Dataplot: Sizing

Percentage Coordinate Scale

Dataplot uses a percentage coordinate scale. That is, it divides the screen into a 0 to 100 scale in both the horizontal and vertical directions. If you use either the MULTIPLOT command or the WINDOW COORDINATES command, this defines a subset of the screen to be used by the next plot. Dataplot defines a new 0 to 100 scale for this sub-plot area. In this case, the percent sizes are relative to this sub-plot area, not the full screen.

Sizes in Percentage Scale

Sizes in Dataplot are specified in terms of this 0 to 100 scale. For example, the command TITLE SIZE 3 sets the height to 3% of the vertical size of the output device.

Sizes by Character Height

In most cases, sizes are specified by the specifying the height of the character. Dataplot then automatically sets the width to be half the size of the height. That is, a TITLE SIZE 3 command sets the height of the character to be 3% of the vertical size of the output device and the width of the character to be 1.5% of the width of the output device.

Sometimes Desirable to Set Character Width Explicitly

In some case, it is desirable to be able to set the width of the character explicitly. This is particularly true when using the MULTIPLOT or WINDOW COORDINATES commands. In these cases, it is possible for the ratio between the height and width of the sub-plot area to be different enough that it drastically distorts the appearance of the character. The table below gives some commands that allow you to specify both the height and width of the character.

Setting Sizes of Individual Plot Elements

Commands to Set Sizes

Dataplot does not restrict all text elements to be the same size on a plot. Dataplot provides the following commands for setting the sizes of various elements of the plot:

HEIGHT Sets the size (height) of characters drawn by the TEXT command.

HW Sets the size (both height and width) of characters drawn by the TEXT command.

TITLE SIZE Sets the size (height) of the plot title.

LABEL SIZE Sets the size (height) of the plot axes labels.

LEGEND SIZE Sets the sizes (height) of the plot legends.

LEGEND HW Sets the sizes (height and width) of the plot legends.

CHARACTER SIZE Sets the sizes (height) of the plot characters.

TIC MARK LABEL SIZE Sets the size (height) of the plot tic mark labels.

Default Sizes

The default size for all plot elements is 2. That is, the height of the character is set to 2% of the vertical size of the graphics device and the width is set to 1% of the width of the graphics device.

Hardware and Software Characters

FONT Command

In setting sizes, there is a distinction between the use of hardware generated characters and software generated characters. The FONT command is used to specify whether hardware or one of seven different software characters are used. The default is to use hardware characters.

Software Characters

Software characters are drawn by Dataplot as a sequence of moves and draws. Their appearance should be consistent across different output devices (subject to the different resolutions of output devices).

Hardware Characters

Hardware characters use the character generating mechanism of that device. This means that the appearance of hardware characters can vary, sometimes substantially, across different graphics devices. For example, Postscript provides for scalable, typeset quality characters in 35+ different fonts. On the other hand, the Tektronix device provides only 4 discrete character sizes with a comparatively low quality appearance. Hardware characters, especially for screen devices, tend to be significantly faster to draw than software characters.

Hardware Characters Often Have Fixed Width

Note that hardware characters also typically fix the width of the character relative to the height. In general, this ratio cannot be changed. This means that the various Dataplot commands that allow you to specify the width independently of the height do not have any effect on hardware characters. Fortunately, the primary reason for wanting to do this, i.e. to correct for distortions resulting from the use of the MULTIPLOT or WINDOW COORDINATES commands, do not apply in this case either.

Hardware Characters May Have Limited Number of Available Sizes

If you change the size of a character and that size is not reflected on the particular device, this probably means that you are using hardware characters on a device with a limited number of sizes (some only support a single size). The documentation for the various output devices indicates how many sizes the output device supports.

DEVICE FONT Command

The command DEVICE <1/2/3>FONT can be used to specify whether the hardware font or a software font is used on a specific device. The most common use of this command is to set a software device for the screen (DEVICE 1), where the hardware fonts might be limited and poor quality, while still preserving the use of hardware characters for a Postscript output device (DEVICE 2). To do this, you could enter the following command:

DEVICE 1 FONT SIMPLEX

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Date created: 06/05/2001
Last updated: 09/20/2016
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