Documentation
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Overview ¶
Package axes calculates the required layout and draws the X and Y axes of a line chart.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
This section is empty.
Types ¶
type Label ¶
type Label struct {
// Value if the value to be displayed.
Value *Value
// Position of the label within the canvas.
Pos image.Point
}
Label is one value label on an axis.
type Value ¶
type Value struct {
// Value is the original unmodified value.
Value float64
// Rounded is the value rounded up to the nonZeroPlaces number of non-zero
// decimal places.
Rounded float64
// ZeroDecimals indicates how many decimal places in Rounded have a value
// of zero.
ZeroDecimals int
// NonZeroDecimals indicates the rounding precision used, it is provided on
// a call to newValue.
NonZeroDecimals int
// contains filtered or unexported fields
}
Value represents one value.
func NewTextValue ¶
NewTextValue constructs a value out of the provided text.
type XDetails ¶
type XDetails struct {
// Start is the point where the X axis starts.
// Both coordinates of Start are less than End.
Start image.Point
// End is the point where the X axis ends.
End image.Point
// Scale is the scale of the X axis.
Scale *XScale
// Labels are the labels for values on the X axis in an increasing order.
Labels []*Label
}
XDetails contain information about the X axis that will be drawn onto the canvas.
func NewXDetails ¶
func NewXDetails(numPoints int, yStart image.Point, cvsAr image.Rectangle, customLabels map[int]string) (*XDetails, error)
NewXDetails retrieves details about the X axis required to draw it on a canvas of the provided area. The yStart is the point where the Y axis starts. The numPoints is the number of points in the largest series that will be plotted. customLabels are the desired labels for the X axis, these are preferred if provided.
type XScale ¶
type XScale struct {
// Min is the minimum value on the axis.
Min *Value
// Max is the maximum value on the axis.
Max *Value
// Step is the step in the value between pixels.
Step *Value
// GraphWidth is the width in cells of the area on the canvas that is
// dedicated to the graph.
GraphWidth int
// contains filtered or unexported fields
}
XScale is the scale of the X axis.
func NewXScale ¶
NewXScale calculates the scale of the X axis, given the number of data points in the series and the width on the canvas that is available to the X axis. The nonZeroDecimals dictates rounding of the calculated scale, see NewValue for details. The numPoints must be zero or positive number. The graphWidth must be a positive number.
func (*XScale) CellLabel ¶
CellLabel given an X coordinate of a cell on the canvas, determines value of the label that should be next to it. The X coordinate must be within the graphWidth provided to NewXScale. X coordinates grow right. The returned value is rounded to the nearest int, rounding half away from zero.
func (*XScale) PixelToValue ¶
PixelToValue given a X coordinate of the pixel, returns its value according to the scale. The coordinate must be within bounds of the canvas width provided to NewXScale. X coordinates grow right.
func (*XScale) ValueToCell ¶
ValueToCell given a value, determines the X coordinate of the cell that most closely represents the value on the line chart according to the scale. The value must be within the bounds provided to NewXScale. X coordinates grow right.
func (*XScale) ValueToPixel ¶
ValueToPixel given a value, determines the X coordinate of the pixel that most closely represents the value on the line chart according to the scale. The value must be within the bounds provided to NewXScale. X coordinates grow right.
type Y ¶
type Y struct {
// contains filtered or unexported fields
}
Y tracks the state of the Y axis throughout the lifetime of a line chart. Implements lazy resize of the axis to decrease visual "jumping". This object is not thread-safe.
func NewY ¶
NewY returns a new Y instance. The minVal and maxVal represent the minimum and maximum value that will be displayed on the line chart among all of the series.
func (*Y) Details ¶
Details retrieves details about the Y axis required to draw it on a canvas of the provided area.
func (*Y) RequiredWidth ¶
RequiredWidth calculates the minimum width required in order to draw the Y axis.
type YDetails ¶
type YDetails struct {
// Width in character cells of the Y axis and its character labels.
Width int
// Start is the point where the Y axis starts.
// Both coordinates of Start are less than End.
Start image.Point
// End is the point where the Y axis ends.
End image.Point
// Scale is the scale of the Y axis.
Scale *YScale
// Labels are the labels for values on the Y axis in an increasing order.
Labels []*Label
}
YDetails contain information about the Y axis that will be drawn onto the canvas.
type YScale ¶
type YScale struct {
// Min is the minimum value on the axis.
Min *Value
// Max is the maximum value on the axis.
Max *Value
// Step is the step in the value between pixels.
Step *Value
// GraphHeight is the height in cells of the area on the canvas that is
// dedicated to the graph itself.
GraphHeight int
// contains filtered or unexported fields
}
YScale is the scale of the Y axis.
func NewYScale ¶
func NewYScale(min, max float64, graphHeight, nonZeroDecimals int, mode YScaleMode) (*YScale, error)
NewYScale calculates the scale of the Y axis, given the boundary values and the height of the graph. The nonZeroDecimals dictates rounding of the calculated scale, see NewValue for details. Max must be greater or equal to min. The graphHeight must be a positive number.
func (*YScale) CellLabel ¶
CellLabel given a Y coordinate of a cell on the canvas, determines value of the label that should be next to it. The Y coordinate must be within the graphHeight provided to NewYScale. Y coordinates grow down.
func (*YScale) PixelToValue ¶
PixelToValue given a Y coordinate of the pixel, returns its value according to the scale. The coordinate must be within bounds of the graph height provided to NewYScale. Y coordinates grow down.
func (*YScale) ValueToPixel ¶
ValueToPixel given a value, determines the Y coordinate of the pixel that most closely represents the value on the line chart according to the scale. The value must be within the bounds provided to NewYScale. Y coordinates grow down.
type YScaleMode ¶ added in v0.6.0
type YScaleMode int
YScaleMode determines whether the Y scale is anchored to the zero value.
const ( // YScaleModeAnchored is a mode in which the Y scale always starts at value // zero regardless of the min and max on the series. YScaleModeAnchored YScaleMode = iota // YScaleModeAdaptive is a mode where the Y scale adapts its base value // according to the min and max on the series. // I.e. it starts at min for all-positive series and at max for // all-negative series. YScaleModeAdaptive )
func (YScaleMode) String ¶ added in v0.6.0
func (ysm YScaleMode) String() string
String implements fmt.Stringer()
Source Files