在Qt中将应用程序方向锁定为横向 [英] Lock app orientation to landscape in Qt

问题描述

即使屏幕显示为纵向，我也希望将使用Qt开发的应用锁定为横向.我尝试将在此处找到的resizeEvent方法添加到我的代码中: http://qt-project.org/doc/qt-4.8/widgets-orientation.html ，但是我的应用仍然无法正确显示.这是我的resizeEvent代码:

void MainWindow::resizeEvent(QResizeEvent *event)
{
    QSize size = event->size();
    qDebug() << size;
    bool isLandscape = size.width() > size.height();

    if (isLandscape == false){
        size.transpose();
    }

    this->setFixedSize(size);
}

有人知道如何在Qt 4.8.5中做到这一点吗?我正在尝试为320x240的显示器显示一个应用程序.

谢谢

解决方案

您不能真正遵循该示例.它根据方向显示了两个不同的小部件.此外，该文档还警告您修改resizeEvent内部的size属性.

一种解决方案是通过重载 https://stackoverflow.com/a/1160476/1122645 中进行了详细讨论./p>

父级的 布局 使用

sizeHint来计算子级窗口小部件的大小.通常，将其实现为

QSize MainWindow::sizeHint() const
{
    int w = //some width you seem fit
    return QSize( w, heightForWidth(w) );
}

，但是如果MainWindow是顶级，则它将保持不变.您还可以更改当前尺寸政策的heightForWidth标志

QSizePolicy currPolicy = this->sizePolicy();
currPolicy->setHeightForWidth(true);
this->SetSizePolicy(currPolicy); 

但是，如果它是一个顶级小部件，我不会做太多改动.

无论如何，您无需致电updateGeometry.

I would like to lock my app developed with Qt to landscape orientation, even if the screen display is portrait. I have tried adding to my code the resizeEvent method found here: http://qt-project.org/doc/qt-4.8/widgets-orientation.html, but my app still does not display correctly. Here is my code for resizeEvent:

void MainWindow::resizeEvent(QResizeEvent *event)
{
    QSize size = event->size();
    qDebug() << size;
    bool isLandscape = size.width() > size.height();

    if (isLandscape == false){
        size.transpose();
    }

    this->setFixedSize(size);
}

Does anyone know how to do this in Qt 4.8.5? I am trying to display an app for a 320x240 display.

Thanks

解决方案

You can't really follow that example. It shows two different widgets depending on the orientation. Furthermore the doc warns about modifying size properties inside resizeEvent.

One solution would be to set a fix aspect ratio similar to 320x240 by overloading QWidget::heightForWidth. You wouldn't need to overload resizeEvent.

It will look like

int MainWindow::heightForWidth( int w ) { 
     return (w * 240 )/320; 
}

heightForWidth is discussed in detail in https://stackoverflow.com/a/1160476/1122645.

edit:

sizeHint is used by the layout of the parent to compute the size of children widgets. In general, it make sense to implement it as

QSize MainWindow::sizeHint() const
{
    int w = //some width you seem fit
    return QSize( w, heightForWidth(w) );
}

but if MainWindow is top level then it will not change anything. You can also alter heightForWidth flag of your current size policy

QSizePolicy currPolicy = this->sizePolicy();
currPolicy->setHeightForWidth(true);
this->SetSizePolicy(currPolicy); 

But again, if it is a top level widget I doesnt change much.

Anyway you don't need to call updateGeometry.

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