C++ Qt：如何调整图像大小并保持其比例？
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Qt: How do I resize an image and maintain its proportions?
提问by Pietro
This Qt exampleshows how to resize an image contained in a dialog, so that when the dialog is resized, the image stretches accordingly.
这个 Qt示例显示了如何调整对话框中包含的图像的大小，以便在调整对话框大小时，图像会相应地拉伸。
How can I resize an image in the same way, without distorting it / keeping its proportions the same?
如何以相同的方式调整图像大小，而不会扭曲它/保持其比例不变？
Of course if the width/height ratio of the dialog is different from the one of the image, I will get a "grey" area.
I found the Qt::KeepAspectRatioenum, but not the function to use it with.
当然，如果对话框的宽高比与图像不同，我会得到一个“灰色”区域。
我找到了Qt::KeepAspectRatio枚举，但没有找到使用它的函数。
Update: This is the code I am trying with:
更新：这是我正在尝试的代码：
QImage image(path);
QImage image2 = image.scaled(200, 200, Qt::KeepAspectRatio);
QLabel *plotImg = new QLabel;
plotImg->setScaledContents(true);
plotImg->setPixmap(QPixmap::fromImage(image2));
The image does not maintain a constant aspect ratio when the label is resized. And it looses resolution after the rescaling.
调整标签大小时，图像不会保持恒定的纵横比。并且在重新缩放后它会失去分辨率。
回答by Guilherme Bernal
Use the QImage::scaledfunction.
使用该QImage::scaled功能。
QImage img("someimage.png");
QImage img2 = img.scaled(100, 100, Qt::KeepAspectRatio);
In case you need it for QPixmap, a function with the same name exists.
如果您需要它QPixmap，则存在同名的函数。
