I have a photo site which renders previews of my photos in a tag when i hover some dots. (see http://johanberntsson.se/photo/).
But it feels kinda stupid to load the full image in to an img-tag. Because as far as i know, theres no difference between loading the image with its original size versus adding height and width attributes to it.
Got any suggestions how to improove my preview function?
Thanks
As far as client side is concerned, there's nothing you can do. If you're worried about how long it takes the image to load, you could always pre-load them with javascript. The only other thing would be to create a few sizes of your image on the server.
You should resize the image to get better speed. Here's an example in php
//Blob if image in database
$blob = mysql_fetch_...();
//else blob point to filename
$blob = "filename.jpg";
$gd = imagecreatefromstring($blob);
$resized = imagecreatetruecolor(X, Y); // new image dimensions
imagecopyresampled(....);
imagejpeg($resized);
Loading all the thumbnails in a giant sprite image used as a background image. Then position the background a the right place to have the right image a the right place.
This will improve the loading speed by loading only 1 image and allow the browser to cache the request of the image so, next time the user come to your site, it will load pretty fast.
Related
I have a UIWebView which has images in it, say that I have the point/coordinates of the x y position of the image, width and height. Can I create an image just by specifying the location of the image in UIWebView? If yes how?
Or is there a way to get an UIImage from a UIWebView without actually looking at the <img src=""> of the html tags? Basically I don't want to make a connection to the internet to pull an image as the image is already there seen on the screen. Question is how do I extract it?
Depending on the cache policy in place, a request to retrieve the image may not result in another connection to download the image... But to answer your actual question...
You can take a 'snapshot' of the UIWebView and then crop to the location of the image in question. Check this question out for details on how to do this: How Do I Take a Screen Shot of a UIView?
This link explain a way to get the image just by grabbing it from the specified coordinates. How to create a UIImage from the current graphics context?.
However there might be a more elegant solution of using some javascript to get the original image by using the stringByEvaluatingJavaScriptFromString: method of UIWebview. But I am not sure if javascript is capable of doing it
I have just made background image for my web-site. But I'm confused - if user have resolution no similar mine, then he will see wrong image right? How can I fix this problem and what resolution is normal for browser?
They will see the correct image, but it will repeat itself.
You have two options:
Create an image, which looks nice when it's repeated. Then you just have to exchange the image.
otherwise you have to disable image repeating, so that the image is just displayed once.
see: http://www.w3schools.com/cssref/pr_background-repeat.asp
It usually looks nice if you define an appropriate background-color after the image ends.
Otherwise there are more advanced ways for full scale background images: http://css-tricks.com/3458-perfect-full-page-background-image/
The "normal" Screen resolution on webpages range from the Smartphone screen (320x480) to 30" screens (2.560 x 1.600). Those are the both (not so uncommon!) extremes. The average is between 1024x768 and 1920x1200.
We're using the facebook graph API http://developers.facebook.com/docs/reference/api/post/ and adding the picture parameter. Our picture is a 30x30 pixel image, which is exactly the size we want for the facebook web version. However, the image will be pixelated when using the FB mobile app on an iPhone4 (retina display).
Is there any way to serve a 60x60 high resolution image, but render it always at 30x30 for facebook wall posts?
Well.. as of this moment, here is what I have found out, and offer a 'solution' that has worked for me based on the time i've had to test & play with this concept. For all the readers out there, who need a quick answer to the question, i don't have the exact solution to the question, but…. Essentially, your 30x30 image is being scaled to 90x90. The 60x60 image is being scaled to 90x90. And I can not find a way to go around this.
Below is what I have tried. Feel free to add input.
Take your feed image, and stroke a 2-5px black line around the frame of the image.
Load up your app, initiate a wall feed on the device. With the image present, take a screenshot. Mail yourself the image. Open it up in Photoshop (or photo editing program). Use a Marquee tool to outline the image. Cut it out of the screenshot and paste it as a new image. What size is it? 90x90, right? (and obviously 180x180 if image is retina)
Create a 90x 90 image. Copy your original 30x30 image and paste it anywhere you want within the new 90x90 images' frame. Upload it to the URL parameter's location. Re-run your app. By re-running it, i mean you have to shut it down completely, it appears as though the SDK is cacheing the image upon first launch of the feed and you can clear that cache by closing the app completely, and rerunning it. When you do, you will see significant improvements with the look of the image. It may not be a retina image, but it at least won't be 'fuzzy ugly'. At this point, it boils down to how nice of illustrative lines that where done in the design process to remove the aliasing effect produced from the conversion to a raster graphic. As well, i'm not sure if a variation of resampling method will produce even better results.
Some things i've tried:
I've also saved it as a png file with no transparency : 144ppi at 90 x 90 size. In other words, save your 90x90 image with a higher resolution (pixels per inch). Remember to not constrain proportions as you image resize. And note that If you are using adobe products, i.e. photoshop ) - don't save for web, just use 'save as…', as this will retain the ppi you specified. Although, i don't believe i see much of a difference in the quality which this is displayed going this route, and best to try to keep the file size down as this will increase the overall image size by about 500% or more.
I've tried variations of hosting the image twice the size (180x180) within the same hosted folder and naming it image#2x.png & image-large.png <--(just for the heck of it). This is not really solving the problem either.
Some other things I have not tried:
Monitoring your web server traffic, and any "not found" errors to a resource to see if FB is trying to access an a potential alternate resource when grabbing your image for display, the wall feed box that comes up is a webview. Meaning web graphics. (It's FB's web page…meaning their rules, and i doubt the pages' source is available to dabble with within the SDK.. so!…
Look at the HTML of the feed itself with safari browser:
The inspection of the HTML within the final resulting image that is posted on my FB wall I can see this….
<img class="img" src="http://platform.ak.fbcdn.net/www/app_full_proxy.php?app=153675474666495&v=1&size=z&cksum=773bba91f6146b2463eed0a0bb77dc42&src=http%3A%2F%2Fwww.thumbwizards.com%2Fspeakinapps%2Fgraphics%2Fboxed%2Faussie.png" alt="">
I am wondering:
Within HTML5 isn't there a mechanism to provide a toolkit type of javascript to display retina graphics from a web page?
Would it be possible to have that code run when grabbing the url to the image (in meaning, the url of the image would be acting as a pointer to the code.? I haven't tried playing with this, since my logic tells me that per the url above that FB is essentially taking control over the image at this point. I have noticed (and not waited long enough to see) that the image is apparently cached and posting to the wall with a new image, sometimes results in the older image still being used. (and yes, i've cleared my browser cache)… perhaps simply cached in another location..
If there is another parameter for the image type, that is not published, I have not stumbled across any yet.
Can anyone figure out if through source of:
[http://platform.ak.fbcdn.net/www/app_full_proxy.php] if this php file is part of an available image processor out there we can access to view what could be done?
Can anyone mention an app that uses a retina graphic in their feed post?
Just thoughts really, I've decided to not really give a crop, and if
you've made it this far. Thanks for tuning in. ..So, Sulf, your 30x30 is being scaled to 90x90. making it UGLY!.
Good luck.. If you figure anything else out, let me know!
Mark
apple specify that if you want to add the retina effect for your ios app then the images you are using in this format -i.e
sampleImag.png- 57*57(size) , 163 (DPI)
sampleImag#2x.png - 114*114(size),326 (DPI) when you use these specific graphic images you will get your app is showing retina effect in iphone 4 and above generation.
Just point your code to a larger scaled image and Facebook will take care of the rest.
I have about 20-ish high quality images (~3840x5800 px) that I need to load in a simple gallery type app. The user clicks a button and the next image is loaded into the UIImageView.
I currently use [UIImage imageWithContentsOfFile:] which takes about 6 seconds to load each image in the simulator :(
if I use [UIImage imageNamed:] it takes even longer to load but caches the images which means its quicker if the user wishes to see the same images again. But it may cause memory problems later with all that caching crashing my app.
I want to know whats the best practice for loading these? I'm experimenting with reducing image file size as much as is possible but I really need them to be high quality image for the purpose of the app (zoomable, etc.).
Thanks for any advice
[EDIT]
Hey again guys,
Thanks for all ye're advice. The project's spec's have changed a little. Now as well as displaying the images they firstly have to be zoomed in to a particular spot and when the user taps next it zooms out and then displays the next image. So I'm not sure if the proposed solutions fits?
Apple's docs recommend against trying to load single images that are larger than 1024x1024. You should look into using CATiledLayer instead, to load pieces of the images as needed.
You can have a look at this Apple sample:
http://developer.apple.com/library/ios/#samplecode/PhotoScroller/Introduction/Intro.html#//apple_ref/doc/uid/DTS40010080
It shows how to load big images, breaking them in tiles for different zoom levels.
You can't see all those pixels at any given time, so there is no need to load them all. Load lower-res copies ("big-thumbnails") to view the complete image, then selected sub-tiles, maybe of 2 or more different resolution sets, after the user zooms in.
The CATiledLayer API may be able to handle some of the latter for you.
I'm displaying a PDF file using UIWebView, and I want to do 2 things:
I want to make the page fit the phone screen without the user has to double tap to do that
I want to remove the margin with gray shadow around the displayed PDF
Thanks for helping
I don't think this will help much, but I think your best option is to render the PDF to an image (of decent DPI) and show the image instead. I do this for an app, but we do that server side using ImageMagick - don't know how you might do that in obj-c. Also note that a mostly-text PDF will be much larger (filesize) when rasterized.
However, you might also try to embed the PDF in HTML page and load that HTML in the WebView - that may at least avoid the gray border/artboard.
webView.transform = CGAffineTransformScale( webView.transform, 1.25, 1.25 );
2 - Checking the Scale Pages to Fit box in IB sorted this for me
I would also like to know the answer to 1.
I guess you want to know how to display the PDF in the same way as when opening as attachment in mail, where the navigation bar only appears on a tap and the status bar also disappears?
You can also use Quartz to do it, as explained here : http://developer.apple.com/iphone/library/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_pdf/dq_pdf.html
Where has CGAFFineTransformScale been all my life?
Seriously, that is a big help. However, it worked better applying it to webView.scrollView.
Finally, is there a similar command to change the offset of the content as well as the scale?