mfc 画多边形,鼠标拖动节点
时间: 2023-11-08 08:37:39 浏览: 60
在 MFC 中,可以通过重载 CWnd::OnLButtonDown、CWnd::OnMouseMove 和 CWnd::OnLButtonUp 函数来实现鼠标拖动多边形的节点。具体步骤如下:
1. 定义多边形的节点结构体:
```cpp
struct PolygonNode
{
CPoint point; // 节点坐标
BOOL selected; // 节点是否被选中
};
```
2. 声明多边形的节点数组:
```cpp
std::vector<PolygonNode> m_nodes;
```
3. 在 OnLButtonDown 函数中判断是否点击了节点:
```cpp
void CPolygonWnd::OnLButtonDown(UINT nFlags, CPoint point)
{
for (auto& node : m_nodes)
{
if (point.x >= node.point.x - 5 && point.x <= node.point.x + 5 &&
point.y >= node.point.y - 5 && point.y <= node.point.y + 5)
{
node.selected = TRUE;
break;
}
}
CWnd::OnLButtonDown(nFlags, point);
}
```
4. 在 OnMouseMove 函数中实现节点的拖动:
```cpp
void CPolygonWnd::OnMouseMove(UINT nFlags, CPoint point)
{
for (auto& node : m_nodes)
{
if (node.selected)
{
node.point = point;
break;
}
}
Invalidate();
CWnd::OnMouseMove(nFlags, point);
}
```
5. 在 OnLButtonUp 函数中取消节点的选中状态:
```cpp
void CPolygonWnd::OnLButtonUp(UINT nFlags, CPoint point)
{
for (auto& node : m_nodes)
{
node.selected = FALSE;
}
CWnd::OnLButtonUp(nFlags, point);
}
```
6. 在 OnPaint 函数中绘制多边形:
```cpp
void CPolygonWnd::OnPaint()
{
CPaintDC dc(this); // device context for painting
CBrush brush(RGB(255, 255, 255));
dc.SelectObject(&brush);
dc.Rectangle(0, 0, 500, 500);
CPen pen(PS_SOLID, 2, RGB(0, 0, 0));
dc.SelectObject(&pen);
int count = m_nodes.size();
if (count > 1)
{
for (int i = 0; i < count; i++)
{
dc.MoveTo(m_nodes[i].point);
dc.LineTo(m_nodes[(i + 1) % count].point);
}
}
}
```
这样就可以实现鼠标拖动多边形的节点了。