＜QT基础(4)＞QLabel使用笔记

Label

前面的文章里面把QLabel批量引入ScrollArea作为预览窗口，这篇把图像填充到QLable的PixelMap展示指定图像。

参数设置

设置QLabel的大小格式

 QWidget* widget = new QWidget;
widget->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
widget->setMinimumSize(QSize(210, 210));QString msg = "Label_" + QString::number(i);
QLabel* label = new QLabel(msg);
label->setGeometry(QRect(0, 0, widget->width(), widget->height()));//全屏铺满
label->setMinimumSize(QSize(200, 200));
label->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);

PixelMap填充

重点是PixelMap的填充，所以这里像素值以渐变对象填充了。

// 创建一个渐变对象，并设置渐变色
QLinearGradient gradient(0, 0, 200, 0); // 从左到右的线性渐变
gradient.setColorAt(0, Qt::red);
gradient.setColorAt(0.5, Qt::green);
gradient.setColorAt(1, Qt::blue);// 创建一个QPixmap，并使用渐变填充
QPixmap pixmap(200, 200);
pixmap.fill(Qt::transparent); // 填充透明背景
QPainter painter(&pixmap);
painter.fillRect(pixmap.rect(), gradient);label->setPixmap(pixmap);

CV::Mat 到PixelMap填充

这里没有写cv::Mat到PixelMap的映射，因为重点是PixelMap的功能展示，以下是一个Mat到PixelMap对照的例子。

cv::Mat image = cv::imread("1.jpg"); // 替换为您的图像路径
QImage qimage(image.data, image.cols, image.rows, image.step, QImage::Format_RGB888);
qimage = qimage.rgbSwapped();
QSize targetSize(200, 200);
qimage = qimage.scaled(targetSize, Qt::KeepAspectRatio);
QPixmap pixmap = QPixmap::fromImage(qimage);
label->setPixmap(pixmap);

总体代码及效果

#pragma once#include <QtWidgets/QMainWindow>
#include <QtWidgets>
#include "ui_dcmimgpro.h"class DcmImgPro : public QMainWindow
{Q_OBJECTpublic:DcmImgPro(QWidget *parent = nullptr);~DcmImgPro();private:Ui::DcmImgProClass ui;
private slots:void pushbtn();void lineEditset();
private:int l_num = 15;
};class ScrollableWidget:public QWidget
{
public:ScrollableWidget(int numWidgets){QVBoxLayout* layout = new QVBoxLayout(this);for (int i = 0; i < numWidgets; i++){QWidget* widget = new QWidget;widget->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);widget->setMinimumSize(QSize(210, 210));QString msg = "Label_" + QString::number(i);QLabel* label = new QLabel(msg);label->setGeometry(QRect(0, 0, widget->width(), widget->height()));//全屏铺满label->setMinimumSize(QSize(200, 200));label->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);// 创建一个渐变对象，并设置渐变色QLinearGradient gradient(0, 0, 200, 0); // 从左到右的线性渐变gradient.setColorAt(0, Qt::red);gradient.setColorAt(0.5, Qt::green);gradient.setColorAt(1, Qt::blue);// 创建一个QPixmap，并使用渐变填充QPixmap pixmap(200, 200);pixmap.fill(Qt::transparent); // 填充透明背景QPainter painter(&pixmap);painter.fillRect(pixmap.rect(), gradient);label->setPixmap(pixmap);QVBoxLayout* widgetlayout = new QVBoxLayout(widget);widgetlayout->addWidget(label);layout->addWidget(widget);}};};

#include "dcmimgpro.h"DcmImgPro::DcmImgPro(QWidget *parent): QMainWindow(parent)
{ui.setupUi(this);ui.scrollArea->setWidgetResizable(true);ScrollableWidget* scrollableWidget = new  ScrollableWidget(l_num);ui.scrollArea->setWidget(scrollableWidget);ui.lineEdit->setText(QString::number(l_num));connect(ui.pushButton, SIGNAL(clicked()), this, SLOT(pushbtn()));connect(ui.lineEdit, SIGNAL(editingFinished()), this, SLOT(lineEditset()));//textChanged   cursorPositionChanged//editingFinished  selectionChanged returnPressed() 
}void DcmImgPro::pushbtn()
{ui.scrollArea->setWidget(nullptr);ScrollableWidget* scrollableWidget = new  ScrollableWidget(l_num);ui.scrollArea->setWidget(scrollableWidget);
}void DcmImgPro::lineEditset()
{l_num = ui.lineEdit->text().toInt();
}
DcmImgPro::~DcmImgPro()
{}