qgraphicsview zoom in

To zoom in a QGraphicsView, you can use the following steps:

1. Get the current transform of the QGraphicsView using the `transform()` function.
2. Scale the transform by the desired zoom factor using the `scale()` function.
3. Set the new transform using the `setTransform()` function.

Here is some sample code to zoom in by a factor of 1.2:

QTransform transform = view->transform();
transform.scale(1.2, 1.2);
view->setTransform(transform);

You can adjust the zoom factor (1.2 in this case) to your liking.

相关问题

qgraphicsview wheel to zoom

QGraphicsView has built-in support for zooming using the mouse wheel. Here's how you can use it:

1. Enable mouse tracking on the view:

view.setMouseTracking(True)

2. Connect the `wheelEvent` of the view to a slot that handles the zooming:

view.wheelEvent = self.handleWheelEvent

3. In the slot, adjust the view's zoom level based on the mouse wheel delta:

def handleWheelEvent(self, event):
    delta = event.angleDelta().y()
    zoomFactor = 1.2
    if delta > 0:
        self.view.scale(zoomFactor, zoomFactor)
    else:
        self.view.scale(1 / zoomFactor, 1 / zoomFactor)

This code will zoom the view in/out by a factor of 1.2 each time the mouse wheel is scrolled up/down. You can adjust the zoom factor to suit your needs.

qgraphicsview缩放

QGraphicsView的缩放可以通过调整其transform来实现。以下是一种常见的方式：

from PySide2.QtGui import QTransform
from PySide2.QtWidgets import QGraphicsView

view = QGraphicsView()

# 设置初始的缩放因子
scale_factor = 1.0

# 缩放函数
def zoom_in():
    global scale_factor
    scale_factor *= 1.2
    view.setTransform(QTransform().scale(scale_factor, scale_factor))

def zoom_out():
    global scale_factor
    scale_factor /= 1.2
    view.setTransform(QTransform().scale(scale_factor, scale_factor))

# 使用缩放函数
zoom_in()
zoom_out()

以上代码演示了如何通过调整QTransform的缩放因子来实现QGraphicsView的缩放。`zoom_in`函数将缩放因子增加20%，而`zoom_out`函数将缩放因子减少20%。每次缩放后，都需要使用`setTransform`方法来更新QGraphicsView的变换矩阵。

请注意，此代码示例使用了PySide2库来进行图形界面开发，如果你使用的是其他Qt绑定，可能会有些许差异。