怎么做出类似拖放文件时那种淡淡的显示效果?

Question

偶是win32sdk/api 方式,不是MFC, ＶＣ６，ｗｉｎ２００0. 打算在WM_NOTIFY 和WM_LBUTTONUP
里画点什么,可是怎么画呢?

Answer 1

为你写了代码！我测试过了，是你要的吧？
int gl_nPrevX;
int gl_nPrevY;
int gl_nStarX;
int gl_nStarY;
int gl_nEndX;
int gl_nEndY;
int gl_nCurrX;
int gl_nCurrY;
int gl_nMouseState;//1--左键按下void DrawRect(HWND hWnd, int left,int top,int right,int bottom)
{
HDC hDC = GetDC(hWnd);
int old_rop = SetROP2(hDC,R2_XORPEN);
SetBkMode(hDC,TRANSPARENT);

HPEN hPen = CreatePen(PS_SOLID,1, RGB(0,200,0));  
HPEN hOldPen = (HPEN)SelectObject(hDC,&hPen);    
HBRUSH hBrush = CreateSolidBrush(RGB(50,0,0));
HBRUSH hOldBr = (HBRUSH)SelectObject(hDC,hBrush);

Rectangle(hDC,left,top,right,bottom);

SelectObject(hDC,hOldPen);
SelectObject(hDC,hOldBr);
SetROP2(hDC,old_rop);
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message) 
{
case WM_COMMAND:
break;
// 2004-11-26 handwolf (add_start)
case WM_LBUTTONDOWN:
{
gl_nStarX = LOWORD(lParam);
gl_nStarY = HIWORD(lParam);
gl_nMouseState = 1;
}
break;    
case WM_LBUTTONUP:
{
int left = min(gl_nStarX,gl_nPrevX);
int right = max(gl_nStarX,gl_nPrevX);
int top = min(gl_nStarY,gl_nPrevY);
int bottom = max(gl_nStarY,gl_nPrevY);
DrawRect(hWnd,left,top,right,bottom);

gl_nEndX = LOWORD(lParam);
gl_nEndY = HIWORD(lParam);
gl_nMouseState = 0;
}
break;    
case WM_MOUSEMOVE:
{
gl_nCurrX = LOWORD(lParam);
gl_nCurrY = HIWORD(lParam);
if(gl_nMouseState == 1)
{
int left = min(gl_nStarX,gl_nPrevX);
int right = max(gl_nStarX,gl_nPrevX);
int top = min(gl_nStarY,gl_nPrevY);
int bottom = max(gl_nStarY,gl_nPrevY);

DrawRect(hWnd,left,top,right,bottom);

left = min(gl_nStarX,gl_nCurrX);
right = max(gl_nStarX,gl_nCurrX);
top = min(gl_nStarY,gl_nCurrY);
bottom = max(gl_nStarY,gl_nCurrY);

DrawRect(hWnd,left,top,right,bottom);
}
gl_nPrevX = LOWORD(lParam);
gl_nPrevY = HIWORD(lParam);
}
break;   
// 2004-11-26 handwolf (add_end)

case WM_PAINT:
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
   }
   return 0;
}

Answer 2

Windows使用了SetLayeredWindowAttributes，当然只支持Window2000及以上版本，98下不支持

Answer 3

To  handwolf(初学者) :好极了,已经做出来了.不过TextOut有点问题,搞得一片黑呼呼的.
怎么使得文字也可以透明地画出呢?

Answer 4

方法一：
 先画到bitmap上，然后再画到视图上

Answer 5

void DrawRect(HWND hWnd, int left,int top,int right,int bottom)
{
HDC hDC = GetDC(hWnd);
int old_rop = SetROP2(hDC,R2_XORPEN);
SetBkMode(hDC,TRANSPARENT);

//text
HDC hDCPic = CreateCompatibleDC(hDC) ;
HBITMAP hBmp = CreateCompatibleBitmap(hDC,(right-left)/2,(bottom-top)/2) ;
SelectObject(hDCPic,hBmp) ;  
PatBlt(hDCPic,0,0,(right-left)/2,(bottom-top)/2,PATCOPY) ;
SetBkColor(hDCPic,RGB(255,255,255)) ;
SetBkMode(hDCPic,TRANSPARENT);
TextOut(hDCPic,10,10,"Hello",5);    
BitBlt(hDC,left+(right-left)/4,top+(bottom-top)/4,(right-left)/2,(bottom-top)/2,hDCPic,0,0,SRCINVERT) ;   


HPEN hPen = CreatePen(PS_SOLID,1, RGB(0,200,0));  
HPEN hOldPen = (HPEN)SelectObject(hDC,&hPen);    
HBRUSH hBrush = CreateSolidBrush(RGB(50,0,0));
HBRUSH hOldBr = (HBRUSH)SelectObject(hDC,hBrush);
//rect
Rectangle(hDC,left,top,right,bottom);


SelectObject(hDC,hOldPen);
SelectObject(hDC,hOldBr);
SetROP2(hDC,old_rop);
}

Answer 6

handwolf(初学者) :偶在newsgroup上看到KB214814,原来的工作算是吃苦了.不过还是非常感谢,分数都给你了.另外,偶有个问题,也是在newsgroup解决的,但是csdn没有回收分数的,你去reply一下吧,
我把分数给你.地址是:http://community.csdn.net/Expert/topic/3586/3586010.xml?temp=.2883722