QChart画大量横向叠加柱状图时，颜色变为白色

Question

QChart画大量横向叠加柱状图时，颜色变为白色
使用QChart画柱状图，大约1000根，展示时，柱子都变成了白色，如何解决。
参考图如下：

QColor GREEN = QColor(0, 230, 0);
QColor RED = QColor(255, 50, 50);

// 创建一个颜色轴对象
QColorAxis *axis = new QColorAxis;

QVector<QColor> colors;
colors << RED << GREEN;

set0->setBrush(QBrush(GREEN, Qt::SolidPattern));
set1->setBrush(QBrush(RED, Qt::SolidPattern));

QHorizontalStackedBarSeries *series = new QHorizontalStackedBarSeries();

for(int i=0; i < 1000; i++) {
    *set0 << 1 + QRandomGenerator::global()->bounded(4.1);
    *set1 << 2+ QRandomGenerator::global()->bounded(1.1);
}


series->append(set0);
series->append(set1);

series->setUseOpenGL(true);

connect(series, SIGNAL(hovered(bool, int, QBarSet*)), this, SLOT(sltTooltip(bool, int, QBarSet*)));

QChart *chart = new QChart();

chart->addSeries(series);
chart->setTitle("Simple horizontal stacked barchart example");
chart->setAnimationOptions(QChart::SeriesAnimations);
chart->setBackgroundBrush(QBrush(QColor(0, 0, 0)));

QStringList categories;
for(int i=0; i< 1000; i++) {
    categories << "Jane" + QString::number(i);
}

QBarCategoryAxis *axisY = new QBarCategoryAxis();
axisY->append(categories);
chart->addAxis(axisY, Qt::AlignLeft);
series->attachAxis(axisY);
QValueAxis *axisX = new QValueAxis();

chart->addAxis(axisX, Qt::AlignBottom);
series->attachAxis(axisX);

chart->legend()->setVisible(true);
chart->legend()->setAlignment(Qt::AlignBottom);

QChartView *chartView = new QChartView(chart);
chartView->setRenderHint(QPainter::Antialiasing);
chartView->setStyleSheet("background-color:black");

问题已解决，代码如下：

QColor GREEN = QColor(0, 230, 0);
QColor RED = QColor(255, 50, 50);

QHorizontalStackedBarSeries *series = new QHorizontalStackedBarSeries();
series->setBarWidth(0.5);

for(int i=0; i < 1000; i++) {
    *set0 << 1 + QRandomGenerator::global()->bounded(4.1);
    *set1 << 2+ QRandomGenerator::global()->bounded(1.1);
}

series->append(set0);
series->append(set1);

set0->setColor(GREEN);
set1->setColor(RED);
set0->setBorderColor(GREEN);
set1->setBorderColor(RED);


series->setUseOpenGL(true);

connect(series, SIGNAL(hovered(bool, int, QBarSet*)), this, SLOT(sltTooltip(bool, int, QBarSet*)));

QChart *chart = new QChart();

chart->addSeries(series);
chart->setTitle("Simple horizontal stacked barchart example");
chart->setAnimationOptions(QChart::SeriesAnimations);

QStringList categories;
for(int i=0; i< 1000; i++) {
    categories << "Jane" + QString::number(i);
}

QBarCategoryAxis *axisY = new QBarCategoryAxis();
axisY->append(categories);
chart->addAxis(axisY, Qt::AlignLeft);
series->attachAxis(axisY);
QValueAxis *axisX = new QValueAxis();

chart->addAxis(axisX, Qt::AlignBottom);
series->attachAxis(axisX);

chart->legend()->setVisible(true);
chart->legend()->setAlignment(Qt::AlignBottom);


QChartView *chartView = new QChartView(chart);
chartView->setRenderHint(QPainter::Antialiasing);
chartView->setStyleSheet("background-color:black");

Answer 1

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首先，在构建柱状图时，可以通过设置柱子的宽度和颜色来控制其大小。当使用QCHART绘制柱状图时，通常需要在PLOTLEGEND方法中指定柱子的样式（如QPLOTITEM::MARKERSTYLE），以确定柱子的大小。如果希望所有柱子都被填充为白色，可以尝试以下步骤：

1. 在绘图区域中添加一个矩形作为背景。
2. 设置PLOTLEGEND方法中的MARKERSTYLE属性，使其为QLINESYMBOL。
3. 使用SETPEN()方法设置柱子的颜色，使其变为白色。

QCHART CHART;
// 建立绘图区域
CHART.ADDSERIES("SERIES");

// 创建柱状图
CONST INT NUMPOINTS = 1000; // 柱子数量
QPOINT P(NUMPOINTS * 2, 5); // 初始点位置
QPAINTER PAINTER(&CHART);
PAINTER.SETPEN(QT::BLACK);

// 绘制柱状图
FOR (INT I = 0; I < NUMPOINTS; ++I) {
    CONST DOUBLE X = P.X() + I / NUMPOINTS * (P.WIDTH() - 2);
    CONST DOUBLE Y = P.Y() + I / NUMPOINTS * (P.HEIGHT() - 2);
    QLINEF LINE(X, Y, X, Y + 4);
    PAINTER.DRAWELLIPSE(LINE);
}

// 显示柱状图
CHART.PLOTLEGEND(QCHART::BOTTOMLEFTCORNER);
CHART.SHOW();

这段代码将创建一个1000个柱状图，并将其填充为白色，从而使所有柱子都被覆盖。