进一步讨论PHP Pear图表创建包Image_Graph

转载请注明出处：Just Do IT :: http://www.toplee.com/blog/?p=178
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我已经喜欢上了Image_Graph， 它简单好用而功能强大，这里在上次入门介绍基础上进一步讨论一下这个包。
Image_Graph入门请参考这篇Blog：http://www.toplee.com/blog/?p=169

使用背景图片
有些时候，我们需要实现效果更加丰富的图表，比如为客户增加必要的背景图片，这里我们在上次讨论的image_graph4.php 基础上增加图表的背景图片.

2image_graph1.php

addNew(‘plotarea’);
$Dataset =& Image_Graph::factory(‘dataset’);
$Dataset->addPoint(‘Jan’, 5, ‘J’);
$Dataset->addPoint(‘Feb’, 13, ‘F’);
$Dataset->addPoint(‘March’, 10, ‘M’);
$Plot =& $Plotarea->addNew(‘bar’, &$Dataset);

$Plot->setLineColor(‘green’);
$Plot->setBackgroundColor(‘green@0.1’);

$fill =& Image_Graph::factory(‘Image_Graph_Fill_Array’);
$fill->addColor(‘red’, ‘J’);
$fill->addColor(‘blue’, ‘F’);
$fill->addColor(‘yellow’, ‘M’);
$Plot->setFillStyle($fill);

//set Background
$bgfill =& Image_Graph::factory(‘Image_Graph_Fill_Image’, ‘images/helicopter.jpg’);
$Plotarea->setFillStyle($bgfill);

$Font =& $Graph->addNew(‘ttf_font’, ‘Bitstream-Vera-Sans-Mono’);
$Font->setSize(12);
$Graph->setFont($Font);

$YAxis =& $Plotarea->getAxis(IMAGE_GRAPH_AXIS_Y);
$YAxis->setTitle(‘Rainy Days’, ‘vertical’);
$XAxis =& $Plotarea->getAxis(IMAGE_GRAPH_AXIS_X);
$XAxis->setTitle(‘Month’);

$Graph->done();
?>

不幸的是，此时我们看到的背景图片被前面的图表遮盖，我们需要让它看起来更好看一些，这里可以通过使图表透明的方法来实现。修改下面的几行代码：

$fill->addColor(‘red@0.8’, ‘J’);
$fill->addColor(‘blue@0.5’, ‘F’);
$fill->addColor(‘yellow@0.2’, ‘M’);

现在我们能看到全部的直升飞机图片，大多数的图片可以在0.2的参数下达到最好的透明效果。

图表堆叠
下面我们将两组数据产生的图表进行堆叠，这里采用上下堆叠的方式。
2image_graph2.php

addNew(‘ttf_font’, ‘Bitstream-Vera-Sans-Mono’);
$Font->setSize(12);

$Graph->setFont($Font);

$Graph->add(
Image_Graph::vertical(
Image_Graph::factory(‘title’, array(‘My way or the highway’, 12)),
Image_Graph::vertical(
$Plotarea = Image_Graph::factory(‘plotarea’),
$Legend = Image_Graph::factory(‘legend’),
90
),
5
)
);
$Legend->setPlotarea($Plotarea);

// Create and populate 3 datasets

$Dataset1 =& Image_Graph::factory(‘dataset’);
$Dataset1->addPoint(‘Jan’, 1);
$Dataset1->addPoint(‘Feb’, 2);
$Dataset1->addPoint(‘Mar’, 2);
$Dataset1->addPoint(‘Apr’, 4);

$Dataset2 =& Image_Graph::factory(‘dataset’);
$Dataset2->addPoint(‘Jan’, 3);
$Dataset2->addPoint(‘Feb’, 4);
$Dataset2->addPoint(‘Mar’, 5);
$Dataset2->addPoint(‘Apr’, 2);

$Dataset3 =& Image_Graph::factory(‘dataset’);
$Dataset3->addPoint(‘Jan’, 10);
$Dataset3->addPoint(‘Feb’, 9);
$Dataset3->addPoint(‘Mar’, 12);
$Dataset3->addPoint(‘Apr’, 34);

$Dataset1->setName(‘The highway’);
$Dataset2->setName(‘Their way’);
$Dataset3->setName(‘My way’);

$Datasets = array($Dataset1,$Dataset2,$Dataset3);

$Plot =& $Plotarea->addNew(‘Image_Graph_Plot_Area’, array($Datasets,’stacked’));

$Plot->setLineColor(‘gray’);

$FillArray =& Image_Graph::factory(‘Image_Graph_Fill_Array’);
$FillArray->addColor(‘slateblue@0.2’);
$FillArray->addColor(‘fuchsia@0.2’);
$FillArray->addColor(‘lime@0.2’);

// set a standard fill style
$Plot->setFillStyle($FillArray);

$XAxis =& $Plotarea->getAxis(IMAGE_GRAPH_AXIS_X);
$XAxis->setTitle(‘Month’);

$YAxis =& $Plotarea->getAxis(IMAGE_GRAPH_AXIS_Y);
$YAxis->setTitle(‘The bigger the better’, ‘vertical’);

// output the Graph
$Graph->done();
?>

在这里我们使用了相同的month作为横轴标记，如果我们改变任何一个点的标记，图表会跟着改变，比如我们在第一个数据集中用Dec替换Jan，修改如下：
$Dataset1->addPoint(‘Dec’, 1);
$Dataset1->addPoint(‘Feb’, 2);
$Dataset1->addPoint(‘Mar’, 2);
$Dataset1->addPoint(‘Apr’, 4);
在数据集2中添加一个新的标记
$Dataset1 =& Image_Graph::factory(‘dataset’);
$Dataset1->addPoint(‘Dec’, 1);
$Dataset1->addPoint(‘Feb’, 2);
$Dataset1->addPoint(‘Mar’, 2);
$Dataset1->addPoint(‘Apr’, 4);

$Dataset2 =& Image_Graph::factory(‘dataset’);
$Dataset2->addPoint(‘Jan’, 3);
$Dataset2->addPoint(‘Feb’, 4);
$Dataset2->addPoint(‘Apr’, 5);
$Dataset2->addPoint(‘May’, 2);