Adding upstream version 1.17.13.upstream/1.17.13upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 149 insertions, 0 deletions

diff --git a/src/image/decode_example_test.go b/src/image/decode_example_test.go
new file mode 100644
index 0000000..526c03f
--- /dev/null
+++ b/src/image/decode_example_test.go
@@ -0,0 +1,149 @@
+// Copyright 2012 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.
+
+// This example demonstrates decoding a JPEG image and examining its pixels.
+package image_test
+
+import (
+	"encoding/base64"
+	"fmt"
+	"image"
+	"log"
+	"strings"
+
+	// Package image/jpeg is not used explicitly in the code below,
+	// but is imported for its initialization side-effect, which allows
+	// image.Decode to understand JPEG formatted images. Uncomment these
+	// two lines to also understand GIF and PNG images:
+	// _ "image/gif"
+	// _ "image/png"
+	_ "image/jpeg"
+)
+
+func Example_decodeConfig() {
+	reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(data))
+	config, format, err := image.DecodeConfig(reader)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println("Width:", config.Width, "Height:", config.Height, "Format:", format)
+}
+
+func Example() {
+	// Decode the JPEG data. If reading from file, create a reader with
+	//
+	// reader, err := os.Open("testdata/video-001.q50.420.jpeg")
+	// if err != nil {
+	//     log.Fatal(err)
+	// }
+	// defer reader.Close()
+	reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(data))
+	m, _, err := image.Decode(reader)
+	if err != nil {
+		log.Fatal(err)
+	}
+	bounds := m.Bounds()
+
+	// Calculate a 16-bin histogram for m's red, green, blue and alpha components.
+	//
+	// An image's bounds do not necessarily start at (0, 0), so the two loops start
+	// at bounds.Min.Y and bounds.Min.X. Looping over Y first and X second is more
+	// likely to result in better memory access patterns than X first and Y second.
+	var histogram [16][4]int
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			r, g, b, a := m.At(x, y).RGBA()
+			// A color's RGBA method returns values in the range [0, 65535].
+			// Shifting by 12 reduces this to the range [0, 15].
+			histogram[r>>12][0]++
+			histogram[g>>12][1]++
+			histogram[b>>12][2]++
+			histogram[a>>12][3]++
+		}
+	}
+
+	// Print the results.
+	fmt.Printf("%-14s %6s %6s %6s %6s\n", "bin", "red", "green", "blue", "alpha")
+	for i, x := range histogram {
+		fmt.Printf("0x%04x-0x%04x: %6d %6d %6d %6d\n", i<<12, (i+1)<<12-1, x[0], x[1], x[2], x[3])
+	}
+	// Output:
+	// bin               red  green   blue  alpha
+	// 0x0000-0x0fff:    364    790   7242      0
+	// 0x1000-0x1fff:    645   2967   1039      0
+	// 0x2000-0x2fff:   1072   2299    979      0
+	// 0x3000-0x3fff:    820   2266    980      0
+	// 0x4000-0x4fff:    537   1305    541      0
+	// 0x5000-0x5fff:    319    962    261      0
+	// 0x6000-0x6fff:    322    375    177      0
+	// 0x7000-0x7fff:    601    279    214      0
+	// 0x8000-0x8fff:   3478    227    273      0
+	// 0x9000-0x9fff:   2260    234    329      0
+	// 0xa000-0xafff:    921    282    373      0
+	// 0xb000-0xbfff:    321    335    397      0
+	// 0xc000-0xcfff:    229    388    298      0
+	// 0xd000-0xdfff:    260    414    277      0
+	// 0xe000-0xefff:    516    428    298      0
+	// 0xf000-0xffff:   2785   1899   1772  15450
+}
+
+const data = `
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