From 445f51fb119789e08889abcb8ae54b4eb5029fad Mon Sep 17 00:00:00 2001 From: Suyash Date: Sun, 11 Sep 2016 12:47:47 +0530 Subject: [PATCH] image/png: add Encode and Decode examples partially addresses #16360 Change-Id: I8274825b9ca6aec46294c8513b4795b0eb3062a2 Reviewed-on: https://go-review.googlesource.com/28992 Reviewed-by: Brad Fitzpatrick Run-TryBot: Brad Fitzpatrick TryBot-Result: Gobot Gobot --- src/image/png/example_test.go | 77 +++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 src/image/png/example_test.go diff --git a/src/image/png/example_test.go b/src/image/png/example_test.go new file mode 100644 index 0000000000..c437632004 --- /dev/null +++ b/src/image/png/example_test.go @@ -0,0 +1,77 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package png_test + +import ( + "encoding/base64" + "fmt" + "image" + "image/color" + "image/png" + "io" + "log" + "os" + "strings" +) + +const gopher = `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` + +// gopherPNG creates an io.Reader by decoding the base64 encoded image data string in the gopher constant. +func gopherPNG() io.Reader { return base64.NewDecoder(base64.StdEncoding, strings.NewReader(gopher)) } + +func ExampleDecode() { + // This example uses png.Decode which can only decode PNG images. + // Consider using the general image.Decode as it can sniff and decode any registered image format. + img, err := png.Decode(gopherPNG()) + if err != nil { + log.Fatal(err) + } + + levels := []string{" ", "░", "▒", "▓", "█"} + + for y := img.Bounds().Min.Y; y < img.Bounds().Max.Y; y++ { + for x := img.Bounds().Min.X; x < img.Bounds().Max.X; x++ { + c := color.GrayModel.Convert(img.At(x, y)).(color.Gray) + level := c.Y / 51 // 51 * 5 = 255 + if level == 5 { + level-- + } + fmt.Print(levels[level]) + } + fmt.Print("\n") + } +} + +func ExampleEncode() { + const width, height = 256, 256 + + // Create a colored image of the given width and height. + img := image.NewNRGBA(image.Rect(0, 0, width, height)) + + for y := 0; y < height; y++ { + for x := 0; x < width; x++ { + img.Set(x, y, color.NRGBA{ + R: uint8((x + y) & 255), + G: uint8((x + y) << 1 & 255), + B: uint8((x + y) << 2 & 255), + A: 255, + }) + } + } + + f, err := os.Create("image.png") + if err != nil { + log.Fatal(err) + } + + if err := png.Encode(f, img); err != nil { + f.Close() + log.Fatal(err) + } + + if err := f.Close(); err != nil { + log.Fatal(err) + } +}