When writing on a bitmap, when the background of the text is set to be transparent, when I write multiple times in the s

lplp80131

As the title ~~~

wintermaul

You can do this, when writing the text for the second time, use the first question at the original position, XOR texture can restore the background color, and then write new text.

falconwbgjdl

Try:
If the text is drawn outside the PAINT message processing function, Invalidate() causes it to erase the background;
If you draw text in the PAINT message, use the space character padding to overwrite the previous text;

lplp80131

The specific approach is:
   I made a window background with a bitmap on a form, and then used a function to write text somewhere on the window background,
My function is:
wf_writetext(char *szstr, hbitmap hbit)
ulong dc, memdc, holdbitmap, htextcolor, htemp
RECT rt

dc=GetDC(handle(this))
memdc=CreateCompatibleDC(dc)
holdbitmap=SelectObject(memdc,hbit)
rt.top=40
rt.left=100
rt.right=200
rt.bottom=70
SetBkMode(memdc, TRANSPARENT)
DrawText(memdc, as_str, len(as_str), rt, DT_LEFT +DT_VCENTER)
BitBlt(dc, rt.left, rt.top, rt.right -rt.left, rt.bottom -rt.top, memdc, rt.left, rt.top, SRCCOPY)

SelectObject(memdc, holdbitmap)
DeleteDC(memdc)
ReleaseDC(handle(this),dc)
When I repeatedly call this function to write numbers at rt, the text will overlap,
Is my approach correct?
Does anyone have an example to solve this problem? Thank you

dymhome

Use a blank brush before each write: dc.SelectStockObject(NULL_BRUSH);