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PegStripChart
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Overview |
Derived from class
PegChart
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The PegStripChart class provides a simple, dynamic,
two dimensional plot of one or more data variables as a function of another
variable (often time).
Y values are plotted left to right along the
X axis as data samples become available.
Each data point is joined to the data point to its left
(if any) by a straight line.
Two presentation styles are supported: scrolled and paged.
The scrolled strip chart operates as follows.
When a data point is finally added to the right edge of the chart,
the previously plotted data points start to shift horizontally to the left.
The oldest (leftmost) data sample is lost as each new data sample
is added at the right edge of the chart.
The paged strip chart operates as follows.
When a data point is finally added to the right edge of the chart,
the color of all previously plotted data points is changed to the
aged color indicating that the data is valid, but old.
New data points are once again added from left to right in the active color
replacing the oldest (leftmost) data points.
An optional vertical line called a leader is drawn to indicate the current
drawing position for new data. The leader acts as a boundary between
new data to its left and aged data to its right.
The strip chart has a single leader.
The strip chart is drawn as a collection of one or more trace lines.
These trace lines can overlap. All trace lines operate in the same way:
either all are scrolled or all are paged.
Each trace line is identified by a line ID, a number
ranging from 1 to 255.
One strip chart can contain at most 255 traces lines.
Line IDs are assigned as you add trace lines to the strip chart.
If a trace line is removed from the strip chart, its line ID
may be reused to identify a subsequent line added to the chart.
For each trace line, a PegStripChartLine structure is
maintained by the PegStripChart class. These private structures
are used to identify the trace lines and control their display.
The pointer to such a trace line structure is called a
line handle. Your application will have access to these
handles as you add, insert or remove the trace lines which form your
strip chart.
For each trace line, the PegStripChart class
maintains an array of data points which make up the trace line.
You can add data points (samples) to the array. However, once in the
array, the data points become private to the class and unaccessible
to your application.
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To use the PegStripChart class or its derivatives,
your KwikPeg configuration must have the following option enabled: |
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Drawing: Charts |
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PegLineChart
PegMultiLineChart
The PegStripChart class supports
the following extended style flags:
CS_AUTOSIZE |
If this flag is set, the chart will always take up the
entire mClient region of its parent.
When the parent is resized or moved, the PegChart
object also resizes itself appropriately. |
CS_DRAWXGRID |
Draw grid lines along the X axis in the chart region. |
CS_DRAWYGRID |
Draw grid lines along the Y axis in the chart region. |
CS_DRAWXTICS |
Draw tick marks along the X axis at the specified intervals. |
CS_DRAWYTICS |
Draw tick marks along the Y axis at the specified intervals. |
CS_DRAWXLABELS |
Draw incremental value labels along the X axis below the chart.
The label values are based on the minimum and maximum possible
values of X. |
CS_DRAWYLABELS |
Draw incremental value labels along the Y axis to the left of the chart.
The label values are based on the minimum and maximum possible
values of Y. |
CS_DUALYLABELS |
Draw Y axis value labels along both the left and right
edges of the chart.
This style flag is ignored if the CS_DRAWYLABELS style flag
is not also set. |
CS_DUALYTICS |
Draw Y axis tick marks along both the left and right
edges of the chart.
This style flag is ignored if the CS_DRAWYTICS style flag
is not also set. |
CS_DRAWLINEFILL |
Fill the area between the trace lines and the (x,y=0) axis
with the currently specified fill color. |
CS_XAXISONZEROY |
Draw the X axis along the Y=0 axis instead of below the chart.
This style flag is ignored if the CS_DRAWXTICS style flag
is not also set. |
CS_DRAWXAXIS |
Draw a horizontal baseline at value Y=0 across the chart region.
Tick marks and labels are not drawn on the line.
This style flag is ignored if style flag CS_XAXISONZEROY
is set. |
CS_PAGED |
This style flag and CS_SCROLLED are mutually exclusive.
Draw data horizontally from left to right and page the data
horizontally. New data is drawn at the leader marker which
advances to the right. When the leader reaches the
right boundary of the chart region, the leader wraps to the
left boundary of the chart region.
At that instant, existing data becomes old and is drawn in an
aged data color specified via the AddLine() member function.
New data continues to be drawn in the active data color at the leader
position as it advances from left to right.
The behavior of the strip chart mimics that of a heart beat
monitor. |
CS_SCROLLED |
This style flag and CS_PAGED are mutually exclusive.
Data is drawn from the left to the right across the chart region.
When the right boundary of the chart region is reached, data
starts to scroll. Old data is shifted to the left. The oldest
data is lost as it shifts past the left boundary of the chart region.
New data continues to be added at the right.
The behavior of the strip chart mimics that of a seismograph. |
CS_DRAWAGED |
For a paged strip chart, the aged data is only drawn if this
style flag is set. If this flag is not set, the strip chart is cleared
of aged data every time the trace reaches the right boundary of the chart.
This style flag is ignored unless the CS_PAGED style flag is set. |
CS_DRAWLEADER |
The vertical leader line which marks the current position at which
data is being added to a paged strip chart is only drawn if this
style flag is set.
This style flag is ignored unless the CS_PAGED style flag is set. |
Constructors:
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PegStripChart(const PegRect &Rect,
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WORD wSamples,
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LONG lMinY, LONG lMaxY,
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WORD wXMajorScale = 0,
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WORD wYMajorScale = 0)
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This constructor creates a strip chart
in the rectangle specified by parameter Rect.
If style flag CS_AUTOSIZE is to be used
(see function SetExStyle()), you may want to draw the chart
in the parent's mClient rectangle.
Parameter wSamples specifies the number of data points
(samples) which are to be drawn at equidistant intervals across the width
of the chart region. This parameter defines the size of the data point array
which will be allocated for each trace line added to the strip chart.
Parameters lMinY and lMaxY specify the
minimum and maximum Y (vertical) values.
Data points which lie outside this range, although not rejected, will not
be viewable in the chart rectangle.
Parameters wXMajorScale and wYMajorScale define
the intervals along the X and Y axes respectively at which major tick marks
will be drawn. Of course, tick marks are only drawn if the object's
CS_DRAWXTICS or CS_DRAWYTICS extended style
flag is set.
For example, if the minimum Y value
is -100, the maximum Y value is 900, the Y scale is 100 and
the CS_DRAWYTICS extended style flag is set, then tick marks
will be drawn on the Y axis at intervals of 100 starting at -100 and ending
at 900. Consequently, there will be 11 tick marks drawn on the Y axis.
If the CS_DRAWYGRID extended style flag is also set,
horizontal grid lines will also be drawn at the same tick mark intervals.
The interval at which axis label values are drawn is independent of
the tick mark/grid line scaling interval. Hence, tick marks might appear
at intervals of 100 with the axis values labeled at intervals of 200.
Another style flag, CS_XAXISONZEROY, is provided
for strip charts to force the X axis to be drawn at the Y=0 position
rather than at the usual minimum Y position.
Style flag CS_DRAWXAXIS is also provided
for strip charts to force a baseline to be drawn at the Y=0 position.
This style flag is ignored if style flag CS_XAXISONZEROY
is used to force the X axis to be drawn at the Y=0 location.
For strip charts, the relationship between the wSamples
and wXScale parameters is important.
Parameter wSamples indicates the number of data samples which will
be presented across the width of the chart.
Parameter wXScale indicates the intervals
at which tick marks will be drawn along the X axis.
It is up to your application to ensure that the data points are
presented sequentially so that the resulting presentation is meaningful.
Public Functions:
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BOOL AddData(UCHAR ucID,
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LONG lRawData,
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BOOL bRedraw = TRUE)
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This function adds the new data point (sample) value lRawData
to the trace line with line ID ucID.
The function returns TRUE if the the data point value was
added successfully, else FALSE.
When adding data to a multitrace strip chart, it is important that you
add one new data point value for each trace line so that every trace has
a data point value for each sample point along the X axis.
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UCHAR AddLine(
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COLORVAL tLineColor, COLORVAL tAgedColor,
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COLORVAL tFillColor = 0)
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This function adds a new trace line to the strip chart.
Parameter tLineColor
indicates the active color to be used to draw the trace as new data
points are added to it.
Parameter tAgedColor
indicates the aged color to be used to redraw the old trace data
for a paged strip chart presentation.
Parameter tFillColor
indicates the color to be used to fill the region between the trace line
and the X axis. This color is only used if
extended style flag CS_DRAWLINEFILL is set.
The function returns the line ID assigned to the new trace line.
The function returns the value 0 if a new trace line
cannot be added.
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void Draw(void)
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The PegStripChart class overrides
the Draw() function to draw each of the trace lines
which make up the strip chart.
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COLORVAL GetLineAgedColor(UCHAR ucID)
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COLORVAL GetLineColor(UCHAR ucID)
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COLORVAL GetLineFillColor(UCHAR ucID)
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These functions return each of the colors being used to draw the
trace line with line ID ucID.
The aged color is only meaningful for a paged strip chart.
The fill color is only meaningful if
extended style flag CS_DRAWLINEFILL is set.
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COLORVAL GetLineLeaderColor(UCHAR ucID)
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This function returns the color being used
to draw the leader for the trace line with line ID ucID.
Since trace leaders are only drawn for paged strip charts,
the color returned by this function is only meaningful
if extended style flag CS_PAGED is set.
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SIGNED IndexToPointX(WORD wIndex)
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This function converts a data array index to an X axis screen location
measured in pixels. The index is used by the strip chart to identify
samples within the data value array maintained for each trace line.
The conversion accounts for the width of the
chart region and the number of samples displayed along the X axis.
This function is used privately by this chart class.
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SIGNED Message(const PegMessage &Mesg)
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The PegStripChart class overrides
the Message() function to recalculate the chart location
or layout when its parent is moved or resized.
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virtual void RecalcSize(
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const PegRect &NewRect,
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BOOL bRedraw = TRUE)
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The PegStripChart class overrides
the RecalcSize() function to adjust the
strip chart's location and size
as specified by the rectangle NewRect.
This function is used privately to redraw the strip chart
if it is moved or resized.
The function uses the Resize() function to
update the screen coordinates of all the data points
associated with each trace line.
If the bRedraw flag is TRUE,
the chart is redrawn.
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BOOL RemoveLine(UCHAR ucID)
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This function removes the trace line with line ID ucID
from the strip chart. If the trace line is successfully removed, the
value TRUE is returned, else FALSE.
Once a trace line has been removed from the chart,
its line ID becomes free.
The line ID may subsequently be reused for a new line.
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virtual void Resize(PegRect NewRect)
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The PegStripChart class overrides
the Resize() function to adjust the strip chart's
location and size as specified by the rectangle NewRect.
The function calls the PegChart base class
RecalcLayout() function
but inhibits redrawing of the chart.
This function is used privately by this chart class.
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void SetLineAgedColor(UCHAR ucID,
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COLORVAL tColor)
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void SetLineColor(UCHAR ucID,
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COLORVAL tColor)
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void SetLineFillColor(UCHAR ucID,
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COLORVAL tColor)
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These functions set each of the colors to be used to draw the
trace line with line ID ucID.
The aged color is only meaningful for a paged strip chart.
The fill color is only meaningful if
extended style flag CS_DRAWLINEFILL is set.
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void SetLineLeaderColor(UCHAR ucID, COLORVAL tColor)
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This function sets the color to be used
to draw the leader for the trace line with line ID ucID.
If a leader color is not defined, the trace line color will be used.
Trace leaders are only drawn for paged strip charts.
Hence, this function has no effect unless
extended style flag CS_PAGED is set.
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SIGNED ValToPointY(LONG lVal)
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This function converts a data value to a Y axis screen location
measured in pixels. The conversion accounts for the height of the
chart region and the range of sample values allowed along the Y axis.
This function is used privately by this chart class.
The following code fragment illustrates the use of a
PegStripChart object to generate the paged strip chart
pictured below. The code needed to dynamically add data points to the
strip chart is not shown.
PegRect Rect;
Rect.Set(40, 40, 590, 240);
PegStripChart *pChart =
new PegStripChart(Rect, 240, -100, 120, 0, 20);
UCHAR mucID = pChart->AddLine(
LIGHTGREEN, DARKGRAY);
Add(pChart);
