简单问题，关于BeginPath？
void CtestView::OnDraw(CDC* pDC)
{
CString str=TEXT( "test ");
pDC-> BeginPath();
pDC-> TextOut(50,50,str);
pDC-> EndPath();
}
不能显示，我用的是vs 2005。
[解决办法]
void COutlineView::OnDraw(CDC* pDC)
{
// Describe a 24-point truetype font of normal weight
LOGFONT lf;
memset(&lf, 0, sizeof(lf));
lf.lfHeight = -MulDiv(24, pDC-> GetDeviceCaps(LOGPIXELSY), 72);
lf.lfWeight = FW_NORMAL;
lf.lfOutPrecision = OUT_TT_ONLY_PRECIS;
// create and select it
CFont newFont;
if (!newFont.CreateFontIndirect(&lf))
return;
CFont* pOldFont = pDC-> SelectObject(&newFont);
// use a path to record how the text was drawn
pDC-> BeginPath();
pDC-> TextOut(10, 10, _T( "Hockey is Best! "));
pDC-> EndPath();
// Find out how many points are in the path. Note that
// for long strings or complex fonts, this number might be
// gigantic!
int nNumPts = pDC-> GetPath(NULL, NULL, 0);
if (nNumPts == 0)
return;
// Allocate memory to hold points and stroke types from
// the path.
LPPOINT lpPoints = new POINT[nNumPts];
if (lpPoints == NULL)
return;
LPBYTE lpTypes = new BYTE[nNumPts];
if (lpTypes == NULL)
{
delete [] lpPoints;
return;
}
// Now that we have the memory, really get the path data.
nNumPts = pDC-> GetPath(lpPoints, lpTypes, nNumPts);
// If it worked, draw the lines. Win95 and Win98 don 't support
// the PolyDraw API, so we use our own member function to do
// similar work. If you 're targeting only Windows NT, you can
// use the PolyDraw() API and avoid the COutlineView::PolyDraw()
// member function.
if (nNumPts != -1)
PolyDraw(pDC, lpPoints, lpTypes, nNumPts);
// Release the memory we used
delete [] lpPoints;
delete [] lpTypes;
// Put back the old font
pDC-> SelectObject(pOldFont);
return;
}
[解决办法]
BeginPath是区域函数
你应该首先建立一个区域，然后再用BeginPath();
EndPath()进行区域图形绘制。
[解决办法]
你运行一下以下代码你就知道BeginPath是做什么的了。
它可以用来做空心字，艺术字等。
// This OnDraw() implementation uses GDI paths to draw the outline of
// some text in a TrueType font. The path is used to record the way
// the TrueType font would be drawn. Then, the function uses the data
// returned from CDC::GetPath() to draw the font--without filling it.
void COutlineView::OnDraw(CDC* pDC)
{
// Describe a 24-point truetype font of normal weight
LOGFONT lf;
memset(&lf, 0, sizeof(lf));
lf.lfHeight = -MulDiv(24, pDC-> GetDeviceCaps(LOGPIXELSY), 72);
lf.lfWeight = FW_NORMAL;
lf.lfOutPrecision = OUT_TT_ONLY_PRECIS;
// create and select it
CFont newFont;
if (!newFont.CreateFontIndirect(&lf))
return;
CFont* pOldFont = pDC-> SelectObject(&newFont);
// use a path to record how the text was drawn
pDC-> BeginPath();
pDC-> TextOut(10, 10, _T( "Hockey is Best! "));
pDC-> EndPath();
// Find out how many points are in the path. Note that
// for long strings or complex fonts, this number might be
// gigantic!
int nNumPts = pDC-> GetPath(NULL, NULL, 0);
if (nNumPts == 0)
return;
// Allocate memory to hold points and stroke types from
// the path.
LPPOINT lpPoints = new POINT[nNumPts];
if (lpPoints == NULL)
return;
LPBYTE lpTypes = new BYTE[nNumPts];
if (lpTypes == NULL)
{
delete [] lpPoints;
return;
}
// Now that we have the memory, really get the path data.
nNumPts = pDC-> GetPath(lpPoints, lpTypes, nNumPts);
// If it worked, draw the lines. Win95 and Win98 don 't support
// the PolyDraw API, so we use our own member function to do
// similar work. If you 're targeting only Windows NT, you can
// use the PolyDraw() API and avoid the COutlineView::PolyDraw()
// member function.
if (nNumPts != -1)
PolyDraw(pDC, lpPoints, lpTypes, nNumPts);
// Release the memory we used
delete [] lpPoints;
delete [] lpTypes;
// Put back the old font
pDC-> SelectObject(pOldFont);
return;
}
void COutlineView::PolyDraw(CDC* pDC, CONST LPPOINT lppt, CONST LPBYTE lpbTypes,
int cCount)
{
int nIndex;
LPPOINT pptLastMoveTo = NULL;
// for each of the points we have...
for (nIndex = 0; nIndex < cCount; nIndex++)
{
switch(lpbTypes[nIndex])
{
// React to information from the path by drawing the data
// we received. For each of the points, record our own
// "last active point " so we can close figures, lines, and
// Beziers.
case PT_MOVETO:
if (pptLastMoveTo != NULL && nIndex > 0)
pDC-> LineTo(pptLastMoveTo-> x, pptLastMoveTo-> y);
pDC-> MoveTo(lppt[nIndex].x, lppt[nIndex].y);
pptLastMoveTo = &lppt[nIndex];
break;
case PT_LINETO | PT_CLOSEFIGURE:
pDC-> LineTo(lppt[nIndex].x, lppt[nIndex].y);
if (pptLastMoveTo != NULL)
pDC-> LineTo(pptLastMoveTo-> x, pptLastMoveTo-> y);
pptLastMoveTo = NULL;
break;
case PT_LINETO:
pDC-> LineTo(lppt[nIndex].x, lppt[nIndex].y);
break;
case PT_BEZIERTO | PT_CLOSEFIGURE:
ASSERT(nIndex + 2 <= cCount);
pDC-> PolyBezierTo(&lppt[nIndex], 3);
nIndex += 2;
if (pptLastMoveTo != NULL)
pDC-> LineTo(pptLastMoveTo-> x, pptLastMoveTo-> y);
pptLastMoveTo = NULL;
break;
case PT_BEZIERTO:
ASSERT(nIndex + 2 <= cCount);
pDC-> PolyBezierTo(&lppt[nIndex], 3);
nIndex += 2;
break;
}
}
// If the figure was never closed and should be,
// close it now.
if (pptLastMoveTo != NULL && nIndex > 1)
pDC-> LineTo(pptLastMoveTo-> x, pptLastMoveTo-> y);
}
[解决办法]
BeginPath/EndPath在当前DC中创建了一个路径对象，这个路径对象要绘制出来，还需要调用StrokeAndFillPath/FillPath/StrokePath等函数。
