用CMemDC双缓冲技术可以避免闪烁。#ifndef _MEMDC_H_ #define _MEMDC_H_// flicker free drawing.class CMemDC : public CDC { private: CBitmap m_bitmap; // Offscreen bitmap CBitmap* m_oldBitmap; // bitmap originally found in CMemDC CDC* m_pDC; // Saves CDC passed in constructor CRect m_rect; // Rectangle of drawing area. BOOL m_bMemDC; // TRUE if CDC really is a Memory DC. public:
CMemDC(CDC* pDC, const CRect* pRect = NULL) : CDC() { ASSERT(pDC != NULL); // Some initialization m_pDC = pDC; m_oldBitmap = NULL; m_bMemDC = !pDC->IsPrinting(); // Get the rectangle to draw if (pRect == NULL) { pDC->GetClipBox(&m_rect); } else { m_rect = *pRect; } if (m_bMemDC) { // Create a Memory DC CreateCompatibleDC(pDC); pDC->LPtoDP(&m_rect); m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), m_rect.Height()); m_oldBitmap = SelectObject(&m_bitmap); SetMapMode(pDC->GetMapMode()); SetWindowExt(pDC->GetWindowExt()); SetViewportExt(pDC->GetViewportExt()); pDC->DPtoLP(&m_rect); SetWindowOrg(m_rect.left, m_rect.top); } else { // Make a copy of the relevent parts of the current DC for printing m_bPrinting = pDC->m_bPrinting; m_hDC = pDC->m_hDC; m_hAttribDC = pDC->m_hAttribDC; } // Fill background FillSolidRect(m_rect, pDC->GetBkColor()); }
~CMemDC() { if (m_bMemDC) { // Copy the offscreen bitmap onto the screen. m_pDC->BitBlt(m_rect.left, m_rect.top, m_rect.Width(), m_rect.Height(), this, m_rect.left, m_rect.top, SRCCOPY);
//Swap back the original bitmap. SelectObject(m_oldBitmap); } else { // All we need to do is replace the DC with an illegal value, // this keeps us from accidently deleting the handles associated with // the CDC that was passed to the constructor. m_hDC = m_hAttribDC = NULL; } }
// Allow usage as a pointer CMemDC* operator->() { return this; } // Allow usage as a pointer operator CMemDC*() { return this; } };#endif
pDC->LineTo(x3,y3);
...
pDC->LineTo(x2,y2);
for(int i=0;i<=n&&i<=x2-x1;i++)
{ 画点(x1+i,y1+i*(y2-y1)/(x2-x1));
}
n++;在OnTime函数中使用Invalidate()函数就可以了
主要思想就是每次都画一条比上次都一个点的线
#define _MEMDC_H_// flicker free drawing.class CMemDC : public CDC {
private:
CBitmap m_bitmap; // Offscreen bitmap
CBitmap* m_oldBitmap; // bitmap originally found in CMemDC
CDC* m_pDC; // Saves CDC passed in constructor
CRect m_rect; // Rectangle of drawing area.
BOOL m_bMemDC; // TRUE if CDC really is a Memory DC.
public:
CMemDC(CDC* pDC, const CRect* pRect = NULL) : CDC()
{
ASSERT(pDC != NULL); // Some initialization
m_pDC = pDC;
m_oldBitmap = NULL;
m_bMemDC = !pDC->IsPrinting(); // Get the rectangle to draw
if (pRect == NULL) {
pDC->GetClipBox(&m_rect);
} else {
m_rect = *pRect;
} if (m_bMemDC) {
// Create a Memory DC
CreateCompatibleDC(pDC);
pDC->LPtoDP(&m_rect); m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), m_rect.Height());
m_oldBitmap = SelectObject(&m_bitmap); SetMapMode(pDC->GetMapMode()); SetWindowExt(pDC->GetWindowExt());
SetViewportExt(pDC->GetViewportExt()); pDC->DPtoLP(&m_rect);
SetWindowOrg(m_rect.left, m_rect.top);
} else {
// Make a copy of the relevent parts of the current DC for printing
m_bPrinting = pDC->m_bPrinting;
m_hDC = pDC->m_hDC;
m_hAttribDC = pDC->m_hAttribDC;
} // Fill background
FillSolidRect(m_rect, pDC->GetBkColor());
}
~CMemDC()
{
if (m_bMemDC) {
// Copy the offscreen bitmap onto the screen.
m_pDC->BitBlt(m_rect.left, m_rect.top, m_rect.Width(), m_rect.Height(),
this, m_rect.left, m_rect.top, SRCCOPY);
//Swap back the original bitmap.
SelectObject(m_oldBitmap);
} else {
// All we need to do is replace the DC with an illegal value,
// this keeps us from accidently deleting the handles associated with
// the CDC that was passed to the constructor.
m_hDC = m_hAttribDC = NULL;
}
}
// Allow usage as a pointer
CMemDC* operator->()
{
return this;
} // Allow usage as a pointer
operator CMemDC*()
{
return this;
}
};#endif
要想不闪,每次就不要重画整个视图,只是重画需要的部分就可以了
调用OnPaint()函数,
Void CView OnPaint()
{
CDC* pDC=GetDC();
pDC->Moveto(x1,y1);
pDC->Lineto(x1+i,y1+i*(y2-y1)/(x2-x1));
i++;
}
其中i定义为全局变量,初始化为0
然后在OnCreate()函数中产生一个计时器SetTimer(1,100,NULL);
调用ONTime函数,在其中发送WW_PAINT消息就可以了
SendMessage(WW_PAINT);
很简单的,保证一点都不闪