CODEWITHSUNDEEP
c++winapi
PsychoMantis
PsychoMantis

Reputation: 1015

WINAPI BeginPaint and TextOut multiple calls within custom function

i've hit another wall in my printText function and have been searching for a while now for a solution with no luck.

Basically, the printText function is called within the WM_PAINT message to paint text to a win32 window. It works fine but only for one call. If i try to call the function for a second time with different parameters nothing appears to happen.

Im sure i am just completely overlooking something again but I can't see what it could possibly be.

the function is as follows:

void controls::printText(unsigned char R, unsigned char G, unsigned char B, int x, int y, LPCSTR text, HWND parent, PAINTSTRUCT pss, HDC hdc)
{

    hdc = BeginPaint(parent, &pss);
    SetBkMode(hdc, TRANSPARENT);
    SetTextColor(hdc, RGB(R,G,B));
    TextOut(hdc, x, y, text, strlen(text));     
    EndPaint(parent, &pss);

}

It is inside a 'controls' class and the calls are as follows:

HDC hdc, hdc2;
PAINTSTRUCT ps, ps2;

ctrls->printText(255,0,0,30,50,"Test text",hWnd,ps,hdc);
ctrls->printText(255,0,0,30,80,"test text 2",hWnd,ps2,hdc2);

There are two(2) HDC and PAINTSTRUCT declarations as I've been playing with the code trying to find a solution; I tried removing the paintstruct and hdc arguments from the function and having them declared inside the function as locals (which doesn't make a great deal of sense to me) with no success.

Basically, the first line,

ctrls->printText(255,0,0,30,50,"Test text",hWnd,ps,hdc);

Will do as it should and print "test text", in red, starting at (30,50) but the second line does not print anything. If i remove the first line, however, the second line works fine also.

please note: i may have used paint and print synonymously here whilst describing.

I think i've included everything relevant here but if any other code is needed just let me know and i'll post it as soon as i see the message :)

Thanks in advance again guys, your time and answers are much appreciated.

Upvotes: 1

Views: 1335

Answers (1)

Puppy
Puppy

Reputation: 147018

The documentation quite clearly states

An application should not call BeginPaint except in response to a WM_PAINT message.

So you should call it once per WM_PAINT and no more.

Upvotes: 4

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