如何于DataGridView控件中以跨数据行方式显示数据

一般来说，每一个字段的内容会单独显示于datagridview控件的一个数据行中。问题是，某些字段拥有大量文字数据，我是不是能够让该字段的内容以跨数据行的方式来显示，以便在有限的画面空间中的呈现出更完整的内容呢？答案当然是肯定的。

以图表1所示的执行画面而言，「自传」字段的内容并未单独显示于一个数据行中，而是以横跨数据行的方式，显示在同笔数据列之各字段内容的下方。相关程序代码列示如下：

using system;
using system.collections.generic;
using system.componentmodel;
using system.data;
using system.drawing;
using system.text;
using system.windows.forms;
using system.data.sqlclient;
…
…
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private int oldrowindex = 0;
private const int custom_content_height = 80;
private dataset mydataset;

private void ch13_demoform009_load(object sender, eventargs e)
{
    padding newpadding = new padding(0, 1, 0, custom_content_height);
    this.datagridview1.rowtemplate.defaultcellstyle.padding = newpadding;

    this.datagridview1.rowtemplate.defaultcellstyle.selectionbackcolor =
        color.transparent;

    this.datagridview1.rowtemplate.height += custom_content_height;

    this.datagridview1.allowusertoaddrows = false;
    this.datagridview1.editmode = datagridvieweditmode.editonkeystrokeorf2;
    this.datagridview1.cellborderstyle = datagridviewcellborderstyle.none;
    this.datagridview1.selectionmode = datagridviewselectionmode.fullrowselect;

    mydataset = loaddatatodataset();

    if(mydataset != null)
    {
        // 将 bindingsource 组件系结至数据集对象中的「飞狐工作室」数据表。
        this.bindingsource1.datamember = "飞狐工作室";
        this.bindingsource1.datasource = mydataset;

        this.bindingsource1.allownew = false;

        // 将 bindingnavigator 控件的数据来源也设定成 bindingsource 组件
        //，如此一来，就可以使用 bindingnavigator 控件去导览
        // datagridview 控件中的数据列。
        this.bindingnavigator1.bindingsource = this.bindingsource1;

        this.datagridview1.datasource = this.bindingsource1;
    }
    else
    {
        return;
    }

    this.datagridview1.columns[4].visible = false;

    this.datagridview1.columns[0].sortmode =
         datagridviewcolumnsortmode.notsortable;
    this.datagridview1.columns[2].sortmode =
         datagridviewcolumnsortmode.notsortable;
    this.datagridview1.columns[3].sortmode =
         datagridviewcolumnsortmode.notsortable;

    this.datagridview1.autoresizerows(
        datagridviewautosizerowsmode.allcellsexceptheaders);
}

private void datagridview1_columnwidthchanged(object sender,
                                         datagridviewcolumneventargs e)
{
    this.datagridview1.invalidate();
}

private void datagridview1_currentcellchanged(object sender, eventargs e)
{
    if(oldrowindex != -1)
    {
        this.datagridview1.invalidaterow(oldrowindex);
    }

    oldrowindex = this.datagridview1.currentcelladdress.y;
}

private void datagridview1_rowprepaint(object sender,
                            datagridviewrowprepainteventargs e)
{
    e.paintparts = e.paintparts & (~datagridviewpaintparts.focus);

    if((e.state & datagridviewelementstates.selected) ==
                                datagridviewelementstates.selected)
    {
        rectangle rowbounds = new rectangle(
            this.datagridview1.rowheaderswidth, e.rowbounds.top,
            this.datagridview1.columns.getcolumnswidth(
            datagridviewelementstates.visible) -
            this.datagridview1.horizontalscrollingoffset + 1,
            e.rowbounds.height);

        system.drawing.drawing2d.lineargradientbrush backbrush =
            new system.drawing.drawing2d.lineargradientbrush(rowbounds,
            this.datagridview1.defaultcellstyle.selectionbackcolor,
            e.inheritedrowstyle.forecolor,
            system.drawing.drawing2d.lineargradientmode.horizontal);

        try
        {
            e.graphics.fillrectangle(backbrush, rowbounds);
        }
        finally
        {
            backbrush.dispose();
        }
    }
}

private void datagridview1_rowpostpaint(object sender,
                               datagridviewrowpostpainteventargs e)
{
    rectangle rowbounds = new rectangle(this.datagridview1.rowheaderswidth,
        e.rowbounds.top, this.datagridview1.columns.getcolumnswidth(
   
    datagridviewelementstates.visible) -
        this.datagridview1.horizontalscrollingoffset + 1, e.rowbounds.height);

    solidbrush forebrush = null;

    try
    {
        if((e.state & datagridviewelementstates.selected) ==
            datagridviewelementstates.selected)
        {
            forebrush = new solidbrush(e.inheritedrowstyle.selectionforecolor);
        }
        else
        {
            forebrush = new solidbrush(e.inheritedrowstyle.forecolor);
        }

        object recipe =
          this.datagridview1.rows.sharedrow(e.rowindex).cells[4].value;

        if(!(recipe == null))
        {
            string text = recipe.tostring();
            rectangle textarea = rowbounds;
            rectanglef clip = textarea;

            textarea.x -= this.datagridview1.horizontalscrollingoffset;
            textarea.width += this.datagridview1.horizontalscrollingoffset;
            textarea.y += rowbounds.height - e.inheritedrowstyle.padding.bottom;
            textarea.height -= rowbounds.height -
                                   e.inheritedrowstyle.padding.bottom;
            textarea.height =
               (textarea.height / e.inheritedrowstyle.font.height) *
                e.inheritedrowstyle.font.height;
           
            clip.width -= this.datagridview1.rowheaderswidth + 1 - clip.x;
            clip.x = this.datagridview1.rowheaderswidth + 1;
                  
            rectanglef oldclip = e.graphics.clipbounds;

            e.graphics.setclip(clip);

            e.graphics.drawstring(text, e.inheritedrowstyle.font,
                                  forebrush, textarea);

            e.graphics.setclip(oldclip);
        }
    }
    finally
    {
        forebrush.dispose();
    }

    if (this.datagridview1.currentcelladdress.y == e.rowindex)
    {
        e.drawfocus(rowbounds, true);
    }
}

private void datagridview1_rowheightchanged(
                    object sender, datagridviewroweventargs e)
{
    int preferrednormalcontentheight =
       e.row.getpreferredheight(e.row.index,
        datagridviewautosizerowmode.allcellsexceptheader, true) -
        e.row.defaultcellstyle.padding.bottom;

    padding newpadding = e.row.defaultcellstyle.padding;
           
    newpadding.bottom = e.row.height - preferrednormalcontentheight;
    e.row.defaultcellstyle.padding = newpadding;
}

// 本程序会连接至数据来源并建立所需的 dataset 对象。
private dataset loaddatatodataset()
{
    // 利用 sqlconnectionstringbuilder 对象来构建连接字符串。
    sqlconnectionstringbuilder sqlstringbuilder =
        new sqlconnectionstringbuilder();

    sqlstringbuilder.datasource = @"(local)/sqlexpress";
    sqlstringbuilder.initialcatalog = "北风贸易";
    sqlstringbuilder.integratedsecurity = true;

    // 建立一个数据集。
    dataset ds = new dataset();

    try
    {
        using (sqlconnection northwindconnection =
            new sqlconnection(sqlstringbuilder.connectionstring))
        {
            sqlcommand cmdliming = new sqlcommand(
              "select 姓名,员工性别,出生日期, 目前薪资, 自传" +
              " from dbo.飞狐工作室 where 自传 is not null",
              northwindconnection);

            northwindconnection.open();

            using (sqldatareader drliming = cmdliming.executereader())
            {
                ds.load(
                  drliming,
                  loadoption.overwritechanges,
                  new string[] { "飞狐工作室" });
            }
        }
    }
    catch (exception)
    {
        messagebox.show(
            "要能够顺利执行本范例程序，您的计算机必须已安装 sql server " +
            "express，并且必须已附加了本书所附的「北风贸易」数据库。" +
            "关于如何安装 sql server express，请参阅附录或相关文件说明。");

        // 无法连接至 sql server。
        return null;
    }

    return ds;
}