Adding upstream version 2.1.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

renderer.go

@@ -0,0 +1,89 @@
+package chart
+
+import (
+	"io"
+
+	"github.com/golang/freetype/truetype"
+	"github.com/wcharczuk/go-chart/v2/drawing"
+)
+
+// Renderer represents the basic methods required to draw a chart.
+type Renderer interface {
+	// ResetStyle should reset any style related settings on the renderer.
+	ResetStyle()
+
+	// GetDPI gets the DPI for the renderer.
+	GetDPI() float64
+
+	// SetDPI sets the DPI for the renderer.
+	SetDPI(dpi float64)
+
+	// SetClassName sets the current class name.
+	SetClassName(string)
+
+	// SetStrokeColor sets the current stroke color.
+	SetStrokeColor(drawing.Color)
+
+	// SetFillColor sets the current fill color.
+	SetFillColor(drawing.Color)
+
+	// SetStrokeWidth sets the stroke width.
+	SetStrokeWidth(width float64)
+
+	// SetStrokeDashArray sets the stroke dash array.
+	SetStrokeDashArray(dashArray []float64)
+
+	// MoveTo moves the cursor to a given point.
+	MoveTo(x, y int)
+
+	// LineTo both starts a shape and draws a line to a given point
+	// from the previous point.
+	LineTo(x, y int)
+
+	// QuadCurveTo draws a quad curve.
+	// cx and cy represent the bezier "control points".
+	QuadCurveTo(cx, cy, x, y int)
+
+	// ArcTo draws an arc with a given center (cx,cy)
+	// a given set of radii (rx,ry), a startAngle and delta (in radians).
+	ArcTo(cx, cy int, rx, ry, startAngle, delta float64)
+
+	// Close finalizes a shape as drawn by LineTo.
+	Close()
+
+	// Stroke strokes the path.
+	Stroke()
+
+	// Fill fills the path, but does not stroke.
+	Fill()
+
+	// FillStroke fills and strokes a path.
+	FillStroke()
+
+	// Circle draws a circle at the given coords with a given radius.
+	Circle(radius float64, x, y int)
+
+	// SetFont sets a font for a text field.
+	SetFont(*truetype.Font)
+
+	// SetFontColor sets a font's color
+	SetFontColor(drawing.Color)
+
+	// SetFontSize sets the font size for a text field.
+	SetFontSize(size float64)
+
+	// Text draws a text blob.
+	Text(body string, x, y int)
+
+	// MeasureText measures text.
+	MeasureText(body string) Box
+
+	// SetTextRotatation sets a rotation for drawing elements.
+	SetTextRotation(radians float64)
+
+	// ClearTextRotation clears rotation.
+	ClearTextRotation()
+
+	// Save writes the image to the given writer.
+	Save(w io.Writer) error
+}