Nateo Concepts -> Row Headers and Flank Controls

# Nateo Concept: Row Headers and Flank Controls

# Row Headers make up the Legend

In the NtTimeChartControl data is organized in rows. In other words: If you have a data set containing different types of data, you might want to see all data elements of one type in a certain row and all data of another type in another row.
In order to let the user know, which data is shown in which row, you might want to label each of the rows accordingly. This is done by a row header which is attached to the left or right of a row. A row header is defined by an object of type NtRowHeader. Row Headers are organized vertically within NtFlankControls.
NtFlankControls are controls by them selves as any button or the NtTimeChartControl. So if you want a Time Chart with two of them, then in your IDE (like Microsoft Visual Studio) you simply place two of them onto your form and locate them properly. See the Tutorials for examples.
Below please see an example of a NtTimeChartControl which is joined by one NtFlankControl on each side, both containing several NtRowHeaders:

The Time Chart is located in the center and the Flank Controls are located to the left and right (that is why they are named 'Flank Controls').
The Flank Controls contain the Row Headers. On the left side there is one Row Header per row, while on the right there are some rows that have no Row Header. So some rows have one Row Header, others have two. The reason is that in some rows there are two different data types shown while in others there is only one. For example the bottom row contains 'Temperature' and 'Pulse' in the same row, so you need two Row Headers to let users know.
It is up to the programmer to assign as many Flank Controls to the Time Chart as wanted. A Time Chart can work with no Flank Control at all, but it can also have one, two or more of them. Of course in general it is recommended to have at least one to let the data have a legend. And if you have more than one type of data in one row, you might want to have another legend like a graph that has one vertical axis on the left and one on the right. Anyway it is no good style to have more than two Flank Controls.

## How the Flank Controls work

In the image above you can see the vertical scroll bar on the very right. When users scroll vertically not only the Time Chart itself moves vertical but also the Flank Controls do so. As a consequence the Row Headers stay always aligned with their data rows. In other words: Time Chart and all Flank Controls always scroll synchronously in vertical direction. Of course this only works if you locate the FlankControls properly: They need to be aligned with the top of the Time Chart and must have the same height.
One important functionality of the Flank Controls is to allow vertical dragging of rows. Holding the Ctrl-Key and pressing the left mouse button, users can drag rows or even categories vertically within the Flank Control and thereby change the order of rows or categories resp. It is needless to say that when changing the row order in one Flank Control the other follow instantly so the actions stays always consistent.
Finally you can drag the entire sheet in vertical direction by holding the left mouse button. This is a good technique if you want to drag the sheet vertically without moving it horizontally (what could happen if you drag the sheet in the Time Chart).
Another thing is worth mentioning: The Flank Controls each have a sheet on their own, which is kind of a back panel the Row Headers a drawn upon. It is quite clear that the height of this sheet is the same as the height of the Time Chart's sheet which again is the sum of all row heights. Meanwhile the width of a Flank Control's sheet is set during initialization. It can be bigger than the ClientSize's width. For example if you want to have longer texts or wider bitmaps in your Header Controls you need a wider space to draw them. In this case the Flank Control can have a horizontal scroll bar on its own that only scrolls the Flank Control horizontally (and leaves the Time Chart untouched) so users can see the entire contents despite the limited space.
It is needless to say that the better practice is not to have the Flank Control's sheet wider than the client area. The additional scroll bars and the cut off view are no good usability and should be left for cases when they are really needed.

## Row Headers

Row Headers are rectangular labels located inside the Flank Control aligned with the rows of the Time Chart. A Row Header is not specific for a row but for a data type that is in a row. If there are more than one data types in one row then a Row Header belongs to only one of them. Please see the bottom row in the image above: The Row Header labeled 'Temperature' is for only one of the curves drawn in that row while the Row Header labeld 'Pulse' is for the other one.
When initializing your NtTimeChartControl you typically create one NtRowHeader per data type you support. You add each of them to the NtTimeChartControl by calling SetRowHeader(). Here you also suppy the data type id you set the Row Header for. As a result the NtTimeChartControl obtains one Row Header for each data type and thereby is able to label all data correctly.
The actual assignment of Row Headers to Flank Controls and to the rows is finally done by the NtPerspective that is active within the NtTimeChartControl: The NtPerspective is responsible for assigning data types to rows (please see Concept Perspective one page before). And when assigning the first data type to a row, it also assigns the Row Header stored for that first data type to the first Flank Control. And if there is a second data type in that row, the Row Header of this second data type is being assigned to the second Flank Control (if there is one) and so on. In other words: The order of assigning Flank Controls to the Time Chart and the order of assigning data types to rows in a Perspective finally defines which Row Header shows up in which Flank Control. As a consequence when you have only one Flank Control, you will always see the Row Header of the first data type of that row.
So how to make a Row Header look right?
In the Nateo name space the Row Headers are made up by the class NtRowHeader that has certain members defining the Row Header's properties and its drawing.
First of all (as you can see in the image on top of this page) a Row Header has a background that is drawn by the bkBrush.
Next it has a bitmap member and a bitmapPos that allow you to define a bitmap that is drawn on top of the colored background. In the example image on top of this page you can see the 'Temperature' Row Header: It has a scale with numbers. This scale is nothing else but a bitmap that has been created by the application while initilaization.
Finally the NtRowHeader also has a String named text and a textPos. Along with the font given while construction you can create the legend text for the Row Header.
So the drawing occurs like this: First the background is drawn using the bkBrush. On top of that the bitmap is drawn at the bitmapPos position. On top of both the text is drawn at the textPos position.
It is perfectly fine to change the text, bitmap, brush and position values at any time in order to dynamically change the Row Header. Please be sure to invalidate the appropriate area of the Flank Control to initiate updating.

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