// this DC is cached and should only be deleted on Dispose or when the size changes.
public Gdi32.HDC GetCachedItemDC(Gdi32.HDC toolStripHDC, Size bitmapSize)
{
if (_cachedHDCSize.Width < bitmapSize.Width ||
_cachedHDCSize.Height < bitmapSize.Height)
{
if (_cachedItemHDC.IsNull)
{
// Create a new DC - we don't have one yet.
_cachedItemHDC = Gdi32.CreateCompatibleDC(toolStripHDC);
}
// Create compatible bitmap with the correct size.
_cachedItemBitmap = Gdi32.CreateCompatibleBitmap(toolStripHDC, bitmapSize.Width, bitmapSize.Height);
Gdi32.HGDIOBJ oldBitmap = Gdi32.SelectObject(_cachedItemHDC, _cachedItemBitmap);
// Delete the old bitmap
if (!oldBitmap.IsNull)
{
Gdi32.DeleteObject(oldBitmap);
}
// remember what size we created.
_cachedHDCSize = bitmapSize;
}
return(_cachedItemHDC);
}
/// <summary>
/// Restores the device context to the specified state. The DC is restored by popping state information off a
/// stack created by earlier calls to the SaveHdc function.
/// The stack can contain the state information for several instances of the DC. If the state specified by the
/// specified parameter is not at the top of the stack, RestoreDC deletes all state information between the top
/// of the stack and the specified instance.
/// Specifies the saved state to be restored. If this parameter is positive, nSavedDC represents a specific
/// instance of the state to be restored. If this parameter is negative, nSavedDC represents an instance relative
/// to the current state. For example, -1 restores the most recently saved state.
/// See MSDN for more info.
/// </summary>
public void RestoreHdc()
{
// Note: Don't use the Hdc property here, it would force handle creation.
Gdi32.RestoreDC(_hDC, -1);
Debug.Assert(_contextStack != null, "Someone is calling RestoreHdc() before SaveHdc()");
if (_contextStack != null)
{
GraphicsState g = _contextStack.Pop();
_hCurrentBmp = g.hBitmap;
_hCurrentBrush = g.hBrush;
_hCurrentPen = g.hPen;
_hCurrentFont = g.hFont;
if (g.font != null && g.font.IsAlive)
{
ActiveFont = g.font.Target as WindowsFont;
}
else
{
WindowsFont?previousFont = ActiveFont;
ActiveFont = null;
if (previousFont != null && MeasurementDCInfo.IsMeasurementDC(this))
{
previousFont.Dispose();
}
}
}
// in this case, GDI will copy back the previously saved font into the DC.
// we dont actually know what the font is in our measurement DC so
// we need to clear it off.
MeasurementDCInfo.ResetIfIsMeasurementDC(_hDC);
}
// 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()
{
_hCurrentPen = _hInitialPen = Gdi32.GetCurrentObject(this, Gdi32.ObjectType.OBJ_PEN);
_hCurrentBrush = _hInitialBrush = Gdi32.GetCurrentObject(this, Gdi32.ObjectType.OBJ_BRUSH);
_hCurrentBmp = _hInitialBmp = Gdi32.GetCurrentObject(this, Gdi32.ObjectType.OBJ_BITMAP);
_hCurrentFont = _hInitialFont = Gdi32.GetCurrentObject(this, Gdi32.ObjectType.OBJ_FONT);
}
public void GetStockBrushes(int id, uint color, uint brushStyle)
{
Gdi32.HGDIOBJ hgdiobj = Gdi32.GetStockObject((Gdi32.StockObject)id);
Assert.False(hgdiobj.IsNull);
Gdi32.GetObjectW(hgdiobj, out Gdi32.LOGBRUSH logBrush);
Assert.Equal(color, logBrush.lbColor);
Assert.Equal((Gdi32.BS)brushStyle, logBrush.lbStyle);
}
private void FillRectDither(Gdi32.HDC dc, RECT rc)
{
Gdi32.HGDIOBJ hbrushOld = Gdi32.SelectObject(dc, _hbrushDither);
if (!hbrushOld.IsNull)
{
int oldTextColor = Gdi32.SetTextColor(dc, ColorTranslator.ToWin32(SystemColors.ControlLightLight));
int oldBackColor = Gdi32.SetBkColor(dc, ColorTranslator.ToWin32(SystemColors.Control));
Gdi32.PatBlt(dc, rc.left, rc.top, rc.right - rc.left, rc.bottom - rc.top, Gdi32.ROP.PATCOPY);
Gdi32.SetTextColor(dc, oldTextColor);
Gdi32.SetBkColor(dc, oldBackColor);
}
}
public void DeleteObject(Gdi32.HGDIOBJ handle, GdiObjectType type)
{
Gdi32.HGDIOBJ handleToDelete = default;
switch (type)
{
case GdiObjectType.Pen:
if (handle == _hCurrentPen)
{
Gdi32.HGDIOBJ currentPen = Gdi32.SelectObject(this, _hInitialPen);
Debug.Assert(currentPen == _hCurrentPen, "DeviceContext thinks a different pen is selected than the HDC");
_hCurrentPen = default;
}
handleToDelete = handle;
break;
case GdiObjectType.Brush:
if (handle == _hCurrentBrush)
{
Gdi32.HGDIOBJ currentBrush = Gdi32.SelectObject(this, _hInitialBrush);
Debug.Assert(currentBrush == _hCurrentBrush, "DeviceContext thinks a different brush is selected than the HDC");
_hCurrentBrush = default;
}
handleToDelete = handle;
break;
case GdiObjectType.Bitmap:
if (handle == _hCurrentBmp)
{
Gdi32.HGDIOBJ currentBmp = Gdi32.SelectObject(this, _hInitialBmp);
Debug.Assert(currentBmp == _hCurrentBmp, "DeviceContext thinks a different brush is selected than the HDC");
_hCurrentBmp = default;
}
handleToDelete = handle;
break;
}
Gdi32.DeleteObject(handleToDelete);
}
