Make it a Go module + minor tweaks

canvas/texture.go

@@ -13,10 +13,11 @@ import (
 
 // Texture can hold on to cached image textures.
 type Texture struct {
-	data   string   // data:image/png URI
-	image  js.Value // DOM image element
-	canvas js.Value // Warmed up canvas element
-	ctx2d  js.Value // 2D drawing context for the canvas.
+	data   string      // data:image/png URI
+	img    image.Image // underlying Go image data
+	image  js.Value    // DOM image element
+	canvas js.Value    // Warmed up canvas element
+	ctx2d  js.Value    // 2D drawing context for the canvas.
 	width  int
 	height int
 }
@@ -39,6 +40,7 @@ func (e *Engine) StoreTexture(name string, img image.Image) (render.Texturer, er
 
 	tex := &Texture{
 		data:   dataURI,
+		img:    img,
 		width:  width,
 		height: height,
 	}

color.go

@@ -53,6 +53,16 @@ func FromColor(from color.Color) Color {
 	)
 }
 
+// ToRGBA converts to a standard Go color.Color
+func (c Color) ToRGBA() color.RGBA {
+	return color.RGBA{
+		R: c.Red,
+		G: c.Green,
+		B: c.Blue,
+		A: c.Alpha,
+	}
+}
+
 // MustHexColor parses a color from hex code or panics.
 func MustHexColor(hex string) Color {
 	color, err := HexColor(hex)

go.mod

@@ -0,0 +1,8 @@
+module git.kirsle.net/go/render
+
+go 1.13
+
+require (
+	github.com/veandco/go-sdl2 v0.4.1
+	golang.org/x/image v0.0.0-20200119044424-58c23975cae1
+)

go.sum

@@ -0,0 +1,5 @@
+github.com/veandco/go-sdl2 v0.4.1 h1:HmSBvVmKWI8LAOeCfTTM8R33rMyPcs6U3o8n325c9Qg=
+github.com/veandco/go-sdl2 v0.4.1/go.mod h1:FB+kTpX9YTE+urhYiClnRzpOXbiWgaU3+5F2AB78DPg=
+golang.org/x/image v0.0.0-20200119044424-58c23975cae1 h1:5h3ngYt7+vXCDZCup/HkCQgW5XwmSvR/nA2JmJ0RErg=
+golang.org/x/image v0.0.0-20200119044424-58c23975cae1/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

image.go

@@ -0,0 +1,55 @@
+package render
+
+import (
+	"errors"
+	"image"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"os"
+	"path/filepath"
+
+	"golang.org/x/image/bmp"
+)
+
+// OpenImage opens an image file from disk.
+//
+// Supported file types are: jpeg, gif, png, bmp.
+func OpenImage(filename string) (image.Image, error) {
+	fh, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	var img image.Image
+
+	switch filepath.Ext(filename) {
+	case ".jpg":
+		fallthrough
+	case ".jpeg":
+		img, err = jpeg.Decode(fh)
+	case ".png":
+		img, err = png.Decode(fh)
+	case ".bmp":
+		img, err = bmp.Decode(fh)
+	case ".gif":
+		img, err = gif.Decode(fh)
+	default:
+		return nil, errors.New("unsupported file type")
+	}
+
+	return img, err
+}
+
+// ImageToRGBA converts a Go image.Image into an image.RGBA.
+func ImageToRGBA(input image.Image) *image.RGBA {
+	var bounds = input.Bounds()
+	var rgba = image.NewRGBA(bounds)
+	for x := bounds.Min.X; x < bounds.Max.X; x++ {
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			color := input.At(x, y)
+			rgba.Set(x, y, color)
+		}
+	}
+	return rgba
+}

sdl/canvas.go

@@ -24,10 +24,9 @@ func (r *Renderer) DrawPoint(color render.Color, point render.Point) {
 
 // DrawLine draws a line between two points.
 func (r *Renderer) DrawLine(color render.Color, a, b render.Point) {
-	if color != r.lastColor {
-		r.renderer.SetDrawColor(color.Red, color.Green, color.Blue, color.Alpha)
+	for pt := range render.IterLine(a, b) {
+		r.DrawPoint(color, pt)
 	}
-	r.renderer.DrawLine(int32(a.X), int32(a.Y), int32(b.X), int32(b.Y))
 }
 
 // DrawRect draws a rectangle.

sdl/events.go

@@ -156,6 +156,7 @@ func (r *Renderer) Poll() (*event.State, error) {
 			case sdl.SCANCODE_DOWN:
 				s.Down = t.State == 1
 			case sdl.SCANCODE_LSHIFT:
+				fallthrough
 			case sdl.SCANCODE_RSHIFT:
 				s.Shift = t.State == 1
 			case sdl.SCANCODE_LALT:

sdl/text.go

@@ -10,7 +10,7 @@ import (
 )
 
 // TODO: font filenames
-var defaultFontFilename = "DejaVuSans.ttf"
+var DefaultFontFilename = "DejaVuSans.ttf"
 
 // Font holds cached SDL_TTF structures for loaded fonts. They are created
 // automatically when fonts are either preinstalled (InstallFont) or loaded for
@@ -37,7 +37,7 @@ func InstallFont(filename string, binary []byte) {
 // LoadFont loads and caches the font at a given size.
 func LoadFont(filename string, size int) (*ttf.Font, error) {
 	if filename == "" {
-		filename = defaultFontFilename
+		filename = DefaultFontFilename
 	}
 
 	// Cached font available?

version.go

@@ -0,0 +1,4 @@
+package render
+
+// Version number of the render library.
+const Version = "0.1.0"