color tests etc.

chart_test.go

@@ -483,3 +483,24 @@ func TestChartCheckRangesWithRanges(t *testing.T) {
 	xr, yr, yra := c.getRanges()
 	assert.Nil(c.checkRanges(xr, yr, yra))
 }
+
+func TestChartE2ELine(t *testing.T) {
+	assert := assert.New(t)
+
+	c := Chart{
+		Series: []Series{
+			ContinuousSeries{
+				XValues: Sequence.Float64(0, 4, 1),
+				YValues: Sequence.Float64(0, 4, 1),
+			},
+		},
+	}
+
+	var buffer = &bytes.Buffer{}
+	err := c.Render(PNG, buffer)
+	assert.Nil(err)
+
+	// do color tests ...
+
+	
+}

drawing/color.go

@@ -46,12 +46,20 @@ func ColorFromHex(hex string) Color {
 	return c
 }
 
+// ColorFromAlphaMixedRGBA returns the system alpha mixed rgba values.
+func ColorFromAlphaMixedRGBA(r, g, b, a uint32) Color {
+	fa := float64(a) / 255.0
+	var c Color
+	c.R = uint8(float64(r) / fa)
+	c.G = uint8(float64(g) / fa)
+	c.B = uint8(float64(b) / fa)
+	c.A = uint8(a | (a >> 8))
+	return c
+}
+
 // Color is our internal color type because color.Color is bullshit.
 type Color struct {
-	R uint8
-	G uint8
-	B uint8
-	A uint8
+	R, G, B, A uint8
 }
 
 // RGBA returns the color as a pre-alpha mixed color set.
@@ -88,6 +96,14 @@ func (c Color) WithAlpha(a uint8) Color {
 	}
 }
 
+// Equals returns true if the color equals another.
+func (c Color) Equals(other Color) bool {
+	return c.R == other.R &&
+		c.G == other.G &&
+		c.B == other.B &&
+		c.A == other.A
+}
+
 // String returns a css string representation of the color.
 func (c Color) String() string {
 	fa := float64(c.A) / float64(255)

drawing/color_test.go

@@ -3,6 +3,8 @@ package drawing
 import (
 	"testing"
 
+	"image/color"
+
 	"github.com/blendlabs/go-assert"
 )
 
@@ -39,3 +41,13 @@ func TestColorFromHex(t *testing.T) {
 	shortBlue := ColorFromHex("00F")
 	assert.Equal(ColorBlue, shortBlue)
 }
+
+func TestColorFromAlphaMixedRGBA(t *testing.T) {
+	assert := assert.New(t)
+
+	black := ColorFromAlphaMixedRGBA(color.Black.RGBA())
+	assert.True(black.Equals(ColorBlack), black.String())
+
+	white := ColorFromAlphaMixedRGBA(color.White.RGBA())
+	assert.True(white.Equals(ColorWhite), white.String())
+}

drawing/image.go

@@ -0,0 +1,23 @@
+package drawing
+
+import "image"
+
+// Image is a helper wraper that allows (sane) access to pixel info.
+type Image struct {
+	Inner *image.RGBA
+}
+
+// Width returns the image's width in pixels.
+func (i Image) Width() int {
+	return i.Inner.Rect.Size().X
+}
+
+// Height returns the image's height in pixels.
+func (i Image) Height() int {
+	return i.Inner.Rect.Size().Y
+}
+
+// At returns a pixel color at a given x/y.
+func (i Image) At(x, y int) Color {
+	return ColorFromAlphaMixedRGBA(i.Inner.At(x, y).RGBA())
+}