implemented image reader

io/reader/image.go

@@ -1,9 +1,74 @@
 package reader
 
-import "maze-solver/maze"
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"os"
 
-type ImageReader struct{}
+	"golang.org/x/image/draw"
+)
 
-func (r *ImageReader) Read(filename string) (*maze.Maze, error) {
-	return nil, nil
+type ImageReader struct {
+	Filename              string
+	PathColor, WallColor  color.Color
+	CellWidth, CellHeight int
+}
+
+func (r *ImageReader) Read() (*RawMaze, error) {
+	image, err := r.getShrunkImage()
+	if err != nil {
+		return nil, err
+	}
+
+	width, height := image.Bounds().Max.X, image.Bounds().Max.Y
+	ret := &RawMaze{
+		Width:  width,
+		Height: height,
+		Data:   make([][]byte, height),
+	}
+
+	n_chunks := width/CHUNK_SIZE + 1
+
+	for i := 0; i < height; i++ {
+		ret.Data[i] = make([]byte, n_chunks)
+	}
+
+	for y := 0; y < height; y++ {
+		for i := 0; i < n_chunks; i++ {
+			var chunk byte = 0 // all walls
+
+			end_index := min((i+1)*CHUNK_SIZE, width)
+
+			for x := i * CHUNK_SIZE; x < end_index; x++ {
+				c := image.At(x, y)
+				if c == r.PathColor {
+					chunk |= 1 << (CHUNK_SIZE - 1 - (x - i*CHUNK_SIZE))
+				}
+			}
+
+			ret.Data[y][i] = chunk
+		}
+	}
+
+	return ret, nil
+}
+
+func (r *ImageReader) getShrunkImage() (*image.RGBA, error) {
+	input, err := os.Open(r.Filename)
+	if err != nil {
+		return nil, err
+	}
+	defer input.Close()
+
+	// Decode the image (from PNG to image.Image):
+	src, _ := png.Decode(input)
+
+	// Set the expected size that you want:
+	dst := image.NewRGBA(image.Rect(0, 0, src.Bounds().Max.X/r.CellWidth, src.Bounds().Max.Y/r.CellHeight))
+
+	// Resize:
+	draw.NearestNeighbor.Scale(dst, dst.Rect, src, src.Bounds(), draw.Over, nil)
+
+	return dst, nil
 }

io/reader/image_test.go

@@ -0,0 +1,112 @@
+package reader
+
+import (
+	"image/color"
+	"maze-solver/utils"
+	"testing"
+)
+
+func TestImageReader(t *testing.T) {
+	white := color.RGBA{255, 255, 255, 255}
+	black := color.RGBA{0, 0, 0, 255}
+	tests := []struct {
+		name                  string
+		width, height         int
+		cellWidth, cellHeight int
+		pathColor, wallColor  color.Color
+		filename              string
+		expected              [][]byte
+	}{
+		{
+			"Trivial",
+			5, 3,
+			40, 40,
+			white, black,
+			"../../assets/trivial.png",
+			[][]byte{
+				{0b_00100_000},
+				{0b_01110_000},
+				{0b_00010_000},
+			},
+		},
+		{
+			"Trivial Bigger",
+			7, 5,
+			40, 40,
+			white, black,
+			"../../assets/bigger.png",
+			[][]byte{
+				{0b_0001000_0},
+				{0b_0001000_0},
+				{0b_0111110_0},
+				{0b_0000010_0},
+				{0b_0000010_0},
+			},
+		},
+		{
+			"Bigger Staggered",
+			7, 5,
+			40, 40,
+
+			white, black,
+			"../../assets/bigger_staggered.png",
+			[][]byte{
+				{0b_0001000_0},
+				{0b_0001000_0},
+				{0b_0111110_0},
+				{0b_0000100_0},
+				{0b_0000100_0},
+			},
+		},
+		{
+			"Normal",
+			11, 11,
+			40, 40,
+			white, black,
+			"../../assets/normal.png",
+			[][]byte{
+				{0b_00000100, 0b000_00000},
+				{0b_01111101, 0b110_00000},
+				{0b_00000100, 0b010_00000},
+				{0b_01110111, 0b110_00000},
+				{0b_01010000, 0b010_00000},
+				{0b_01011111, 0b110_00000},
+				{0b_00010001, 0b010_00000},
+				{0b_01110111, 0b010_00000},
+				{0b_01000000, 0b010_00000},
+				{0b_01111101, 0b110_00000},
+				{0b_00000100, 0b000_00000},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		reader := ImageReader{
+			Filename:   test.filename,
+			PathColor:  test.pathColor,
+			WallColor:  test.wallColor,
+			CellWidth:  test.cellWidth,
+			CellHeight: test.cellHeight,
+		}
+		got, err := reader.Read()
+		if err != nil {
+			t.Fatalf("%s: got error while reading, got\n%v", test.filename, err)
+		}
+
+		utils.AssertEqual(t, got.Width, test.width, "%s: width of raw maze don't match", test.name)
+		utils.AssertEqual(t, got.Height, test.height, "%s: height of raw maze don't match", test.name)
+		utils.AssertEqual(t, len(got.Data), len(test.expected), "%s: don't have the same number of rows", test.name)
+
+		for y, line_exp := range test.expected {
+			line_got := got.Data[y]
+			utils.AssertEqual(t, len(line_got), len(line_exp), "%s (line %v): don't have same number of chunks", test.name, y)
+
+			for i, chunk_exp := range line_exp {
+				chunk_got := line_got[i]
+				if chunk_got != chunk_exp {
+					t.Fatalf("%s (line %v): chunk %v don't coincide, %08b, want %08b", test.name, y, i, chunk_got, chunk_exp)
+				}
+			}
+		}
+	}
+}