SVG Word Wrap - Show stopper? - svg

For fun I am trying to see how far I can get at implementing an SVG browser client for a RIA I'm messing around with in my spare time.
But have hit what appears to be a HUGE stumbling block. There is no word wrap!!
Does anyone know of any work around (I'm thinking some kind of JavaScript or special tag I don't know)?
If not I'm either going to have to go the xhtml route and start sticking HTML elements in my SVG (ouch), or just come back again in ten years when SVG 1.2 is ready.

This SVG stuff is baffling, isn't it ?
Thankfully, you can achieve some good results, but it takes more work than using the HTML 5 .
Here's a screenshot of my ASP.Net / SVG app, featuring a bit of "faked" word wrapping.
The following function will create an SVG text element for you, broken into tspan pieces, where each line is no longer than 20 characters in length.
<text x="600" y="400" font-size="12" fill="#FFFFFF" text-anchor="middle">
<tspan x="600" y="400">Here a realy long </tspan>
<tspan x="600" y="416">title which needs </tspan>
<tspan x="600" y="432">wrapping </tspan>
</text>
It's not perfect, but it's simple, fast, and the users will never know the difference.
My createSVGtext() JavaScript function takes three parameters: an x-position, y-position and the text to be displayed. The font, maximum-chars-per-line and text color are all hardcoded in my function, but this can be easily changed.
To display the right-hand label shown in the screenshot above, you would call the function using:
var svgText = createSVGtext("Here a realy long title which needs wrapping", 600, 400);
$('svg').append(svgText);
And here's the JavaScript function:
function createSVGtext(caption, x, y) {
// This function attempts to create a new svg "text" element, chopping
// it up into "tspan" pieces, if the caption is too long
//
var svgText = document.createElementNS('http://www.w3.org/2000/svg', 'text');
svgText.setAttributeNS(null, 'x', x);
svgText.setAttributeNS(null, 'y', y);
svgText.setAttributeNS(null, 'font-size', 12);
svgText.setAttributeNS(null, 'fill', '#FFFFFF'); // White text
svgText.setAttributeNS(null, 'text-anchor', 'middle'); // Center the text
// The following two variables should really be passed as parameters
var MAXIMUM_CHARS_PER_LINE = 20;
var LINE_HEIGHT = 16;
var words = caption.split(" ");
var line = "";
for (var n = 0; n < words.length; n++) {
var testLine = line + words[n] + " ";
if (testLine.length > MAXIMUM_CHARS_PER_LINE)
{
// Add a new <tspan> element
var svgTSpan = document.createElementNS('http://www.w3.org/2000/svg', 'tspan');
svgTSpan.setAttributeNS(null, 'x', x);
svgTSpan.setAttributeNS(null, 'y', y);
var tSpanTextNode = document.createTextNode(line);
svgTSpan.appendChild(tSpanTextNode);
svgText.appendChild(svgTSpan);
line = words[n] + " ";
y += LINE_HEIGHT;
}
else {
line = testLine;
}
}
var svgTSpan = document.createElementNS('http://www.w3.org/2000/svg', 'tspan');
svgTSpan.setAttributeNS(null, 'x', x);
svgTSpan.setAttributeNS(null, 'y', y);
var tSpanTextNode = document.createTextNode(line);
svgTSpan.appendChild(tSpanTextNode);
svgText.appendChild(svgTSpan);
return svgText;
}
The logic for word-wrapping is based on this HTML5 Canvas tutorial
I hope you find this useful !
Mike
http://www.MikesKnowledgeBase.com
UPDATE
One thing I forgot to mention.
That "Workflow diagram" screen that I've shown above was originally just written using an HTML 5 canvas. It worked beautifully, the icons could be dragged, popup menus could appear when you clicked on them, and even IE8 seemed happy with it.
But I found that if the diagram became "too big" (eg 4000 x 4000 pixels), then the would fail to initialise in all browsers, nothing would appear - but - as far as the JavaScript code was concerned, everything was working fine.
So, even with error-checking, my diagram was appearing blank, and I was unable to detect when this showstopper problem was occurring.
var canvasSupported = !!c.getContext;
if (!canvasSupported) {
// The user's browser doesn't support HTML 5 <Canvas> controls.
prompt("Workflow", "Your browser doesn't support drawing on HTML 5 canvases.");
return;
}
var context = c.getContext("2d");
if (context == null) {
// The user's browser doesn't support HTML 5 <Canvas> controls.
prompt("Workflow", "The canvas isn't drawable.");
return;
}
// With larger diagrams, the error-checking above failed to notice that
// the canvas wasn't being drawn.
So, this is why I've had to rewrite the JavaScript code to use SVG instead. It just seems to cope better with larger diagrams.

There is also foreignObject tag. Then you can embed HTML in SVG which gives the greatest flexibility. HTML is great for document layout and has been hacked to no end to support application layout, drawing, and everything us developers want. But it's strength is word wrapping and document layout. Let HTML do what it does best, and let SVG do what it does best.
http://www.w3.org/TR/SVG/extend.html
This works for most browsers FireFox, Opera, Webkit, except IE (as of IE11). :-( Story of the web ain't it?

SVGT 1.2 introduces the textArea element http://www.w3.org/TR/SVGTiny12/text.html#TextInAnArea , but it is only experimentally supported by Opera 10 at the moment. I don't know if other browsers will ever plan on implementing it, though I hope they will.

Per this document, it appears that tspan can give the illusion of word wrap:
The tspan tag is identical to the text tag but can be nested inside text tags and inside itself. Coupled with the 'dy' attribute this allows the illusion of word wrap in SVG 1.1. Note that 'dy' is relative to the last glyph (character) drawn.

The svg.js library has a svg.textflow.js plugin. It's not ultra fast but it does the trick. It even stores overflowing text in a data attribute so you can use it to create continuously flowing columns. Here the text flow example page.

An alternative method is to use Andreas Neuman's text box object.

These days, flowPara can do word wrapping, but I have yet to find a browser that supports it properly.

I've been looking for a solution about word wrapping in svg so many hours (or many days).
If you can in your app, edit your code to put some tspan, or any other method, go in it.
Text wrapping will be implement in the 1.2 version but except opera, no browser fully implement it yet (4 years, the specification are on the W3 ...).
Because I had to use some alignment settings, i couldn't use any of the code that many forum can provide (no foreign object, no carto script or anything).
If I post this message, it's just in order to be usefull to some other people when googling word wrapping svg because this post on the top result and in many case, this post doesn't help.
Here is a cool, easy and light solution :
http://dev.w3.org/SVG/profiles/1.1F2/test/svg/text-dom-01-f.svg

Related

Change visible property sometimes change the center position of the view (possible bug?)

I've 3 (loader, locker and debug view) hidden views (touchEnabled and visible set to false, and zIndex to 1) above the main view (zIndex = 2).
Each 'over' view has this method:
$.debugView.show = function() {
$.debugView.touchEnabled = $.debugView.visible = true;
$.debugView.zIndex = 3;
};
$.debugView.hide = function() {
$.debugView.touchEnabled = $.debugView.visible = false;
$.debugView.zIndex = 1;
};
This screen has the 3 'over' views hidden:
Now, I'm opening the 'debug view', but, SOMETIMES it seems like it changes the positions (as if the center it's on the top left corner instead of the center of the device).
Instead of the required result:
If I use the opacity instead of the visible property, it works properly.
This might be an SDK bug right?
<Alloy>
<Window>
<View id="content"/>
<View id="locker"/>
<View id="loader"/>
<View id="debugView"/>
</Window>
</Alloy>
All of these 4 views don't have width or height (so it uses the Ti.UI.FILL as default)
I have noticed this too with a completely different implementation. I had just one view that I included in a window.
Apparently the left and top calculations were not done properly if the elements is hidden.
What I did to solve the issue is to hardcode the left/top position by calculating the left position using this:
$.content.left = (Ti.Platform.displayCaps.platformWidth - 75) / 2;
Where in my case 75 is the width the element has, so that'll be bigger in your case. You can do the same for height.
Now, this is an iOS only solution. On Android you will need to take DPI into consideration calculating it.
I do think it is a bug, though this solution works perfectly for me. I recommend looking at JIRA and see if it is a known issue, and if not, raise it with a very specific explanation of the problem, preferably with a reproducible case delivered as an app. Classic would help most. And if it is not reproducible in classic it might be an alloy issue.

D3js: finding path's bounding box (without getBBox() )?

The following code works on Chromium :
var node = window.d3.selectAll('#L1 > *:nth-child(2)');
var bbox = node.node().getBBox();
console.log(bbox) // {height: 44, width: 44, y: -13, x: 144}
but not with nodejs + jsdom:
"TypeError: Object [ PATH ] has no method 'getBBox' "
M. Bostock pointed out that JSDOM doesn't support getBBox()
What D3js replacement to use to get the bounding box of #L1 > *:nth-child(2) ?
Past efforts lead me there : getBBox() based fiddle
Path's bounding box
Digging straight into the element's path data d="..." should work. An svg line is basically a set of x,y points. Assuming absolute coordinates without translation nor big bezier curves, which is the case of my D3js-generated svg lines, I'am finding in this data the min and max values for both x and y.
To do so, I get the d="..." svg line or multilines code. For simplicity sake, I rudely removes possible relative jumps such h30 or v20 since I never saw any in my D3js output, then clean out letters (aka svg commands : M,L,H,V,C,S,Q,T,A,Z), simplify the spaces and line jumps, then split by the remaining spaces. I get a clean arrays of coordinates.
Important to note, my selector directly target a single non-translated path.
var getBBox = function(selector){
var xmin, xmax, ymin, ymax,p;
// clean up path
var t = d3.select(selector).attr("d"); // get svg line's code
console.log(t)
t = t.replace(/[a-z].*/g," ") // remove relative coords, could rather tag it for later processing to absolute!
.replace(/[\sA-Z]+/gi," ").trim().split(" "); // remove letters and simplify spaces.
console.log(t)
for(var i in t){ // set valid initial values
if(t[i].length>1){
p = t[i].split(",");
xmin = xmax = p[0]; ymin = ymax = p[1]; }
}
for(var i in t){ // update xmin,xmax,ymin,ymax
p = t[i].split(",");
if(!p[1]){ p[0]=xmin; p[1] = ymin;} // ignore relative jumps such h20 v-10
xmin = Math.min(xmin, p[0]);
xmax = Math.max(xmax, p[0]);
ymin = Math.min(ymin, p[1]);
ymax = Math.max(ymax, p[1]);
} return [[xmin,ymax],[xmax,ymin]]; // [[left, bottom], [right, top]] as for https://github.com/mbostock/d3/wiki/Geo-Paths#bounds
}
var bb = getBBox("path");
JSfiddle DEMO
Groups bounding boxes
For groups of multiple paths, you may want to traverse the svg DOM to loop upon each single path of the group in order to update xmin, ymin, xmax, ymax.
Translated elements
To handle translated elements, adapt further.
Alternatives
Other better approaches may exist. Remember to check if getBBox() and getBoundingClientRect() are available in your context, since they are native and very convenient.
The reason why getBBox/getBoundingClientRect/getClientRect does not work in NodeJS+JSDOM is that calculating these values of an SVG (or HTML) element involves massive amounts of computation.
First, all CSS code in <style> elements must be parsed (which is already not trivial). Then the CSS selectors, cascading and inheritance rules must be applied to know what size, position or line width an element has. And even after you know all style property values, you need to do some non-trivial maths to calculate the bounding boxes: definition of different SVG transform functions, compositions of these, bounding boxes of SVG primitives and Bezier curves. Browsers support all of these (they have to, in order to draw the element), but JSDOM is simply not meant for all of these.
But fortunately, canvg is a JavaScript implementation of most of SVG, which uses a <canvas> element to draw the image. It does support most of the above, and although it does not have an interface for giving you those data, fortunately it has very nice (and MIT licensed) code, so hopefully you can copy and reuse parts of it. As of now, the code is written in a single file, and it has CSS parsing, applying cascading rules, path data parsing, definitions of SVG transforms, applying transformations, and bezier curve bounding box calculation. That is, almost everything you need to calculate bounding boxes :) It does not, however, support CSS selectors, but it can reuse another library. But unfortunately, as far as I can tell, canvg is not ready for running in NodeJS, you probably need some tweaks.
There is, however canvgc, an SVG to JS compiler, which contains an older version of canvg, and it is capable of running in NodeJS. So it is easier to start with that.

how to get text bounding box in famo.us

I am attempting to draw an SVG bezier curve that starts at the end of a text string that is in a Surface. I can set the size of the Surface to [true, true], which is supposed to make the size equal the text bounding box. But if I later try "mySurface.size[0]" in order to get the width, it returns "true"! I need to get a number for the width and height of that bounding box, in order to calculate the end point of my bezier curve! The equivalent DOM approach would just be to use the .getBBox() function.. how do I do this in Famo.us?
this is maybe because the surface hasn't rendered yet. there are a few similar questions here, one of them from me:
how can we get the size of a surface within famo.us?
you could also try deferring or using a setTimeout or Engine.nextTick() to check the size on the next loop through.
if you find an elegant solution let us know as this is a big problem in many places using famous - having to do multiple highjinks where you can't really position a scene on the initial setup - you have to let it render and then adjust...
You can use the 'getSize' function and specify 'true' to get the real size of the surface:
var realSize = surface.getSize(true);
#ljzerenHein, thanks for the hint.. unfortunately, surface.getSize(true) returns null!
#dcsan, thanks for the link. I believe you may be right, however the solution linked to ends up being much too involved for me.
After much searching, hacking, and experimenting, I've settled on the following approach:
-] use the DOM to get untransformed bounding boxes for text strings
-] format the text strings in SVG form
-] make it so the strings are invisible (set fill and stroke to none)
-] reuse the same "div" element for all the strings that I want to measure
-] once I have the untransformed bounding box, then set the famous surface size to that and then apply modifiers.
-] if I need the bounding box after all transforms have been applied, then get the total accumulated transforms for the surface and multiply that with the original untransformed bounding box
Here's the code to create the DOM element, insert SVG text, then get the bounding box:
//Do this part once, of creating a DOM element and adding it to the document
var el1 = document.createElement("div");
document.body.appendChild(el1); //only need to append once -- just set innerHTML after
//now set the SVG text string -- from this point down can be repeated for multiple
// strings without removing or re-adding the element, nor fiddling with the DOM
var text1_1_1_SVG = '<svg> <text x="0" y="0" style="font-family: Arial; font-size: 12;fill:none;stroke:none" id="svgText1">' + myFamousSurface.content + '</text> </svg>';
//note the id is inside the text element! Also the fill and stroke are null so nothing paints
el1.innerHTML = text1_1_1_SVG;
//now get the element -- this seems to be what triggers the bounding box calc
var test = document.getElementById("svgText1"); //this is ID in the text element
//get the box, take the values out of it, and display them
var rect = test.getBoundingClientRect();
var str = "";
for (i in rect) { //a trick for getting all the attributes of the object
str += i + " = " + rect[i] + " ";
}
console.log("svgText1: " + str);
FYI, all of the SVGTextElement methods seem to be callable upon gotElem.
SVGTextElement docs here: http://msdn.microsoft.com/en-us/library/ie/ff972126(v=vs.85).aspx
#seanhalle
I'm pretty sure .getSize(true) is returning null because the element has not yet been added to the DOM. Keep in mind that famo.us is synchronized with animation-frames, and updates to the DOM happen don't happen instantly. Accesssing the DOM directly (aka pinging) is strongly disadviced because you will loose the performance benefits that famo.us promises.
What I would do is create a custom view to wrap your surface inside and implement a render-method in it. In the render-method, use getSize(true) to get the size. If it returns null,
you know it has not yet been committed to the DOM.
view in action as jsfiddle
define('MyView', function (require, exports, module) {
var View = require('famous/core/View');
var Surface = require('famous/core/Surface');
function MyView() {
View.apply(this, arguments);
this.surface = new Surface();
this.add(this.surface);
}
MyView.prototype = Object.create(View.prototype);
MyView.prototype.constructor = MyView;
MyView.prototype.render = function() {
var size = this.getSize(true);
if (size) {
if (!this.hasSize) {
this.hasSize = true;
console.log('now we have a size: ' + size);
}
this.surface.setContent('Size: ' + JSON.stringify(size));
} else {
console.log('no size yet');
}
return this._node.render();
};
module.exports = MyView;
});

D3 - Positioning tooltip on SVG element not working

I have a webpage with an SVG. On some of its shapes I need to display a tooltip. However, I can't get the tooltip to appear where it should, just some pixels away from the shape itself.
It appears way on the right hand side of the screen, maybe some 300px away.
The code I am using to get the coordinates is as follows:
d3.select("body")
.select("svg")
.select("g")
.selectAll("circle")
.on("mouseover", function(){return tooltip.style("visibility", "visible");})
.on("mousemove", function(){
var svgPos = $('svg').offset(),
/*** Tooltip ***/
//This should be the correct one, but is displaying at all working at all.
/*x = svgPos.left + d3.event.target.cx.animVal.value,
y = svgPos.top + d3.event.target.cy.animVal.value;*/
//This displays a tool tip but way much to the left of the screen.
x = svgPos.left + d3.event.target.cx.animVal.value,
y = svgPos.top + d3.event.target.cy.animVal.value;
Tooltip
window.alert("svgPos: "+svgPos+" top: "+y+"px left: "+x+"px "+d3.event.target.cx.animVal.value);
return tooltip.style("top", x+"px").style("left",y+"px");
})
.on("mouseout", function(){return tooltip.style("visibility", "hidden");});
I got to this code following this SO post.
I have changed $(ev.target).attr(cx) as it is not returning a value on my machine; d3.event.target.cx is, even though it seems it is not affecting the end result anyway.
What am I doing wrong? Could somebody help me please? Thank you very much in advance for your time.
If your tooltip is an HTML element, then you want to position it relative to the page as a whole, not the internal SVG coordinates, so accessing the cx/cy value is just complicating things. I can't say for sure without looking at your code, but if you have any transforms on your <svg> or <g> elements, then that could be what's throwing you off.
However, there is a much easier solution. Just access the mouse event's default .pageX and .pageY properties, which give the position of the mouse relative to the HTML body, and use these coordinates to position your tooltip div.
Example here: http://fiddle.jshell.net/tPv46/1/
Key code:
.on("mousemove", function () {
//console.log(d3.event);
return tooltip
.style("top", (d3.event.pageY + 16) + "px")
.style("left", (d3.event.pageX + 16) + "px");
})
Even with rotational transforms on the SVG circles, the mouse knows where it is on the page and the tooltip is positioned accordingly.
There are other ways to do this, including getting a tooltip to show up in a fixed location relative to the circle instead of following the mouse around, but I just checked the examples I was working on and realized they aren't cross-browser compatible, so I'll have to standardize them and get back to you. In the meantime, I hope this gets you back on track with your project.
Edit 1
For comparison, here is the same example implemented with both an HTML tooltip (a <div> element) and an SVG tooltip (a <g> element).
http://fiddle.jshell.net/tPv46/4/
The default mouse event coordinates may be great for positioning HTML elements that are direct children of <body>, but they are less useful for positioning SVG elements. The d3.mouse() function calculates the mouse coordinates of the current event relative to a specified SVG element's coordinate system, after all transformations have been applied. It can therefore be used to get the mouse coordinates in the form we need to position an SVG tooltip.
Key code:
.on("mousemove", function () {
var mouseCoords = d3.mouse(
SVGtooltip[0][0].parentNode);
//the d3.mouse() function calculates the mouse
//position relative to an SVG Element, in that
//element's coordinate system
//(after transform or viewBox attributes).
//Because we're using the coordinates to position
//the SVG tooltip, we want the coordinates to be
//with respect to that element's parent.
//SVGtooltip[0][0] accesses the (first and only)
//selected element from the saved d3 selection object.
SVGtooltip
.attr("transform", "translate(" + (mouseCoords[0]-30)
+ "," + (mouseCoords[1]-30) + ")");
HTMLtooltip
.style("top", (d3.event.pageY + 16) + "px")
.style("left", (d3.event.pageX + 16) + "px");
})
Note that it works even though I've scaled the SVG with a viewBox attribute and put the tooltip inside a <g> with a transform attribute.
Tested and works in Chrome, Firefox, and Opera (reasonably recent versions) -- although the text in the SVG tooltip might extend past its rectangle depending on your font settings. One reason to use an HTML tooltip! Another reason is that it doesn't get cut off by the edge of the SVG.
Leave a comment if you have any bugs in Safari or IE9/10/11. (IE8 and under are out of luck, since they don't do SVG).
Edit 2
So what about your original idea, to position the tooltip on the circle itself? There are definite benefits to being able to position the tip exactly: better layout control, and the text doesn't wiggle around with the mouse. And most importantly, you can just position it once, on the mouseover event, instead of reacting to every mousemove event.
But to do this, you can no longer just use the mouse position to figure out where to put the tooltip -- you need to figure out the position of the element, which means you have to deal with transformations. The SVG spec introduces a set of interfaces for locating SVG elements relative to other parts of the DOM.
For converting between two SVG transformation systems you use SVGElement.getTransformToElement(SVGElement); for converting between an SVG coordinate system and the screen, you use SVGElement.getScreenCTM(). The result are transformation matrices from which you can
extract the net horizontal and vertical translation.
The key code for the SVG tooltip is
var tooltipParent = SVGtooltip[0][0].parentNode;
var matrix =
this.getTransformToElement(tooltipParent)
.translate(+this.getAttribute("cx"),
+this.getAttribute("cy"));
SVGtooltip
.attr("transform", "translate(" + (matrix.e)
+ "," + (matrix.f - 30) + ")");
The key code for the HTML tooltip is
var matrix = this.getScreenCTM()
.translate(+this.getAttribute("cx"),
+this.getAttribute("cy"));
absoluteHTMLtooltip
.style("left",
(window.pageXOffset + matrix.e) + "px")
.style("top",
(window.pageYOffset + matrix.f + 30) + "px");
Live example: http://fiddle.jshell.net/tPv46/89/
Again, I'd appreciate a confirmation comment from anyone who can test this in Safari or IE -- or any mobile browser. I'm pretty sure I've used standard API for everything, but just because the API is standard doesn't mean it's universally implemented!

getting text width in SVG prior to rendering

I want to put a rectangle around a text in SVG.
The height of the text is known to me (the font-size attribute of the text element). But the width is dependent on the actual content. Using getBBox() or getComputedTextLength() should work. But this only works after rendering.
Is there a way to specify that in an other way? For example defining the x and width attributes relative to other values? I didn't find anything like that in the SVG Spec.
Figuring where text ends presumably requires roughly the same underlying code path as the rendering itself implements - going through the width of each character based on the font and style, etc... As I am not aware the SVG standards define a method for directly getting this information without doing the actual full rendering, till such methods emerge or are reported here by others, the approach should be to render invisibly before doing the actual rendering.
You can do that in a hidden layer (z-index, opacity and stuff) or outside the visible viewport, whichever works best in experimentation. You just need to get the browser do the rendering to find out, so you render invisibly for that sake, then use getComputedTextLength()
I know this is old, but a few ideas:
If you can choose a mono-spaced font, you know your width by a simple constant multiplication with glyph count
If you are bound to proportional fonts, you can find an average glyph size, do the math as with mono-space, and leave enough padding. Alternatively you can fill the padding with text element textLength attribute. If the constant is chosen carefully, the results are not very displeasing.
EDIT: As matanster found it to be hacky
Predetermine glyph widths with getComputedTextLength() and build a lookup table. Downside is that it does not account for kerning, but if your cache size is not a problem, you can append glyph-pair widths to this lookup.
Going beyond that is to find some way to do server side rendering: Is there a way to perform server side rendering of SVG graphics using React?
It is possible using canvas with measureText():
// Get text width before rendering
const getTextWidth = (text, font) => {
const element = document.createElement('canvas');
const context = element.getContext('2d');
context.font = font;
return context.measureText(text).width;
}
// Demo
const font = '16px serif';
const text = 'My svg text';
const textWidth = getTextWidth(text, font);
document.body.innerHTML = `
<svg>
<text x="0" y="20" font="${font}">${text}</text>
<rect x="0" y="30" width="${textWidth}" height="4" fill="red" />
</svg>
`;
Adapted from https://stackoverflow.com/a/31305410/1657101

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