如何在pyqt5上用QPixmap实现图片缩放？

Question

我试图用QPixmap来放大一张图片，但没有任何效果。我是这样实现的。(self.hauteur是一个表示高度的浮子)

self.label.setPixmap(QPixmap(self.image).scaledToHeight(self.hauteur))

我把我的标签放到了一个布局中，以便把它放在一个滚动小部件中，那么。

self.layout6.addWidget(self.label)

...

self.widget1=QWidget()
    self.widget1.setLayout(self.layout6)
    self.scroll1.setWidget(self.widget1)
    self.tab1.layout.addWidget(self.scroll1,0,1,1,2)

...

self.tab1.setLayout(self.tab1.layout)

如果我想建立一个方法，通过按下按钮来放大或缩小窗口中的图片，我应该怎么做？我试过调整标签的大小，但没有用。

self.action5=QAction(QIcon("Icon/in"),"Zoom in",self)
    self.action5.triggered.connect(self.zoomin)

...

 def zoomin(self):
    self.hauteur+=100
    self.label.scaledToHeight(self.hauteur)
    self.update()

Answer 1

我会调整原图的大小 QPixmap 再放进去 label

    self.scale *= 2

    size = self.pixmap.size()

    scaled_pixmap = self.pixmap.scaled(self.scale * size)

    self.label.setPixmap(scaled_pixmap)

最小的工作代码。

from PyQt5.QtWidgets import *
from PyQt5.QtGui import *

class MyApp(QWidget):

    def __init__(self, *args):
        super().__init__(*args)

        self.layout = QVBoxLayout()
        self.setLayout(self.layout)

        self.button_zoom_in = QPushButton('Zoom IN', self)
        self.button_zoom_in.clicked.connect(self.on_zoom_in)
        self.layout.addWidget(self.button_zoom_in)

        self.button_zoom_out = QPushButton('Zoom OUT', self) 
        self.button_zoom_out.clicked.connect(self.on_zoom_out)
        self.layout.addWidget(self.button_zoom_out)

        self.pixmap = QPixmap('image.jpg')

        self.label = QLabel(self)
        self.label.setPixmap(self.pixmap)
        self.layout.addWidget(self.label)

        self.scale = 1

        self.show()

    def on_zoom_in(self, event):
        self.scale *= 2
        self.resize_image()

    def on_zoom_out(self, event):
        self.scale /= 2
        self.resize_image()

    def resize_image(self):
        size = self.pixmap.size()

        scaled_pixmap = self.pixmap.scaled(self.scale * size)

        self.label.setPixmap(scaled_pixmap)

# --- main ---

app = QApplication([])
win = MyApp()
app.exec()

---

EDIT： 同样使用 self.height += 100 而不是 self.scale *= 2

from PyQt5.QtWidgets import *
from PyQt5.QtGui import *

class MyApp(QWidget):

    def __init__(self, *args):
        super().__init__(*args)

        self.layout = QVBoxLayout()
        self.setLayout(self.layout)

        self.button_zoom_in = QPushButton('Zoom IN', self)
        self.button_zoom_in.clicked.connect(self.on_zoom_in)
        self.layout.addWidget(self.button_zoom_in)

        self.button_zoom_out = QPushButton('Zoom OUT', self) 
        self.button_zoom_out.clicked.connect(self.on_zoom_out)
        self.layout.addWidget(self.button_zoom_out)

        self.pixmap = QPixmap('image.jpg')
        self.height = self.pixmap.height()

        self.label = QLabel(self)
        self.label.setPixmap(self.pixmap)
        self.layout.addWidget(self.label)

        self.show()

    def on_zoom_in(self, event):
        self.height += 100
        self.resize_image()

    def on_zoom_out(self, event):
        self.height -= 100
        self.resize_image()

    def resize_image(self):
        scaled_pixmap = self.pixmap.scaledToHeight(self.height)
        self.label.setPixmap(scaled_pixmap)

# --- main ---

app = QApplication([])
win = MyApp()
app.exec()