How can I remove text after clicking? - c

Question

I'm making the prototype for my own visual novel game engine.
while (i < 5)
{
switch (iMessage)
{
case WM_LBUTTONDOWN:
{
//InvalidateRect(hWnd, NULL, TRUE);
HDC hdc;
hdc = GetDC(hWnd);
_wsetlocale(LC_ALL, L"Korean");
ReadScn(buf);
//MultiByteToWideChar(CP_ACP, MB_PRECOMPOSED, char, strlen(buf), buf3, 256);
CharToWChar(buf, buf2);
TextOut(hdc, 320, 300, buf2, lstrlen(buf2)); //읽어들여서 출력함.
//TCHAR*str = TEXT("beautiful korea");
//TextOut(hdc, 320, 240, str, lstrlen(str));
ReleaseDC(hWnd, hdc);
i++;
return 0;
}
}
I wrote 5 lines of text to scn.txt. Then the program prints the texts to a window, but the text lines are overlapped.
How can I remove the previous text after clicking and print new text line?

Answer 1

The correct way to handle this is to NOT draw anything on the window from inside of the WM_LBUTTONDOWN message handler at all. That logic belongs in the WM_PAINT message handler instead. Have the WM_LBUTTONDOWN handler save the current line of text to a variable and then InvalidateRect() the window to trigger a repaint. The WM_PAINT handler can then draw the current line whenever the window needs to be painted (which can happen more than once between button clicks).
Try this:
case WM_LBUTTONDOWN:
{
_wsetlocale(LC_ALL, L"Korean");
ReadScn(buf); //read text from scn.txt and keep it in buf line by line.
CharToWChar(buf, buf2); //convert char into wChar.
InvalidateRect(hwnd, NULL, TRUE); //trigger a repaint
return 0;
}
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
TextOut(hdc, 320, 300, buf2, lstrlen(buf2));
EndPaint(hwnd, &ps);
return 0;
}