Flex 分页预览，分页打印

Flex 打印常使用PrintDataGrid，但会有一些问题，不支持表格单元格合并，有的可能需要打印一些flex组件和容器（VBox, HBox, Text, Image）等。重写flex的Grid表格，Grid类似HTML的table, 能很好支持单元格合并，单元格中加入组件和容器。

自定义PrintDataGrid：

public class PrintDataGrid extends Grid
{
public static const pageHeight:int = 1023;

private var _realWidth:int;

public function PrintDataGrid()
{
this.horizontalScrollPolicy = ScrollPolicy.OFF;
this.verticalScrollPolicy = ScrollPolicy.OFF;

super();
}

public function addGridRow(gridRow:RowGrid):void {
addCells(gridRow.getAvailableCell(), gridRow.height);
}

private function addCells(cells:Array, height:Number):void {
var gridRow:GridRow = new GridRow();
for each(var cell:GridCell in cells) {
gridRow.addChild(cell);
}
gridRow.height = height;
this.addChild(gridRow);
}

public function get realWidth():int
{
return _realWidth;
}

public function set realWidth(value:int):void
{
_realWidth = value;
}
}

Adobe对于多页打印或打印预览都没有提供一个很好的解决办法，但可以根据Grid中GridRow的height,计算自动拆分表格，将一个大的Grid拆分每一个页面一个Grid，进行分页预览和打印。大概的算法：根据每页的height值计算一个页面能存放多少Grid的GridRow，超过的拆分到下一个页面，如果需要拆分的单元格存在被合并的情况，也就是GridItem
中RowSpan > 1, 则需要将一个GridItem，分为两个GridItem，而这两个的GridItem的rowSpan之和为原来的GridItem的RowSpan。

合并单元格拆分：

public function splitRowSpan(gridCellArray:GridCellArray):void {
if(cells.length == 0) {
return;
}
for(var i:int = 0; i < cells.length; i++) {
var gridCell:GridCell = cells[i] as GridCell;
if(gridCell == null) {
continue;
}
var splitCell:GridCell = null;
if (gridCell.isRemove) {
splitCell = gridCell.mergerCell;
}
if (splitCell == null) {
continue;
}
if (gridCell.rNum == splitCell.rNum) {
continue;
}
var orgRowSpan:int = splitCell.rowSpan;
var extRowSpan:int = gridCell.rNum - splitCell.rNum;

var content:DisplayObject = splitCell.getChildAt(0);

var topCellHeight:Number = getExtRowSpanHeight(splitCell.rNum, splitCell.rNum + extRowSpan, gridCellArray);
var bottomCellHeight:Number = getExtRowSpanHeight(splitCell.rNum + extRowSpan, splitCell.rNum + splitCell.rowSpan, gridCellArray);

splitCell.rowSpan = extRowSpan;
splitCell.height = topCellHeight;
if(topCellHeight < bottomCellHeight) {
splitCell.removeAllChildren();
}

var  bottomCell:GridCell = splitCell.newGridCell();
bottomCell.rowSpan = orgRowSpan - extRowSpan;
bottomCell.colSpan = splitCell.colSpan;
bottomCell.height = bottomCellHeight;
bottomCell.rNum = gridCell.rNum;
bottomCell.cNum = gridCell.cNum;
if(topCellHeight < bottomCellHeight) {
bottomCell.addChild(content);
}

var gridRow:RowGrid = gridCellArray.getRowGrid(gridCell.rNum);
gridRow.setCell(bottomCell, bottomCell.cNum);
if (bottomCell.rowSpan > 1 || bottomCell.colSpan > 1) {
gridCellArray.mergerGridCell(bottomCell);
}
}
}

原文出处：http://www.anyrt.com/blog/list/201609131739.html