private void CacheInitialState()
{
this.hCurrentPen = this.hInitialPen = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, this.hDC), 1);
this.hCurrentBrush = this.hInitialBrush = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, this.hDC), 2);
this.hCurrentBmp = this.hInitialBmp = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, this.hDC), 7);
this.hCurrentFont = this.hInitialFont = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, this.hDC), 6);
}
/// <summary>
/// Creates a WindowsFont from the font selected in the supplied dc.
/// </summary>
public static WindowsFont FromHdc(IntPtr hdc)
{
IntPtr hFont = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(null, hdc), IntNativeMethods.OBJ_FONT);
// don't call DeleteObject on handle from GetCurrentObject, it is the one selected in the hdc.
return(FromHfont(hFont));
}
// Due to a problem with calling DeleteObject() on currently selected GDI objects,
// we now track the initial set of objects when a DeviceContext is created. Then,
// we also track which objects are currently selected in the DeviceContext. When
// a currently selected object is disposed, it is first replaced in the DC and then
// deleted.
private void CacheInitialState()
{
Debug.Assert(hDC != IntPtr.Zero, "Cannot get initial state without a valid HDC");
hCurrentPen = hInitialPen = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, hDC), IntNativeMethods.OBJ_PEN);
hCurrentBrush = hInitialBrush = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, hDC), IntNativeMethods.OBJ_BRUSH);
hCurrentBmp = hInitialBmp = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, hDC), IntNativeMethods.OBJ_BITMAP);
hCurrentFont = hInitialFont = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, hDC), IntNativeMethods.OBJ_FONT);
}
internal void DisposeFont(bool disposing)
{
if (disposing)
{
DeviceContexts.RemoveDeviceContext(this);
}
if ((this.selectedFont != null) && (this.selectedFont.Hfont != IntPtr.Zero))
{
if (IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, this.hDC), 6) == this.selectedFont.Hfont)
{
IntUnsafeNativeMethods.SelectObject(new HandleRef(this, this.Hdc), new HandleRef(null, this.hInitialFont));
IntPtr hInitialFont = this.hInitialFont;
}
this.selectedFont.Dispose(disposing);
this.selectedFont = null;
}
}
internal void DisposeFont(bool disposing)
{
if (disposing)
{
DeviceContexts.RemoveDeviceContext(this);
}
if (selectedFont != null && selectedFont.Hfont != IntPtr.Zero)
{
IntPtr hCurrentFont = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, hDC), IntNativeMethods.OBJ_FONT);
if (hCurrentFont == selectedFont.Hfont)
{
// select initial font back in
IntUnsafeNativeMethods.SelectObject(new HandleRef(this, Hdc), new HandleRef(null, hInitialFont));
hCurrentFont = hInitialFont;
}
selectedFont.Dispose(disposing);
selectedFont = null;
}
}
public static WindowsFont FromHdc(IntPtr hdc)
{
return(FromHfont(IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(null, hdc), 6)));
}
