Initial data commit

Task/Grayscale-image/Go/grayscale-image.go

@@ -0,0 +1,100 @@
+package raster
+
+import (
+    "math"
+    "math/rand"
+)
+
+// Grmap parallels Bitmap, but with an element type of uint16
+// in place of Pixel.
+type Grmap struct {
+    Comments   []string
+    rows, cols int
+    px         []uint16
+    pxRow      [][]uint16
+}
+
+// NewGrmap constructor.
+func NewGrmap(x, y int) (b *Grmap) {
+    g := &Grmap{
+        Comments: []string{creator}, // creator a const in bitmap source file
+        rows:     y,
+        cols:     x,
+        px:       make([]uint16, x*y),
+        pxRow:    make([][]uint16, y),
+    }
+    x0, x1 := 0, x
+    for i := range g.pxRow {
+        g.pxRow[i] = g.px[x0:x1]
+        x0, x1 = x1, x1+x
+    }
+    return g
+}
+
+func (b *Grmap) Extent() (cols, rows int) {
+    return b.cols, b.rows
+}
+
+func (g *Grmap) Fill(c uint16) {
+    for i := range g.px {
+        g.px[i] = c
+    }
+}
+
+func (g *Grmap) SetPx(x, y int, c uint16) bool {
+    defer func() { recover() }()
+    g.pxRow[y][x] = c
+    return true
+}
+
+func (g *Grmap) GetPx(x, y int) (uint16, bool) {
+    defer func() { recover() }()
+    return g.pxRow[y][x], true
+}
+
+// Grmap method of Bitmap, converts (color) Bitmap to (grayscale) Grmap
+func (b *Bitmap) Grmap() *Grmap {
+    g := NewGrmap(b.cols, b.rows)
+    g.Comments = append([]string{}, b.Comments...)
+    for i, p := range b.px {
+        g.px[i] = uint16((int64(p.R)*2126 + int64(p.G)*7152 + int64(p.B)*722) *
+            math.MaxUint16 / (math.MaxUint8 * 10000))
+    }
+    return g
+}
+
+// Bitmap method Grmap, converts Grmap to Bitmap.  All pixels in the resulting
+// color Bitmap will be (very nearly) shades of gray.
+func (g *Grmap) Bitmap() *Bitmap {
+    b := NewBitmap(g.cols, g.rows)
+    b.Comments = append([]string{}, g.Comments...)
+    for i, p := range g.px {
+        roundedSum := int(p) * 3 * math.MaxUint8 / math.MaxUint16
+        rounded := uint8(roundedSum / 3)
+        remainder := roundedSum % 3
+        b.px[i].R = rounded
+        b.px[i].G = rounded
+        b.px[i].B = rounded
+        if remainder > 0 {
+            odd := rand.Intn(3)
+            switch odd + (remainder * 3) {
+            case 3:
+                b.px[i].R++
+            case 4:
+                b.px[i].G++
+            case 5:
+                b.px[i].B++
+            case 6:
+                b.px[i].G++
+                b.px[i].B++
+            case 7:
+                b.px[i].R++
+                b.px[i].B++
+            case 8:
+                b.px[i].R++
+                b.px[i].G++
+            }
+        }
+    }
+    return b
+}