More efficient method for obtaining an image width and height #695
Description
The current method for obtaining the width and height of a png or jpg is inefficient if
only the
the dimensions are required
What steps will reproduce the problem?
Given the program and two images:
/Users/ajstarks/Images/yankee-stadium.jpg 8708 2086
/Users/ajstarks/Images/ys.jpg 8648 1872
real 0m3.554s
user 0m3.269s
sys 0m0.271s
by comparison, the python script:
import sys, Image
for f in sys.argv[1:]:
i=Image.open(f)
print f, i.size[0], i.size[1]
/Users/ajstarks/Images/yankee-stadium.jpg 8708 2086
/Users/ajstarks/Images/ys.jpg 8648 1872
real 0m0.039s
user 0m0.020s
sys 0m0.018s
package main
import (
"image/png"
"image/jpeg"
"strings"
"fmt"
"os"
)
func main() {
for i := 1; i < len(os.Args); i++ {
f, fok := os.Open(os.Args[i], os.O_RDONLY, 0)
defer f.Close()
if fok == nil {
if strings.HasSuffix(os.Args[i], ".jpg") {
j, ok := jpeg.Decode(f)
if ok == nil {
fmt.Printf("%s %d %d\n", os.Args[i], j.Width(), j.Height())
} else {
fmt.Printf("%v: %v\n", os.Args[i], ok)
}
} else {
p, ok := png.Decode(f)
if ok == nil {
fmt.Printf("%s %d %d\n", os.Args[i], p.Width(), p.Height())
} else {
fmt.Printf("%v: %v\n", os.Args[i], ok)
}
}
} else {
fmt.Printf("Cannot open " + os.Args[i])
}
}
}
What is the expected output? What do you see instead?
the output is correct, yet slower than needed. Time is dependent on image size
What is your $GOOS? $GOARCH?
darwin amd64
Which revision are you using? (hg identify)
9482fde11a02 release.2010-03-22/release
Please provide any additional information below.