qgraphicsview zoom to area

要将 QGraphicsView 缩放到指定区域，您可以使用以下步骤：

1. 计算要缩放的区域的边界框（bounding box）。

2. 将视图缩放到该边界框，使其填满视图。

以下是实现此操作的示例代码：

# 计算要缩放的区域的边界框
rect = QRectF(x, y, width, height)

# 将边界框转换为视图坐标系
rect = self.mapToScene(rect).boundingRect()

# 缩放视图以填充边界框
self.fitInView(rect, Qt.KeepAspectRatio)

其中，`x`、`y`、`width` 和 `height` 是要缩放的区域的左上角坐标和宽度、高度。`mapToScene` 方法将边界框从视图坐标系转换为场景坐标系。`fitInView` 方法将视图缩放以填充边界框，同时保持长宽比。`Qt.KeepAspectRatio` 参数指定保持长宽比。

相关问题

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.

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.