The overall size of the graph is specified in the initial creation of the "$graph" instance. This is mandatory.

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$graph = new Graph($width,$height);

The margin determines the space between the edges of the plotarea and edge of the graph. Please note that the edge does not include the frame around the entire graph area, i.e. whatever weight the frame edge has it doesn't impact on the margin area. The margin is specified in the order left,right,top and bottom margin and the size is specified in pixels.

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$graph->SetMargin(30,10,40,20);

The default margin will be as narrow as possible but still have enough space to show the titles and labels. The final adjustments is wheter or not the graph will have a frame or not. There are two distinctions to be made here. No frame meaning that the margin area will not be colored (i.e. painted) and no frame as in no edge around the graph area. The first case is achieved by calling the SetFrame() method on the Graph class

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$graph->SetFrame(false);

and the second case is achieved by setting the frame edge to have weight zero. Since the weight is given as the third argument we wtill have to put in valid "dummy" argument for the on/off flag and the frame color parameter.

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$graph->SetFrame(true,'black',0);

Refer to Figure 12.1. Commonly used objects in a graph (common-obj-graph.php) for definitoin of plot aea and margin.

A graph can have a drop shadow specified with the method SetShadow() which has the signature

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SetShadow($aShowShadow=true,$aShadowWidth=5,$aShadowColor=array(102,102,102))

by default there will be no dropshadow. Note that the drop shadow is a straight simple shadow and has no Gaussian blur.

There are three possible standard titles in the graph

Each title is an instance of the Text class which means it supports the standard text adjusting methods SetFont(), Set(), SetColor() etc. The title s will be centered on the top of the graph area with the title highest up, subtitle below and finally the subsubtitle below that as shown in Figure 14.6. The various titles in a graph (titleex1.php)

Figure 14.6. The various titles in a graph (titleex1.php)

In addition to the above standard titles there is also another type of graph titles called the "Tabular title". This is a title that sits directly on the plot area looking like a "tab" in a sorting cabinet. Figure 14.7. Tabtitle and gradient background (gradbkgex1.php) and Figure 14.8. Tabtitle and image marker in a line plot (imgmarkerex1.php) shows examples of this.

Figure 14.7. Tabtitle and gradient background (gradbkgex1.php)

Figure 14.8. Tabtitle and image marker in a line plot (imgmarkerex1.php)

These type of titles are created by using the

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$graph->tabtitle

property in the Graph class. For example the tabtitle in Figure 7.2. Making use of transparency to combine two plots (barlinealphaex1.php) was generated by adding the lines

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$graph->tabtitle->Set('Year 2003');
$graph->tabtitle->SetFont(FF_ARIAL,FS_BOLD,10);

As described in Necessary system requirements for the library the actual image compression available depends on the system setup. Assuming the needed sewtup is done then the image format can be specified by using the method Graph::SetImgFormat() and specifying the wanted format as a string. For example as

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$graph->SetImgFormat('jpg',80);

The method call above selects JPEG image compression algorithm and tells the algorithm to set the quality parameter to 80%. This additional parameter is only applicable together with JPG formatting.

Any lines in the library can have a number of formatting option. Attributes that can be adjusted are

It is possible to add a footer to the graph as well. The footer can have a left, center and right part. The footer is accessed trough the footer property of the Graph class and its three parts "left", "right" and "center". These parts are instances of the Text class and hence all normal text formatting c an be applied to each part of the footer. The following code snippet shows how the footer parts can be set.

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$graph->footer->left->Set('Left footer');
                        $graph->footer->center->Set('Center footer');
                        $graph->footer->right->Set('Right footer');

An example of using a footer is shown in Figure 14.11. Adding a left,right and center footer (footerex1.php)

Figure 14.10. Using a footer in a graph

Figure 14.11. Adding a left,right and center footer (footerex1.php)

The footer in the bottom of the graph can also be used to show an approximative timing of the graph generation. This is done with the help of class JpgTimer. This timer class offers two methods

(The stack based design makes it possible to have multiple timers running at the same time without interfering each other.)

The footer class (Adding a footer to the graph) have a special provision to handle an instance of the timer class

At the end of the graph generation the specified timer will be sent the sign pop and the resulting timer value will be stored in the right footer of the graph (appended to any previous value in the footer). For example the following simple lines would time the graph generation.

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<?php
// Create a new timer instance
$timer = new JpgTimer();
 
// Start the timer
$timer->Push();
 
// Create the graph. These two calls are always required
$graph = new Graph(300,200);
$graph->SetScale("textlin");
 
// Make the bottom margin large enough to hold the timer value
$graph->SetMargin(40,20,20,60);
 
$graph->title->Set("Timing a graph");
$graph->footer->right->Set('Timer (ms): ');
$graph->footer->right->SetFont(FF_COURIER,FS_ITALIC);
$graph->footer->SetTimer($timer);
 
// The rest of the script as normal ..

Figure 14.12. Adding a timer to the graph (in the footer) (example11.php) shows an example of using a timer to add the time (in ms) it took to generate the graph

Figure 14.12. Adding a timer to the graph (in the footer) (example11.php)