GetTextExtentPoint causes aliasing - c++

Question

To whom it may concern,
GetTextExtentPoint and GetTextExtentPoint32 is giving me a bad day.
They are the only method MSDN offers for measuring text but they have two flaws, but nobody else seems to have these problems.
Firstly, they dont take into account newline. They treat the measurement as one long one liner.
Secondly and most importantly, they are causing aliasing when I do DrawText(). I am using ClearType for HFONT but still get aliasing text being drawn.
Kindly let me know precisely what is the problem. Or I might have to create my own measuring text function.
EDIT_________
// note font is created with CLEAR_TYPE_QUALITY
// so it should be antialiased
HFONT createFont(const char *face_name,int height)
{
return CreateFont(height,cHeight,0,0,0,FW_NORMAL,false,false,false,0,0,0,CLEAR_TYPE_QUALITY,0,face_name);
}
RECT box{0,0,640,480);
POINT pos{};
HFONT font = createFont("MyFavouriteFont",30);
HDC canvas = CreateCompatableDC(NULL);
HBITMAP bmp = CreateCompatibleBitmap(NULL,640,480);
SelectBitmap(canvas,bmp);
SelectFont(canvas,font);
SelectBrush(canvas,GetStockObject(DC_BRUSH));
SetDCBrushColor(RGB(255,255,255));
SetBkMode(TRANSPARENT);
SIZE measureText_Msdn(const char *s,HDC font)
{
SIZE sz;
GetTextExtentPoint(font,s,strlen(s),&sz);
return sz;
}
SIZE measureText_Custom(const char *s,HDC font)
{
SIZE sz;
TEXTMETRICSA metrics;
INT char_width, line_width;
// get char height
GetTextMetrics(font,&metrics);
while(*it)
{
if(*it == '\n' || *it == '\r')
{
if(line_width > sz.cx) sz.cx = line_width; // sz.cx stores max width
sz.cy += metrics.tmHeight;
line_width = 0;
}
else
{
GetCharWidth32(font,*it,*it,&char_width);
line_width += char_width;
}
++it;
}
if(line_width > sz.cx) sz.cx = line_width;
if(line_width > 0) sz.cy += metrics.tmHeight; // If there are no chars on this line, the line has no size
return sz;
}
void drawText(HDC dest_ctx)
{
auto s = ,"Text will look blocky";
measureText_Msdn(s,font);
// or measureText_Custom(s,font); will cause font to look blocky and ugly
// If you comment out measureText_* text will be drawn smooth.
FillRect(canvas, &box,(HBRUSH)GetCurrentObject(canvas,OBJ_BRUSH));
DrawTextA(canvas,s,-1,&box,DT_LEFT);
BitBlt(dest_ctx,pos.x,pos.y,box.right,box.bottom,
canvas,0,0,SRCCOPY);
}
SOLUTION_____
I have posted a solution as an answer. I dont like to have to do it. As I said earlier, nobody else seems to have this problem so nobody else would need the solution.

Answer 1

As I said earlier nobody seems to get blocky text when using any of the text measuring functions. I get it when using any of them.
What I noticed is that calling these functions require a context, and the functions seems to be currupting the context. Even if I select a new font into the context I still get blocky text output.
Thus I create a context on the fly and add the desired font into it. And measure with that context, collect the result and delete that context. I tested this and my text are drawn smooth as my original context is unaffected.
Reasons I hate this method:
- I am afraid of the expense of creating and deleting context on the fly.
- I dont think GetTextExtent should currupt my context in the first place.
If you guys have a better way, or know my problem, or why I shouldnt be having this problem kindly post.
EDIT_________
After looking at using keyboard tutorial on MSDN, I saw where the author using a window context instead of memory context for calls to GetTextExtent. It appears that GetTextExtent and the other measurement functions are only meant to be used with window contexts. Which is perfectly fine for me as I dont like Creating Memory Context anyhow.