边框中的黑边如何去掉，qt

Question

#include "PDFBrow.h"
#include <QGraphicsScene>
#include <QGraphicsPixmapItem>
#include <QGraphicsView>
#include <QLineF>
#include <QDebug>
PDFBrow::PDFBrow(QWidget *parent)
    : QWidget{parent}
{  //关闭在析构函数里呢
    FPDF_InitLibrary();
    setAttribute(Qt::WA_OpaquePaintEvent);
    setAttribute(Qt::WA_StaticContents);
    setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    m_scrollArea = new QScrollArea(this);
    m_scrollArea->setBackgroundRole(QPalette::Base);
    m_scrollArea->setAlignment(Qt::AlignCenter);
    m_scrollArea->setWidgetResizable(false);
    m_scrollArea->setFrameShape(QFrame::NoFrame);
    view = new QGraphicsView();
    view->setVerticalScrollBarPolicy(Qt::ScrollBarPolicy::ScrollBarAlwaysOn);
    view->setFrameShape(QFrame::NoFrame);
    view->setVerticalScrollBarPolicy(Qt::ScrollBarPolicy::ScrollBarAlwaysOff);
    view->setHorizontalScrollBarPolicy(Qt::ScrollBarPolicy::ScrollBarAlwaysOff);
    view->setSceneRect(0, 0, view->viewport()->width(), view->viewport()->height());
    view->setAlignment(Qt::AlignLeft | Qt::AlignTop);
    view->setFixedSize(this->parentWidget()->size());
    vScrollBar =  m_scrollArea->verticalScrollBar();
    hScrollBar =  m_scrollArea->horizontalScrollBar();
    scene =  new QGraphicsScene() ;
    m_scrollAreaContentLayout = new QVBoxLayout;
    m_scrollAreaContentLayout->addWidget(view);
    m_scrollAreaContentLayout->addStretch();
    layout_di = new QVBoxLayout;
    m_scrollArea->viewport()->setLayout(m_scrollAreaContentLayout);
    layout_di->addWidget(m_scrollArea);
    this->setLayout(layout_di);
    connect(vScrollBar, &QScrollBar::valueChanged, this, &PDFBrow::onScrollBarValueChanged);
    connect(hScrollBar, &QScrollBar::valueChanged, this, &PDFBrow::onScrollBarValueChanged);
    document = nullptr;
}

void PDFBrow::onScrollBarValueChanged(){
       redraw();
}


PDFBrow::~PDFBrow(){
    if(m_scrollArea)
       delete m_scrollArea;
    if(vScrollBar)
        delete vScrollBar;
    if(hScrollBar)
        delete hScrollBar;

    if(document)
        delete document;
    if(scene)
        delete scene;

    FPDF_DestroyLibrary();
}


void PDFBrow::resizeEvent(QResizeEvent *event){
    //在widget重新变更位置时改变scrollba
     QWidget::resizeEvent(event);

   //  this->view ->resize(this->size());

}
PDFDocument* PDFBrow::loadPDF(const QString& fileName){


    FPDF_DOCUMENT pdocument = FPDF_LoadDocument(fileName.toStdString().c_str(), nullptr);
    if (pdocument) {
        PDFDocument* document = new PDFDocument(pdocument);
        document->loadAllPage();
        this->document = document;
        int totalHeight = document->getTotalHeightInPixel();
        int maxWidth = document->getMaxWidthInPixel();
        vScrollBar->setSingleStep(20);
        vScrollBar->setPageStep(20);
        hScrollBar->setSingleStep(20);
        hScrollBar->setPageStep(20);
        vScrollBar->setVisible(true);
        hScrollBar->setVisible(true);
        vScrollBar->setRange(0, totalHeight - view->height());

        hScrollBar->setRange(0, maxWidth - view->width());


    };

    redraw();

    return  this->document;
}


void PDFBrow::redraw(){

            if (document == nullptr) {
                return;
            }


            // 获取widget大小
            int canvasWidth = view->width();
            int canvasHeight = this->view->viewport()->height();
            qDebug()<<"canvasHeight:"+QString::number(canvasHeight);

            int selection = vScrollBar->value();
            int hSelection = hScrollBar->value();

            QSize canvasSize = view->viewport()->size();
            //居中
            int beginX = 0;
            if (canvasSize.width() > document->getMaxWidthInPixel()) {
                beginX = (canvasSize.width() - document->getMaxWidthInPixel()) / 2;
            }

            // Draw PDF pages to QPixmap and show it on canvas


            QList<QGraphicsPixmapItem*> items;

            int pageAtY = selection;
            PDFPage *page = document->getPageAtPixel(pageAtY);
            //获取当前页是第几页
            int index = page->getIndex();
            //前几页的总长度
            int temp = 0;
            for(int i=0;i<index;i++){
                temp+=document->getAllPage()[i].getPageSizeInPixel(document->getFPdf_DOCUMENT())[1];
            }


            // 当前页应该在这个位置绘制
            int maginY = temp - selection;
            int paintedCount = 0;
            int drawY = maginY;
            PDFPage *currentPage = nullptr;

            while (paintedCount <=canvasHeight) {
                page = document->getPageAtPixel(pageAtY);

                if(page==nullptr)
                    break;

                if (currentPage == page) {
                    break;
                }

                currentPage = page;
                int pageWidth = currentPage->getPageSizeInPixel(this->document->getFPdf_DOCUMENT())[0];
                int pageHeight = currentPage->getPageSizeInPixel(this->document->getFPdf_DOCUMENT())[1];
                QGraphicsPixmapItem* item = new QGraphicsPixmapItem(currentPage->render(-hSelection + beginX, drawY, pageWidth, pageHeight, 0, 0));
                item->setPos(-hSelection + beginX, drawY+1);
                items.append(item);
                 drawY += pageHeight;
                // 已经绘制了这么多，离整个clientArea还有一段距离,不够的话接着取下一页
                 qDebug()<<"pageWidth:"+QString::number(pageWidth)+"pageInDex:"+QString::number(page->getIndex())+"本页pageAtY："+QString::number(pageAtY)+"pageHeight:"+QString::number(pageHeight)+"maginY:"+QString::number(maginY)+" selection:"+QString::number(selection);
                // 下一页的坐标(滚动条偏移+当前页大小+偏移），多一个像素去寻找下一页
                pageAtY += pageHeight  + 1;

                paintedCount = drawY ;
                // 下一页画的y坐标

            }

            scene->clear();
            foreach(QGraphicsPixmapItem* item, items) {

                scene->addItem(item);

            }
            view->setScene(scene);
}

Answer 1

在PDFBrow类的构造函数中添加以下代码试试

QPalette p = palette();
p.setColor(QPalette::Window, Qt::white);
setPalette(p);
setStyleSheet("PDFBrow { border-style: none; }");

将设置窗口背景为白色，并将边框样式设置为无。