Golang Canvas.Contains方法代码示例

// Plot implements the Plotter interface, drawing labels.
func (l *Labels) Plot(c draw.Canvas, p *plot.Plot) {
	trX, trY := p.Transforms(&c)
	for i, label := range l.Labels {
		x := trX(l.XYs[i].X)
		y := trY(l.XYs[i].Y)
		if !c.Contains(draw.Point{x, y}) {
			continue
		}
		x += l.XOffset
		y += l.YOffset
		c.FillText(l.TextStyle, x, y, l.XAlign, l.YAlign, label)
	}
}

// naivePlot implements the a naive rendering approach for contours.
// It is here as a debugging mode since it simply draws line segments
// generated by conrec without further computation.
func (h *Contour) naivePlot(c draw.Canvas, plt *plot.Plot) {
	var pal []color.Color
	if h.Palette != nil {
		pal = h.Palette.Colors()
	}

	trX, trY := plt.Transforms(&c)

	// Sort levels prior to palette scaling since we can't depend on
	// sorting as a side effect from calling contourPaths.
	sort.Float64s(h.Levels)
	// ps is a palette scaling factor to scale the palette uniformly
	// across the given levels. This enables a discordance between the
	// number of colours and the number of levels.
	ps := float64(len(pal)-1) / (h.Levels[len(h.Levels)-1] - h.Levels[0])
	if len(h.Levels) == 1 {
		ps = 0
	}

	levelMap := make(map[float64]int)
	for i, z := range h.Levels {
		levelMap[z] = i
	}

	// Draw each line segment as conrec generates it.
	var pa vg.Path
	conrec(h.GridXYZ, h.Levels, func(_, _ int, l line, z float64) {
		if math.IsNaN(z) {
			return
		}

		pa = pa[:0]

		x1, y1 := trX(l.p1.X), trY(l.p1.Y)
		x2, y2 := trX(l.p2.X), trY(l.p2.Y)

		if !c.Contains(draw.Point{x1, y1}) || !c.Contains(draw.Point{x2, y2}) {
			return
		}

		pa.Move(x1, y1)
		pa.Line(x2, y2)
		pa.Close()

		style := h.LineStyles[levelMap[z]%len(h.LineStyles)]
		var col color.Color
		switch {
		case z < h.Min:
			col = h.Underflow
		case z > h.Max:
			col = h.Overflow
		case len(pal) == 0:
			col = style.Color
		default:
			col = pal[int((z-h.Levels[0])*ps+0.5)] // Apply palette scaling.
		}
		if col != nil && style.Width != 0 {
			c.SetLineStyle(style)
			c.SetColor(col)
			c.Stroke(pa)
		}
	})
}

// Plot implements the Plot method of the plot.Plotter interface.
func (h *HeatMap) Plot(c draw.Canvas, plt *plot.Plot) {
	pal := h.Palette.Colors()
	if len(pal) == 0 {
		panic("heatmap: empty palette")
	}
	// ps scales the palette uniformly across the data range.
	ps := float64(len(pal)-1) / (h.Max - h.Min)

	trX, trY := plt.Transforms(&c)

	var pa vg.Path
	cols, rows := h.GridXYZ.Dims()
	for i := 0; i < cols; i++ {

		var right, left float64
		switch i {
		case 0:
			right = (h.GridXYZ.X(i+1) - h.GridXYZ.X(i)) / 2
			left = -right
		case cols - 1:
			right = (h.GridXYZ.X(i) - h.GridXYZ.X(i-1)) / 2
			left = -right
		default:
			right = (h.GridXYZ.X(i+1) - h.GridXYZ.X(i)) / 2
			left = -(h.GridXYZ.X(i) - h.GridXYZ.X(i-1)) / 2
		}

		for j := 0; j < rows; j++ {
			v := h.GridXYZ.Z(i, j)
			if math.IsNaN(v) || math.IsInf(v, 0) {
				continue
			}

			pa = pa[:0]

			var up, down float64
			switch j {
			case 0:
				up = (h.GridXYZ.Y(j+1) - h.GridXYZ.Y(j)) / 2
				down = -up
			case rows - 1:
				up = (h.GridXYZ.Y(j) - h.GridXYZ.Y(j-1)) / 2
				down = -up
			default:
				up = (h.GridXYZ.Y(j+1) - h.GridXYZ.Y(j)) / 2
				down = -(h.GridXYZ.Y(j) - h.GridXYZ.Y(j-1)) / 2
			}

			x, y := trX(h.GridXYZ.X(i)+left), trY(h.GridXYZ.Y(j)+down)
			dx, dy := trX(h.GridXYZ.X(i)+right), trY(h.GridXYZ.Y(j)+up)

			if !c.Contains(draw.Point{x, y}) || !c.Contains(draw.Point{dx, dy}) {
				continue
			}

			pa.Move(x, y)
			pa.Line(dx, y)
			pa.Line(dx, dy)
			pa.Line(x, dy)
			pa.Close()

			var col color.Color
			switch {
			case v < h.Min:
				col = h.Underflow
			case v > h.Max:
				col = h.Overflow
			default:
				col = pal[int((v-h.Min)*ps+0.5)] // Apply palette scaling.
			}
			if col != nil {
				c.SetColor(col)
				c.Fill(pa)
			}
		}
	}
}

// drawCap draws the cap if it is not clipped.
func (e *YErrorBars) drawCap(c *draw.Canvas, x, y vg.Length) {
	if !c.Contains(draw.Point{x, y}) {
		return
	}
	c.StrokeLine2(e.LineStyle, x-e.CapWidth/2, y, x+e.CapWidth/2, y)
}