亲们，这是一个简单的记事本程序，但是第二行代码#define BUFFER(x,y) * (pBuffer + y * cxBuffer + x)是什么意思，到都有什么用途请详细解答。拜托哦
#include<windows.h>
#define BUFFER(x,y) * (pBuffer + y * cxBuffer + x)
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,PSTR szCmdLine, int iCmdShow)
{
HWND hwnd;
WNDCLASS wndclass;
MSG msg;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "文本编辑器";
RegisterClass (&wndclass);
hwnd = CreateWindow("文本编辑器", "文本编辑器",WS_OVERLAPPEDWINDOW|WS_VSCROLL|WS_HSCROLL,
CW_USEDEFAULT, 0,600, 500,NULL, NULL, hInstance, NULL);
ShowWindow(hwnd, iCmdShow);
UpdateWindow (hwnd);
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static DWORD dwCharSet = DEFAULT_CHARSET; //1
static int cxChar, cyChar, cxClient, cyClient, cxBuffer, cyBuffer, xCaret, yCaret;
static TCHAR *pBuffer = NULL;
HDC hdc;
int x, y, i;
PAINTSTRUCT ps;
TEXTMETRIC tm;
HFONT ft; //字体句柄
HGDIOBJ GD,gd;
static int V_ScrollValue, H_ScrollValue;
switch(message)
{
case WM_INPUTLANGCHANGE:
dwCharSet = wParam; // fall through
case WM_CREATE:
SetScrollRange(hwnd,SB_VERT,0,30,FALSE);
SetScrollRange(hwnd,SB_HORZ,0,30,FALSE);
SetScrollPos(hwnd,SB_VERT,0,TRUE);
SetScrollPos(hwnd,SB_HORZ,0,TRUE);
hdc = GetDC(hwnd);
ft = CreateFont(0, 0, 0, 0, 0, 0, 0, 0,dwCharSet, 0, 0, 0, FIXED_PITCH, NULL);
//返回一个当前字体的句柄 //1 //1
SelectObject(hdc,ft);
GetTextMetrics(hdc, &tm);
cxChar = tm.tmAveCharWidth;
cyChar = tm.tmHeight;
GD = GetStockObject(SYSTEM_FONT);//获取固定字体
gd = SelectObject(hdc, GD); //字体写入环境中
DeleteObject(gd);
ReleaseDC(hwnd, hdc); // fall through
case WM_SIZE:
cxClient = LOWORD(lParam);
cyClient = HIWORD(lParam);
// calculate window size in characters
cxBuffer = max(1, cxClient / cxChar);//当前窗口每行可以写入字体的个数
cyBuffer = max(1, cyClient / cyChar);
// allocate memory for buffer and clear it
if(pBuffer != NULL)
free(pBuffer);
pBuffer = (TCHAR *)malloc(cxBuffer*cyBuffer*sizeof(TCHAR));
for(y = 0; y < cyBuffer; y++)
for(x = 0; x < cxBuffer; x++)
BUFFER(x,y) = ' ';
// set caret to upper left corner
xCaret = 0;
yCaret = 0;
if(hwnd == GetFocus())//GetFocus()函数没参数返回一个句柄
SetCaretPos(xCaret * cxChar, yCaret * cyChar);
InvalidateRect(hwnd, NULL, TRUE);
return 0 ;
case WM_SETFOCUS:
CreateCaret(hwnd, NULL, cxChar, cyChar);//创建插入符
SetCaretPos(xCaret * cxChar, yCaret * cyChar);
ShowCaret (hwnd);
return 0;
case WM_KILLFOCUS:
// hide and destroy the caret
HideCaret(hwnd);
DestroyCaret();
return 0;
case WM_VSCROLL:
switch(LOWORD(wParam))
{
case SB_LINEDOWN:
V_ScrollValue += 1;
//yCaret += cyChar;
break;
case SB_LINEUP:
V_ScrollValue -= 1;
break;
case SB_PAGEUP:
V_ScrollValue -= 5;
break;
case SB_PAGEDOWN:
V_ScrollValue += 5;
break;
case SB_THUMBTRACK:
V_ScrollValue = HIWORD(wParam);
break;
}
SetScrollPos(hwnd,SB_VERT,V_ScrollValue,TRUE);
InvalidateRect(hwnd,NULL,TRUE);
return 0;
case WM_HSCROLL:
switch(LOWORD(wParam))
{
case SB_LINELEFT:
H_ScrollValue -= 1;
break;
case SB_LINERIGHT:
H_ScrollValue += 1;
break;
case SB_PAGELEFT:
H_ScrollValue -= 5;
break;
case SB_PAGERIGHT:
H_ScrollValue += 5;
break;
case SB_THUMBTRACK:
H_ScrollValue = HIWORD(wParam);
break;
}
SetScrollPos(hwnd,SB_HORZ,H_ScrollValue,TRUE);
InvalidateRect(hwnd,NULL,TRUE);
return 0;
case WM_KEYDOWN:
switch(wParam)
{
case VK_HOME:
xCaret = 0;
break;
case VK_END:
xCaret = cxBuffer - 1;
break;
case VK_PRIOR:
yCaret = 0;
break;
case VK_NEXT:
yCaret = cyBuffer - 1;
break;
case VK_LEFT:
xCaret = max(xCaret - 1, 0);
break;
case VK_RIGHT:
xCaret = min(xCaret + 1, cxBuffer - 1);
break;
case VK_UP:
yCaret = max(yCaret - 1, 0);
break;
case VK_DOWN:
yCaret = min(yCaret + 1, cyBuffer - 1);
break;
case VK_DELETE:
for(x = xCaret; x < cxBuffer - 1; x++)
BUFFER(x, yCaret) = BUFFER(x + 1, yCaret);
BUFFER(cxBuffer - 1, yCaret) = ' ';
HideCaret(hwnd);
hdc = GetDC(hwnd);
SelectObject(hdc, CreateFont (0, 0, 0, 0, 0, 0, 0, 0,dwCharSet, 0, 0, 0, FIXED_PITCH, NULL));
TextOut(hdc, xCaret * cxChar, yCaret * cyChar, &BUFFER(xCaret, yCaret),cxBuffer - xCaret);
DeleteObject(SelectObject(hdc, GetStockObject(SYSTEM_FONT)));
ReleaseDC(hwnd, hdc);
ShowCaret(hwnd);
break;
}
SetCaretPos(xCaret * cxChar, yCaret * cyChar);
return 0;
case WM_CHAR:
for(i = 0; i < (int)LOWORD(lParam); i++)
{
switch(wParam)
{
case '\b': // backspace
if (xCaret > 0)
{
xCaret--;
SendMessage(hwnd, WM_KEYDOWN, VK_DELETE, 1);
}
break;
case '\t': // tab
do
{
SendMessage(hwnd, WM_CHAR, ' ', 1);
}
while (xCaret % 8 != 0);
break;
case '\n': // line feed换行
if (++yCaret == cyBuffer)
yCaret = 0;
break;
case '\r': // carriage return回车
xCaret = 0;
if (++yCaret == cyBuffer)
yCaret = 0;
break;
case '\x1B': // escape ESC键
for (y = 0; y < cyBuffer; y++)
for (x = 0; x < cxBuffer; x++)
BUFFER (x, y) = ' ';
xCaret = 0;
yCaret = 0;
InvalidateRect(hwnd, NULL, TRUE);
break;
default: // character codes
BUFFER(xCaret, yCaret) = (TCHAR)wParam;
HideCaret(hwnd);
hdc = GetDC(hwnd);
SelectObject(hdc, CreateFont(0, 0, 0, 0, 0, 0, 0, 0,dwCharSet, 0, 0, 0, FIXED_PITCH, NULL));
TextOut(hdc, xCaret * cxChar, yCaret * cyChar,& BUFFER(xCaret, yCaret), 1);
DeleteObject(SelectObject(hdc, GetStockObject(SYSTEM_FONT)));
ReleaseDC(hwnd, hdc);
ShowCaret(hwnd);
if(++xCaret == cxBuffer)
{
xCaret = 0;
if(++yCaret == cyBuffer)
yCaret = 0;
}
break;
}
}
SetCaretPos(xCaret * cxChar, yCaret * cyChar);
return 0;
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
SelectObject(hdc, CreateFont(0, 0, 0, 0, 0, 0, 0, 0,dwCharSet, 0, 0, 0, FIXED_PITCH, NULL));
for (y = 0; y < cyBuffer; y++)
TextOut(hdc, 0, y * cyChar, &BUFFER(0,y), cxBuffer);
DeleteObject(SelectObject(hdc, GetStockObject(SYSTEM_FONT)));
EndPaint(hwnd, &ps);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc (hwnd, message, wParam, lParam);
}