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綆浠嬶細鍐呭瓨DC錛屽張鍚嶁滃弻緙撳啿鈥濓紝鏄В鍐硍indows紿楀彛鑷粯涓嚭鐜扳滈棯灞忊濈殑甯歌鎵嬫銆?/p>
1)銆佷負灞忓箷 DC 鍒涘緩鍏煎鐨勫唴瀛?DC
2)銆佸垱寤轟綅鍥?br>3)銆佹妸浣嶅浘閫夊叆璁懼鐜
4)銆佹妸緇樺埗濂界殑鍥懼艦鈥滄嫹璐濃滃埌灞忓箷涓?
鐪嬭繖涓唬鐮侊細
棣栧厛鐪嬫瀯閫狅紝浠庝竴涓狢DC鏋勯犮傜劧鍚庣湅浜嗕竴涓嬫垚鍛樺嚱鏁幫紝濂藉儚娌″嚑涓紝浼拌榪欐槸涓涓彲浠ュ畬鍏ㄦ浛鎹㈢殑CDC鐨勭渷蹇冪殑涓滀笢銆?/p>
鐒跺悗鐪嬫瀽鏋勶細鏋愭瀯鏄竴涓狟itBit錛岃仈鎯寵嚜宸卞仛鍐呭瓨DC鐨勬椂鍊欙紝鏈鍚庝竴姝ヤ篃鏄唴瀛樺埌DC鐨勮創鍥懼姩浣溿?/p>
鍏紑鎺ュ彛灝變袱涓紝閲嶈澆鐨凜DC* 鍜?->鎿嶄綔錛岀洿鎺ヨ兘褰撲綔CDC浣跨敤銆?/p>
榪欏嚑涓粏鑺傞渶瑕佹敞鎰忥細
1.m_bMemDC = !pDC->IsPrinting(); // 浠ュ墠鍏蟲敞涓嶅錛岃繖鏄敤浜庡垽鏂繖涓狣C鏄笉鏄敤浜巔rint錛屽鏋滄槸灝變笉浣跨敤鈥滃唴瀛楧C鈥濓紝鑷充簬涓轟粈涔堣繕涓嶄簡瑙ｃ傛垜鐞嗚В鏄病鏈夐渶瑕併?/p>
2.FillSolidRect(m_rect, pDC->GetBkColor()); // WM_ERASEBKGND錛岄拡瀵硅繖涓秷鎭殑緇嗚妭澶勭悊銆?/p>
榪欎釜綾繪寔鏈変簡涓涓滃墠鍙扳滵C錛屽畠鏈韓鏄竴涓滃悗鍙扳滵C錛屾瘡嬈″悗鍙板厠闅嗗墠鍙版墽琛岀粯鐢葷劧鍚庢妸緇撴灉璐村洖鍘匯?/p>
榪欓噷榪樻湁涓涓粏鑺傦紝灝辨槸SelectObject銆備負浜嗕繚璇佷笉娉勬紡錛屾渶濂界殑鍔炴硶鏄紝姣忔宸ヤ綔瀹屾垚灝嗘墍鏈夌殑GDI瀵硅薄澶嶄綅銆?/p>
///////////////////////////////////////////////////////////////
class CMemDC : public CDC
{
public:
// constructor sets up the memory DC
CMemDC(CDC* pDC) : CDC()
{
ASSERT(pDC != NULL);
m_pDC = pDC;
m_pOldBitmap = NULL;
#ifndef _WIN32_WCE_NO_PRINTING
m_bMemDC = !pDC->IsPrinting();
#else
m_bMemDC = FALSE;
#endif
if (m_bMemDC) // Create a Memory DC
{
pDC->GetClipBox(&m_rect);
CreateCompatibleDC(pDC);
m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), m_rect.Height());
m_pOldBitmap = SelectObject(&m_bitmap);
#ifndef _WIN32_WCE
SetWindowOrg(m_rect.left, m_rect.top);
#endif
// EFW - Bug fix - Fill background in case the user has overridden
// WM_ERASEBKGND. We end up with garbage otherwise.
// CJM - moved to fix a bug in the fix.
FillSolidRect(m_rect, pDC->GetBkColor());
}
else // Make a copy of the relevent parts of the current DC for printing
{
#if !defined(_WIN32_WCE) || ((_WIN32_WCE > 201) && !defined(_WIN32_WCE_NO_PRINTING))
m_bPrinting = pDC->m_bPrinting;
#endif
m_hDC = pDC->m_hDC;
m_hAttribDC = pDC->m_hAttribDC;
}
}
// Destructor copies the contents of the mem DC to the original DC
~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_pOldBitmap);
} 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;}
private:
CBitmap m_bitmap; // Offscreen bitmap
CBitmap* m_pOldBitmap; // 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.
};