Rename *MatrixI -> New*Matrix

colormatrix.go

@@ -32,8 +32,8 @@ type ColorMatrix struct {
 	es [ColorMatrixDim - 1][ColorMatrixDim]float64
 }
 
-// ColorMatrixI returns an identity color matrix.
+// NewColorMatrix returns an identity color matrix.
-func ColorMatrixI() ColorMatrix {
+func NewColorMatrix() ColorMatrix {
 	return ColorMatrix{
 		[ColorMatrixDim - 1][ColorMatrixDim]float64{
 			{1, 0, 0, 0, 0},

colormatrix_test.go

@@ -20,7 +20,7 @@ import (
 )
 
 func TestColorIdentity(t *testing.T) {
-	m := ColorMatrixI()
+	m := NewColorMatrix()
 	got := m.IsIdentity()
 	want := true
 	if want != got {

geometrymatrix.go

@@ -27,8 +27,8 @@ type GeometryMatrix struct {
 	es [GeometryMatrixDim - 1][GeometryMatrixDim]float64
 }
 
-// GeometryMatrixI returns an identity geometry matrix.
+// NewGeometryMatrix returns an identity geometry matrix.
-func GeometryMatrixI() GeometryMatrix {
+func NewGeometryMatrix() GeometryMatrix {
 	return GeometryMatrix{
 		[GeometryMatrixDim - 1][GeometryMatrixDim]float64{
 			{1, 0, 0},

geometrymatrix_test.go

@@ -20,7 +20,7 @@ import (
 )
 
 func TestGeometryIdentity(t *testing.T) {
-	m := GeometryMatrixI()
+	m := NewGeometryMatrix()
 	got := m.IsIdentity()
 	want := true
 	if want != got {

graphicscontext.go

@@ -67,7 +67,7 @@ func (c *graphicsContext) postUpdate() error {
 
 	scale := float64(c.screenScale)
 	geo := ScaleGeometry(scale, scale)
-	clr := ColorMatrixI()
+	clr := NewColorMatrix()
 	option := &DrawImageOptions{
 		GeometryMatrix: &geo,
 		ColorMatrix:    &clr,

image.go

@@ -69,12 +69,12 @@ func (i *innerImage) drawImage(img *innerImage, options *DrawImageOptions) error
 	}
 	geo := options.GeometryMatrix
 	if geo == nil {
-		i := GeometryMatrixI()
+		i := NewGeometryMatrix()
 		geo = &i
 	}
 	clr := options.ColorMatrix
 	if clr == nil {
-		i := ColorMatrixI()
+		i := NewColorMatrix()
 		clr = &i
 	}
 
@@ -155,10 +155,16 @@ func (i *Image) Fill(clr color.Color) (err error) {
 }
 
 // DrawImage draws the given image on the receiver image.
-// This method accepts the parts of the given image at the parts of the destination as the options.
-// After determining parts to draw, this applies the geometry matrix and the color matrix as the options.
 //
-// If you want to draw a whole image simply, use DrawWholeImage.
+// This method accepts the options.
+// The parts of the given image at the parts of the destination.
+// After determining parts to draw, this applies the geometry matrix and the color matrix.
+//
+// If options is nil or its members are nil, the default values are used.
+//     DstParts:       (0, 0) - (source width, source height)
+//     SrcParts:       (0, 0) - (source width, source height) (i.e. the whole source image)
+//     GeometryMatrix: Identity matrix
+//     ColorMatrix:    Identity matrix (that changes no colors)
 func (i *Image) DrawImage(image *Image, options *DrawImageOptions) (err error) {
 	return i.drawImage(image.inner, options)
 }