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conversion.go
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conversion.go
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// Copyright 2014 Andreas Koch. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package thumbnail
import (
"github.com/andreaskoch/allmark/common/logger"
// "github.com/andreaskoch/allmark/common/route"
"github.com/andreaskoch/allmark/common/util/fsutil"
"github.com/andreaskoch/allmark/dataaccess"
"github.com/andreaskoch/allmark/services/imageconversion"
"fmt"
"io"
"path/filepath"
)
var (
SizeSmall = ThumbDimension{
MaxWidth: 320,
MaxHeight: 240,
}
SizeMedium = ThumbDimension{
MaxWidth: 640,
MaxHeight: 480,
}
SizeLarge = ThumbDimension{
MaxWidth: 1024,
MaxHeight: 768,
}
)
func NewConversionService(logger logger.Logger, repository dataaccess.Repository, thumbnailIndex *Index) *ConversionService {
// create a new conversion service
conversionService := &ConversionService{
logger: logger,
repository: repository,
index: thumbnailIndex,
thumbnailFolder: thumbnailIndex.GetThumbnailFolder(),
}
// start the conversion
conversionService.startConversion()
return conversionService
}
type ConversionService struct {
logger logger.Logger
repository dataaccess.Repository
updates chan dataaccess.Update
index *Index
thumbnailFolder string
}
// Start the conversion process.
func (conversion *ConversionService) startConversion() {
// listen for updates
repositoryUpdates := make(chan dataaccess.Update, 1)
conversion.repository.Subscribe(repositoryUpdates)
go func() {
for update := range repositoryUpdates {
// create thumbnails for new items
for _, newItemRoute := range update.New() {
conversion.createThumbnailsForItem(conversion.repository.Item(newItemRoute))
}
// create thumbnails for modified items
for _, modifiedItemRoute := range update.Modified() {
conversion.createThumbnailsForItem(conversion.repository.Item(modifiedItemRoute))
}
}
}()
// full run
go conversion.fullConversion()
}
// Process all items in the repository.
func (conversion *ConversionService) fullConversion() {
for _, item := range conversion.repository.Items() {
conversion.createThumbnailsForItem(item)
}
}
// Create thumbnail for all image files found in the supplied item.
func (conversion *ConversionService) createThumbnailsForItem(item dataaccess.Item) {
if item == nil {
return
}
for _, file := range item.Files() {
conversion.createThumbnailsForFile(file)
}
}
// Create thumbnail for all image files found in the supplied item.
func (conversion *ConversionService) createThumbnailsForFile(file dataaccess.File) {
conversion.createThumbnail(file, SizeSmall)
conversion.createThumbnail(file, SizeMedium)
conversion.createThumbnail(file, SizeLarge)
}
// Creates a thumbnail for the supplied file with the specified dimensions.
func (conversion *ConversionService) createThumbnail(file dataaccess.File, dimensions ThumbDimension) {
// get the mime type
mimeType, err := file.MimeType()
if err != nil {
conversion.logger.Warn("Unable to detect mime type for file. Error: %s", err.Error())
return
}
// check the mime type
if !imageconversion.MimeTypeIsSupported(mimeType) {
conversion.logger.Debug("The mime-type %q is currently not supported.", mimeType)
return
}
// determine the file name
fileExtension := imageconversion.GetFileExtensionFromMimeType(mimeType)
filename := fmt.Sprintf("%s-%v-%v.%s", file.Id(), dimensions.MaxWidth, dimensions.MaxHeight, fileExtension)
thumb := newThumb(file.Route(), filename, dimensions)
// check the index
if conversion.isInIndex(thumb) {
conversion.logger.Debug("Thumb %q already available in the index", thumb.String())
return
}
// determine the file path
filePath := filepath.Join(conversion.thumbnailFolder, filename)
// create the target file
created, createError := fsutil.CreateFile(filePath)
if !created {
conversion.logger.Warn("Could not create thumbnail file %q. Error: %s", filePath, createError.Error())
return
}
// open the target file
target, fileError := fsutil.OpenFile(filePath)
if fileError != nil {
conversion.logger.Warn("Unable to detect mime type for file. Error: %s", fileError.Error())
return
}
defer target.Close()
// convert the image
conversionError := file.Data(func(content io.ReadSeeker) error {
return imageconversion.Resize(content, mimeType, dimensions.MaxWidth, dimensions.MaxHeight, target)
})
// handle errors
if conversionError != nil {
conversion.logger.Warn("Unable to create thumbnail for file %q. Error: %s", file, conversionError.Error())
return
}
// add to index
conversion.addToIndex(thumb)
conversion.logger.Debug("Adding Thumb %q to index", thumb.String())
}
func (conversion *ConversionService) isInIndex(thumb Thumb) bool {
// check if there are thumb for the route
thumbs, entryExists := conversion.index.GetThumbs(thumb.Route)
if !entryExists {
return false
}
// check if there is a thumb with that dimensions
if _, thumbExists := thumbs[thumb.Dimensions.String()]; thumbExists {
// check if the file exists
thumbnailFilePath := conversion.index.GetThumbnailFilepath(thumb)
return fsutil.FileExists(thumbnailFilePath)
}
return false
}
func (conversion *ConversionService) addToIndex(thumb Thumb) {
thumbs, entryExists := conversion.index.GetThumbs(thumb.Route)
if !entryExists {
thumbs = make(Thumbs)
}
thumbs[thumb.Dimensions.String()] = thumb
conversion.index.SetThumbs(thumb.Route, thumbs)
}