The Graph Control displays information sequentially left to right along
the horizontal axis and is measured with respect to the vertical axis.
For example, showing the sales figures per month would consist of the
categorized month variable on the horizontal axis, and their respective
sales would be measured against the vertical axis. The developer passes
only one data-set, YData. Within the demo, see example
000 on how to implement a simple Graph control .
The Graph and Scientific Graph controls are designed to help your users assimilate
their data. The developer can pass large amounts of data into the graph
and the user can view the information in smaller/clearer increments via
zooming or dialog adjustments. Zooming can be invoked by left-button dragging
a zoom box. Once zoomed, the user can horizontally pan left and right via
the horizontal scrollbar. Pressing the spacebar, the letter "Q",
double-clicking, or right-mouse clicking are ways to invoke the customization
dialog. This dialog allows for various forms of data-zooming via subset/point
selection, and/or selecting the quantity of subsets/points to view. Depending
upon the Scrolling Subsets adjustments, subset information can be viewed
incrementally via the vertical scrollbar. See AllowZooming,
ScrollingSubsets, and PointsToGraph.
Due to the data being sequentially plotted, the Graph control can display
a table with or without an accompanying graph. This table is synchronized
with the graph and as the user horizontally scrolls, the table and graph
scroll together. See TableWhat.
Note that the Scientific Graph uses both XData
and YData and thus data can be plotted
randomly within the charting region. For this reason, an automatic table
can not be displayed with the Scientific Graph. It can however place data
values next to data points, see GraphDataLabels.
The Graph, Scientific Graph, Polar/Smith, and the scatter mode of the
3D Scientific Graph control have a data comparison mechanism. This mechanism
allows subsets to be plotted in two different styles along with the ability
to make selected subsets permanent while scrolling through the remaining
non-selected subset information. See ComparisonSubsets
For a more detailed discussion on Comparison Subsets, see Chapter
6: Comparison Subsets. Within the demo, see
Instead of using Comparison Subsets, optionally use PlottingMethods
to control plotting method on a per subset basis. This property also designates
whether the subset should be plotted with respect to the left, right,
top and right, or top and left axes. If using this property, you will
never set any of the Comparison Subset type properties. ComparisonSubsets,
RYAxisComparisonSubsets, and TXAxisComparisonSubsets should all be zero
when using PlottingMethods. Within the demo, see example
ProEssentials Graph and Scientific Graph support multiple y axes with
up to 32 y axes in 16 vertically stacked sub-graphs. Each sub-graph (we
commonly call them Multi-Axes) can have a left and or right y axis, two
plotting styles, and its own annotation layers. The Scientific Graph also
supports two x axes, one at top and one at bottom. Any axis can be log
or linear in any combination and all plotting styles work with log or
linear scaling, including the best fit lines and curves. See MultiAxesSubsets
and WorkingAxis. Clipping is enabled by default and
can be disabled with DisableClipping.
ProEssentials takes multiple axes one more step and allows for overlapping
multiple axes. This features groups axes in overlapping sections. The
left and right y axes start growing outward as needed. This allows for
sub-graphs (or Multi-Axes) to be superimposed where each axis can utilize
the entire charting area or partial-area as needed. See OverlapMultiAxes.
If all axes are overlapped into one region, there is support vertical
scrolling in combination with overlapped multiple axes. See ScrollingVertZoom.
See Common Question 18 for more
information on Multi-Axes. Within the demo, see
examples 012, 013, 103 and 104.
The Graph and Scientific Graph support zooming across multiple-axes.
Zooming can be restrained to either horizontal or vertical extents, or
unrestrained allowing the user to drag a rectangle of any shape/size.
If desired, the zoom-box rectangle can be used purely for user-interface.
This allows the user to select an area of interest on the chart. You will
use the ZoomIn event and ZoomMinX, ZoomMaxY, ZoomMaxX, and ZoomMinY properties
to know where the user zoomed. You can also provide a line-drawing tool
with this feature. See PEP_bZOOMINTERFACEONLY.
the demo, see example 107.
ProEssentials has several methods of annotating a chart. These allow for mixing
text and symbols in a tabular fashion within the chart or boundary of
a chart. Table annotations can contain header columns and rows, hot spots,
and real-time updating. The Graph, Scientific Graph, and Polar/Smith controls
also support other annotation mechanisms. The PieChart control has only table annotation type properties.
Annotations form the third layer of graphics in combination with the two
plotting methods. It's simple to place lines, text, symbols, and shapes.
Annotations can also be hot-spot locations and the user can toggle the
annotations on and off via the customization dialog and popup menu. Horizontal
line annotations can now contain one line feed to handle two lines of
text. Graph Annotations have a paragraph annotation for annotating several
lines of text. See TAType, GraphAnnotationType,
and XAxisAnnotation. Within the demo, see examples
015, 026, 027, 028, 029 and 030.
The Graph and Scientific Graph provide a data-cursor. This feature provides
a horizontal line, cross-hair, or inverted block designating data-point
focus. This cursor can be moved by the user by clicking another data-point
or with the arrow keys. Up/Down keys revolve through data-series and the
Left/Right keys move the focus to adjacent data-points. The developer
can programmatically move the data-point focus. If programmatically moved
out of view, the graph will automatically scroll left/right so the cursor
is in view, much like a word-processor.
The most commonly used will be PECM_FLOATINGXY which provides a floating
cross-hair cursor which follows the mouse. In this mode, the cursor
does not give a data-point the focus. See CursorMode,
CursorSubset, and CursorPoint.
Within the demo, see examples 028,105.
The Graph, Scientific Graph, and Polar/Smith controls handle Null-Data.
The Null-Data value can be defined by the developer and the default Null-Data
value is zero. Anytime ProEssentials sees a Null-Data value it is ignored.
Since zero is the default Null-Data value, zero data values will be ignored
by default. If you need to plot data where zero is a valid data value,
then you must change the Null-Data value property. For a line/area graph,
the line/area extends to the next non-null data point, forming a bridge
across null-data. For bars/points, the bar/point will not be drawn. There
is also a mechanism to form gaps rather than bridges for line graphs with
Null-Data. See NullDataValue,
NullDataGaps and LineGapThreshold.
Within the demo, see example 006.
The Graph and Scientific Graph can be continuously fed data and a moving
strip-chart can be implemented. This process is very easy to implement
since setting AppendYData not
only transfers the new data, but first shifts the existing data, appends
the new data, and finally updates the image. Generally you will use AppendYData
and related properties inside event code attached to a Timer control or
WM_TIMER event. Note that the Scientific Graph takes a little more work
to implement a real-time strip chart. Refer to the included example code
for help with implementing your own data monitoring solutions. Within the demo, see examples
017, 020, 115, 116, 117, 118 and 119.
Date/Time handling is supported by the Graph and Scientific Graph. The
Graph control can be configured so that a linear date/time calendar is
placed along the x axis. This calendar scaling is dynamic and will change
in structure as the user zooms inward. Because this mechanism is dynamic,
its tough to also make it flexible, so this feature is purely automatic.
This feature works much like the Scientific Graphs Date/Time handling
except the time scale does not have to be continuous. The Scientific Graph
has a continuous time scale limitation. For example, if you need to handle
data from 8am to 4pm, Monday through Friday, this is perfect for use with
the Graph control. The Scientific Graph must show a scale which includes
all hours of the day and all days of the week. One note though with respect
to the Graph control is that the data needs to be quantified in equal increments.
If you dont have data for a particular time increment, you will have
to supply a Null-Data value as a place holder. The Graphs Date/Time handling
is great for financial developers and was added with financial developers
in mind. See DateTimeMode, DeltaX, and DeltasPerDay.
the demo, see examples 016, 030 and 106.
The axes can be formatted with dollar signs and commas marking thousands.
For example, $1,400.00 can be automatically produced for a y axis grid
number of 1400. See AxisFormatY.
Event based axis formatting features allows the
developer to programmatically construct grid number labels on a per grid
line basis. See CustomGridNumbersY
the demo, see examples 109 and 132.
control Customization Dialog allows the user to customize the Graph. The
dialog is made up of tabs, with possible tabs of General, Plot, Subsets,
Points, Axis, Font, Color, and Style. This dialog as well as other customization
dialogs are invoked by either 1) the spacebar, 2) double-clicking the
graph's desk area, 3) right-mouse clicking to show the popup menu, or
4) pressing the "Q" key to invoke the popup menu. See AllowUserInterface,
AllowCustomization and AllowPopup.
We wont discuss every item on these dialogs but concentrate only on
those which arent self explanatory. Its a good idea to have the demo
running and open up the Graph controls customization dialog while reading
the following sections.
The Graph control offers the following plotting methods: Line, Bar, Point/Scatter,
Area, Area Stacked, Area Stacked Percent, Bar Stacked, Bar Stacked Percent,
Points plus Best-Fit-Line, Points plus Best-Fit-Curve, Points plus Line,
Points plus Spline, Spline, Step, Ribbon, Horizontal Bar, Horizontal Stacked
Bar, High-Low Line, High-Low Bar, High-Low-Close, Open-High-Low-Close,
Box Plot/Candlestick, and Histogram. See PlottingMethod.
The Graph and Scientific Graph support two plotting methods per left/right
axis pair. Each axis pair can contain a primary plotting method and a
secondary comparison plotting method. Comparison subsets are plotted in
the secondary plotting method. See PlottingMethodII
Display Graph plus Table
The Graph control can display a graph, a table, and both a graph and
table. See GraphPlusTable.
The user can choose to have both y axis (horizontal) and x axis (vertical)
grid lines, or only y axis, x axis, or no grid lines. If Grid in Front
of Data is checked, the grid is drawn after the plotting method, otherwise,
the grid is drawn before the plotting method. See GridLineControl
Subsets to Graph
This group consists of a listbox of subsets and scrollbar/slider controlling
the Scrolling Subsets quantity. These allow the user to view subset information
in a variety of ways.
If nothing is selected
in the listbox and Scrolling Subsets equals zero, then the Graph will
display all subsets.
If there are selections
in the listbox and Scrolling Subsets equals zero, then the Graph will
display only those subsets selected.
If nothing is selected
in the listbox and Scrolling Subsets is non-zero, then the Graph will
scroll through subset information (via the vertical scrollbar) by the
amount defined by Scrolling Subsets.
- If there are selections in the listbox and Scrolling
Subsets is non-zero, then the Graph will maintain those selected subsets
as permanent subsets and revolve through the remaining subsets in increments
of Scrolling Subsets.
The following table summarizes the Subsets to Graph variations.
Display all subsets.
Display only those selected subsets.
Scroll through all subsets.
Permanent selected subsets & scroll remaining
See ScrollingSubsets and
Points to Graph
This group allows the user to view point information in a variety of
If Sequential is selected, then the Graph control will display the number
of points specified. If the number of points specified is less than the
total number of points contained in the control, there will be a horizontal
scrollbar allowing the user to scroll through the remaining point information.
If Selected is chosen, then the user uses the listbox to select only those
points to include into the image. See PointsToGraph,
This group allows the user to view axes as linear or log. It also allows
the user to adjust how the axis range is determined. Possible selections
are Automatic, Manual Min, Manual Max, and Both Manual Min and Manual
Max. See YAxisScaleControl
Note that if using multiple y axes or chart is zoomed, the Axis tab is
not visible. Within
the demo, see example 112 and 110.
This group allows the user to adjust a subsets color, line style, and
point style. Double clicking the color selection box will invoke a custom
color selector. See SubsetColors,
SubsetLineTypes, and SubsetPointTypes.