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; // 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 DC.
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:
return DefWindowProc(hwnd, message, wParam, lParam);
}
return 0;
}