar)dataVisible.at(bPos);
            if ( ch < 0x20 )
                ch = '.';
            painter.drawText(x, y, QChar(ch));
            x += 2*pxWidth;
            bPos += 1;
        }
        y+= pxHeight;
    }
}

void MemoryViewer::adjustContent()
{
    int w = addressWidth() + hexWidth() + asciiWidth();
    horizontalScrollBar()->setRange(0, w - viewport()->width());
    horizontalScrollBar()->setPageStep(viewport()->width());

    nRowsVisible = viewport()->height()/pxHeight;
    int val = verticalScrollBar()->value();
    startPos = (qint64)val*mBytesPerLine;
    endPos = startPos + nRowsVisible*mBytesPerLine -1;

    int lineCount = size/mBytesPerLine;
    verticalScrollBar()->setRange(0,  lineCount-nRowsVisible);
    verticalScrollBar()->setPageStep(nRowsVisible);

    if(endPos >= size){
        endPos = size-1;
    }
    dataVisible = data(startPos, endPos-startPos + mBytesPerLine +1);
    dataHex = dataVisible.toHex();
    viewport()->update();
}

该实现的一个优点是您不必直接加载所有字节，因为您可以传递一个继承自 QIODevice 的对象，例如 QFile 并读取通过消除内存开销，在 View 需要数据时调用数据。另外你可以传递一个QByteArray

在下面link你会找到一个例子