I am looking for the best approach for generating images of text on the server side (preferably Node.js). It will need to accommodate things like paging (so generating multiple images of text for one text input if it is too long to fit on one page). I am looking for something that is fairly precise and allows for a good deal of type configuration.
I have looked at a few options:
Use Canvas. This approach would work for most of the use cases. I could use a text engine like textjs for the layout. However, this is somewhat limiting as Canvas doesn't have specific text metrics (for things like text height used for exact positioning). This could make paging difficult.
Use normal HTML with something like PhantomJS to generate and them capture an image of the text. While this approach will work for some use cases, it makes it hard to handle things like paging.
Use some other text engine. I've looked around and found some options - but it would need to be something that I could call from Nodejs (as I'll likely use this on AWS Lambda).
What would you recommend?
I lately did something very similar - also with node.js on Lambda. In my opinion the best approach is using PhantomJS and maybe taking the detour of generating a PDF.
With HTML and CSS you can conveniently style the output exactly how you want it, which is a great advantage about the way more complicated Canvas approach. You only have to take care of adding some horizontal space wherever you expect the pagebreak (of course this depends on your usecase and may not be necessary). Having the rendered HTML page you now have two options:
You could generate a PDF - which will take care of generating multiple pages - and then rasterize that to images
Or you directly generate an image with Screen Capture (example Code) and then splitt that image horizontally
Both approaches worked fine for me.
Related
I'd like to be able to produce PDF files in NodeJS.
Currently, we use puppeteer. We need to produce highly designed documents and so puppeteer/chromium gives me the ability to create a complex layout in HTML with the added benefit of also having the HTML version of the file.
It's great for relatively small documents where design is key.
The problem is when I try to produce long report documents. These documents do not require elaborate design. These are pretty much just a header with some information, and then a simple table with lots of records that stretch far as the eye can see, so they tend to be large. Like, really really large.
When I try using puppeteer for that, well pretty much just crashes and burns because loading such huge layouts into the underlying browser is just too much.
Currently I do "stitching". I create the document by having puppeteer create the doc in parts, and then I connect all those "doclets" into one using PDFKit.
But then I have problems like when one "doclet" ends and a new one begins, there are blank lines. (partially empty pages for no good reason from the perspective of a customer viewing it)
What I'm looking for is a library that has basic layout functionality but that doesn't use a browser (or perhaps uses something lightweight).
Problem is that libraries like PDFkit and pdf-lib seem to be too low level.
I'm going to literally have to "draw" the documents by telling it where exactly the text should be.
If I want tables, I'm going to straight up have to draw rectangles and stuff.
Having to create all of this manually would be a nightmare.
All I want is the ability to create simple layouts (tables, titles, text wrapping, background color) without having to use a library that just launches chromium.
Please, let me know if you know of any such option.
Thanks in advance!
What I tried:
PDFkit/pdf-lib - too low level. Unless I'm getting something wrong, there doesn't seem to be a way to create word wrapped layouts with basic tables.
jsPDF doesn't seem to be able to use the HTML functionality on the server(I think to get it to work I'd have to let it use a browser...? if so, doesn't really help).
Puppeteer/other libraries that pilot a browser - well, it uses a browser so a no-go for large docs.
Praying to Odin - No luck so far.
I just started at a new company and have been asked to do what I believe impossible, but I need confirmation on this. The website that my company has allows users to view images in extremely high resolution using SVGs. We've built a custom viewer for these images that allow you to zoom and scroll around the image and it works well. Because of this, the image format "needs" to remain SVG. However, we need to include a watermark to this image. The way we're doing this right now is passing the SVG and PNG watermark to the client, inserting the watermark into the SVG, and displaying it to the user. This is very obviously easily hacked as anyone with client-side experience knows (The dev team here is mostly older developers and don't have much web experience). Even if the raw SVG isn't intercepted, they can still just delete the watermark from the source. I've convinced my boss to make the watermark be injected on the server-side, so this leaves just the problem that SVGs are editable by the end-client.
What I want to know is if one of these two things are possible:
1) Is there another image format akin to SVG that could be used to keep this highly scalable image without loosing resolution, and without it being directly editable by an end-client? The only options that people seem to discuss for the web is JPG, GIF, PNG, and SVG. I've looked at Adobe Illustrator ".ai" files and EPS (Encapsulated PostScript) as other vector options, but I can't find anywhere if I can modify these images in PHP, which is key if I want to overlay a watermark in server-side code.
2) Is there a way to obfuscate the raw SVGs content so that the use can't go and manipulate it? I've seen SVGs that have <image ...> tags inside them with PNGs represented as long and complex strings before. Something like xlink:href="data:image/png;base64...". I was wondering if there's a way to display an SVG as this string, so that the data can't be directly manipulated. I'm sure there's an algorithm to reverse these, but so long as we're sticking with SVGs, I need to make this as secure as possible with as many hoops to jump through as possible if someone wants to steal the data.
Either way would be acceptable, as long as removing this watermark is more complex than just hitting F12 and removing the element inside the dev tools.
Is there another image format akin to SVG that could be used to keep this highly scalable image without loosing resolution, and without it being directly editable by an end-client?
SVG is a vector format, and to maintain extreme scalability, you need to stick with vectors, be it any format. However, in that case it will always be possible to remove the vectors that belong to your watermark. There are of course vector formats that are stored as binary, which would make it somewhat harder for an enduser to parse and edit, but those are not editable in PHP either, and are much less compatible. So you probably don't want to do this.
Is there a way to obfuscate the raw SVGs content so that the user can't go and manipulate it?
First, it will never be "secure" in the sense that as said above, it will always be possible to remove the watermark from a vector image. (Btw the only difference to bitmap formats like JPG is that content below the watermark in bitmap is actually missing, while in SVG it's still there.)
However, depending on how "good" you want this to be, you can do a few things. I think the "goodness" here means the effort needed to remove the watermark, and you can raise the bar relatively easily. You don't have to (and you probably can't reasonably) obfuscate the whole SVG.
One thing that comes to mind is that SVG is basically just XML, it consists of tags like <rect>, <line>, <circle> etc. The order of these tags doesn't matter much (mostly, with exceptions of course). So you could entwine the tags that draw your watermark pretty much randomly among existing tags. I mean really randomly, so different downloads would produce different results. If you do this well (eg. you find line tags to "hide" your watermark line tags, and so on), it will be hard to automatically remove the watermark, because it's all over relevant data that is your actual image. Of course, the watermark could still be visually in a corner, and this is already a weakness, anything drawn to a corner could possibly be removed automatically. And it will be easy to remove by hand with any decent editor I suppose. So it depends on what the purpose is.
But I still think this sort of thing could make it hard enough in many scenarios (and would be totally inadequate in others).
I am a freelancer who wants to start using Sketchapp to make more trendy websites (slanted and curved line backgrounds, UI assets that have shadows, assets that go over 2 divs (see examples). Can and do freelancers (do both their own design and code) use Sketchapp to create the entire site for everything (including text) as their normal best practice and to speed up workflow and then just export everything to text editor and then tweak? Below are 2 examples that I aspire to be able to create.
Example 1 from Pinterest
Example 2 from Pinterest
The answer is Yes and No. The first example is highly using textures and graphics which is hard to do in Sketch. But for that you need to use Photoshop. For the second example is more flat and not using much graphical effect. its minimal and flat. Sketch is really fasten up your working flow to create something like that.
Hope this helps.
You definitely could create both designs in sketch but it won't be the only program you have to use to finish this job. At least if you produce each used graphic yourself.
In the first design for example you have quite a lot gradients an brush technics between the sections. Here you would need to use brushes in Photoshop to achive this look. After this you could export the layers as PNGs with transparent background and import those into sketch...
Sketch is perfect to use with SVG. I would say wen you work with SVGs you can almost only use sketch.
Hope this answer helps!
to speed up workflow and then just export everything to text editor and then tweak
First you create the website design in Sketch and then you start writing the HTML/CSS code by hand. This is how the web development process goes.
You could also use helper tools like Desech Studio to import the Sketch file and then adjust the html/css faster.
Unfortunately it's not possible to create a website in the design stack like Sketch, and also work in the web stack. These 2 stacks are different in how they work.
Alternatively you could start designing the website directly in HTML/CSS and skip the design stack completely, but you will be slower and it will be harder to make changes, compared to the design stack.
Are there any open source scripts that will allow you to enter a website url and it will generate a color palette based on your site? I would prefer something that ran on a typical LAMP stack. I've been able to find many websites that offer the functionality as a service but no downloadable scripts...
Update: I'm looking for the palette to contain the hex color values
Presumably easiest would be to render the page and count the pixels of different colors from a screenshot, because otherwise you can't tell which colors from the CSS file actually cover large areas. It's unlikely you could script this easily from command line but if you have a windowing environment, writing such a program wouldn't be too complicated. If you use QT, you can load the page into a QWebView, use QPixmap.grabWindow to get the pixels, convert it to QImage and then loop through the pixels counting them.
When converting the web page to an image, a big point to have in mind is that a user could send it to a malicious website to take advantage of a security problem in whatever rendering engine you are using, and even take over the server. Make sure to at least disable JavaScript and Flash, even though that will make some websites look different from normal. Otherwise it's far too easy to get the program stuck in an infinite loop even if nothing else.
Let me describe the "battlefield" of my task:
Multi-room audio/video chat with more than 1M users;
Custom Direct3D renderer;
What I need to implement is a TextOverVideo feature. The Text itself goes via network and is to be rendered on the recipient side with Direct3D renderer. AFAIK, it is commonly used in game development to create your own texture with letters/numbers and draw this items. Because our application must support many languages, we ought to use a standard. That's why I've been working with ID3DXFont interface but I've found out some unsatisfied limitations.
What I've faced is a lack of scalability. E.g. if user is resizing video window I have to RE-create D3DXFont with new D3DXFONT_DESC while he's doing that. I think it is unacceptable.
That is why the ONLY solution I see (due to my skills) is somehow render the text to a texture and therefore draw sprite with scaling, translation etc.
So, I'm not sure if I go into the correct direction. Please help with advice, experience, literature, sources...
Your question is a bit unclear. As I understand it, you want easily scalable font.
I think it is unacceptable
As far as I know, this is standard behavior for fonts - even for system fonts. They aren't supposed to be easily scalable.
Possible solutions:
Use ID3DXRenderTarget for rendering text onto texture. Font will be filtered when you scale it up too much. Some people will think that it looks ugly.
Write custom library that supports vector fonts. I.e. - it should be able to extract font outline from font, and build text from it. It will be MUCH slower than ID3DXFont (which is already slower than traditional "texture" fonts). Text will be easily scalable. Using this way, you are very likely to get visible artifacts ("noise") for small text. I wouldn't use that approach unless you want huge letters (40+ pixels). Freetype library may have functions for processing font outlines.
Or you could try using D3DXCreateText. This will create 3D text for ONE string. Won't be fast at all.
I'd forget about it. As long as user is happy about overall performance, improving font rendering routines (so their behavior looks nice to you) is not worth the effort.
--EDIT--
About ID3DXRenderTarget.
EVen if you use ID3DXRenderTarget, you'll need ID3DXFont. I.e. you use ID3DXFont to render text onto texture, and then use texture to blit text onto screen.
Because you said that performance is critical, you can delay creation of new ID3DXFont until user stops resizing video. I.e. When user starts resizing video, you use old font, but upscale it using texture. There will be filtering, of course. Once user stops resizing, you create new font when you have time. you probably can do that in separate thread, but I'm not sure about it. OR you could simply always render text in the same resolution as video. This way you won't have to worry about resizing it (it still will be filtered - along with the video). Some video players work this way.
Few more things about ID3DXFont. There is one problem with ID3DXFont - it is slow in situations where you need a lot of text (but you still need it, because it supports unicode, and writing texturefont with unicode support is pain). Last time I worked with it I optimized things by caching commonly used strings in the textures. I.e. any string that was drawn more than 3 frames in the row were rendered onto D3DFMT_A8R8G8B8 texture/render target, and then I've been copying that string from texture instead of using ID3DXFont. Strings that weren't rendered for a while, were removed from texture. That gave some serious boost. This solution, however is tricky - monitoring empty space in the texture, removing unused strings, and defragmenting the texture isn't exactly trivial (there is nothing exceptionally complicated, but it is easy to make a mistake). You won't need such complicated system unless your screen is literally covered by text.
ID3DXFont fonts are flat, always parallel to the screen. D3DXCreateText are meshes that can be scaled and rotated.
Texture fonts are fuzzy and don't look very clear. Not good for an app that uses lots of small text.
I am writing an app that can create 500 text meshes, each mesh averaging 3,000-5,000 vertices. The text meshes are created once, then are static. I get 700 fps on a GeForce 8800.