cVBar class

Draws vertical bars into the screen buffer: a single bar, a row of bars from an array, bars coloured by value, a bar with a label, and a history of values that scrolls to the left.

A cVBar keeps the Buffer of the console it was made with. Each bar is one column wide and height rows high, and grows from the bottom. The members draw into the buffer only; Refresh of the console shows it.

Dim con As New cConsole
Dim chart As cVBar
Dim ci As ConsoleCharInfo
Dim y As Long

con.EnterFullScreenMode
Set chart = New cVBar(con)

chart.Render 3, 0, 4, 50                  ' a bar 4 rows high, half full
For y = 0 To 3
    ci = con.Buffer.GetChar(3, y)
    Debug.Print y & " " & Hex$(AscW(ci.Char))
Next
con.ExitFullScreenMode
' Output:
' 0 20
' 1 20
' 2 2588
' 3 2588

How a bar is drawn
Enumeration
Constructor
Methods
See Also

In the syntax lines of this page, object is a cVBar. Columns and rows are counted from 0 in the buffer.

How a bar is drawn

A bar of height rows is drawn in the rows row to row + height - 1 of one column. The number of filled rows is CLng(percent / 100 * height), which rounds half to even, and a bar with a percent above 0 has at least one filled row. The filled rows are the bottom ones, drawn with the bar character in the colours fore on back. The rows above them are overwritten with spaces in the same colours, so a bar that is drawn again on top of a taller one clears it.

A percent outside 0 to 100 is limited to the range. In the members that take minValue and maxValue, each value is first converted to a percentage with 100 * (value - minValue) / (maxValue - minValue); a maxValue equal to minValue raises error 11, Division by zero.

A bar that is made before the console enters full-screen mode holds no buffer, and its first draw raises error 91, Object variable or With block variable not set; see How a component works.

Enumeration

BarCharStyle

The character of the filled rows. The enumeration is declared in the class, and its members are written without the class, as in BarCharStyle.Dark.

Member	Value	Character
Block	0	U+2588, a full block; the default
Light	1	U+2591, a light shade
Medium	2	U+2592, a medium shade
Dark	3	U+2593, a dark shade
Custom	4	U+2588, as Block

Custom is meant for a character chosen by the program, but no member has a parameter for one, so Custom draws the same character as Block. A value outside 0 to 4 leaves the character empty, and a bar with at least one filled row then raises error 5, Invalid procedure call or argument.

Constructor

New

Creates a bar chart for a console.

Syntax: New cVBar ( console )

console: required A cConsole that is in full-screen mode.

Keeps the console and its current Buffer. When the console is not in full-screen mode, the buffer is Nothing and every draw raises error 91.

Methods

Render

Draws one bar.

Syntax: object.Render ( col , row , height , percent [ , fore [ , back [ , charStyle ] ] ] )

col, row: required Long values, the column of the bar and the row of its top.
height: required A Long, the number of rows.
percent: required A Double, 0 to 100.
fore: optional A ConsoleColor, the colour of the bar. The default is Green.
back: optional A ConsoleColor, the background. The default is Black.
charStyle: optional A BarCharStyle. The default is Block.

RenderBars

Draws a bar for each value of an array, side by side.

Syntax: object.RenderBars ( col , row , height , values [ , spacing [ , minValue [ , maxValue [ , fore [ , back [ , charStyle ] ] ] ] ] ] )

col, row, height: required Long values: the column of the first bar, the row of the top of the bars, and their height.
values: required An array of Double, passed by reference. The bars follow the order of the array, from its lower bound to its upper bound.
spacing: optional A Long, the number of blank columns between two bars. The default is 1. The bars are 1 + spacing columns apart; the blank columns are not written.
minValue, maxValue: optional Double values, the values that give an empty bar and a full bar. The defaults are 0 and 100.
fore, back, charStyle: optional, as for Render.

The bar for the first value is in column col, and the next bars are at col + (1 + spacing), and so on.

RenderHistory

Draws a series of values as bars with no gap, the last value at the right.

Syntax: object.RenderHistory ( col , row , height , history [ , minValue [ , maxValue [ , fore [ , back [ , charStyle ] ] ] ] ] )

col, row, height: required Long values: the column of the last bar, the row of the top of the bars, and their height.
history: required An array of Double, passed by reference, that starts at index 0. The last element is the newest value.
minValue, maxValue, fore, back, charStyle: optional, as for RenderBars.

The last element of the array is drawn in column col, the one before it in column col - 1, and so on to the left, one column each, so col is the right end of the chart and not its start. Columns left of the buffer are dropped. Nothing is drawn for an array with no element. The drawing code addresses the values by position from 0, so an array with a lower bound of 1 raises error 9, Subscript out of range. A program that shows a moving history keeps its own array, shifts it by one value for each new reading, and draws it again.

RenderWithGradient

Draws a bar for each value, coloured by its value.

Syntax: object.RenderWithGradient ( col , row , height , values [ , spacing [ , minValue [ , maxValue [ , lowColor [ , midColor [ , highColor [ , back [ , charStyle ] ] ] ] ] ] ] ] )

col, row, height, values, spacing, minValue, maxValue: As for RenderBars.
lowColor: optional A ConsoleColor, for bars below 50 percent. The default is Green.
midColor: optional A ConsoleColor, for bars from 50 percent up to, but not including, 80 percent. The default is Yellow.
highColor: optional A ConsoleColor, for bars of 80 percent and more. The default is Red.
back, charStyle: optional, as for Render.

The colour of each bar is one of the three; there is no gradient between them. Note the order of the parameters: the three colours come before back, and there is no fore.

RenderWithLabel

Draws one bar and a label below it.

Syntax: object.RenderWithLabel ( col , row , height , percent , label [ , fore [ , back [ , charStyle [ , labelColor ] ] ] ] )

col, row, height, percent, fore, back, charStyle: As for Render.
label: required A String.
labelColor: optional A ConsoleColor, the colour of the label. The default is Gray.

Draws the bar with Render, and writes the label in the row row + height + 1, which leaves one blank row under the bar. The label starts in column col - Len(label) \ 2 + 1, or in column 0 when that is negative. That is one column to the right of the column that would centre the label under the bar.