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Publish Vulpes Preview 15 sources for desktop, Android and Tundra

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Share Gaia assets and adapters, keep private profiles and development documents local, and update both public READMEs.
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OverSu 2026-09-30 23:13:03 +02:00
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gaia/shared/js/media/media_frame.js Executable file
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'use strict';
/* global Downsample, VideoPlayer */
/*
* media_frame.js:
*
* A MediaFrame displays a photo or a video. The gallery app uses
* three side by side to support smooth panning from one item to the
* next. The Camera app uses one for image and video preview. The
* Gallery app's open activity uses one of these to display the opened
* item.
*
* MediaFrames have different behavior depending on whether they display
* images or videos. Photo frames allow the user to zoom and pan on the photo.
* Video frames allow the user to play and pause but don't allow zooming.
*
* When a frame is displaying a video, it handles mouse events.
* When displaying a picture, however, it expects the client to handle events
* and call the pan() and zoom() methods.
*
* The pan() method is a little unusual. It "uses" as much of the pan
* event as it can, and returns a number indicating how much of the
* horizontal motion it did not use. The gallery uses this returned
* value for transitioning between frames. If a frame displays a
* photo that is not zoomed in at all, then it can't use any of the
* pan, and returns the full amount which the gallery app turns into a
* panning motion between frames. But if the photo is zoomed in, then
* the MediaFrame will just move the photo within itself, if it can, and
* return 0.
*
* MediaFrame uses the #-moz-samplesize media fragment (via the downsample.js
* module) to downsample large jpeg images while decoding them when necessary.
* You can specify a maximum image decode size (in megapixels) when invoking
* the constructor. The MediaFrame code also includes a runtime check for
* the amount of RAM available on the device, and may limit the image decode
* size on low-memory devices.
*/
function MediaFrame(container, includeVideo, maxImageSize) {
this.clear(); // Set all the properties we'll use to default values
if (typeof container === 'string') {
container = document.getElementById(container);
}
this.container = container;
this.maximumImageSize = maxImageSize || 0;
// Create an <img> element to display the image
this.image = new Image();
this.image.className = 'image-view';
this.image.style.opacity = 0; // Start off hidden.
this.image.onload = function () { // When image loads...
this.style.opacity = 1; // make it visible
};
this.image.style.transformOrigin = 'center center'; // for zooming
this.image.style.backgroundImage = 'none';
this.image.style.backgroundSize = 'contain';
this.image.style.backgroundRepeat = 'no-repeat';
this.image.style.backgroundColor = '#222'; // should be overridable somehow
this.container.appendChild(this.image);
// Create the video player element unless we know we'll never need it
if (includeVideo !== false) {
this.video = new VideoPlayer(container);
this.video.hide();
}
// Add a class to the container so we could find it later and use it as
// a key in the instance weakmap.
container.classList.add('media-frame-container');
MediaFrame.instancesToLocalize.set(container, this);
}
// WeakMap with the container nodes as keys and MediaFrame instances as values.
MediaFrame.instancesToLocalize = new WeakMap();
function localize() {
// Retrieve MediaFrame instances by searching for container nodes.
for (var container of document.querySelectorAll('.media-frame-container')) {
var instance = MediaFrame.instancesToLocalize.get(container);
if (instance) {
instance.localize();
}
}
}
document.addEventListener('DOMRetranslated', localize);
MediaFrame.computeMaxImageDecodeSize = function(mem) {
if (!mem) {
return 0;
}
else if (mem < 256) { // This is a Tarako-class device ultra low-end device.
return 2 * 1024 * 1024; // 2 megapixels
}
else if (mem < 512) { // This is a low-end 256mb device
// Normally we can handle 3mp images on devices like this, but if
// this device has a big screen and low memory (like a memory
// throttled Flame) then it needs something smaller than 3mp.
var screensize = screen.width * window.devicePixelRatio *
screen.height * window.devicePixelRatio;
if (mem < 325 && screensize > 480 * 800) {
return 2.5 * 1024 * 1024; // 2.5mp megapixels for throttled Flame
}
return 3 * 1024 * 1024; // 3 megapixels otherwise
}
else if (mem < 1024) { // A mid-range 512mb device
return 5 * 1024 * 1024; // 5 megapixels
}
else { // A high-end device with 1 gigabyte or more of memory
// Allow 10 megapixels of image decode size per gigabyte of memory
return (mem / 1024) * 10 * 1024 * 1024;
}
};
//
// Find out how much memory this device has because we may need to limit image
// decode size on low-end devices. Note that navigator.getFeature requires
// the "feature-detection" permission (at least for now) so we only run this
// code if the client app has that permission.
//
if (navigator.getFeature) {
MediaFrame.pendingPromise = navigator.getFeature('hardware.memory');
MediaFrame.pendingPromise.then(
function resolve(mem) {
delete MediaFrame.pendingPromise;
MediaFrame.maxImageDecodeSize = MediaFrame.computeMaxImageDecodeSize(mem);
},
function reject(err) {
// This should never happen!
delete MediaFrame.pendingPromise;
MediaFrame.maxImageDecodeSize = 0;
}
);
}
MediaFrame.prototype.displayImage = function displayImage(blob,
width,
height,
preview,
rotation,
mirrored)
{
var self = this;
// If we are still querying the device memory, wait for that query to
// complete and then try again.
if (MediaFrame.pendingPromise) {
MediaFrame.pendingPromise.then(function resolve() {
self.displayImage(blob, width, height, preview, rotation, mirrored);
});
return;
}
this.clear(); // Reset everything
// Remember what we're displaying. This doesn't really need to be public
// but the Gallery app uses it.
this.imageblob = blob;
// Figure out if we are going to downsample the image before displaying it
// We expose fullSampleSize as part of the public api only for testing.
this.fullSampleSize = computeFullSampleSize(blob, width, height);
this.fullsizeWidth = this.fullSampleSize.scale(width);
this.fullsizeHeight = this.fullSampleSize.scale(height);
// Valid small EXIF preview used for setting css background image
this.tinyPreviewURL = null;
// Create a blob URL for the image and combine it with the media fragment.
// imageurl is what we'll call revokeObjectURL on. fullImageURL may
// have a media fragment appended, so we need to track both properties.
this.imageurl = URL.createObjectURL(blob);
this.fullImageURL = this.imageurl + this.fullSampleSize;
// Note: There is a default value for orientation/mirrored since some
// images don't have EXIF data to retrieve this information.
this.rotation = rotation || 0;
this.mirrored = mirrored || false;
// Keep track of what kind of content we have
this.displayingImage = true;
this.localize();
function isValidPreview(preview) {
// If no preview at all, we can't use it.
if (!preview) {
return false;
}
// If we don't know the preview size, we can't use it.
if (!preview.width || !preview.height) {
return false;
}
// If there isn't a preview offset or file, we can't use it
if (!preview.start && !preview.filename) {
return false;
}
// If the aspect ratio does not match, we can't use it
if (Math.abs(width / height - preview.width / preview.height) > 0.01) {
return false;
}
return true;
}
function isBigEnoughPreview(preview) {
// Check if we have preview before continuing with size check
if (!preview) {
return false;
}
// If setMinimumPreviewSize has been called, then a preview is big
// enough if it is at least that big.
if (self.minimumPreviewWidth && self.minimumPreviewHeight) {
return Math.max(preview.width, preview.height) >=
Math.max(self.minimumPreviewWidth, self.minimumPreviewHeight) &&
Math.min(preview.width, preview.height) >=
Math.min(self.minimumPreviewWidth, self.minimumPreviewHeight);
}
// Otherwise a preview is big enough if at least one dimension is >= the
// screen size in both portrait and landscape mode.
var screenWidth = window.innerWidth * window.devicePixelRatio;
var screenHeight = window.innerHeight * window.devicePixelRatio;
return ((preview.width >= screenWidth ||
preview.height >= screenHeight) && // portrait
(preview.width >= screenHeight ||
preview.height >= screenWidth)); // landscape
}
// To save memory, we want to avoid displaying the image at full size
// whenever we can display a smaller preview of it. In general, we only
// want to decode the full-size image if the user zooms in on it.
// This code determines whether we have a usable preview image (or whether
// we can downsample the full-size image) and if so, displays that image
var isValid = isValidPreview(preview);
var isBigEnough = isBigEnoughPreview(preview);
if (isValid && isBigEnough) {
if (preview.start) {
gotPreview(blob.slice(preview.start, preview.end, 'image/jpeg'),
preview.width, preview.height);
}
else {
var storage = navigator.getDeviceStorage('pictures');
var getreq = storage.get(preview.filename);
getreq.onsuccess = function() {
gotPreview(getreq.result, preview.width, preview.height);
};
getreq.onerror = function() {
noPreview();
};
}
}
else if (isValid) {
// If we have valid small EXIF preview use it for css background image
// This will help to load large downsampled preview images without flash
// See bug 1188286
// Create a blob URL for the tiny preview
this.tinyPreviewURL = URL.createObjectURL(
blob.slice(preview.start, preview.end, 'image/jpeg'));
noPreview(this.tinyPreviewURL);
}
else {
noPreview();
}
// If we've got a usable preview blob from EXIF or an external file,
// this is what we do with it.
function gotPreview(previewblob, previewWidth, previewHeight) {
// Create a blob URL for the preview
self.previewurl = URL.createObjectURL(previewblob);
// In this case previewImageURL is the same as previewurl. In some other
// cases, previewImageURL may have a media fragment appended, so we need
// two distinct properties, however.
self.previewImageURL = self.previewurl;
// Remember the preview size
self.previewWidth = previewWidth;
self.previewHeight = previewHeight;
// Start off with the preview image displayed
self.displayingPreview = true;
self._displayImage(self.previewImageURL,
self.previewWidth, self.previewHeight);
}
// If we don't have a preview image we can use this is what we do.
function noPreview(bgURL) {
self.previewurl = null;
// Figure out whether we can downsample the fullsize image for
// use as a preview
var previewSampleSize = computePreviewSampleSize(blob, width, height);
// If we can create a preview by downsampling...
if (previewSampleSize !== Downsample.NONE) {
// Combine the full image url with the downsample media fragment
// to create a url for the downsampled preview.
self.previewImageURL = self.imageurl + previewSampleSize;
// Compute the preview size based on the downsample amount.
self.previewWidth = previewSampleSize.scale(width);
self.previewHeight = previewSampleSize.scale(height);
// Now start off with the downsampled image displayed
self.displayingPreview = true;
self._displayImage(self.previewImageURL,
self.previewWidth, self.previewHeight, bgURL);
}
else {
// If we can't (or don't need to) downsample the full image then note
// that we don't have a preview and display the image at full size.
self.previewImageURL = null;
self.displayingPreview = false;
self._displayImage(self.fullImageURL,
self.fullsizeWidth, self.fullsizeHeight);
}
}
// If the blob is a JPEG then we can use #-moz-samplesize to downsample
// it while decoding. If this is a particularly large image then to avoid
// OOMs, we may not want to allow it to ever be decoded at full size
function computeFullSampleSize(blob, width, height) {
if (blob.type !== 'image/jpeg') {
// We're not using #-moz-samplesize at all
return Downsample.NONE;
}
// Determine the maximum size we will decode the image at, based on
// device memory and the maximum size passed to the constructor.
var max = MediaFrame.maxImageDecodeSize || 0;
if (self.maximumImageSize && (max === 0 || self.maximumImageSize < max)) {
max = self.maximumImageSize;
}
if (!max || width * height <= max) {
return Downsample.NONE;
}
return Downsample.areaAtLeast(max / (width * height));
}
function computePreviewSampleSize(blob, width, height) {
// If the image is not a JPEG we can't use a samplesize
if (blob.type !== 'image/jpeg') {
return Downsample.NONE;
}
//
// Determine how much we can scale the image down and still have it
// big enough to fill the screen in at least one dimension.
//
// For example, suppose we have a 1600x1200 photo and a 320x480 screen
//
// portraitScale = Math.min(.2, .4) = 0.2
// landscapeScale = Math.min(.3, .266) = 0.266
// scale = 0.266
//
var screenWidth = window.innerWidth * window.devicePixelRatio;
var screenHeight = window.innerHeight * window.devicePixelRatio;
// To display the image in portrait orientation, this is how much we
// have to scale it down to ensure that both dimensions fit
var portraitScale = Math.min(screenWidth / width, screenHeight / height);
// To display the image in landscape, this is we need to scale it
// this much
var landscapeScale = Math.min(screenHeight / width, screenWidth / height);
// We need an image that is big enough in either orientation
var scale = Math.max(portraitScale, landscapeScale);
// Return the largest samplesize that still produces a big enough preview
return Downsample.sizeNoMoreThan(scale);
}
};
// An internal method to set the url and size of the img element and to
// reposition the image appropriately. We use this when first displaying an
// image and when switching from the preview image to the full image and back.
// The url argument is used as the img.src. The bg argument, if specified, is
// a URL used for the CSS background-image property. This is useful for
// switching from a preview image to a full-size image (when the user zooms
// in) without a flash while the full-size image is decoded.
MediaFrame.prototype._displayImage = function(url, width, height, bg) {
// Set the size of the image
this.image.style.width = width + 'px';
this.image.style.height = height + 'px';
// If a background was specfied, use it. If this is the preview image URL
// and it is already decoded, it gives us something to display while the
// full-size image is decoding.
if (bg) {
this.image.style.backgroundImage = 'url(' + bg + ')';
// Wait one frame before loading the main image in this case
// to ensure that this background image actually gets displayed
requestAnimationFrame(() => { this.image.src = url; });
}
else {
this.image.style.backgroundImage = 'none';
// Start loading and decoding the main image
this.image.src = url;
}
// Remember the width and height, but swap them for rotated images.
if (this.rotation === 0 || this.rotation === 180) {
this.itemWidth = width;
this.itemHeight = height;
} else {
this.itemWidth = height;
this.itemHeight = width;
}
// The image div has a new size, so we have to change its transform
this.computeFit();
this.setPosition();
// Query the position of the image in order to flush the changes
// made by setPosition() above. This prevents us from accidentally
// animating those changes when the user double taps to zoom.
var temp = this.image.clientLeft; // jshint ignore:line
};
// This function adds a label for accessibility to the image frame.
// Videos are localized within the video player, so this is only for images.
MediaFrame.prototype.localize = function localize() {
if (!this.displayingImage) {
return;
}
var portrait = this.fullsizeWidth < this.fullsizeHeight;
if (this.rotation == 90 || this.rotation == 270) {
// If rotated sideways, the width and height are swapped.
portrait = !portrait;
}
var timestamp = this.imageblob.lastModifiedDate;
var orientationL10nId = portrait ? 'orientationPortrait' :
'orientationLandscape';
document.l10n.formatValue(orientationL10nId).then((orientationText) => {
if (timestamp) {
if (!this.dtf) {
// XXX: add localized/timeformatchange event to reset
this.dtf = Intl.DateTimeFormat(navigator.languages, {
hour12: navigator.mozHour12,
hour: 'numeric',
minute: 'numeric',
day: 'numeric',
month: 'numeric',
year: 'numeric'
});
}
var ts = this.dtf.format(new Date(timestamp));
document.l10n.setAttributes(
this.image,
'imageDescription',
{
orientation: orientationText,
timestamp: ts
}
);
} else {
document.l10n.setAttributes(
this.image,
'imageDescriptionNoTimestamp',
{ orientation: orientationText }
);
}
});
};
MediaFrame.prototype._switchToFullSizeImage = function _switchToFull() {
if (!this.displayingImage || !this.displayingPreview) {
return;
}
this.displayingPreview = false;
this._displayImage(this.fullImageURL,
this.fullsizeWidth, this.fullsizeHeight,
this.previewImageURL);
};
MediaFrame.prototype._switchToPreviewImage = function _switchToPreview() {
// If we're not displaying an image or already displaying preview
// or don't have a preview to display then there is nothing to do.
if (!this.displayingImage || this.displayingPreview ||
!this.previewImageURL) {
return;
}
this.displayingPreview = true;
this._displayImage(this.previewImageURL,
this.previewWidth, this.previewHeight);
};
// The video and poster image can have different sizes, but they must
// have the same aspect ratio and rotation. The aspect ratio is the raw
// media width divided by the raw media height before any rotation is applied.
MediaFrame.prototype.displayVideo = function displayVideo(videoblob, posterblob,
aspectRatio, rotation)
{
if (!this.video) {
return;
}
this.clear(); // reset everything
// Keep track of what kind of content we have
this.displayingVideo = true;
// Remember the blobs
this.videoblob = videoblob;
this.posterblob = posterblob;
// Get new URLs for the blobs
this.videourl = URL.createObjectURL(videoblob);
this.posterurl = URL.createObjectURL(posterblob);
// Display them in the video element.
// The VideoPlayer class takes care of positioning itself, so we
// don't have to do anything here with computeFit() or setPosition()
this.video.load(this.videourl, this.posterurl, aspectRatio, rotation || 0,
videoblob.lastModifiedDate);
// Show the player controls
this.video.show();
};
// Reset the frame state, release any urls and and hide everything
MediaFrame.prototype.clear = function clear() {
// Reset the saved state
this.displayingImage = false;
this.displayingPreview = false;
this.displayingVideo = false;
this.itemWidth = this.itemHeight = null;
this.imageblob = null;
this.videoblob = null;
this.posterblob = null;
this.fullSampleSize = null;
this.fullImageURL = null;
this.previewImageURL = null;
this.fullsizeWidth = this.fullsizeHeight = null;
this.previewWidth = this.previewHeight = null;
this.fit = null;
if (this.imageurl) {
URL.revokeObjectURL(this.imageurl);
}
this.imageurl = null;
if (this.previewurl) {
URL.revokeObjectURL(this.previewurl);
}
this.previewurl = null;
if (this.tinyPreviewURL) {
URL.revokeObjectURL(this.tinyPreviewURL);
}
this.tinyPreviewURL = null;
// hide the image and release anything it was displaying
if (this.image) {
this.image.style.opacity = 0;
this.image.style.backgroundImage = 'none';
this.image.src = '';
this.image.removeAttribute('aria-label');
}
// Hide the video player
if (this.video) {
this.video.reset();
this.video.hide();
if (this.videourl) {
URL.revokeObjectURL(this.videourl);
}
this.videourl = null;
if (this.posterurl) {
URL.revokeObjectURL(this.posterurl);
}
this.posterurl = null;
}
};
// Set the item's position based on this.fit
// The VideoPlayer object fits itself to its container, and it
// can't be zoomed or panned, so we only need to do this for images
MediaFrame.prototype.setPosition = function setPosition() {
if (!this.fit || !this.displayingImage) {
return;
}
var dx = this.fit.left, dy = this.fit.top;
// We have to adjust the translation to account for the fact that the
// scaling is being done around the middle of the image, rather than the
// upper-left corner. And we have to make this adjustment differently
// for different rotations.
switch (this.rotation) {
case 0:
case 180:
dx += (this.fit.width - this.itemWidth) / 2;
dy += (this.fit.height - this.itemHeight) / 2;
break;
case 90:
case 270:
dx += (this.fit.width - this.itemHeight) / 2;
dy += (this.fit.height - this.itemWidth) / 2;
break;
}
var sx = this.mirrored ? -this.fit.scale : this.fit.scale;
var sy = this.fit.scale;
var transform =
'translate(' + dx + 'px, ' + dy + 'px) ' +
'scale(' + sx + ',' + sy + ')' +
'rotate(' + this.rotation + 'deg) ';
this.image.style.transform = transform;
};
MediaFrame.prototype.computeFit = function computeFit() {
if (!this.displayingImage) {
return;
}
this.viewportWidth = this.container.offsetWidth;
this.viewportHeight = this.container.offsetHeight;
var scalex = this.viewportWidth / this.itemWidth;
var scaley = this.viewportHeight / this.itemHeight;
var scale = Math.min(Math.min(scalex, scaley), 1);
// Set the image size and position
var width = Math.floor(this.itemWidth * scale);
var height = Math.floor(this.itemHeight * scale);
this.fit = {
width: width,
height: height,
left: Math.floor((this.viewportWidth - width) / 2),
top: Math.floor((this.viewportHeight - height) / 2),
scale: scale,
baseScale: scale
};
};
MediaFrame.prototype.reset = function reset() {
// If we're not displaying the preview image, but we have one,
// and it is the right size, then switch to it
if (this.displayingImage && !this.displayingPreview &&
this.previewImageURL) {
this._switchToPreviewImage(); // resets image size and position
return;
}
// Otherwise, just resize and position the item we're already displaying
this.computeFit();
this.setPosition();
// If frame is resized, the video's size also need to reset.
if (this.displayingVideo) {
this.video.setPlayerSize();
}
};
// We call this from the resize handler when the user rotates the
// screen or when going into or out of fullscreen mode. If the user
// has not zoomed in, then we just fit the image to the new size (same
// as reset). But if the user has zoomed in (and we need to stay
// zoomed for the new size) then we adjust the fit properties so that
// the pixel that was at the center of the screen before remains at
// the center now, or as close as possible
MediaFrame.prototype.resize = function resize() {
var oldWidth = this.viewportWidth;
var oldHeight = this.viewportHeight;
var newWidth = this.container.offsetWidth;
var newHeight = this.container.offsetHeight;
var oldfit = this.fit; // The current image fit
// If this is triggered by a resize event before the frame has computed
// its size, then there is nothing we can do yet.
if (!oldfit) {
return;
}
// Compute the new fit.
// This updates the the viewportWidth, viewportHeight and fit properties
this.computeFit();
// This is how the image would fit at the new screen size
var newfit = this.fit;
// If no zooming has been done (or almost no zooming), then a resize is just
// a reset. The same is true if the new fit base scale is greater than the
// old scale.
// The scale is calculated with division, the value may not be accurate
// because of IEEE 754. We use abs difference to do the equality checking.
if (Math.abs(oldfit.scale - oldfit.baseScale) < 0.01 ||
newfit.baseScale > oldfit.scale) {
this.reset();
return;
}
// Otherwise, just adjust the old fit as needed and use that so we
// retain the zoom factor.
oldfit.left += (newWidth - oldWidth) / 2;
oldfit.top += (newHeight - oldHeight) / 2;
oldfit.baseScale = newfit.baseScale;
this.fit = oldfit;
// Reposition this image without resetting the zoom
this.setPosition();
};
// Zoom in by the specified factor, adjusting the pan amount so that
// the image pixels at (fixedX, fixedY) remain at that position.
// Assume that zoom gestures can't be done in the middle of swipes, so
// if we're calling zoom, then the swipe property will be 0.
// If time is specified and non-zero, then we set a CSS transition
// to animate the zoom.
MediaFrame.prototype.zoom = function zoom(scale, fixedX, fixedY, time) {
// Ignore zooms if we're not displaying an image
if (!this.displayingImage) {
return;
}
// If we were displaying the preview switch to the full-size image.
if (this.displayingPreview) {
this._switchToFullSizeImage();
}
// Never zoom in farther than the native resolution of the image
if (this.fit.scale * scale > 1) {
scale = 1 / (this.fit.scale);
}
// And never zoom out to make the image smaller than it would normally be
else if (this.fit.scale * scale < this.fit.baseScale) {
scale = this.fit.baseScale / this.fit.scale;
}
this.fit.scale = this.fit.scale * scale;
// Change the size of the photo
this.fit.width = Math.floor(this.itemWidth * this.fit.scale);
this.fit.height = Math.floor(this.itemHeight * this.fit.scale);
// fixedX and fixedY are in viewport coordinates.
// These are the photo coordinates displayed at that point in the viewport
var photoX = fixedX - this.fit.left;
var photoY = fixedY - this.fit.top;
// After zooming, these are the new photo coordinates.
// Note we just use the relative scale amount here, not this.fit.scale
photoX = Math.floor(photoX * scale);
photoY = Math.floor(photoY * scale);
// To keep that point still, here are the new left and top values we need
this.fit.left = fixedX - photoX;
this.fit.top = fixedY - photoY;
// Now make sure we didn't pan too much: If the image fits on the
// screen, fixed it. If the image is bigger than the screen, then
// make sure we haven't gone past any edges
if (this.fit.width <= this.viewportWidth) {
this.fit.left = (this.viewportWidth - this.fit.width) / 2;
}
else {
// Don't let the left of the photo be past the left edge of the screen
if (this.fit.left > 0) {
this.fit.left = 0;
}
// Right of photo shouldn't be to the left of the right edge
if (this.fit.left + this.fit.width < this.viewportWidth) {
this.fit.left = this.viewportWidth - this.fit.width;
}
}
if (this.fit.height <= this.viewportHeight) {
this.fit.top = (this.viewportHeight - this.fit.height) / 2;
}
else {
// Don't let the top of the photo be below the top of the screen
if (this.fit.top > 0) {
this.fit.top = 0;
}
// bottom of photo shouldn't be above the bottom of screen
if (this.fit.top + this.fit.height < this.viewportHeight) {
this.fit.top = this.viewportHeight - this.fit.height;
}
}
// If a time was specified, set up a transition so that the
// call to setPosition() below is animated
if (time) {
// If a time was specfied, animate the transformation
var transition = 'transform ' + time + 'ms ease';
this.image.style.transition = transition;
var self = this;
this.image.addEventListener('transitionend', function done() {
self.image.removeEventListener('transitionend', done);
self.image.style.transition = '';
});
}
this.setPosition();
};
// If the item being displayed is larger than the continer, pan it by
// the specified amounts. Return the "unused" dx amount for the gallery app
// to use for sideways swiping
MediaFrame.prototype.pan = function(dx, dy) {
// We can only pan images, so return the entire dx amount
if (!this.displayingImage) {
return dx;
}
// Handle panning in the y direction first, since it is easier.
// Don't pan in the y direction if we already fit on the screen
if (this.fit.height > this.viewportHeight) {
this.fit.top += dy;
// Don't let the top of the photo be below the top of the screen
if (this.fit.top > 0) {
this.fit.top = 0;
}
// bottom of photo shouldn't be above the bottom of screen
if (this.fit.top + this.fit.height < this.viewportHeight) {
this.fit.top = this.viewportHeight - this.fit.height;
}
}
// Now handle the X dimension. If we've already panned as far as we can
// within the image (or if it isn't zoomed in) then return the "extra"
// unused dx amount to the caller so that the caller can use them to
// shift the frame left or right.
var extra = 0;
if (this.fit.width <= this.viewportWidth) {
// In this case, the photo isn't zoomed in, so it is all extra
extra = dx;
}
else {
this.fit.left += dx;
// If this would take the left edge of the photo past the
// left edge of the screen, then some of the motion is extra
if (this.fit.left > 0) {
extra = this.fit.left;
this.fit.left = 0;
}
// Or, if this would take the right edge of the photo past the
// right edge of the screen, then we've got extra.
if (this.fit.left + this.fit.width < this.viewportWidth) {
extra = this.fit.left + this.fit.width - this.viewportWidth;
this.fit.left = this.viewportWidth - this.fit.width;
}
}
this.setPosition();
return extra;
};
MediaFrame.prototype.setMinimumPreviewSize = function(w, h) {
this.minimumPreviewWidth = w;
this.minimumPreviewHeight = h;
};