icat: a program to print images in the terminal.

Thanks to WizardCoder for implementing the first version of this code. I
had to clean it up quite a bit though.

1 files changed, 80 insertions, 0 deletions

diff --git a/icat.go b/icat.go
new file mode 100644
index 0000000..2b2a847
--- /dev/null
+++ b/icat.go
@@ -0,0 +1,80 @@
+package main
+
+import (
+	"fmt"
+	"golang.org/x/term"
+	"image"
+	_ "image/jpeg"
+	_ "image/png"
+	"os"
+)
+
+func load(filename string) (image.Image, error) {
+	file := os.Stdin
+	if filename != "-" {
+		var err error
+		file, err = os.Open(filename)
+		if err != nil {
+			return nil, err
+		}
+		defer file.Close()
+	}
+
+	img, _, err := image.Decode(file)
+	if err != nil {
+		return nil, fmt.Errorf("decode %q: %s", filename, err)
+	}
+
+	return img, nil
+}
+
+func printImg(filename string) error {
+	img, err := load(filename)
+	if err != nil {
+		return err
+	}
+
+	cols, lines, err := term.GetSize(1)
+	if err != nil {
+		return fmt.Errorf("terminal size: %s", err)
+	}
+	lines-- // Leave a line for the status bar.
+
+	// Try not to stretch the image.
+	if img.Bounds().Dy()*cols <= img.Bounds().Dx()*lines*5/2 {
+		lines = img.Bounds().Dy() * cols / (img.Bounds().Dx() * 5 / 2)
+	} else {
+		cols = img.Bounds().Dx() * lines * 5 / 2 / img.Bounds().Dy()
+	}
+
+	// nearest-neighbor interpolation
+	for y := 0; y < lines; y++ {
+		for x := 0; x < cols; x++ {
+			sx := x*img.Bounds().Dx()/cols + img.Bounds().Min.X
+			sy := y*img.Bounds().Dy()/lines + img.Bounds().Min.Y
+			r, g, b, _ := img.At(sx, sy).RGBA()
+			fmt.Printf("\033[48;2;%d;%d;%dm ", r>>8, g>>8, b>>8)
+		}
+		fmt.Println("\033[49m")
+	}
+	return nil
+}
+
+func icat(args []string) error {
+	if len(args) == 0 {
+		args = []string{"-"}
+	}
+	for _, f := range args {
+		if err := printImg(f); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func main() {
+	if err := icat(os.Args[1:]); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed: %s\n", err)
+		os.Exit(1)
+	}
+}