I have a site where images will needed to be presented in multiple sizes. I'd like to allow users to upload an image and not have to wait for the process (or background job) to resize it into the various sizes it needs to be stored in.
Ideally, I would like to set size attributes in the view, and the first time a user renders that view, for carrier wave to generate a new resized image and serve it up at render time.
Is this possible, and if so, is there any documentation on how to go about it?
Thanks.
Related
I'm working on a photography website in which full resolution photos can be uploaded but full-res should not be able to be displayed/accessed (download of the full res will take place through a token.)
I've tried the "restrictTo" setting but resolutions need to not be reliant on specified dimensions.
Is there a way to have myphoto.jpg by default without a querystring display at for example 700x700 yet still have the full resolution file available through a token download? Pretty much, an image without a querystring is still processed by Imageprocessor but with a default resize rule.
I can request an image with a native width of 5000px by myphoto.jpg?width=1400 but the resulting image is the full 5000px width image, why doesn't the max width 1400px image serve up?
If you are getting the full image back it means something has gone wrong. (You've probably ran out of contiguous memory) so make sure you're in 64bit mode.
maxWidth restricts the resize param to an upper limit only. So does nothing on it's own.
What you are probably looking for is the ValidatingRequest event
http://imageprocessor.org/imageprocessor-web/imageprocessingmodule/#events
I would first set ImageProcessor.Web to intercept all image requests in the processing.config file by changing the interceptAllRequests property. That will ensure you capture any attempts to view the image without a token.
In the event you can cancel the request and also alter/add any querystring parameters to limit your size transparently without showing the querystring to the end user.
I would use a query string for the image.
url?width=1400&height=900&mode=crop&anchor=center
I would also use a lazy load so the page loads faster with small blurry images and then afterwards replaces them all with the full res or querystring for max size you want to display at.
I wrote a script for this.
http://www.codeshare.co.uk/blog/lazy-loading-images/
Also on my site now, when I upload an image, I automatically resize it down to 1080p resolution when it saves. So I can upload a massive image and not have to worry about resizing it first or it taking up too much space on my server.
Here's the code for that too
http://www.codeshare.co.uk/blog/automatically-resize-your-media-images-in-umbraco/
in our website we are retrieving data from an API, which does not pull images bigger than 100 × 75 pixels, then we show them listed. example We need to double up this size to match with our design.
Is there any Gem that does this, without loosing quality and not impacting performance?
There is no way to upscale an image without losing quality - you're basically asking an algorithm to fill in image data that simply does not exist in the file in the first place.
However, depending on the rate of the scaling and the images themselves, you could have acceptable results.
Since you want to do this effectively and there is no benefit of doing the resizing on the server anyway, I'd advise simply using CSS to achieve this on the client side - just set the desired width/height attributes for the specific img elements.
If you really want to do this on the server (e.g. if you need to save the resulting images), one option would be to use the Paperclip gem's image processing capabilities.
I have a tableview that is populated from images on my server that I download. My question is How would I go about getting different images for the different resolutions for the devices? 6 vs 6plus etc?
Do I write code that is device specific? e.g
if device is equal to 6 load #2x images 'from #2x url'
else if
device is equal to 6 plus load #3x images 'from #3x url'
and so on.
Or is there a more efficient way of going about this?
You've got several options, depending on the back-end technology stack you're connecting to.
Options if you're using a custom server that you've built yourself, or have control over the code:
Add device scale detection into your image service that checks the inbound user-agent for device scale, and serves the appropriate image for that device. This is hands down probably the simplest solution to implement if you manage your own back-end.
Write into your API a url path param that serves the appropriate image scale; you can then use the UIScreen class (UIScreen.mainScreen().scale) to adjust your target URL accordingly, e.g.:
https://api.yourbackend.service/images/{imageid}/#2x.jpg
This is arguably more difficult to implement, but it's also a lot more robust (doesn't rely on potentially changing user-agent strings), and it's a lot cleaner when logging or querying analytics.
You could probably also use something like retina.js to handle this on your back-end, though I can't tell you whether or not it will work heedlessly (haven't tried it).
Options if you're using a CDN image host:
Use their built in HiDPI support (Cloudinary, for example, provides this -- read about it here).
If your CDN doesn't support this, switch to one that does ;)
You are coming at this exactly backwards.
A table view cell's image view is tiny. You are not going to be showing these images at full size anyway. So there is no point whatever downloading larger and larger images only to be displayed at tiny sizes. That's a massive waste of time, bandwidth, and ultimately memory (if you really try to display large images in every cell, you will run out of memory and crash).
If you have a choice of image size to be retrieved from the server, you should be doing just the opposite of what you are suggesting: download a thumbnail of your image suitable for display in the table view. If the thumbnail is twice the size of the image view, it will look good at all resolutions with minimal waste of memory.
If this app is about also fetching the real full-sized image, outside your table view, you can do that later when requested by the user.
I'll start by explaining what I would like to do.
I have an image gallery grid layout page with thumbnails. Each thumbnail image is to be the same size, say 120px x 80px. I would like to display all the images on page load and more as a user scrolls down on the page. There will be hover and click states for individual images in the grid where the full size image pops up to display in a lightbox.
What solutions (gems, techniques, etc.) are there for loading images that are larger (1024 x 768) into my database (Photo) model such that I can generate a small thumbnail image of predefined smaller size?
Is the best way to load a whole page of small images if my goal is to allow more to load as the user scrolls down on the page? Or should I load only what the user sees, then use AJAX to load more as they scroll down?
Is Paperclip a common solution in this case? I'm looking into this and CarrierWave on RailsCasts.
If using something like Paperclip, can it handle cropping an image that isn't the same aspect ratio as others? ie, scale and crop a square image the same as a rectangle image to a defined size.
I'm new to handling a large number of images in a rails application and appreciate any advice, books, tutorials, techniques people are familiar with out there.
Thanks!
1) I prefer paperclip, though this may be due to less experience with other gems.
2) Generally, the best way to handle lots of images on a page is with sprite sheets. If the images on the page are always going to be the same, this might be a good option. If you are doing something with infinite scrolling, ajax is the way to go (railscast on infinite scrolling)
3) I'm not sure if paperclip is a common solution, but it certainly is one that you should consider.
4) Yes, cropping works in paperclip.
I have to create a custom photolib like the default one, with animation etc. I had some doubts..
1. Doubt
Should I create 3 images (Thumbnail image, 320*480 image to display full image and original size image in case user share the image) (I am storing this all in app doc directory)
Or should I only store the original image and crop them wen required in 2 other images? In this case, if I use scroll view to display cropped images, how do I know what the user is seeing? And when do I crop next images to keep them ready to display?
(Can anything like reusable cells be created here like in tableview? If yes, can you give me some idea?)
Also, I am fetching images from doc directory. In this case should I load all images in Array or load in batches?
2. Problem Major:
Also need to compress original image and keep it of same size (I used uijpegrepresentation with compression ratio but with some jpegs after compression. It increases sizes even double the size).
You can use single image and for thumbnail you can Resize at run time else it increase size and performance issue. there is lots of open source library are there which do same what you needed. Please have a look below.
https://github.com/arturgrigor/AGImagePickerController
https://github.com/gdavis/FGallery-iPhone