Class: TEgDBGridEx
property OnBeforeDrawTitle: TEgDBGridBeforeDrawTitleEvent;Fired once per title cell, just before it is filled and painted,
whenever assigned - the title-row counterpart of OnBeforeDrawCell,
same mirrored parameter shape. Never fires for the fixed corner cell
(see CornerImageIndex),
which has no TColumn of its own.
FontColor, BackColor, and Font
arrive already resolved to what the title cell would normally use (VCL
Style and Title.Font/Title.Color already
applied); change them to override. Font is the actual
Canvas.Font about to be used, not a copy.
CellText arrives as the raw Title.Caption
(still substituted through
<var>/<br> at the final paint
step, not before - see OnGetVariableValue).
ImageIndex/ImageAlignment default from the
column’s own TitleImageIndex/
TitleImageAlignment.
Fires before the sort arrow, title image, and title text are drawn,
so any override here - including a changed
ImageIndex/ImageAlignment - is already in
effect for the rest of that cell’s own layout. A BackColor
change triggers a flat re-fill first; leaving BackColor
untouched lets a themed header element, or a gradient FixedCellStyle,
show through underneath exactly as it would without this handler
assigned - the same trade-off OnBeforeDrawCell
already makes.
If the column has a SubTitle, three
further parameters are available: SubTitleFontColor,
SubTitleFont (a scratch TFont, freshly copied
from the column’s own SubTitleFont before every fire -
changes here never leak back into the column’s persistent property, the
same safety Font already has for the main title), and
SubTitleText (defaults to the raw SubTitle,
parsed the same way CellText is). Setting
SubTitleText to an empty string suppresses that column’s
SubTitle for this one paint - but the event cannot make a
column show a SubTitle that was empty to begin with, since
row height is only reserved for a SubTitle that is
statically non-empty.
After both handlers have run (grid then column),
SubTitleFontColor can still change once more: if it ends up
too close in perceived brightness to the cell’s own final
BackColor, it is automatically nudged lighter or darker to
restore legibility, whether the handler set it explicitly or left the
resolved default in place. A handler that needs its exact color to reach
the screen unmodified should make sure that color already has enough
contrast against BackColor itself.
Replaces the older OnDrawTitleImage, which only covered
the title image and had no color, font, or text control. Also available
at column level (see TEgColumn.OnBeforeDrawTitle);
when both are assigned, the grid-level handler runs first. See TEgDBGridBeforeDrawTitleEvent.