c – 使用QGraphicsView时窗口小部件背景不透明但使用QGridLayout时透明

当我使用QGridLayout显示我的小部件时,只显示了小部件,并且未显示透明的图像部分.现在我切换到使用QGraphicsScene和QGraphicsView,现在我的图像在任何地方都是透明的灰色背景.

void Piece::paintEvent(QPaintEvent *)
{
    string image = ":/images/" + color + piece + ".png";
    pixmap.load(image.c_str());
    //pixmap.setMask(pixmap.createMaskFromColor(QColor(240, 240, 240)));

    QPainter paint(this);
    paint.drawPixmap(0, 0, pixmap);
} 

这就是图像在我的小部件上的显示方式.当我使用代码时,

layout->addWidget(0,0,1,1);

背景是透明的.但是当我用的时候,

scene->addWidget(piece);

小部件具有灰色背景.我怎样才能让它透明？如有必要,可在此处找到完整代码(可能不需要)：https://github.com/gsingh93/Chess

编辑：我根本无法解决这个问题…我尝试使用setAutoFillBackground(false);但那没用.所以我最后的希望是将我的全班从QWidget转换为QGrahhicsItem.这不起作用,图像的背景仍然是灰色而不是透明.如果您无法弄清楚此代码有什么问题,有人可以发布或链接我的示例如何使用QGraphicsScene显示具有透明背景的图像？这是原始代码,后跟QGraphicsItem代码,后跟我的main函数.

#include "headers/piece.h"
#include <QPainter>
#include <QMouseEvent>
#include <QBitmap>
#include <QCursor>
using namespace std;

Piece::Piece(string color, string piece, QWidget *parent) :
    QWidget(parent)
{
    this->piece = piece;
    this->color = color;
    this->setMaximumHeight(36);
    this->setMaximumWidth(36);
    x = 0;
    y = 0;
    setMouseTracking(false);
}

void Piece::paintEvent(QPaintEvent *)
{
    string image = ":/images/" + color + piece + ".png";
    pixmap.load(image.c_str());
    //pixmap.setMask(pixmap.createMaskFromColor(QColor(240, 240, 240)));

    QPainter paint(this);
    paint.drawPixmap(0, 0, pixmap);
}

void Piece::setPosition(int file, int rank)
{
    pixmap.load(":/images/whitepawn.png");
    QImage image = pixmap.toImage();
    x = (file-1)*50 + 18;// - image.width()/2;
    y = (rank-1)*50 + 18;// - image.height()/2;
    move(x, y);
}

void Piece::mouseMoveEvent(QMouseEvent *event)
{
    if(event->buttons() == Qt::LeftButton)
    {
    x = event->globalX()-18;
    y = event->globalY()-18;
    move(x,y);
    }
}

.

#include "piece2.h"
#include <QPainter>
#include <QMouseEvent>
#include <QBitmap>
#include <QCursor>
#include <QGraphicsSceneMouseEvent>
using namespace std;

Piece2::Piece2(string color, string piece, QObject *parent) :
    QGraphicsItem()
{
    this->piece = piece;
    this->color = color;
    //this->setMaximumHeight(36);
    //this->setMaximumWidth(36);
    x = 0;
    y = 0;
    //setMouseTracking(false);
}

void Piece2::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    string image = ":/images/" + color + piece + ".png";
    pixmap.load(image.c_str());
    //pixmap.setMask(pixmap.createMaskFromColor(QColor(240, 240, 240)));

    //QPainter paint(this);
    painter->drawPixmap(0, 0, pixmap);
}

void Piece2::setPosition(int file, int rank)
{
    pixmap.load(":/images/whitepawn.png");
    QImage image = pixmap.toImage();
    x = (file-1)*50 + 18;// - image.width()/2;
    y = (rank-1)*50 + 18;// - image.height()/2;
    setPos(x, y);
}

void Piece2::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
    if(event->buttons() == Qt::LeftButton)
    {
//  x = event->globalX()-18;
//  y = event->globalY()-18;
    setPos(x,y);
    }
}

.

#include <QtGui>
#include <QGraphicsScene>
#include <QGraphicsView>
#include "headers/board.h"
#include "headers/pawn.h"
#include "headers/knight.h"
#include "headers/bishop.h"
#include "headers/rook.h"
#include "headers/king.h"
#include "headers/queen.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QGraphicsScene *scene = new QGraphicsScene();
    QGraphicsView *view = new QGraphicsView();
    Board board;

    scene->addWidget(&board);
    scene->addWidget(board.pawn2);
    board.pawn2->setPosition(1,1);

    //view->viewport()->setPalette(QColor(Qt::transparent));
    //view->viewport()->setAutoFillBackground(false);
    view->setScene(scene);
    //view->setBackgroundRole(QPalette::NoRole);
    view->show();
    return app.exec();
}

解决方法:

您是否尝试使用样式表来设置背景透明度？

yourWidget->setStyleSheet("background-color: transparent;");

标签：qgraphicsview,c,qt,qt4,qt4-7
来源： https://codeday.me/bug/20190723/1515231.html