DataGrid 背景颜色的控制（一）

设置行(row)的背景色
主要是通过对DataGrid扩展，对protected函数drawRowBackground()进行重写，具体代码如下：

override protected function drawRowBackground(s:Sprite, rowIndex:int, y:Number, height:Number,color:uint, dataIndex:int):void

{

     if (dataIndex >= dataProvider.length) {

         super.drawRowBackground(s,rowIndex,y,height,color,dataIndex);

         return;

     }


     if (dataProvider.getItemAt(dataIndex).col3 < 2000) {//set color accordint to datas

         super.drawRowBackground(s,rowIndex,y,height,0xC0C0C0,dataIndex);

     } else {

         super.drawRowBackground(s,rowIndex,y,height,color,dataIndex);

     }

}

这段代码中根据DataGrid的数据源进行判断来设置背景色，但是它有个缺陷，就是这个具体的背景色我们无法自己灵活指定。因此派生出新的CustomRowColorDataGrid，具体代码如下：

package cwmlab.controls

{

      import mx.controls.*;

      import flash.display.Shape;

      import mx.core.FlexShape;

      import flash.display.Graphics;

      import flash.display.Sprite;

      import mx.rpc.events.AbstractEvent;

      import mx.collections.ArrayCollection;

      import flash.events.Event;



      /**

       * This is an extended version of the built-in Flex datagrid.

       * This extended version has the correct override logic in it

       * to draw the background color of the cells, based on the value of the

       * data in the row.

       **/

      public class CustomRowColorDataGrid extends DataGrid

      {

            private var _rowColorFunction:Function;

           

            public function CustomRowColorDataGrid()

            {

                  super();

            }

            /**

             * A user-defined function that will return the correct color of the

             * row. Usually based on the row data.

             *

             * expected function signature:

             * public function F(item:Object, defaultColor:uint):uint

             **/

            public function set rowColorFunction(f:Function):void

            {

                  this._rowColorFunction = f;

            }

           

            public function get rowColorFunction():Function

            {

                  return this._rowColorFunction;

            }

           

          /**

             *  Draws a row background

             *  at the position and height specified using the

             *  color specified.  This implementation creates a Shape as a

             *  child of the input Sprite and fills it with the appropriate color.

             *  This method also uses the <code>backgroundAlpha</code> style property

             *  setting to determine the transparency of the background color.

             *

             *  @param s A Sprite that will contain a display object

             *  that contains the graphics for that row.

             *

             *  @param rowIndex The row's index in the set of displayed rows.  The

             *  header does not count, the top most visible row has a row index of 0.

             *  This is used to keep track of the objects used for drawing

             *  backgrounds so a particular row can re-use the same display object

             *  even though the index of the item that row is rendering has changed.

             *

             *  @param y The suggested y position for the background

             *  @param height The suggested height for the indicator

             *  @param color The suggested color for the indicator

             *

             *  @param dataIndex The index of the item for that row in the

             *  data provider.  This can be used to color the 10th item differently

             *  for example.

           */

          override protected function drawRowBackground(s:Sprite,rowIndex:int,y:Number, height:Number, color:uint, dataIndex:int):void

          {

            if( this.rowColorFunction != null ){

                  if( dataIndex < this.dataProvider.length ){

                        var item:Object = this.dataProvider.getItemAt(dataIndex);

                        color = this.rowColorFunction.call(this, item, color);

                  }

            }           

            super.drawRowBackground(s, rowIndex, y, height, color, dataIndex);

          }

      }

}



在具体使用过程中可以这样调用：

<cwmlab:CustomRowColorDataGrid dataProvider="{dp}" rowColorFunction="setCustomColor">



private function setCustomColor(item:Object, color:uint):uint

{

    if( item['col3'] >= 2000 )

    {

        return 0xFF0033;

    }

    return color;

}

设置DataGrid列的背景色
这个很简单，只要设置DataGridColumn的属性backgroundColor="0x0000CC"即可。

设置DataGrid单元格(cell)的背景色
这个主要通过itemRenderer进行设置，itemRenderer可以是Label，也可以是其他如DataGridItemRenderer。

先看看用Label如何设置背景色

<mx:DataGridColumn headerText="Make" dataField="col1">

      <mx:itemRenderer>

             <mx:Component>

                  <mx:Label>  <!--using label as itemRenderer-->

                      <mx:Script><![CDATA[

                          override public function set data(value:Object):void

                          {

                              super.data = value;

                              if(value.col1 == 'Toyota'){

                                 this.opaqueBackground =0xCC0000;

                              }

                          }

                      ]]></mx:Script>

                  </mx:Label>

             </mx:Component>

      </mx:itemRenderer>

</mx:DataGridColumn>

用DataGridItemRenderer进行背景色设置如下：

<mx:DataGridColumn headerText="Year" dataField="col3">

     <mx:itemRenderer>

          <mx:Component>

              <mx:DataGridItemRenderer><!--using DataGridItemRenderer as itemRenderer-->

                   <mx:Script><![CDATA[

                       override public function set data(value:Object):void

                       {

                           super.data = value;

                           if(value.col3 >= 2000){

                                this.background = true;

                                this.backgroundColor =0x00cc00;

                           }

                        }

                   ]]></mx:Script>

              </mx:DataGridItemRenderer>

          </mx:Component>

     </mx:itemRenderer>

</mx:DataGridColumn>