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// 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.
package present
import (
"fmt"
"strings"
)
func init() {
Register("image", parseImage)
}
type Image struct {
URL string
Width int
Height int
}
func (i Image) TemplateName() string { return "image" }
func parseImage(ctx *Context, fileName string, lineno int, text string) (Elem, error) {
args := strings.Fields(text)
img := Image{URL: args[1]}
a, err := parseArgs(fileName, lineno, args[2:])
if err != nil {
return nil, err
}
switch len(a) {
case 0:
// no size parameters
case 2:
// If a parameter is empty (underscore) or invalid
// leave the field set to zero. The "image" action
// template will then omit that img tag attribute and
// the browser will calculate the value to preserve
// the aspect ratio.
if v, ok := a[0].(int); ok {
img.Height = v
}
if v, ok := a[1].(int); ok {
img.Width = v
}
default:
return nil, fmt.Errorf("incorrect image invocation: %q", text)
}
return img, nil
}