c++mfc对话框通过鼠标点击可以拖动放缩控件加载的图片
时间: 2023-10-01 15:06:39 浏览: 37
在MFC对话框中,可以通过以下步骤实现拖动和缩放控件加载的图片:
1. 在对话框类的头文件中定义相关的变量和函数,例如:
```cpp
private:
CBitmap m_bitmap;
int m_bitmapWidth;
int m_bitmapHeight;
CPoint m_lastPos;
bool m_bDragging;
bool m_bScaling;
private:
void LoadBitmap(LPCTSTR lpszFileName);
void DrawBitmap(CDC* pDC);
void ScaleBitmap(int cx, int cy);
```
2. 在OnInitDialog函数中加载图片,并获取图片的宽度和高度,例如:
```cpp
BOOL CMyDialog::OnInitDialog()
{
CDialogEx::OnInitDialog();
// Load bitmap
LoadBitmap(TEXT("test.bmp"));
// Get bitmap size
BITMAP bm;
m_bitmap.GetBitmap(&bm);
m_bitmapWidth = bm.bmWidth;
m_bitmapHeight = bm.bmHeight;
return TRUE;
}
```
3. 实现LoadBitmap函数,用于加载指定的图片文件,例如:
```cpp
void CMyDialog::LoadBitmap(LPCTSTR lpszFileName)
{
m_bitmap.LoadBitmap(lpszFileName);
}
```
4. 实现DrawBitmap函数,用于在对话框上绘制加载的图片,例如:
```cpp
void CMyDialog::DrawBitmap(CDC* pDC)
{
CDC memDC;
memDC.CreateCompatibleDC(pDC);
memDC.SelectObject(&m_bitmap);
pDC->StretchBlt(0, 0, m_bitmapWidth, m_bitmapHeight, &memDC, 0, 0, m_bitmapWidth, m_bitmapHeight, SRCCOPY);
}
```
5. 在OnPaint函数中调用DrawBitmap函数,绘制加载的图片,例如:
```cpp
void CMyDialog::OnPaint()
{
CPaintDC dc(this); // device context for painting
DrawBitmap(&dc);
}
```
6. 在OnLButtonDown函数中记录鼠标点击位置,并判断是否在图片上点击,例如:
```cpp
void CMyDialog::OnLButtonDown(UINT nFlags, CPoint point)
{
if (point.x >= 0 && point.y >= 0 && point.x < m_bitmapWidth && point.y < m_bitmapHeight)
{
m_lastPos = point;
m_bDragging = true;
}
else
{
m_bScaling = true;
}
CDialogEx::OnLButtonDown(nFlags, point);
}
```
7. 在OnMouseMove函数中实现拖动和缩放图片的功能,例如:
```cpp
void CMyDialog::OnMouseMove(UINT nFlags, CPoint point)
{
if (m_bDragging)
{
int dx = point.x - m_lastPos.x;
int dy = point.y - m_lastPos.y;
CRect rect;
GetWindowRect(&rect);
rect.OffsetRect(dx, dy);
MoveWindow(&rect);
}
else if (m_bScaling)
{
int cx = point.x - m_lastPos.x;
int cy = point.y - m_lastPos.y;
ScaleBitmap(cx, cy);
m_lastPos = point;
}
CDialogEx::OnMouseMove(nFlags, point);
}
```
8. 实现ScaleBitmap函数,用于缩放加载的图片,例如:
```cpp
void CMyDialog::ScaleBitmap(int cx, int cy)
{
BITMAP bm;
m_bitmap.GetBitmap(&bm);
m_bitmapWidth = max(1, bm.bmWidth + cx);
m_bitmapHeight = max(1, bm.bmHeight + cy);
CDC memDC;
memDC.CreateCompatibleDC(NULL);
CBitmap bitmap;
bitmap.CreateCompatibleBitmap(&memDC, m_bitmapWidth, m_bitmapHeight);
memDC.SelectObject(&bitmap);
memDC.SetStretchBltMode(COLORONCOLOR);
memDC.StretchBlt(0, 0, m_bitmapWidth, m_bitmapHeight, &memDC, 0, 0, bm.bmWidth, bm.bmHeight, SRCCOPY);
m_bitmap.DeleteObject();
m_bitmap.Attach(bitmap);
}
```
通过以上步骤,就可以实现在MFC对话框中拖动和缩放控件加载的图片的功能了。