The exact position of the labels can be adjusted with the methods

By default the color of the labels will be the same as for the axis but it is possible to use a different color for the labels by supplying a second argument to the SetColor() method for the axis.

The font family for the labels can be specified with

By default a bitmap font is used for the labels (since those are the only fonts guaranteed to be available everywhere)

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$graph->xaxis->SetFont(FF_ARIAL,FS_NORMAL,9);
$graph->xaxis->SetColor('black','blue');

As a kind of a very special formatting it is also possible to set a specific background for just the labels on the graph. This is most often used when there is background image that risks of hiding the clarity of the labels. In those cases it can be suitable to have a some lighter background to make it easier to read the labels.

The method that controls this is

The way these possible background types works is best described by viewing the example figures below

Figure 14.25. LABELBKG_NONE (axislabelbkgex01.php)	Figure 14.26. LABELBKG_XAXIS (axislabelbkgex02.php)	Figure 14.27. LABELBKG_YAXIS (axislabelbkgex03.php)
Figure 14.28. LABELBKG_YAXISFULL (axislabelbkgex04.php)	Figure 14.29. LABELBKG_XAXISFULL (axislabelbkgex05.php)	Figure 14.30. LABELBKG_XYFULL (axislabelbkgex06.php)
Figure 14.31. LABELBKG_XY (axislabelbkgex07.php)

For the x-axis it is common to rotate the label to better fit long text labels. This is done with a call to

There are actually five variant for hiding the aaxis

By default the auto-scaling algorithm tries ot find as tight upper and lower bands as possible as long as they are even multiple of the chosen major step size. In some instances some more space is needed. For example to have extra room at the top of the graph to show data labels. In order to have some extra space the method

should be used. This method will adjust the autos calling algorithm by adding the specified extra "grace"at the minimum and maximum value of the scale. The grace value is specified as an integer [0,100] and specifies a percentage to add to the min and max value before the auto scaling is made. Depending on the scale step and overall scale several scale values might give the same resulting scale. For example

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$graph->yscale->scale->SetGrace(20,20);

will add 20% extra values on the top and bottom values of the data series before the auto scale is determined. The following four examples shows how this can be used in practice. In Figure 14.32. The original graph (grace_ex0.php) a bar graph without grace value is created. As can be seen since the scale is very tight the labels of the individual bars are almost out of the graph plot area. In the following three plots results of using different values for grace are shown.

Figure 14.32. The original graph (grace_ex0.php)	Figure 14.33. Using a 10% grace (grace_ex1.php)
Figure 14.34. Using a 50% grace (grace_ex2.php)	Figure 14.35. Using a 100% grace (grace_ex3.php)

We finish this section by noting that adding a large grace value might sometimes make it necessary to move one or both of the axis manually. To explain this we start with the graph in Figure 14.36. The original line graph (example3.2.php)

Figure 14.36. The original line graph (example3.2.php)

as can be seen the added plot marks (see ??) are outside the boundary of the plot area and to solve this problem we add the line

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$graph->yaxis->scale->SetGrace( 10 , 10 );

to the script. This now gives the result shown in Figure 14.37. Adding grace values. Note x-axis position at y=0 (example3.2.1.php)

Figure 14.37. Adding grace values. Note x-axis position at y=0 (example3.2.1.php)

The problem is now apparent. Since the x-axis is placed at y=0 by default the x-axis is no longer at the bottom of the plot as was probably the intention. To remedy this situation we have to manually place the x-axis at the minimum y-scale position. This is done by adding the line

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$graph->xaxis->SetPos( 'min' );

to the previous script. Doing this gives us back the wanted position of the x-axis as shown in Figure 14.38. Adjusting the position of the x-axis manually (example3.2.2.php)

Figure 14.38. Adjusting the position of the x-axis manually (example3.2.2.php)

To adjust the appearance of the tick marks the following three methods can be used

As was mentioned before it is perfectly possible to manually specify the scale labels. This is normally done for "text" scales that are most commonly used with bar graphs.

Specifying a text scale for the axis (normally the x-axis) will "reserve" a position for every data value that must be manually set. In some ways this is the same as having a linear scale with major and minor step size set to 1.

As a very basic example of a text scale with a bar graph Figure 14.40. Manual text scale with month labels (manual_textscale_ex1.php) shows some fictive values for each month of the year. In that example the scale has been set to a text scale and each value has been specified as an array containing all the names of the months.

Figure 14.39. Manual text scale example

Figure 14.40. Manual text scale with month labels (manual_textscale_ex1.php)

Since the manual text scale sets a scale label for every single data point this would give problem for the case where we have a large number of data points where it is not possible to label every data point. In order to control this the following two methods are used

Finally we show an example where there is a need to combine the above two methods to get a reasonable looking scale. This happens when there are so many data points that it is not possible to show every tick marks. To show that text scales can also be used with other plot types than bar we have chosen to show a line graph where we show data that has 40 data points per month (480 data points per year). Let us assume that in this application we want to have tick marks at every 40 points (i.e. a total of 12 tick marks) and have labels only on every 2:th tick label (i.e. a total of 6 labels).

Example 14.4. Adjusting both text tick mark and label interval

Figure 14.43. Tick marks every 40 points and labels every 2:nd tick mark (manual_textscale_ex4.php)

In addition to the text scale is it in principle also possible to use a manual scale with integer scale as shown in Graphing the number of sun spots during the 19th Century

Sometimes it is a good idea to emphasize part of the scale. It can be on either the x- or the y-axis. The library offers the possibility to add a band with a separate background color for part of the scale in either x, y (or both) directions.

A plotband is defined as an instance of class PlotBand that is added to the graph in the same way as normal plots. A plot band can have a number of different styles to achieve the wanted affect and it can be placed either on top or behind the plot.

An instance is created and added to the graph as shown by the following example

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// Add a horizontal band
$band = new PlotBand(HORIZONTAL,BAND_RDIAG,15,35,'khaki4');
$band->ShowFrame(false); // No border around the plot band
$graph->Add($band);

The code snippet above adds a horizontal band with a diagonal pattern (from top left to bottom right). The horizontal band is shown between the y-scale values [15,35].

The types of plotbands supported by the library is shown in the table below

Example 14.5. Different densities for plot bands

Figure 14.44. BAND_RDIAG (smallstaticbandsex1.php)	Figure 14.45. BAND_LDIAG (smallstaticbandsex2.php)	Figure 14.46. BAND_DIAGCROSS (smallstaticbandsex10.php)
Figure 14.47. BAND_HLINE (smallstaticbandsex7.php)	Figure 14.48. BAND_VLINE (smallstaticbandsex6.php)	Figure 14.49. BAND_HVCROSS (smallstaticbandsex5.php)
Figure 14.50. BAND_3DPLANE (smallstaticbandsex4.php)	Figure 14.51. BAND_SOLID (smallstaticbandsex3.php)

For some of these patterns it is also possible to specify an additional density parameter via the method PlotBand::SetDensity() that specifies how dense the pattern should be. For example Example 14.6. Different densities for various plot bands shows three variants of the 3D plane with different density parameters.

Example 14.6. Different densities for various plot bands

Figure 14.52. SetDensity(10) (plotbanddensity_ex0.php)

Figure 14.53. SetDensity(40) (plotbanddensity_ex1.php)

Figure 14.54. SetDensity(80) (plotbanddensity_ex2.php)

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 $band ->prect->SetHorizon( $aHorizon)

To finish this section we show one slightly more creative use of background plot bands in Figure 14.56. Creative use of plot bands (staticbandbarex7.php)

Figure 14.55. Creative use of plot bands

Figure 14.56. Creative use of plot bands (staticbandbarex7.php)

In addition to the plot band it is possible to add static lines to emphasize a specific scale value. A pot line is added to the graph by creating an instance of the class PlotLine in much the same way as for plot bands. The following code snippets show how this can be done

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// Add mark graph with static lines
$line = new PlotLine(HORIZONTAL,10,"black",2);
$graph->AddLine($line);

The above code snippets adds a black plot line (weight=2) at scale position y=10.

In addition to using this feature to show min/max values (or perhaps critical limits) another usage can be to show a zero-line as the following example in Figure 14.58. Adding a static line at y=0 to simulate an extra 0-axis (impulsex4.php) shows.

Figure 14.57. Use of a static line to simulate an extra x-axis at y=0

Figure 14.58. Adding a static line at y=0 to simulate an extra 0-axis (impulsex4.php)