/// <summary>
/// Draw one cell of the header
/// </summary>
/// <param name="g"></param>
/// <param name="columnIndex"></param>
/// <param name="itemState"></param>
protected void CustomDrawHeaderCell(Graphics g, int columnIndex, int itemState)
{
Rectangle r = this.GetItemRect(columnIndex);
OLVColumn column = this.ListView.GetColumn(columnIndex);
const int CDIS_SELECTED = 1;
bool isPressed = ((itemState & CDIS_SELECTED) == CDIS_SELECTED);
// Calculate which style should be used for the header
HeaderStateStyle stateStyle = this.CalculateStyle(column, columnIndex == this.ColumnIndexUnderCursor, isPressed);
// If there is an owner drawn delegate installed, give it a chance to draw the header
if (column.HeaderDrawing != null)
{
if (!column.HeaderDrawing(g, r, columnIndex, column, isPressed, stateStyle))
{
return;
}
}
// Draw the background
if (this.ListView.HeaderUsesThemes &&
VisualStyleRenderer.IsSupported &&
VisualStyleRenderer.IsElementDefined(VisualStyleElement.Header.Item.Normal))
{
this.DrawThemedBackground(g, r, columnIndex, isPressed);
}
else
{
this.DrawUnthemedBackground(g, r, columnIndex, isPressed, stateStyle);
}
// Draw the sort indicator if this column has one
if (this.HasSortIndicator(column))
{
if (this.ListView.HeaderUsesThemes &&
VisualStyleRenderer.IsSupported &&
VisualStyleRenderer.IsElementDefined(VisualStyleElement.Header.SortArrow.SortedUp))
{
this.DrawThemedSortIndicator(g, r);
}
else
{
r = this.DrawUnthemedSortIndicator(g, r);
}
}
if (this.HasFilterIndicator(column))
{
r = this.DrawFilterIndicator(g, r);
}
// Finally draw the text
this.DrawHeaderImageAndText(g, r, column, stateStyle);
}
private bool NeedsCustomDraw(HeaderStateStyle style)
{
if (style == null)
{
return(false);
}
// If we want fancy colors or frames, we have to custom draw. Oddly enough, we
// can handle font changes without custom drawing.
if (!style.BackColor.IsEmpty)
{
return(true);
}
if (style.FrameWidth > 0f && !style.FrameColor.IsEmpty)
{
return(true);
}
return(!style.ForeColor.IsEmpty && style.ForeColor != Color.Black);
}
/// <summary>
/// Draw the header's image and text
/// </summary>
/// <param name="g"></param>
/// <param name="r"></param>
/// <param name="column"></param>
/// <param name="stateStyle"></param>
protected void DrawHeaderImageAndText(Graphics g, Rectangle r, OLVColumn column, HeaderStateStyle stateStyle)
{
TextFormatFlags flags = this.TextFormatFlags;
flags |= TextFormatFlags.VerticalCenter;
if (column.HeaderTextAlign == HorizontalAlignment.Center)
{
flags |= TextFormatFlags.HorizontalCenter;
}
if (column.HeaderTextAlign == HorizontalAlignment.Right)
{
flags |= TextFormatFlags.Right;
}
Font f = this.ListView.HeaderUsesThemes ? this.ListView.Font : stateStyle.Font ?? this.ListView.Font;
Color color = this.ListView.HeaderUsesThemes ? Color.Black : stateStyle.ForeColor;
if (color.IsEmpty)
{
color = Color.Black;
}
// Tweak the text rectangle a little to improve aethestics
r.Inflate(-3, 0);
r.Y -= 2;
const int imageTextGap = 3;
if (column.IsHeaderVertical)
{
DrawVerticalText(g, r, column, f, color);
}
else
{
// Does the column have a header image and is there space for it?
if (column.HasHeaderImage && r.Width > column.ImageList.ImageSize.Width * 2)
{
DrawImageAndText(g, r, column, flags, f, color, imageTextGap);
}
else
{
DrawText(g, r, column, flags, f, color);
}
}
}
/// <summary>
/// Draw a background for the header, without using Themes.
/// </summary>
/// <param name="g"></param>
/// <param name="r"></param>
/// <param name="columnIndex"></param>
/// <param name="isSelected"></param>
/// <param name="stateStyle"></param>
protected void DrawUnthemedBackground(Graphics g, Rectangle r, int columnIndex, bool isSelected, HeaderStateStyle stateStyle)
{
if (stateStyle.BackColor.IsEmpty)
{
// I know we're supposed to be drawing the unthemed background, but let's just see if we
// can draw something more interesting than the dull raised block
if (VisualStyleRenderer.IsSupported &&
VisualStyleRenderer.IsElementDefined(VisualStyleElement.Header.Item.Normal))
{
this.DrawThemedBackground(g, r, columnIndex, isSelected);
}
else
{
ControlPaint.DrawBorder3D(g, r, Border3DStyle.RaisedInner);
}
}
else
{
using (Brush b = new SolidBrush(stateStyle.BackColor))
g.FillRectangle(b, r);
}
// Draw the frame if the style asks for one
if (!stateStyle.FrameColor.IsEmpty && stateStyle.FrameWidth > 0f)
{
RectangleF r2 = r;
r2.Inflate(-stateStyle.FrameWidth, -stateStyle.FrameWidth);
g.DrawRectangle(new Pen(stateStyle.FrameColor, stateStyle.FrameWidth),
r2.X, r2.Y, r2.Width, r2.Height);
}
}
/// <summary>
/// What font should be used to draw the header text?
/// </summary>
/// <param name="column"></param>
/// <param name="isHot"></param>
/// <param name="isPressed"></param>
/// <returns></returns>
protected Font CalculateFont(OLVColumn column, bool isHot, bool isPressed)
{
HeaderStateStyle stateStyle = this.CalculateStyle(column, isHot, isPressed);
return(stateStyle.Font ?? this.ListView.Font);
}
