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Getting
started
Basic Charts can be built
and implemented using the Chart Editor with little or no use of code.
The Chart Editor is two Editors in one as the Chart may be thought
of as being distinct from its data Series contents. You may define
the Chart appearance, titles, Legend characteristics and 3D aspect
without having to include a data Series. That gives you the freedom to
add and remove different data Series types at runtime without having
to redefine the whole Chart look and feel.
Everything comes together to make the final Chart, with Chart axes
being the interface between Chart and Series. A Series has data and
its values will influence the label characteristics of the Chart axes.
The axes appearance, colours, grid frequency and label fonts may all
be defined for the Chart before adding data Series. TeeChart will make
a best estimate of most values to minimise the need for you to
manually define Chart and Series properties
Add multiple series
types with the Chart editor The "Chart distinct from
Series" design paradigm of TeeChart allows you to mix a variety
of Series types without being limited to a choice of predefined Chart
formats.
Internet
And Internet ! For this
area of growing demand for applications, we have included features
such as JPEG Chart save or TeeChart "tee" templates for low
bandwidth charting. Where we haven't had the time to include all we
wanted we have included comprehensive demo code to help you build
network applications.
The steps in this tutorial highlight how easy it is to build a Chart
from scratch and will introduce you to the Chart Editor to enable you,
through later tutorials, to modify and further enhance the appearance
and functionality of the Chart. Good Charting !!
Building a Chart
Including TeeChart on a Form
By following the installation
instructions for TeeChart you should have succeeded in adding the
TeeChart Pro icons to the Delphi Component palette. If your version of
Delphi already had TeeChart Standard version included then you will
see no immediate difference when you open Delphi. You can check that
TeeChart Pro is correctly installed by adding a TeeChart to a Form and
then, with the Add Series button checking that the Gallery
offers you Extended Series Types. The TeeChart icon is a
representation of a circled (Pie) Chart. You will find TeeChart,
TChart component, in the Additional section of the Delphi
Component Palette.
In addition TeeChart Pro installs 2
more Chart icons:
-TDBChart in the Data Controls
section (TDBChart uses the Borland Database Engine.
If you are coding Chart data use TChart.)
-TQRChart in the QuickReport
section
For a list of other TeeChart installed
components follow this link: Non Chart
components
Select the first icon of the three and
click and drag out to size TChart on a Form. You will see TChart as a
panel with some basic Chart features such as Axis and Title. TeeChart
is derived from a Delphi TPanel, you could use the Chart Editor to
delete the existing visual features and you would be left with a
perfectly servicable 3D panel complete with Border and Bevel
properties ! We hope you'll want to use it for more than that though !
Right click on the new TChart and you will see a menu displayed.
Select the Properties option to access the Chart Editor.
(Double-mouseclicking on the Chart will achieve the same goal).
The Chart Editor
The Chart Editor contains access to
most commonly used Chart properties.
To add a new Series, mouseclick on the Add..
button and select the Series type from the Series Gallery. If, after
selecting a Series type now, you wish to change it later you may do so
(with a few exceptions where Series data content may be incompatible)
by returning to the first Editor screen and selecting the Change..
button.
The Chart Series Gallery
The Gallery consists of four tabbed
pages:
Standard Series
Standard Series types, those likely to
be called upon most frequently.
Functions
Statistical functions which may be used
to follow trends in your other data Series.
Extended Series
Extended Series include more
specialised Series types for Financial, planning or mapping
applications.
Sample Series
We have included some example Custom
Series types.
Select a Series type. For this exercise
we will choose a Bar Series type. The Gallery will close and the new
Series will be displayed in the first Chart Editor screen.
Populate the new data Series
Select the Series tab in the Chart
Editor to display the Series configuration properties. The fourth tab
on the Series page is the the data source tab.
Coding data input with TChart
For programmed input of data you
will need to write some code. If you are coding data input the use TChart
rather than TDBChart to avoid needing the Borland Database Engine.
This section will show you the steps necessary to build a chart with
coded input.
The Series that you previously added with the Chart Editor shows
random data at design time. At runtime however, the Series will be
empty of data unless you manually populate it. Select a Command button
from the Component palette and place it on your Form. Double-click on
the button to access the code editor. In the code Editor type these
lines:
With Series1 do
begin
Add (3, 'Pears', clRed);
Add (4, 'Apples', clBlue);
Add (2, 'Oranges', clGreen);
end;
Run the project and press the command button. Three new
bars will appear on your Chart. That's it !! There's no more to it.
The Series' Add method accepts 3
variables, Value, Label and Colour. The Add method thus assumes equal
spacing of values on the Label axis (in this case the X-Axis). If your
data contains 2 variables you may use the . Add another Command button
to your project and put this code in it. Run the Project and add
points using this code:
With Series1 do
begin
If Count > 0 Then
//Increment X Axis value and add a new random point
AddXY (XValues.Last+(Round(100)), (YValues.Last/YValues.Last-1)+(Round(100)), '', clBlue)
Else
//Add a new random point
AddXY (1, (Round(100)), '', vbBlue);
end;
Selecting a Series Type to suit your data needs
The last coded example generated
new X and Y values. The X axis distance between points is not constant
which will cause overlapping of Bars in some cases, which would be
desirable for some but not all applications. Using the Chart Editor to
Change the Series type (Enter the Chart Editor at Design time and use
the Change button on the first page) to a LineSeries shows an
alternative way to graphically represent data with 2 variables. If
your data contains more than 2 variables there are other Series Types
suited to displaying the data. See the TeeChart helpfile User guide
for a complete listing.
Accessing datasources with TDBChart
If your data is from a Delphi TDataset,
TTable, TQuery or TClientDataset then you may map your data directly
in the Chart editor. Place any one of these components on your Form.
TDBChart does not need a Datasource component to access one of these
TDataset components.
Select Datasource from the
dropdown listbox on the Data Source page. The Datasource
characteristics fields will activate on the page. Select the Dataset:
Listbox to add a new Data source for the Series.
You may select an existing datasource
(TTable, TQuery, etc) for the Series from Datasource drop-down
combo box. When you have selected the datasource TeeChart will
automatically populate the Chart with the data it finds in the
Dataset.
According to the table above which
shows what Series Types require which values, you may add the columns
of the Dataset to the 'Labels', X and Y fields. If your data only has
Labels and Y values (the X values are index 1, 2 ,3, etc.) you are
only required to populate 'Labels' and 'Y' values.
The dataset data will show in design
time and when you run the application the data will automatically
populate the Chart at runtime.
TeeChart Pro version 4 includes several
non-Chart components that may be used to enhance the functionality or
appearance of your Charting application. You can find these components
in the TeeChart section of the component palette.
© 2000 Steema. All
rights reserved.
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