Data commit

Task/Bitmap-Write-a-PPM-file/Go/bitmap-write-a-ppm-file-1.go

@@ -0,0 +1,54 @@
+package raster
+
+import (
+    "fmt"
+    "io"
+    "os"
+)
+
+// WriteTo outputs 8-bit P6 PPM format to an io.Writer.
+func (b *Bitmap) WritePpmTo(w io.Writer) (err error) {
+    // magic number
+    if _, err = fmt.Fprintln(w, "P6"); err != nil {
+        return
+    }
+
+    // comments
+    for _, c := range b.Comments {
+        if _, err = fmt.Fprintln(w, c); err != nil {
+            return
+        }
+    }
+
+    // x, y, depth
+    _, err = fmt.Fprintf(w, "%d %d\n255\n", b.cols, b.rows)
+    if err != nil {
+        return
+    }
+
+    // raster data in a single write
+    b3 := make([]byte, 3*len(b.px))
+    n1 := 0
+    for _, px := range b.px {
+        b3[n1] = px.R
+        b3[n1+1] = px.G
+        b3[n1+2] = px.B
+        n1 += 3
+    }
+    if _, err = w.Write(b3); err != nil {
+        return
+    }
+    return
+}
+
+// WriteFile writes to the specified filename.
+func (b *Bitmap) WritePpmFile(fn string) (err error) {
+    var f *os.File
+    if f, err = os.Create(fn); err != nil {
+        return
+    }
+    if err = b.WritePpmTo(f); err != nil {
+        return
+    }
+    return f.Close()
+}

Task/Bitmap-Write-a-PPM-file/Go/bitmap-write-a-ppm-file-2.go

@@ -0,0 +1,19 @@
+package main
+
+// Files required to build supporting package raster are found in:
+// * This task (immediately above)
+// * Bitmap task
+
+import (
+    "raster"
+    "fmt"
+)
+
+func main() {
+    b := raster.NewBitmap(400, 300)
+    b.FillRgb(0x240008) // a dark red
+    err := b.WritePpmFile("write.ppm")
+    if err != nil {
+        fmt.Println(err)
+    }
+}