package drawing import ( "image" "image/color" "github.com/golang/freetype/truetype" ) // StackGraphicContext is a context that does thngs. type StackGraphicContext struct { current *ContextStack } // ContextStack is a graphic context implementation. type ContextStack struct { Tr Matrix Path *Path LineWidth float64 Dash []float64 DashOffset float64 StrokeColor color.Color FillColor color.Color FillRule FillRule Cap LineCap Join LineJoin FontSizePoints float64 Font *truetype.Font Scale float64 Previous *ContextStack } // NewStackGraphicContext Create a new Graphic context from an image func NewStackGraphicContext() *StackGraphicContext { gc := &StackGraphicContext{} gc.current = new(ContextStack) gc.current.Tr = NewIdentityMatrix() gc.current.Path = new(Path) gc.current.LineWidth = 1.0 gc.current.StrokeColor = image.Black gc.current.FillColor = image.White gc.current.Cap = RoundCap gc.current.FillRule = FillRuleEvenOdd gc.current.Join = RoundJoin gc.current.FontSizePoints = 10 return gc } // GetMatrixTransform returns the matrix transform. func (gc *StackGraphicContext) GetMatrixTransform() Matrix { return gc.current.Tr } // SetMatrixTransform sets the matrix transform. func (gc *StackGraphicContext) SetMatrixTransform(tr Matrix) { gc.current.Tr = tr } // ComposeMatrixTransform composes a transform into the current transform. func (gc *StackGraphicContext) ComposeMatrixTransform(tr Matrix) { gc.current.Tr.Compose(tr) } // Rotate rotates the matrix transform by an angle in degrees. func (gc *StackGraphicContext) Rotate(angle float64) { gc.current.Tr.Rotate(angle) } // Translate translates a transform. func (gc *StackGraphicContext) Translate(tx, ty float64) { gc.current.Tr.Translate(tx, ty) } // Scale scales a transform. func (gc *StackGraphicContext) Scale(sx, sy float64) { gc.current.Tr.Scale(sx, sy) } // SetStrokeColor sets the stroke color. func (gc *StackGraphicContext) SetStrokeColor(c color.Color) { gc.current.StrokeColor = c } // SetFillColor sets the fill color. func (gc *StackGraphicContext) SetFillColor(c color.Color) { gc.current.FillColor = c } // SetFillRule sets the fill rule. func (gc *StackGraphicContext) SetFillRule(f FillRule) { gc.current.FillRule = f } // SetLineWidth sets the line width. func (gc *StackGraphicContext) SetLineWidth(lineWidth float64) { gc.current.LineWidth = lineWidth } // SetLineCap sets the line cap. func (gc *StackGraphicContext) SetLineCap(cap LineCap) { gc.current.Cap = cap } // SetLineJoin sets the line join. func (gc *StackGraphicContext) SetLineJoin(join LineJoin) { gc.current.Join = join } // SetLineDash sets the line dash. func (gc *StackGraphicContext) SetLineDash(dash []float64, dashOffset float64) { gc.current.Dash = dash gc.current.DashOffset = dashOffset } // SetFontSize sets the font size. func (gc *StackGraphicContext) SetFontSize(fontSizePoints float64) { gc.current.FontSizePoints = fontSizePoints } // GetFontSize gets the font size. func (gc *StackGraphicContext) GetFontSize() float64 { return gc.current.FontSizePoints } // SetFont sets the current font. func (gc *StackGraphicContext) SetFont(f *truetype.Font) { gc.current.Font = f } // GetFont returns the font. func (gc *StackGraphicContext) GetFont() *truetype.Font { return gc.current.Font } // BeginPath starts a new path. func (gc *StackGraphicContext) BeginPath() { gc.current.Path.Clear() } // IsEmpty returns if the path is empty. func (gc *StackGraphicContext) IsEmpty() bool { return gc.current.Path.IsEmpty() } // LastPoint returns the last point on the path. func (gc *StackGraphicContext) LastPoint() (x float64, y float64) { return gc.current.Path.LastPoint() } // MoveTo moves the cursor for a path. func (gc *StackGraphicContext) MoveTo(x, y float64) { gc.current.Path.MoveTo(x, y) } // LineTo draws a line. func (gc *StackGraphicContext) LineTo(x, y float64) { gc.current.Path.LineTo(x, y) } // QuadCurveTo draws a quad curve. func (gc *StackGraphicContext) QuadCurveTo(cx, cy, x, y float64) { gc.current.Path.QuadCurveTo(cx, cy, x, y) } // CubicCurveTo draws a cubic curve. func (gc *StackGraphicContext) CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64) { gc.current.Path.CubicCurveTo(cx1, cy1, cx2, cy2, x, y) } // ArcTo draws an arc. func (gc *StackGraphicContext) ArcTo(cx, cy, rx, ry, startAngle, angle float64) { gc.current.Path.ArcTo(cx, cy, rx, ry, startAngle, angle) } // Close closes a path. func (gc *StackGraphicContext) Close() { gc.current.Path.Close() } // Save pushes a context onto the stack. func (gc *StackGraphicContext) Save() { context := new(ContextStack) context.FontSizePoints = gc.current.FontSizePoints context.Font = gc.current.Font context.LineWidth = gc.current.LineWidth context.StrokeColor = gc.current.StrokeColor context.FillColor = gc.current.FillColor context.FillRule = gc.current.FillRule context.Dash = gc.current.Dash context.DashOffset = gc.current.DashOffset context.Cap = gc.current.Cap context.Join = gc.current.Join context.Path = gc.current.Path.Copy() context.Font = gc.current.Font context.Scale = gc.current.Scale copy(context.Tr[:], gc.current.Tr[:]) context.Previous = gc.current gc.current = context } // Restore restores the previous context. func (gc *StackGraphicContext) Restore() { if gc.current.Previous != nil { oldContext := gc.current gc.current = gc.current.Previous oldContext.Previous = nil } }