This section contains a code sample that enables the user to select a font of a particular point size (by using the Choose Font dialog box), select a clip path (by using text drawn with this font), and then view the result of clipping to the text.
This code sample was used to create the illustration that appears in Clip Paths.
CHOOSEFONT cf; /* common dialog box font structure */
LOGFONT lf; /* logical font structure */
HFONT hfont; /* new logical font handle */
HFONT hfontOld; /* original logical font handle */
HDC hdc; /* display DC handle */
int nXStart, nYStart; /* drawing coordinates */
RECT rc; /* rect structure for painting window */
SIZE sz; /* structure that receives text extents */
double aflSin[90]; /* sine of 0-90 degrees */
double aflCos[90]; /* cosine of 0-90 degrees */
double flRadius,a; /* radius of circle */
int iMode; /* clipping mode */
HRGN hrgn; /* clip region handle */
LRESULT APIENTRY MainWndProc(
HWND hwnd, /* window handle */
UINT message, /* type of message */
WPARAM wParam, /* additional information */
LPARAM lParam) /* additional information */
{
PAINTSTRUCT ps;
switch (message) {
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
EndPaint(hwnd, &ps);
break;
case WM_COMMAND: /* command from app's menu */
switch (wParam) {
case IDM_VANISH: /* erases client area */
hdc = GetDC(hwnd);
GetClientRect(hwnd, &rc);
FillRect(hdc, &rc, GetStockObject(WHITE_BRUSH));
ReleaseDC(hwnd, hdc);
break;
case IDM_AND: /* sets clip mode to RGN_AND */
iMode = RGN_AND;
break;
case IDM_COPY: /* sets clip mode to RGN_COPY */
iMode = RGN_COPY;
break;
case IDM_DIFF: /* sets clip mode to RGN_DIFF */
iMode = RGN_DIFF;
break;
case IDM_OR: /* sets clip mode to RGN_OR */
iMode = RGN_OR;
break;
case IDM_XOR: /* sets clip mode to RGN_XOR */
iMode = RGN_XOR;
break;
case IDM_CLIP_PATH:
/* Retrieve a cached DC for the window. */
hdc = GetDC(hwnd);
/*
* Use the font requested by the user in the
* Choose Font dialog box to create a logical font,
* then select that font into the device context.
*/
hfont = CreateFontIndirect(cf.lpLogFont);
hfontOld = SelectObject(hdc, hfont);
/*
* Retrieve the dimensions of the rectangle
* that surrounds the text.
*/
GetTextExtentPoint32(hdc, "Clip Path", 9, &sz);
/*
* Set a clipping region using the rect that
* surrounds the text.
*/
hrgn = CreateRectRgn(nXStart, nYStart,
nXStart + sz.cx,
nYStart + sz.cy);
SelectClipRgn(hdc, hrgn);
/*
* Create a clip path using text drawn with
* the user's requested font.
*/
BeginPath(hdc);
TextOut(hdc, nXStart, nYStart, "Clip Path", 9);
EndPath(hdc);
SelectClipPath(hdc, iMode);
/* Compute the sine of 0, 1, ... 90 degrees. */
for (i = 0; i < 90; i++) {
aflSin[i] = sin( (((double)i) / 180.0)
* 3.14159);
}
/* Compute the cosine of 0, 1,... 90 degrees. */
for (i = 0; i < 90; i++) {
aflCos[i] = cos( (((double)i) / 180.0)
* 3.14159);
}
/* Set the radius value. */
flRadius = (double)(2 * sz.cx);
/*
* Draw the 90 rays extending from the
* radius to the edge of the circle.
*/
for (i = 0; i < 90; i++) {
MoveToEx(hdc, nXStart, nYStart,
(LPPOINT) NULL);
LineTo(hdc, nXStart + ((int) (flRadius
* aflCos[i])),
nYStart + ((int) (flRadius
* aflSin[i])));
}
/* Reselect the original font into the DC. */
SelectObject(hdc, hfontOld);
/* Delete the user's font. */
DeleteObject(hfont);
/* Release the DC. */
ReleaseDC(hwnd, hdc);
break;
case IDM_FONT:
/* Initialize necessary members. */
cf.lStructSize = sizeof (CHOOSEFONT);
cf.hwndOwner = hwnd;
cf.lpLogFont = &lf;
cf.Flags = CF_SCREENFONTS | CF_EFFECTS;
cf.rgbColors = RGB(0, 255, 255);
cf.nFontType = SCREEN_FONTTYPE;
/*
* Display the Font dialog box, allow the user
* to choose a font, and render text in the
* window with that selection.
*/
if (ChooseFont(&cf)) {
hdc = GetDC(hwnd);
hfont = CreateFontIndirect(cf.lpLogFont);
hfontOld = SelectObject(hdc, hfont);
crOld = SetTextColor(hdc, cf.rgbColors);
TextOut(hdc, nXStart, nYStart,
"Clip Path", 9);
SetTextColor(hdc, crOld);
SelectObject(hdc, hfontOld);
DeleteObject(hfont);
ReleaseDC(hwnd, hdc);
}
break;
default:
return DefWindowProc(hwnd, message, wParam,
lParam);
}
break;
case WM_DESTROY: /* window is being destroyed */
PostQuitMessage(0);
break;
default: /* if unprocessed... */
return DefWindowProc(hwnd, message, wParam, lParam);
}
return 0;
}