1 files changed, 71 insertions, 0 deletions
diff --git a/pkg/plot/heatmap.go b/pkg/plot/heatmap.go
new file mode 100644
index 0000000..2667b40
--- /dev/null
+++ b/pkg/plot/heatmap.go
@@ -0,0 +1,71 @@
+package plot
+
+import (
+	"bytes"
+
+	"github.com/sgreben/jp/pkg/data"
+	"github.com/sgreben/jp/pkg/draw"
+)
+
+// HeatMap is a heatmap
+type HeatMap struct{ draw.Heatmap }
+
+// NewHeatMap returns a new line chart
+func NewHeatMap(buffer *draw.Buffer) *HeatMap { return &HeatMap{draw.Heatmap{buffer}} }
+
+func (c *HeatMap) drawAxes(paddingX, paddingY int, minX, maxX, minY, maxY float64) {
+	buffer := c.GetBuffer()
+	// X axis
+	buffer.SetRow(1, paddingX, buffer.Width, draw.HorizontalLine)
+	// Y axis
+	buffer.SetColumn(1, buffer.Height, paddingX, draw.VerticalLine)
+	// Corner
+	buffer.Set(1, paddingX, draw.CornerBottomLeft)
+	// Labels
+	buffer.WriteRight(1, 1, Ff(minY))
+	buffer.WriteLeft(buffer.Height-1, paddingX, Ff(maxY))
+	buffer.WriteRight(0, paddingX, Ff(minX))
+	buffer.WriteLeft(0, buffer.Width, Ff(maxX))
+}
+
+// Draw implements Chart
+func (c *HeatMap) Draw(heatmap *data.Heatmap) string {
+	var scaleY, scaleX float64
+
+	minX := heatmap.X[0].LeftInclusive
+	maxX := heatmap.X[len(heatmap.X)-1].Right
+	minY := heatmap.Y[0].LeftInclusive
+	maxY := heatmap.Y[len(heatmap.Y)-1].Right
+	minLabelWidth := len(Ff(minY))
+	maxLabelWidth := len(Ff(maxY))
+
+	paddingX := minLabelWidth + 1
+	paddingY := 2
+	if minLabelWidth < maxLabelWidth {
+		paddingX = maxLabelWidth + 1
+	}
+	chartWidth := c.Size().Width - (paddingX + 1)
+	chartHeight := c.Size().Height - paddingY
+	scaleX = float64(chartWidth) / (maxX - minX)
+	scaleY = float64(chartHeight) / (maxY - minY)
+
+	for i := range heatmap.Z {
+		for j := range heatmap.Z[i] {
+			x0 := int((heatmap.X[j].LeftInclusive-minX)*scaleX + float64(paddingX+1))
+			y0 := int((heatmap.Y[i].LeftInclusive-minY)*scaleY + float64(paddingY))
+			x1 := int((heatmap.X[j].Right-minX)*scaleX + float64(paddingX+1))
+			y1 := int((heatmap.Y[i].Right-minY)*scaleY + float64(paddingY))
+			z := heatmap.Z[i][j]
+			for x := x0; x < x1; x++ {
+				for y := y0; y < y1; y++ {
+					c.Set(y, x, z)
+				}
+			}
+		}
+	}
+	c.drawAxes(paddingX, paddingY, minX, maxX, minY, maxY)
+
+	b := bytes.NewBuffer(nil)
+	c.GetBuffer().Render(b)
+	return b.String()
+}