在 Qt 中根据 display/screen 大小定位动态 QDialog

Question

我想定位然后显示一个关于显示器的对话框。该对话框有一个标签。对话框根据标签的大小展开。

下面是我的代码不起作用。它试图在屏幕中央显示对话框（对话框默认显示在中央，此代码仅用于评估）：

QDialog splash;
QVBoxLayout *laySplash = new QVBoxLayout(&splash);
QLabel *lblText = new QLabel;
laySplash->addWidget(lblText);
lblText->setText("hello world! hello world! hello world! hello world! hello world! ");

int intScreenHeight = QApplication::desktop()->screenGeometry().height();
int intScreenWidth = QApplication::desktop()->screenGeometry().width();

splash.layout()->update();
splash.layout()->activate();

int intSplashLeft = (intScreenWidth / 2) - (splash.width() / 2);
int intSplashTop = (intScreenHeight /2) - (splash.height() / 2);
splash.move(intSplashLeft, intSplashTop);

splash.exec();

我做错了什么？

（我在 Linux 中使用 Qt5）

Answer 1

你的问题是布局只会在小部件可见后更新它的大小，一个可能的解决方案是通过调用 QDialog 的方法 adjustSize() 来强制它.

有几种方法可以使小部件居中：

第一种形式：

QDialog splash;
QVBoxLayout *laySplash = new QVBoxLayout(&splash);
QLabel *lblText = new QLabel;
laySplash->addWidget(lblText);
lblText->setText("hello world! hello world! hello world! hello world! hello world! ");
splash.adjustSize();

splash.setGeometry(
    QStyle::alignedRect(
        Qt::LeftToRight,
        Qt::AlignCenter,
        splash.size(),
        qApp->desktop()->availableGeometry()
    )
);

splash.exec();

第二形式：

QDialog splash;
QVBoxLayout *laySplash = new QVBoxLayout(&splash);
QLabel *lblText = new QLabel;
laySplash->addWidget(lblText);
lblText->setText("hello world! hello world! hello world! hello world! hello world! ");
splash.adjustSize();
QPoint p = QApplication::desktop()->geometry().center()-splash.rect().center();
splash.move(p);

splash.exec();

第三种形式（你的方法）：

QDialog splash;
QVBoxLayout *laySplash = new QVBoxLayout(&splash);
QLabel *lblText = new QLabel;
laySplash->addWidget(lblText);
lblText->setText("hello world! hello world! hello world! hello world! hello world! ");

splash.adjustSize();
int intScreenHeight = QApplication::desktop()->screenGeometry().height();
int intScreenWidth = QApplication::desktop()->screenGeometry().width();

int intSplashLeft = (intScreenWidth / 2) - (splash.width() / 2);
int intSplashTop = (intScreenHeight /2) - (splash.height() / 2);
splash.move(intSplashLeft, intSplashTop);

splash.exec();

Answer 2

试试我的代码，它有效创建一个名为 set geometry 的函数，并传递您的 QDialog 指针和相对于屏幕的大小百分比。假设您希望对话框的大小占整个屏幕的 50%，然后传递 50

void setGeometry(QDialog *dialogBox, int PercentageOfScreen)
{
    int x, y, w, h;
    QRect rect = QApplication::desktop()->screenGeometry();
    int screen_width = rect.width();
    int screen_height = rect.height();

    //Represent Percentage in decimals
    float PercentageOfScreenFloat = (float)PercentageOfScreen/100;

    //Calculate w and h
    w = (PercentageOfScreenFloat * screen_width);
    h = (PercentageOfScreenFloat * screen_height);

    //Check for max and min size hints
    int minW = dialogBox->minimumWidth();
    int minH = dialogBox->minimumHeight();

    int maxW = dialogBox->maximumWidth();
    int maxH = dialogBox->maximumHeight();

    if(w<minW || h<minH)
    {
        w = minW;
        h = minH;
    }
    else if(w>maxW || h>maxH)
    {
        w = maxW;
        h = maxH;
    }

    //Now Calculate x and y
    x = screen_width / 2;
    x = x - w / 2;

    y = screen_height / 2;
    y = y - h / 2;

    dialogBox->setGeometry(x, y, w, h);

}

在 Qt 中根据 display/screen 大小定位动态 QDialog

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