I am working on an xpages app, where the client wants to restrict the size of images that are pasted into the document. I have restricted docs with the upload component, but not with a pasted image.
Has anyone done anything like this?
Thanks
walt
Yes it is possible, I haven't done this but there are a few ways you could go about it.
Excuse me if you already know this, but it is worth pointing out for anyone who comes across this question in the future, RichText as we knew it from Notes/Domino is not used XPages, it is all MIME. When I started Xpages I knew nothing about MIME so after understanding it all I have written a little summary on my blog to help anyone get used to the idea. If you are going to do anything with the InputRichText control and File Uploads etc. it is worth getting familiar with MIMEEntity's.
http://camerongregor.com/2016/04/21/webmail-ui-you-must-learn-about-mime/
There are 2 ways that images can make it into the 'rich text field', either uploaded using the 'Image' button on the editor toolbar, or alternatively in some web browsers, the image can be pasted from the clipboard. The 2 different methods will include the image in 2 different ways
Uploaded
If the image is uploaded, then the image becomes a multipart/related mime entity of some sort of image/jpeg, image/png etc., related to the text/html. Between the time that the image is uploaded, and the time that the Document is saved, the image file will be located on the server's disk, in the xpages persistence folder associated with the Document e.g.
xsppers_directory/application-id/session-id/document-id/someimage.png
Pasted
When pasted the image is not uploaded as a file to the server's persistence folder, but is instead included within the text/html as a data URI image (as Stephan mentioned in the comment above).
So, if you want a true solution you will need to address both avenues.
Handling Pasted images
I have shared a plugin on my blog which blocks pasted images, so this could be used to eliminate the 'paste' avenue altogether, and force users down the upload avenue.
http://camerongregor.com/2016/11/14/preventing-pasting-of-images-in-ckeditor/
Alternatively, if you are happy with having smaller pasted images, you could just 'restrict' it by modifying the plugin so that it checks the 'length' of the data URI (as Stephan suggested above) and allows the paste if the length is below your predetermined limit.
If even more alternatively, you could find some sort of client side javascript library that will resize images and do it there in the client before the paste.
Or another server-side option is you could process the contents of the 'text/html' MIMEEntity when saving, and find any img tag's that used Data URI's and strip it out, resize the image using some server side library such as ImageMagick and replace it.
Handling Uploaded Images
For uploaded images, an intense solution would be to extend the InputRichText control (similar to how the have demonstrated in the Mastering Xpages 2nd edition) and override the processAjaxRequest event so that it resizes the image during the process of uploading of the image and putting it in the persistence folder. You could resize it there and then using something like ImageMagick.
Or a less intense version would be to process the 'pending' attachments during a before save event. If you get the DominoRichTextItem from the DominoDocument, you should be able to iterate through the Attachments, checking their attachment state, there will be a state which means 'pending/about to upload' and for these ones you can process them while they are in the persistence folder, before they are finally attached to the document.
Finally if you don't want the xpages runtime / persistence directory to be involved, you could do it all after save, just using the backend NotesDocument and MimeEntity processing. Extract the Image MimeEntities to disk, process them with ImageMagick or similar, and then re-attach them.
Someone else may have a simpler solution that I haven't thought of but at least this gives you some idea of what may be involved.
Related
I have a lot galleries displayed with Lightbox2 and it works fine.
Now I want to delete the larger version of the pictures, but keep the gallery with the thumbnails for visitors.
How can I manage, that lightbox2 displays an alternative image, if the given file in the html is not existing?
I couldn't find an option in lightbox.js to handle with missing targets.
I had the same question, but after a little research I decided that Lightbox2 is not the right place to handle missing images. Instead, that should be handled at the server or application level.
The web server will respond with a 404 error for any missing resource, whether a web page, image, or anything else. In most cases, it also returns a small HTML page to alert the user (such as this example at Google).
You can usually configure your server or application to return a default 404-style image instead of an HTML page if the requested resource was an image. That will then be displayed to the user instead of the broken image symbol.
How you do this of course depends on the particular server/application stack you are using, but here is a good solution for Apache.
Ok, there is a lot of tutorials on the net, how to upload images to express.js servers. But I couldn't find how to upload images while doing other things, e.g:
there is a form, in which I would like to create article. Users fill it with title, some content... after that, he have to upload images. I would like to give him ability to see thumbnails of those images before he create this article. Of course I can just push them through ajax post with jquery, and put them on the screen with javascript, but: when I upload them on to the server, and user closes browser before finishing creating this article, I still have does images on my server, even though no one will use them.
I'm sorry, I couldn't think of simpler explanation of what I want.
So how to handle such a situation?
You can upload image to a temporary folder first and move that image to desired location while actually saving article.
Set up a cron to cleanup the temp folder.
I need to create, for a specific project, an image manager that works via Ajax (to get the list of images, display them, ...).
The upload of new images, or image modification, is done via an Ajax script (using the new javascript File API).
The upload works fine, but I encounter a problem in case of image modification : the image displayed by the browser after upload is the cached one and not the uploaded one !!
I know it's a classic cache problem, that can be solved via the 'imagesrc?new Date.getTime()' hack, but I can't use it here.
in fact, this hack doesn't really reload the image, it only create a new instance of the image into the cache, associated to the image url 'imagesrc?new Date.getTime()'.
So, if at any moment, into the image manager, I retry to display the image, without adding the '?new Date.getTime()' to the src, it will display again the old image.
And I either cannot add this hack systematically (because, for example, if the image manager needs to display a lot of very heavy images, it's usefull to get them from the browser cache until they are modified).
I searched a way to solve this problem on internet (really replace the cached image after a javascript upload instead of using the above hack), but I found nothing.
Is there a way to do this, or is it totally impossible ?
Any help or suggestion would be greatly appreciated.
Many thanks in advance
Olivier
Configure your server to send ETag-headers for the images.
An ETag is a hash-value of the file that changes when the file is modified. If an ETag is sent, the browser will add an If-None-Match-header containing the last received ETag of that ressource on its next request and the server will respond with 304: not modified to save traffic if nothing has changed or send the new file if there is one.
I'm coming from a php/mysql background. I'm most familiar with the Kohana PHP framework and I'm trying to learn Docpad. I have a loose understand at this point and I've built out my first website and blog. Static content makes a lot of sense to me on Docpad.
I'm working on my photography site where I want to be able to upload new images to a portfolio. The backend needs to handle an uploaded high-resolution image and create several different copies at different resolutions of the image. My biggest question is how do I keep track of the image meta data that I want to display? Do I generate a physical file for each image that has all the particulars I want to track and use those files as my searchable database, much like how blog posts are setup?
Or should I go the route of using something like MongoDB to store image data there where it can be queried and plugged into a layout?
Regarding handling POST or GET data, should I be reading up on the express.js docs? I'm not really sure where to turn for that.
Wordpress uses TimThumb to re-size it's images: How does WordPress.com resize images dynamically?
Then there is this re-sizing library for node: node package for file attachments and image resizing
If you wanted to created like 3 different image sizes and use the backbone collection in DocPad, then you'd add your different re-sized images to those three different collections/folders. For access the images you might just be able to do it via it's file name. So when you copy, re-size and rename the image, in the rename step, concat the image size at the end, like: coolPhoto-med.jpg and then you could just do hard links to get to the image like /spring-collection/med/coolPhoto-med.jpg or you could use query engine to access them.
The file model has a meta attribute: https://github.com/bevry/docpad/blob/master/src/lib/models/file.coffee#L17
I've yet to learn how to use it yet though.
I know we chatted yesterday on #docpad IRC but I just wanted to answer you here too. If you do code something that re-sizes images for DocPad, please do consider putting it up on Github to share with the community.
I've got an app on Google App Engine that will accept image uploads from users. The problem that I envision is that users will upload these images directly from their cameras, and file sizes are often greater than 1MB, which is the limit for the image API (which would be used to resize the images).
What's the best way to accept the upload of say a 1.5MB image file, and resize it to under 1MB?
While this is not clear in the App Engine documentation, this is possible by using a combination of the Blobstore and the Image Manipulation Service.
You must:
Upload the Image into the Blobstore
Retrieve the Image from the Blobstore
Perform the Image Manipulation with an Image resulting in less than 1mb in size
I've written up a post about this -> http://socialappdev.com/uploading-and-re-sizing-large-images-on-app-engine-11-2010.
Here are two (similar) ways to solve this:
If you want to keep everything controlled yourself, you can put a resize script on a server of yours, which takes the URL to the raw uploaded image (which can be up to 10MB due to HTTP response size limit, but you would have to store it as 1MB chunks in the datastore), downloads it from your application, resizes it, and then POSTs it back to your application. All this interaction would need some kind of authorization of course, so that it can't be abused. Alternatively, POST the image directly to your external server, but then you have to either send the other form data back to your application, or use a separate form for the image upload.
Use an external imaging service. I would recommend Picnik. See their API documentation. As you can see, it lets you make a form that posts the image directly to their servers, then the user can edit the image (and resize), then the image is posted back to your server. With this solution you have to upload the image in a separate form, since Picnik receives all your POST data.
I recommend point 2, because it doesn't require you to go around Google App Engine limitations and since your users are uploading images straight from the camera, they will probably want to do something with them anyways (such as crop.)
That's a conundrum. The "obvious" answer, using google.appengine.api.images.resize, won't work because it's too big. :) So you will have to use third-party software, either on the server (which will be tricky because of App Engine's limitations) or the cilent (e.g. a Java uploader).