i want to know wheter open laszlo has data uri feature. The following example will show a red dot where the red dot is an image and base64 data is passed to it. Is it possible to do something like this?
example is given below
<div>
<p>Taken from wikpedia</p>
<img src="data:image/png;base64, iVBORw0KGgoAAAANSUhEUgAAAAUA
AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
9TXL0Y4OHwAAAABJRU5ErkJggg==" alt="Red dot" />
</div>
You are referring to Data URLs as specified in RFC 2397. That feature not supported in OpenLaszlo, and it only would be relevant for DHTML applications anyway. For the SWF runtime, images can be compiled into a SWF file as static resources, increasing the file size and reducing the number of requests needed to send to the server.
There are size limitations for inline images as well. Browsers are only required to support URLs up to 1,024 bytes in length, according to the above RFC. Browsers are more liberal in what they'll accept, however. Opera limits data URLs to about 4,100 characters. Firefox supports data URLs up to 100K, which means you should only use the technique for small to medium size images.
Even though Data URLs are not supported in OpenLaszlo, a similar - and in my eyes - more powerful option is available. The automatic generation of a CSS sprites for images you add as static resources. When you select the 'Use master sprite' compile option, the OpenLaszlo compiler will create one PNG sprite map containing all those static resources.
Here is an example of the master sprite PNG for the OpenLaszlo weather widget. Instead of making multiple requests to download the individual images, the browser just has to make one request.
Related
On my TYPO3 v10 website I have some SVG icons in use, no problem.
I also have a few more complex SVG Figures (created with Inkscape), that I want to include in TYPO3 website. Of course I can upload the .svg files to the fileadmin/ folder, and link to them with the Text+Image (or Text+Media) Content Elements.
In the Backend, TYPO3 generates some fine png-thumbnails for preview. So far so good.
The file can be downloaded directly, from its fileadmin/images ... location.
However, inside web pages, my SVGs are not displayed as they should.
A lot of styling information gets removed from the SVG and I don't know where.
Here is a screenshot of the original vs corrupted image (as displayed in the TYPO3 frontend).
Here is a graphical diff that shows the difference between the figures.
It turns out that at some time during the rendering process, TYPO3 removes the values from the style="...." SVG attributes. See reddish boxes.
All my more complex SVGs look like the one on the right when embedded in TYPO3.
Here is the SVG if you want to try yourself: image on SVGshare.com
On the right, many style attributes have been set to style="".
but why?
It's Firefox, not TYPO3, who removes the style="..." attribute values. This seems to be a longstanding Firefox Issue, solved.
See Bugzilla Issue 1262842: [CSP] Blocks the use of style attributes inside SVG without generating console errors.
Look for "triply confusing" in the first comment.
Inline CSS styles can be a security Problem, and therefore Firefox has a Content-Security-Policy (CSP) in place, in order to correct this.
An explainer for the mitigation strategies, written jointly by professional Security Engineers is given in this Google Doc and in Gihub Repo (Content Security Policy), Issue 45, Further granularity of unsafe-inline styles.
Script inline attributes are a difficult subject to approach when it
comes to CSP, they have the same amount of power as any other script
element but they don’t have ways to be whitelisted, for example, by a
nonce or hash. This means that the actual content of the attribute is
mostly the only deciding factor.
I don't understand everything mentioned in these docs and discussions. Inline-style Elements seem to be vulnerable to XSS attacks, and then attacker can put CSS url() in there for instance.
Quick-and-dirty solution
Use Inkscape and save as "optimized SVG", and check the option "Convert CSS Attributes to XML attributes". See attached screenshot of the Inkscape Dialog (Linux).
This solution was proposed by a web-developer from the GIMP devteam.
TYPO3 9 introduced an SVG Sanitizer, which automatically modifies SVG files during "fileadmin upload time", meaning it removes any <style ...> elements from the uploaded SVG file.
In TYPO3 10 and later versions, this SVG Sanitizer is by default automatically set up via Symfony dependency injection via core's Services.yaml.
You can remove the SVG Sanitizer via your own site extension's Services.yaml, e.g. for your myextension/Configuration/Services.yaml:
services:
_defaults:
autowire: true
autoconfigure: true
public: false
# ...
# remove TYPO3's default-autowired SvgSanitizer, which tampers with filadmin uploaded SVGs (e.g. removes necessary <style> information)'
TYPO3\CMS\Core\Resource\Security\SvgEventListener: ~
The tilde (~) removes/overwrites the definition previously set up by core's Services.yaml ( https://symfony.com/doc/current/service_container/service_decoration.html ).
This seems to be a problem of your individual TYPO3 installation. I've just tested your SVG image in a brand new TYPO3 v10 installation and the image is rendered properly in backend and frontend.
Maybe you have some 3rd party extensions installed who postprocess the HTML output of TYPO3, e.g EXT:sourceopt or EXT:scriptmerger.
Using 2sxc on DNN, I have a website that uses SVGs for icons in content types. The client wants to be able to upload the SVG icons to 2sxc via a Link field but then instead of rendering <img src="#Content.SVG" />, they want it to render the source code of the SVG (so we could manipulate the fill color via CSS). Is this even possible and how could it be done?
Basically 2 steps
Get the real file name using 2sxc and DNN
Then load the file as a string using normal .net stuff System.IO and add it to your html - https://learn.microsoft.com/en-us/dotnet/api/system.io.file.readalltext?view=netframework-4.5.1
ca. like this
<div>
#Html.Raw(System.IO.File.ReadAllText(fileName)
</div>
Some examples of how to do this can be found below
Using the fetch API
How to convert image (svg) to rendered svg in javascript?
Older methods such as XMLHttpRequest or jQuery
Include SVG files with HTML, and still be able to apply styles to them?
Using D3
(Embed and) Refer to an external SVG via D3 and/or javascript
Using a custom JS library
One example: SVGInjector
Interestingly Dnn is doing this nowadays and you can look at the code here. If you ignore the caching, you might be able to do similar in a View.
https://github.com/dnnsoftware/Dnn.Platform/blob/0d3b931d8483b01aaad0291a5fde2cbc0bac60ca/DNN%20Platform/Website/admin/Skins/Logo.ascx.cs#L123
And that is called from above, see ~line 71, so they are doing a real inject of the file contents to inline. Obviously caching file-access stuff should be a priority for caching if the website is high-traffic, but otherwise it is not needed or at least secondary.
In my hybrid Android app I use inline SVG to display images that are large (of the order of 2Mb) and complex (several hundred SVG elements per image). When I need to change the image I do the following
var puzzle = document.createElementNS(SVGNS,'svg'),
kutu = document.getElementById('kutu');
puzzle.id = 'puzzle';
puzzle.setAttribute('preserveAspectRatio','none');
puzzle.setAttribute('width','100vw');
puzzle.setAttribute('height','85.5vh');
puzzle.setAttribute('xmlns',SVGNS);
puzzle.setAttribute('xmlns:xlink',XLINK);
puzzle.setAttribute('fill-rule','evenodd');
puzzle.setAttribute('clip-rule','evenodd');
puzzle.setAttribute('stroke-linejoin','round');
puzzle.setAttribute('stroke-miterlimit','1.414');
puzzle.setAttribute('viewBox','0 0 1600 770');
puzzle.innerHTML = SVG;
//SVG here is the SVG image content shorn off the outer <svg>..</svg>
if (0 < kutu.children.length) kutu.children[0].remove();
//remove old image, iff any
kutu.appendChild(puzzle);
//append the new image
While this is working the process of displaying the new image is slow. I suspect it is because of the innerHTML assignment above. Recreating through a sequence of createElementNS, puzzle.àppendChild would require me to first parse the incoming raw SVG content etc. Is that the way to go or would there be a faster way to display the content.
Once again for clarity - SVG here is the content of the new SVG image to be displayed shorn of its outer <svg>...</svg> wrrapper.
Just a side note it would probably be better to use setAttributeNS in place of setAttribute for consistency purpose since createElementNS is used, though it might not make a difference in speeding up the SVG image change.
In the case of a native app, a tool like the Android Profiler if using Android Studio 3.0 and higher can be used to analyze performance bottleneck. However since your app is a hybrid app, some sort of performance profiler that's applicable to the hybrid app (Whether it's Ionic or Cordova, etc.) can help to pinpoint where your performance bottleneck is.
Since your app is a hybrid, without knowing the resource capacity of your android app session, the guess is it seems to be a possible cause that it calls something like .setAttribute to set session-level attributes on the fly during the change of the image and the session resource might not be enough, and also the DOM has to perform .innerHTML and appendChild, which are dynamic operations. DOM manipulation is known to be slow.
Conversion of attributes of all the SVGs and store the result in some sort of storage or cache, and when needed, call it from the persistent storage or cache might be helpful.
Or consider using AngularJS to do the SVG change beforehand and preload the SVG images, refer to easily preload images in your Angular app. Here is another similar code to yours except it's using AngularJS to add SVG for starters.
Another simpler way, without changing your code, if you could minify the incoming SVGs beforehand, is to use SVG Optimizer or SVGO, a node.js open source project to compress your SVGs. Quoted from the SVGO link it says:
"SVG files, especially those exported from various editors, usually contain a lot of redundant and useless information. This can include editor metadata, comments, hidden elements, default or non-optimal values and other stuff that can be safely removed or converted without affecting the SVG rendering result." Although the performance gain might not be obvious going this route.
I am inspecting a portal's page for loading of images ,its loading very slow.
We pick images from a filesystem , images name from database and read them, create a list and show results using a4j:mediaOutput tag. but the images are being loaded very slowly.
http://www.easyrenting.com/list-detail/3bhk-ardee-city-sector-52/6263
The first problem I see is that all your pictures are high-res (1800px x 2400px).
You really should create thumbnails server side to meet your view requirement and load images according of the size you want to show on the client size.
Have you only verified that your web page weight about 6.5MB including all images? (Check with Firebug).
I would recommand you a custom servlet like this one FileServlet supporting resume and caching with GZIP, and create a URL pattern according to load full res or thumbnail depending of the requirement.
There is no problem using the a4j:mediaOutput tag.
The images are getting loaded slowly because the size is too large, you need to find out a way to optimize the image size. Probably you can re-size the images before saving it to your file system.
Unless you are giving the zoom functionality, you do not need these big images.
That should help!
I made the following observation:
If I create an svg image that references an external raster image via xlink:href and try to load the svg in browsers, the external images are only shown if I use the <object> tag, but not when using the <img> tag.
Rendering with the <object> tag is quite slow and not as clean as using the img tag for images so I was wondering if there's a way to make it work through the <img> tag.
At first I thought it doesn't work because of a same origin policy, but even if the referenced image is in the same directory and I reference it through its name only, it wont load.
Any ideas?
Are you using IE? IE doesnt recognize SVG anyway. Microsoft is always ten years behind, yet they are more popular and far more costly, for some reason. Name brand propaganda?
SVG loads in Firefox. Both as an XML document referenced directly in the URL, and also if you embed it into an XHTML (fully XML compliant) document with proper namespacing, the SVG should render properly. The great thing about this option is that DHTML can manipulate your SVG. Everything I said in this paragraph also applies to MathML, if youre curious.
Aside from that, SVG doesn't load from an image tag. I do believe Firefox is working on this upgrade, though. Im not entirely sure.
Using the object or embed tag is reasonable, I suppose... but one of my earlier fixes was to use an iframe. Embed an iframe in your html that references the complete SVG file. Using CSS you can make the iframe look flush with the rest of your document, appearing and acting like an image. Encased in a div or span tag, you can have onhover and onclick event handlers.
Using the image tag, your src can be a PHP file on server side. If properly coded and with the appropriate cgi apps, you can rasterize your SVG on server-side, and have that PNG data sent back to your image via the PHP src.
There's no particular reason <object> should be any slower to load than <img> apart from possibly the interaction aspect (img's are static while object's are fully interactive documents). The images inside the svg should load in both scenarios, so it sounds like a bug in the browser.
Could you post a link to your example?
I think you are at least 10 months behind...IE9 supports SVG, and pre-release versions (including a beta) have been out for quite a while. Check out www.ietestdrive.com to grab the platform preview - it's pretty good. In my opinion, parts of their SVG support are much better than Firefox currently (but they don't support SMIL yet).