I'm currently working on a system right now that involves the use of many images. There are some images (specially background images) that I used where when I updated the images that includes the picture path, the image does not update. I checked the path if it's correct and even the folder containing the picture.
However, I noticed that when I clear the history of the picture, that is the time the picture becomes accurate. I did not use any session or cookie for saving my image. Is there an explanation for this?
Add some parameter to image link and change this parameter after image update ;)
Example :
src="image.png?timestamp=20180602" ;
Related
I Googled a lot but no sufficient ans was found.
I need to place an image (900 X 5200 px) in one of my pages. As the image is sensitive, I need to prevent users from copying the image. I have an idea that can do this:
I will divide the image into pieces. Then the image grid will be loaded into some divs. So user won't be able to save the image. Or he/she will save only 1 square cm part of the whole image.
But this plan will not work if some small parts of the grid fails to load. So, I want to do another thing. I want to load the full image then cut the image into parts. Then show the parts altogether in divs.
This requires javascript. But I am confused how to start and need your help.
Now you know the matter, if you have better idea please share.
Thanks in advance.
The trick is simple. Create a div with the background being the image you want to display. Layer a div with a transparent image over it. When user goes to save the image, they get a blank. Program your server to not return "direct" requests for the image (so some clever chap can't just look at the css and retrieve the URL to the image).
Granted the image will still be in their cache but so would the sliced image so it won't make it impossible just more difficult for a determined person to retrieve the picture.
TL;DR Don't over engineer a solution, print screen will get around anything you do.
You are not going to be able to prevent people from copying this image. Plain and simple. Regardless of your best efforts, a simple PRT SCRN and paste into Paint will be enough.
Your best bet will be to not over engineer this and simply place a watermark and copyright notice on the page. Other options can include placing a transparent <div> over the top of the image so it cannot be right-click'ed and saved, but it still will not prevent the image from being stored in the user's cache. Or stop them from using developer tools or Firebug to find the source image.
You can do this with:
http://www.pixastic.com/lib/docs/actions/crop/
Yet you need to develop your logic around that library.
I have made example, you can see it on this link:
http://simplestudio.rs/yard/crop_img/
Basically you can get URL to your image via php and using my code or code similar to it crop your image into pieces and display them on canvas.
This way image is not accessible via browser or inspect element or what so ever. User can save the pieces individually but you can configure my code for piece to be 5px, I set it to 20x20px.
* test saving image piece by doing right click anywhere on image and do a "Save image as.." option.
Also you need to think of way how to hide src to image provided by php, if you need help on that I can help you.
Setting up a live image stream on a website, using images from a webcam. Trying to work out the implementation of it. The webcam takes a picture and requires a crop, resize and upload (not necessarily in that order), before it is displayed to the user, with a new image every minute. Currently I have a php script that does the cropping and resizing, while a webcam program automates the picture taking and uploading. However...
Uploading directly over the existing image causes an issue if the user reloads the page while the upload is taking place, resulting in a missing image.
Uploading with a different filename, then renaming it causes an issue if the user reloads the page during the renaming, resulting in a combination of both images.
Using a sequential filename system then gets tricky with the webpage requiring to know the new upcoming file every minute, along with a potential backlog of images.
Any suggestions are appreciated. Hopefully I'm missing something simple.
Thanks.
Just upload your image with different name, set the current image name somewhere, either in config file or MySQL, and after upload change it.
I allow users to add a profile picture of themselves to an account, pretty standard stuff.
To make things simple, when they update their image I simply overwrite the image they currently have stored (its not a big part of what we do so simple approach)
So, page is shown with their current image, they can then choose to upload a new one, the uploaded file is then saved, image URL updated in MySQL table and page is displayed again.
The image is uploaded correctly, MySQL table updated correctly, but the image is cached so old image shows on page even though they have uploaded a new one.
Can I un cache one image? Is there a better way to do this?
For avoiding image caching you can simply add a query sting in the image src. Best would be adding a date time.
{$t = getDate();}
and in your image src add: src= "path.jpg?t=".$t
For this you need not to change anything for new image..Date time automatically gets changed every second ;)
Hope it helps..
Use versioning. In the link for the image, instead of abc.jpg say abc.jpg?v=5. And when a new image is uploaded, change the number.
see this question
Okay, so on my website a user can upload a profile picture. But the issue is, if they update it by uploading and overwriting the existing profile picture they have to wait for their browser cache to clear and the same for everyone else on the site.
I know I could easily beat this by sticking a string on the end of the image URL e.g. ?id=22185 , but that will make my site loading times VERY slow.
Could any of you recommend a way of making the user's profile picture update instantly for every user on the site?
Use the file modified time as the URL variable. That way the image will be cached until that number changes, which only would happen of the file is updated.
Set unique name for each image. When user change image, e filename change too and browser will load new image instead of serving old FROM cache
You could easily add a timestamp to your files or you could use the "headers" function of PHP to change the "Expire" param.
Image this scenario:
There is a picture locally in my server, where a sketch is displayed, and there is a "blank hole" area on it.
Then, a user can upload another picture to my server.
What i'm trying to achieve is this:
After image upload is finished, the first image (the one with the "hole") is displayed, and behind it is displayed the user's photo, so that you can see it through the "blank hole" area of the first photo.
Then the user can move his picture (drag & drop style) so he can choose which area of it is visible through the "blank hole".
Then i would like to save the result - by merging the 2 photos or keeping the position of the user's picture in a db so i can display it again later.
(Something like this more or less)
What kind of technollogy should i look for? I'd guess javascript(for the drag & drop) or html5 or php(for merging the photo)?
Are there any libraries that i can use?
I hope my explanation isn't too messy, i didn't even know how to google for it.
I don't know if there are better solutions (and I suspect there are), but I suspect all of this can be done with not too much trouble. Here's a rundown of one way to approach the problem:
Use a JavaScript-powered "upload widget" such as uploadify to enable your user to upload "his" image to the server. The server will do some processing on the image (e.g. resize and crop to suitable dimensions) and save it using e.g. PHP's gd library. It will return a URL to the "prepared" image back to the browser -- all of this through AJAX.
The browser then has a URL to the user's image, so using more Javascript you can dynamically add an element that displays it inside the page and allow the user to move it around with e.g. jQuery draggable. Compositing the draggable image behind your static content (the image with the "hole") is a detail you will have to take care of using a combination of HTML, CSS and again Javascript.
When the user is done, use an AJAX call (e.g. again jQuery) to inform the server of the image's positioning (this will be available through the facilities of the Javascipt framework you have selected). The server can then "compose" the two images together (gd or something equivalent once more) and return to the browser a URL through which the final product can be accessed.
Of course there are lots of details to take care of here, but knowing exactly what the plan is should help you get started.
Have a look at the PHP GD extension. If it's installed, it's pretty easy to have an image (with a transparent center) to be merged on top of a second image that a user would upload.
Have a look at http://php.net/manual/en/function.imagecopymerge.php
Ok to get you started, yes use a JavaScript drag and drop module for the placing of the image. You can record the x /y cordinates relative to the container. Do the image merging with a PHP image library / Class. Something like this : http://www.phpclasses.org/package/3930-PHP-Generate-an-image-from-the-combination-of-2-images.html