Chart Drawing Solution

Environment: Windows 95/98, Visual C++ 5.0 SP3

These are two classes I'm using to draw easy (absolutely not complex) graphs. I wrote it because I need a light (and cheap) control that could solve some problems about data showing.

What This Control Can Do

• draw on the same chart few (up to 64, but you can change if you prefer) graphs with different styles
• each graph can has up to 32k data (I never try this !)
• draw NULL datas (undrawing them) so that you can show graphs with different X timebase
• copy to clipboard
• copy to file

What This Control Can Not Do

• show data in 3d styles
• print graph directly to printer
• do a lot of things that I don't remember at this time...

How to use it

1. First you must include the two classes in you project: add the files HMXChart.* and HMXDataset.* in your project
2. include the HMXChart.h header in the CFormView that will show chart; the form must contain a static text control (modify its ID, e.g. IDC_CHART)
3. create an object (in your formview object) derived from CHMXChart
4. in formview initialization routine subclass the static text control
5. set data and make-up

To set the data must be used following function

m_chart.SetData ( n, xxx );

m_chart.SetData ( n, idx, xxx );

To create a new dataset its enought that a single value is added.

Following questions convinced me to design a new feature for this chart: NULL data.

What about if I have an hole in my data?

This is an example:

I have 2 datasets (Y1 and Y2):

HMX_DATASET_VALUE_INVALID = 1.7976931348623158e+308

In the example you can set to HMX_DATASET_VALUE_INVALID all the values that have no digits.

Even if the HMX_DATASET_VALUE_INVALID is a right concept for all dataset styles, in vertical bar style the value HMX_DATASET_VALUE_INVALID looks like 0.0, because all bars (positive and negative) starts from the zero line, thus the value 0.0 is represented with a 0 height bar.

There are three data formats: line, vertical bar and area; and the function to use to set the right format is:

m_chart.SetDatasetStyle( n, xxx );

HMX_DATASET_STYLE_LINE,
HMX_DATASET_STYLE_VBAR,
HMX_DATASET_STYLE_AREA;

m_chart.SetDatasetMarker( n, xxx );

HMX_DATASET_MARKER_TRI,
HMX_DATASET_MARKER_BOX,
HMX_DATASET_MARKER_SPH,
HMX_DATASET_MARKER_DIA,

To set the pen size use following function:

m_chart.SetDatasetPenSize( n, size );

It's possible (of course) to set the X and Y labels; Y labels depend on the datasets and on the Y Ticks, X labels are added manually. They're strings, so it's possible to show numbers, text, date and so on.

Another interesting function allows the chart to have a good readability: rounding. It's possible to round the upper and lower chart limits to the multiple of each number, usually 2, 5, 10, 20, 500, and so on. This is its use:

m_chart.SetRoundY( n );

There are al lot of self-explaining functions that improve chart readability.

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