Analyse du fonctionnement du graphique PHP JPgraph

<?php
include ("src/jpgraph.php");
include("src/jpgraph_bar.php");
include ("src/jpgraph_line.php");
//设置显示的数据数组；
//调用类库
//设置图像的大小
$graph = new Graph(400,200,"auto");
$graph->SetScale("textlin");
//设置图形的边距
$graph->img->SetMargin(40,180,40,40);
//设置图形的背景图片，填充方式有：BGIMG_FILLPLOT, BGIMG_FILLFRAME, BGIMG_COPY
$graph->SetBackgroundImage("abc.jpg",BGIMG_FILLPLOT);
$graph->img->SetAngle(45); //设置图形在图像中的角度
//设置背景图片的对比度，must be between -1 <= x <= 1, (0,0)=original image
$graph->AdjBackgroundImage(0,0);
//设置投影；
//$graph->SetShadow();
//设置标题
$graph->title->Set("test image");
//设置标题字体样式
$graph->title->SetFont(FF_FONT1,FS_BOLD);
//设置标题的边距
$graph->title->SetMargin(3);
//设置图列的位置
$graph->legend->Pos(0.05,0.5,"right","center");
//设置图列的投影，颜色
$graph->legend->SetShadow(&#39;darkgray@0.1&#39;);
$graph->legend->SetFillColor(&#39;lightblue@0.3&#39;);
//设置x轴的标记
$graph->xaxis->SetTickLabels($label_x);
//设置X轴的显示值的角度;
$graph->xaxis->SetLabelAngle(30);
//设置x轴标题和字体颜色
$graph->xaxis->title->Set(&#39;Year 2006&#39;);
$graph->xaxis->title->SetFont(FF_FONT1,FS_BOLD);
$graph->xaxis->title->SetColor(&#39;white&#39;);
//设置x轴的字体和颜色
$graph->xaxis->SetFont(FF_FONT1,FS_BOLD);
$graph->xaxis->SetColor(&#39;yellow&#39;);
//设置y轴的字体和颜色
$graph->yaxis->SetFont(FF_FONT1,FS_BOLD);
$graph->yaxis->SetColor(&#39;yellow&#39;);
//设置是否显示格子。默认为显示；
//$graph->ygrid->Show(false);
//设置格子的颜色和粗细。值越小，格子越粗。
$graph->ygrid->SetColor(&#39;yellow@0.5&#39;);
//设置y轴更优美一些
$graph->yaxis->scale->SetGrace(20);
//设置图列的数据
$bplot1 = new BarPlot($datay1);
$bplot2 = new BarPlot($datay2);
//设置图列的填充颜色
$bplot1->SetFillColor(&#39;orange@0.4&#39;);
$bplot2->SetFillColor(&#39;brown@0.4&#39;);
//设置值的格式
$bplot1->value->SetFormat(&#39;%d&#39;);
//设置图列标签
$bplot1->SetLegend(&#39;Label 1&#39;);
$bplot2->SetLegend(&#39;Label 2&#39;);
//设置图列在图中的阴影
$bplot1->SetShadow(&#39;black@0.4&#39;);
$bplot2->SetShadow(&#39;black@0.4&#39;);
//生成图列
$gbarplot = new GroupBarPlot(array($bplot1,$bplot2));
$gbarplot->SetWidth(0.9);
$graph->Add($gbarplot);
//生成图形
$graph->Stroke();
//上面所说的时在生成柱形图，当生成线性图时用下面的方法
$p1 = new LinePlot($datay);
$p1->mark->SetType(MARK_FILLEDCIRCLE);
$p1->mark->SetFillColor("red");
$p1->mark->SetWidth(4);
$p1->SetColor("blue");
$p1->SetCenter();
$p1->SetLegend("Triumph Tiger -98");
$graph->Add($p1);
$p2 = new LinePlot($data2y);
$p2->mark->SetType(MARK_STAR);
$p2->mark->SetFillColor("red");
$p2->mark->SetWidth(4);
$p2->SetColor("red");
$p2->SetCenter();
$p2->SetLegend("New tiger -99");
$graph->Add($p2);
// Style can also be specified as SetStyle([1|2|3|4]) or
// SetStyle("solid"|"dotted"|"dashed"|"lobgdashed")
$lineplot->SetStyle("dashed");//设置线的样式
$graph->yaxis->scale->SetGrace(20); //设置y轴更优美一些
?>

if($tag == 1)
{
$graph = new Graph(600,400,"auto");
$graph->SetScale("textlin");
$graph->setMarginColor('lightblue');
$graph->SetShadow();
$graph->setMargin(30,100,30,60);
//设置标题;
$graph->title->set("文章分类汇总");
$graph->title->SetMargin(3);
$graph->title->setfont(FF_SIMSUN,FS_BOLD);
$graph->title->setcolor('black@0.5');
$graph->yaxis->title->SetFont(FF_SIMSUN,FS_BOLD);
$graph->xaxis->title->SetFont(FF_SIMSUN,FS_BOLD);
$graph->xaxis->SetFont(FF_SIMSUN,FS_NORMAL);
$graph->xaxis->SetColor('darkblue','black');
$graph->xaxis->SetTickLabels($name);
$graph->xaxis->SetLabelAngle(30);
$bplot = new BarPlot($article_num);
$bplot->SetFillColor("orange");
$bplot->value->SetFormat('%d');
$bplot->SetShadow('darkgray');
$bplot->value->show();
$graph->legend->SetFont(FF_SIMSUN,FS_BOLD);
$bplot->SetLegend("文章数");
$graph->Add($bplot);
$graph->Stroke();
}
else
{
$graph1 = new PieGraph(600,400,"auto");
$graph1->SetScale("textlin");
$graph1->SetShadow();
$graph1->title->setFont(FF_SIMSUN,FS_BOLD);
$graph1->title->set("用户文章饼形图");
$graph1->setMargin(30,100,30,60);
$p1 = new pieplot3d($article_num);
$p1->setAngle(80);
$p1->setsize(0.5);
$p1->setShadow();
$p1->ExplodeSlice(2);
$p1->SetCenter(0.4);
$graph1->legend->SetFont(FF_SIMSUN,FS_NORMAL);
$graph1->legend->setshadow();
$p1->SetLegends($name);
$graph1->Add($p1);
$graph1->Stroke();
}
//生成本地图片
$graph->Stroke("路径/文件名.png");