draw2d/samples/appengine/server.go

73 lines
1.6 KiB
Go

// +build appengine
// Package gae demonstrates draw2d on a Google appengine server.
package gae
import (
"fmt"
"image"
"image/png"
"net/http"
"github.com/llgcode/draw2d/draw2dimg"
"github.com/llgcode/draw2d/draw2dpdf"
"github.com/llgcode/draw2d/samples/android"
"appengine"
)
type appError struct {
Error error
Message string
Code int
}
type appHandler func(http.ResponseWriter, *http.Request) *appError
func (fn appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if e := fn(w, r); e != nil { // e is *appError, not os.Error.
c := appengine.NewContext(r)
c.Errorf("%v", e.Error)
http.Error(w, e.Message, e.Code)
}
}
func init() {
http.Handle("/pdf", appHandler(pdf))
http.Handle("/png", appHandler(imgPng))
}
func pdf(w http.ResponseWriter, r *http.Request) *appError {
w.Header().Set("Content-type", "application/pdf")
// Initialize the graphic context on an pdf document
dest := draw2dpdf.NewPdf("L", "mm", "A4")
gc := draw2dpdf.NewGraphicContext(dest)
// Draw sample
android.Draw(gc, 65, 0)
err := dest.Output(w)
if err != nil {
return &appError{err, fmt.Sprintf("Can't write: %s", err), 500}
}
return nil
}
func imgPng(w http.ResponseWriter, r *http.Request) *appError {
w.Header().Set("Content-type", "image/png")
// Initialize the graphic context on an RGBA image
dest := image.NewRGBA(image.Rect(0, 0, 297, 210.0))
gc := draw2dimg.NewGraphicContext(dest)
// Draw sample
android.Draw(gc, 65, 0)
err := png.Encode(w, dest)
if err != nil {
return &appError{err, fmt.Sprintf("Can't encode: %s", err), 500}
}
return nil
}