/// <summary>
/// 重写绘制单元格函数。
/// 首先调用DataGridViewTextBoxCell基类实现，
/// 删除错误图标和前景内容，这两个部分由自定义实现，
/// 在这个实例中通过调用Control.DrawToBitmap来实现，但这并不是最高性能的方式。
/// 另外一种是绘制图片的形式
/// </summary>
/// <param name="graphics"></param>
/// <param name="clipBounds"></param>
/// <param name="cellBounds"></param>
/// <param name="rowIndex"></param>
/// <param name="cellState"></param>
/// <param name="value"></param>
/// <param name="formattedValue"></param>
/// <param name="errorText"></param>
/// <param name="cellStyle"></param>
/// <param name="advancedBorderStyle"></param>
/// <param name="paintParts"></param>
protected override void Paint(Graphics graphics,
Rectangle clipBounds,
Rectangle cellBounds,
int rowIndex,
DataGridViewElementStates cellState,
object value,
object formattedValue,
string errorText,
DataGridViewCellStyle cellStyle,
DataGridViewAdvancedBorderStyle advancedBorderStyle,
DataGridViewPaintParts paintParts)
{
if (this.DataGridView == null)
{
return;
}
//首先绘制单元格的边框和背景
base.Paint(graphics, clipBounds, cellBounds, rowIndex, cellState, value, formattedValue, errorText, cellStyle, advancedBorderStyle,
paintParts & ~(DataGridViewPaintParts.ErrorIcon | DataGridViewPaintParts.ContentForeground));
Point ptCurrentCell = this.DataGridView.CurrentCellAddress;
bool cellCurrent = ptCurrentCell.X == this.ColumnIndex && ptCurrentCell.Y == rowIndex;
bool cellEdited = cellCurrent && this.DataGridView.EditingControl != null;
//如果单元格处于编辑模式则不绘制任何东西
if (!cellEdited)
{
if (PartPainted(paintParts, DataGridViewPaintParts.ContentForeground))
{
//绘制TrackBar,并将边界也考虑其中
Rectangle borderWidths = BorderWidths(advancedBorderStyle);//获取边框跨距宽度
Rectangle valBounds = cellBounds;
valBounds.Offset(borderWidths.X, borderWidths.Y);
valBounds.Width -= borderWidths.Right;
valBounds.Height -= borderWidths.Bottom;
//将填充也考虑在内
if (cellStyle.Padding != Padding.Empty)
{
if (this.DataGridView.RightToLeft == RightToLeft.Yes)
{
valBounds.Offset(cellStyle.Padding.Right, cellStyle.Padding.Top);
}
else
{
valBounds.Offset(cellStyle.Padding.Left, cellStyle.Padding.Top);
}
valBounds.Width -= cellStyle.Padding.Horizontal;
valBounds.Height -= cellStyle.Padding.Vertical;
}
//
valBounds = GetAdjustedEditingControlBounds(valBounds, cellStyle);
bool cellSelected = (cellState & DataGridViewElementStates.Selected) != 0;
if (renderingBitmap.Width < valBounds.Width || renderingBitmap.Height < valBounds.Height)
{
//图像太小，需重新绘制一个大点的
renderingBitmap.Dispose();
renderingBitmap = new Bitmap(valBounds.Width, valBounds.Height);
}
//确定TrackBar控件是一个可见的父控件
if (paintingTrackBar.Parent == null || !paintingTrackBar.Parent.Visible)
{
paintingTrackBar.Parent = this.DataGridView;
}
//设置相关属性
paintingTrackBar.Width = valBounds.Width;
paintingTrackBar.Height = valBounds.Height;
paintingTrackBar.RightToLeft = this.DataGridView.RightToLeft;
paintingTrackBar.Location = new Point(0, -paintingTrackBar.Height - 100);
paintingTrackBar.Value = (int)formattedValue;
//Color backColor;
//if (PartPainted(paintParts, DataGridViewPaintParts.SelectionBackground) && cellSelected)
//{
// backColor = cellStyle.SelectionBackColor;
//}
//else {
// backColor = cellStyle.BackColor;
//}
//if (PartPainted(paintParts, DataGridViewPaintParts.Background)) {
// if (backColor.A < 255) {
// //TrackBar不知吃透明的背景颜色
// backColor = Color.FromArgb(255,backColor);
// }
// //TrackBar.DefaultBackColor = backColor;
//}
//最后绘制TrackBar控件
Rectangle srcRect = new Rectangle(0, 0, valBounds.Width, valBounds.Height);
if (srcRect.Width > 0 && srcRect.Height > 0)
{
paintingTrackBar.DrawToBitmap(renderingBitmap, srcRect);
graphics.DrawImage(renderingBitmap, new Rectangle(valBounds.Location, valBounds.Size),
srcRect, GraphicsUnit.Pixel);
}
if (PartPainted(paintParts, DataGridViewPaintParts.ErrorIcon))
{
//在TrackBar上面绘制潜在的错误图标
base.Paint(graphics, clipBounds, cellBounds, rowIndex, cellState, value, formattedValue, errorText,
cellStyle, advancedBorderStyle, DataGridViewPaintParts.ErrorIcon);
}
}
}
}
