labels.go

Documentation: gonum.org/v1/plot/plotter

     1  // Copyright ©2015 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package plotter
     6  
     7  import (
     8  	"errors"
     9  
    10  	"gonum.org/v1/plot"
    11  	"gonum.org/v1/plot/font"
    12  	"gonum.org/v1/plot/text"
    13  	"gonum.org/v1/plot/vg"
    14  	"gonum.org/v1/plot/vg/draw"
    15  )
    16  
    17  var (
    18  	// DefaultFont is the default font for label text.
    19  	DefaultFont = plot.DefaultFont
    20  
    21  	// DefaultFontSize is the default font.
    22  	DefaultFontSize = vg.Points(10)
    23  )
    24  
    25  // Labels implements the Plotter interface,
    26  // drawing a set of labels at specified points.
    27  type Labels struct {
    28  	XYs
    29  
    30  	// Labels is the set of labels corresponding
    31  	// to each point.
    32  	Labels []string
    33  
    34  	// TextStyle is the style of the label text. Each label
    35  	// can have a different text style.
    36  	TextStyle []text.Style
    37  
    38  	// Offset is added directly to the final label location.
    39  	Offset vg.Point
    40  }
    41  
    42  // NewLabels returns a new Labels using the DefaultFont and
    43  // the DefaultFontSize.
    44  func NewLabels(d XYLabeller) (*Labels, error) {
    45  	xys, err := CopyXYs(d)
    46  	if err != nil {
    47  		return nil, err
    48  	}
    49  
    50  	if d.Len() != len(xys) {
    51  		return nil, errors.New("plotter: number of points does not match the number of labels")
    52  	}
    53  
    54  	strs := make([]string, d.Len())
    55  	for i := range strs {
    56  		strs[i] = d.Label(i)
    57  	}
    58  
    59  	styles := make([]text.Style, d.Len())
    60  	for i := range styles {
    61  		styles[i] = text.Style{
    62  			Font:    font.From(DefaultFont, DefaultFontSize),
    63  			Handler: plot.DefaultTextHandler,
    64  		}
    65  	}
    66  
    67  	return &Labels{
    68  		XYs:       xys,
    69  		Labels:    strs,
    70  		TextStyle: styles,
    71  	}, nil
    72  }
    73  
    74  // Plot implements the Plotter interface, drawing labels.
    75  func (l *Labels) Plot(c draw.Canvas, p *plot.Plot) {
    76  	trX, trY := p.Transforms(&c)
    77  	for i, label := range l.Labels {
    78  		pt := vg.Point{X: trX(l.XYs[i].X), Y: trY(l.XYs[i].Y)}
    79  		if !c.Contains(pt) {
    80  			continue
    81  		}
    82  		pt = pt.Add(l.Offset)
    83  		c.FillText(l.TextStyle[i], pt, label)
    84  	}
    85  }
    86  
    87  // DataRange returns the minimum and maximum X and Y values
    88  func (l *Labels) DataRange() (xmin, xmax, ymin, ymax float64) {
    89  	return XYRange(l)
    90  }
    91  
    92  // GlyphBoxes returns a slice of GlyphBoxes,
    93  // one for each of the labels, implementing the
    94  // plot.GlyphBoxer interface.
    95  func (l *Labels) GlyphBoxes(p *plot.Plot) []plot.GlyphBox {
    96  	bs := make([]plot.GlyphBox, len(l.Labels))
    97  	for i, label := range l.Labels {
    98  		bs[i] = plot.GlyphBox{
    99  			X:         p.X.Norm(l.XYs[i].X),
   100  			Y:         p.Y.Norm(l.XYs[i].Y),
   101  			Rectangle: l.TextStyle[i].Rectangle(label).Add(l.Offset),
   102  		}
   103  	}
   104  	return bs
   105  }
   106  
   107  // XYLabeller combines the XYer and Labeller types.
   108  type XYLabeller interface {
   109  	XYer
   110  	Labeller
   111  }
   112  
   113  // XYLabels holds XY data with labels.
   114  // The ith label corresponds to the ith XY.
   115  type XYLabels struct {
   116  	XYs
   117  	Labels []string
   118  }
   119  
   120  // Label returns the label for point index i.
   121  func (l XYLabels) Label(i int) string {
   122  	return l.Labels[i]
   123  }
   124  
   125  var _ XYLabeller = (*XYLabels)(nil)
   126
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