I need to show an image in the largest size possible so I use javascript to create a square div with the maximum dimensions that fit the browser window.
I load the image and then I then change the width and height attributes to values that will make the image fit.
This works fine for 99% of images, but I have some that are shown in landscape format when they actually in portrait. I know they should be portrait because they are shown correctly in Windows explorer, Photoshop etc, and even when I right-click on the displayed image in a browser and select "show image in new window"
I have even rotated the image with PhotoShop and it is still shown landscape.
This makes me think that metadata is not being respected.
In ASPX Page_Load... imgImage.ImageUrl = "~/" & tPath
In HTML
function resizeImg() {
var windowWidth = window.innerWidth || document.documentElement.clientWidth;
var windowHeight = window.innerHeight || document.documentElement.clientHeight;
var imgMax = windowHeight - 54;
var div = document.getElementById('divImage');
div.style.width = imgMax + 'px';
div.style.height = imgMax + 'px';
var divW = div.offsetWidth;
var divH = div.offsetHeight;
var winR = divW/divH
var newImgH = imgH;
var newImgW = imgW;
if(newImgW > divW) {
newImgW=divW
newImgH = Math.floor(Math.round(divW / imgR));
}
if(newImgH > divH) {
newImgH=divH
newImgW =Math.floor(Math.round(divH * imgR));
}
img.setAttribute('width',newImgW);
img.setAttribute('height',newImgH);
img.setAttribute('hspace',(divW - newImgW)/2);
img.setAttribute('vspace', (divH - newImgH) / 2);
}
I'm calling an API that returns a URL to an image, the image could be any size and it's completely random.
I'm trying to resize images to fit within the page, ensuring the content is not pushed below the fold, or that the image doesn't hit the width of the page.
I've written some Javascript below, I've been testing it and am getting some strange results - the console logs are saying that the image is one size, but the element selector in Chrome's dev tools is usually saying something completely different. I'm sure I've made some basic mistake in my code, if you could take a look that would be great.
Javascript sets viewport height and width, checks if a photo src is available. Once the image has loaded, it checks if the natural dimensions are greater than that of the viewport, if so it attempts to resize - this is where the script is failing.
//check viewport
var viewportWidth = getWidth();
var viewportHeight = getHeight();
//get the media
if (data[2] == "photo") {
var tweetImage = document.getElementById("tweetImage");
//when it loads check the size against the browser size
tweetImage.onload = function () {
console.log('image height: ' + tweetImage.naturalHeight);
console.log('viewport height: ' + viewportHeight);
//does it matter if its landscape?
if (viewportWidth - tweetImage.naturalWidth < 1) {
tweetImage.width = Math.floor(tweetImage.naturalWidth - (viewportWidth - tweetImage.naturalWidth) * 1.2);
console.log('w');
} else if (Math.floor(viewportHeight - tweetImage.naturalHeight) < 1) {
console.log('h');
console.log(viewportHeight - tweetImage.naturalHeight);
console.log('changed result: ' + Math.floor(tweetImage.naturalHeight - (Math.abs(viewportHeight - tweetImage.naturalHeight))));
tweetImage.height = Math.floor(tweetImage.naturalHeight - (Math.abs(viewportHeight - tweetImage.naturalHeight)*1.2));
} else {
tweetImage.height = Math.floor(viewportHeight / 2);
}
tweetImage.align = "center";
tweetImage.paddingBottom = "10px";
};
//tweetImage.height = Math.floor(viewportHeight / 2);
tweetImage.src = data[3];
}
One option would be to use a CSS-based solution like viewport height units.
.example {
height: 50vh; // 50% of viewport height
}
See http://web-design-weekly.com/2014/11/18/viewport-units-vw-vh-vmin-vmax/
I have a background image that gets moved while scrolling. When the page is scrolled to top, the top edge of the background image touches to top edge of the window and when scrolled down 100%, the bottom image edge touches the bottom window edge.
This is my working code:
document.addEventListener('scroll', function() {
var backgroundImage = document.querySelector('#background img');
var scrollHeight = document.body.scrollHeight;
var scrollTop = document.body.scrollTop;
var innerHeight = window.innerHeight;
backgroundImage.style.top = (((backgroundImage.scrollHeight - innerHeight) / 100) * ((scrollTop / (innerHeight - scrollHeight)) * 100)) + 'px';
});
The result is what I'm expecting, but the scrolling gets extremely laggy. Is there a possibility to make this animation smoother?
EDIT
I added requestAnimationFrame like so:
document.addEventListener('scroll', function() { requestAnimationFrame(process); });
function process() {
// calculation code goes here
}
This makes the scrolling much smoother and the image movement is kinda perfect. But still the DOM isn't scrolling really smooth. Better, though not good. Any ideas for further improvements?
Using CSS transforms might help... I use a 3d transform here, hopefully giving you even more performance thanks to hardware acceleration.
The code would look something like this:
var updateImgPosition = function () {
var backgroundImage = document.querySelector('#background img');
var scrollHeight = document.body.scrollHeight;
var scrollTop = document.body.scrollTop;
var innerHeight = window.innerHeight;
backgroundImage.style.webkitTransform = "translate3d(0,"+ (((backgroundImage.scrollHeight - innerHeight) / 100) * ((scrollTop / (innerHeight - scrollHeight)) * 100)) + "px,0)"
};
document.addEventListener('scroll', updateImgPosition)
UPDATED DEMO
You can easily see the problem on the first page here: http://m.vancouverislandlife.com/
Scroll down (slide up) and allow the content to leave the page, and it doesn't bounce back and is lost forever. However, on pages whose content does overflow the page and is therefore supposed to be scrollable, the scrolling works correctly (see Accomodations > b&b's and scroll down for an example of this).
I noticed that on my computer, the scrolling on the first page is always stuck at -899px. I can't find anybody else who's experienced this problem and no matter what I try, I just can't fix it! Help!
(It's not exactly urgent, however, as the target audience of iPhones and iPod Touches aren't affected by this since they have so little screen room.)
Okay, new problem. To solve the iScroll issue, I just created a custom script. However, it's not working correctly on the actual device. On desktop browsers, it works just fine. On mobile, it occasionally jumps back to the top and won't recognize some touches. This is probably because of the way I cancelled the default event and had to resort to a bit of a hack. How can I fix this? (Yup - simple problem for a +500 bounty. Not bad, huh?)
Here's the script, and the website is at the usual place:
function Scroller(content) {
function range(variable, min, max) {
if(variable < min) return min > max ? max : min;
if(variable > max) return max;
return variable;
}
function getFirstElementChild(element) {
element = element.firstChild;
while(element && element.nodeType !== 1) {
element = element.nextSibling;
}
return element;
}
var isScrolling = false;
var mouseY = 0;
var cScroll = 0;
var momentum = 0;
if("createTouch" in document) {
content.addEventListener('touchstart', function(evt) {
isScrolling = true;
mouseY = evt.pageY;
evt.preventDefault();
}, false);
content.addEventListener('touchmove', function(evt) {
if(isScrolling) {
evt = evt.touches[0];
var dY = evt.pageY - mouseY;
mouseY = evt.pageY;
cScroll += dY;
momentum = range(momentum + dY * Scroller.ACCELERATION, -Scroller.MAX_MOMENTUM, Scroller.MAX_MOMENTUM);
var firstElementChild = getFirstElementChild(content);
content.style.WebkitTransform = 'translateY(' + range(cScroll, -(firstElementChild.scrollHeight - content.offsetHeight), 0).toString() + 'px)';
}
}, false);
window.addEventListener('touchend', function(evt) {
isScrolling = false;
}, false);
} else {
content.addEventListener('mousedown', function(evt) {
isScrolling = true;
mouseY = evt.pageY;
}, false);
content.addEventListener('mousemove', function(evt) {
if(isScrolling) {
var dY = evt.pageY - mouseY;
mouseY = evt.pageY;
cScroll += dY;
momentum = range(momentum + dY * Scroller.ACCELERATION, -Scroller.MAX_MOMENTUM, Scroller.MAX_MOMENTUM);
var firstElementChild = getFirstElementChild(content);
content.style.WebkitTransform = 'translateY(' + range(cScroll, -(firstElementChild.scrollHeight - content.offsetHeight), 0).toString() + 'px)';
}
}, false);
window.addEventListener('mouseup', function(evt) {
isScrolling = false;
}, false);
}
function scrollToTop() {
cScroll = 0;
content.style.WebkitTransform = '';
}
function performAnimations() {
if(!isScrolling) {
var firstElementChild = getFirstElementChild(content);
cScroll = range(cScroll + momentum, -(firstElementChild.scrollHeight - content.offsetHeight), 0);
content.style.WebkitTransform = 'translateY(' + range(cScroll, -(firstElementChild.scrollHeight - content.offsetHeight), 0).toString() + 'px)';
momentum *= Scroller.FRICTION;
}
}
return {
scrollToTop: scrollToTop,
animationId: setInterval(performAnimations, 33)
}
}
Scroller.MAX_MOMENTUM = 100;
Scroller.ACCELERATION = 1;
Scroller.FRICTION = 0.8;
I think Andrew was on the right track with regards to setting the height of the #wrapper div. As he pointed out that,
that.maxScrollY = that.wrapperH - that.scrollerH;
Normally, this would work. But now that you've changed your #content to position: fixed, the wrapper element is no longer "wrapping" your content, thus that.wrapperH has a value of 0, things break.
Disclaimer: I did not go through the entire script so I may be wrong here
When manually setting a height to #wrapper, say 500px, it becomes,
that.maxScrollY = 500 - that.scrollerH;
The folly here is that when there's a lot of content and the window is small, that.scrollerH is relatively close in value to 500, say 700px. The difference of the two would be 200px, so you can only scroll 200 pixels, thus giving the appearance that it is frozen. This boils down to how you set that maxScrollY value.
Solution (for Chrome browser at least):
Since #wrapper effectively contains no content, we cannot use it in the calculations. Now we are left with the only thing that we can reliably get these dimensions from, #content. In this particular case, it appears that using the content element's scrollHeight yield what we want. This is most likely the one that has the expected behavior,
that.maxScrollY = that.scrollerH - that.scroller.scrollHeight;
scrollerH is the offsetHeight, which is roughly the height of what you see in the window. scroller.scrollHeight is the height that's considered scrollable. When the content does not exceed the length of the page, they are roughly equivalent to one another. That means no scroll. When there are a lot of content, the difference of these two values is the amount of scroll you need.
There is still a minor bug, and this looks like it's already there. When you have a lot of content, the last few elements are covered up by the bar when scrolled to the bottom. To fix this, you can set an offset such as,
that.maxScrollY = that.scrollerH - that.scroller.scrollHeight - 75;
The number 75 arbitrary. It's probably best if it's the height of the bar itself with 2 or 3 pixels for a bit of padding. Good luck!
Edit:
I forgot to mention last night, but here are the two sample pages that I used in trying to debug this problem.
Long page
Short page
This may be a CSS issue. In your stylesheet (mobile.css line 22), try removing position:fixed from #content.
That should allow the document to scroll normally (vertical scrollbar on a computer, "slideable" on a mobile browser).
Elements with position:fixed exit the normal flow of the document, their positioning is relative to the browser window. This is probably why you're having issues with scrolling. Fixed positioning is generally for elements which should always remain in the same place, even when the page is scrolled (ie. a notification bar "pinned" at the top of a page).
No definite solution, but more a direction I'd go for:
#wrapper and #content's overflow:hidden paired #content's postion:fixed and seem to be the cause of the issue.
If position: fixed is removed from #content, scrolling is possible but the "blank" divs are wrongly layered (tested in Firefox 5).
Your wrapper div seems to have a height of 0. So all the calculations are negative, setting it's height to the window height will correct the scroll issue. When I manually set the wrappers height via firebug and chromes debug bar the scroll functions as it should.
You #content div seems to have its size change on resize, probably a better idea to have the #wrapper div have its size change and then have #content inherit the size.
[Edit]
You don't believe me so codez, From iscroll-lite.js
refresh: function () {
var that = this,
offset;
that.wrapperW = that.wrapper.clientWidth;
that.wrapperH = that.wrapper.clientHeight;
that.scrollerW = that.scroller.offsetWidth;
that.scrollerH = that.scroller.offsetHeight;
that.maxScrollX = that.wrapperW - that.scrollerW;
that.maxScrollY = that.wrapperH - that.scrollerH;
In your page that translates to,
that.wrapperH = 0;
that.maxScrollY = -that.scrollerH
When a scroll finishes, this code gets called.
var that = this,
resetX = that.x >= 0 ? 0 : that.x < that.maxScrollX ? that.maxScrollX : that.x,
resetY = that.y >= 0 || that.maxScrollY > 0 ? 0 : that.y < that.maxScrollY ? that.maxScrollY : that.y;
...
that.scrollTo(resetX, resetY, time || 0);
See that that.maxScrollY > 0 ? ? If maxScrollY is negative then scrolling up will never bounce back.
I ended up just making my own, small script to handle the scrolling:
// A custom scroller
function range(variable, min, max) {
if(variable < min) return min > max ? max : min;
if(variable > max) return max;
return variable;
}
var isScrolling = false;
var mouseY = 0;
var cScroll = 0;
if("createTouch" in document) {
// TODO: Add for mobile browsers
} else {
content.addEventListener('mousedown', function(evt) {
isScrolling = true;
mouseY = evt.pageY;
}, false);
content.addEventListener('mousemove', function(evt) {
if(isScrolling) {
var dY = evt.pageY - mouseY;
mouseY = evt.pageY;
cScroll += dY;
var firstElementChild = content.getElementsByTagName("*")[0];
content.style.WebkitTransform = 'translateY(' + range(cScroll, -(firstElementChild.scrollHeight - content.offsetHeight), 0).toString() + 'px)';
}
}, false);
window.addEventListener('mouseup', function(evt) {
isScrolling = false;
}, false);
}
and modifying a few other parts. It does save a lot of download time, I suppose, also.
I'm still going to accept answers and award the bounty in 5 days, though.
Changed question warrants a new answer. I took a look at the code and I saw that you calculated the momentum on each step of the "move" function. This does not make sense because the momentum is used after the move has ended. What this meant was to capture the mouse position at the beginning, and then calculate the difference at the end. So I added two new variables,
var startTime;
var startY;
Inside the start event (mousedown/touchstart), I added,
startY = evt.pageY;
startTime = evt.timeStamp || Date.now();
Then I have the following for my end handler,
var duration = (evt.timeStamp || Date.now()) - startTime;
if (duration < 300) {
var dY = evt.pageY - startY;
momentum = range(momentum + dY * Scroller.ACCELERATION, -Scroller.MAX_MOMENTUM, Scroller.MAX_MOMENTUM);
} else {
momentum = 0;
}
I also removed the momentum calculation from inside of mousemove/touchmove. Doing this removed the jumping around behavior that I was seeing on my iPhone. I am seeing other unwanted behaviors as well (the whole window "scrolls"), but I'm guessing that you've been working to get rid of those so I didn't attempt.
Good luck. Here's a coded up page that I duplicated for my testing. I also took the liberty to refactor the code for this section to remove some duplicated code. It's under mobile3.js if you want to look at it.
The code: http://jsfiddle.net/LPF85/6/
In FF, IE7, and IE9 (the only browsers I've tested that don't run WebKit), it seems that the left attribute is either always set to 0, or, in IE's case, negative.
My positioning code is all based off the dimensions of the document.
function open_img_in_face_box(id, width){
max_width = $j(document).width();
max_height = $j(document).height();
padding = 150;
passed_width = width || (max_width - (2 * padding));
var img = $j('#' + id);
dom_img = document.getElementById(id);
$j(document).bind('reveal.facebox', function() {
$j("#facebox .image img").width(passed_width);
})
// display
jQuery.facebox({
image: img.attr('src')
});
// center and adjust size
var aspect_ratio = img.width() / img.height();
var img_width = passed_width;
var img_height = passed_width / aspect_ratio;
window_center_y = max_height / 2;
window_center_x = max_width / 2;
offset_y = window_center_y - (img_height / 2);
offset_x = window_center_x - (img_width / 2);
var fbx = $j('#facebox');
fbx.css('position', 'absolute');
fbx.css('left', offset_x + 'px !important');
fbx.css('top', offset_y + 'px !important');
fbx.css('margin-left', 'auto');
fbx.css('margin-right', 'auto');
}
margin-left and margin-right don't appear to do anything here, which I'm fine with, because the left math should work across all browsers, right? (It is just math)
The goal of the facebox / lightbox, is to be centered both horizontally and vertically.
Why would you even programatically calculate the position in the first place? What if the user resizes the page? This can easily be done in pure CSS.
I don't really understand your jsFiddle (or am I not seeing the same thing?) so I'll just give you this script: http://jsfiddle.net/minitech/8U4Ke/ that can be modified however you like. It's commented. ;)
Now it's easy to hide and show - to hide, fade out .overlay. To show, fade it in. To change the contents, replace the HTML in .popup. Add close boxes and whatnot liberally.