How can we make SVG transparent on Canvas? - svg

how can we achieve this?
I got the SVG in the function, how can i make it transparent on top of canvas?? Currently i have all my functions working on the canvas. But I found out that SVG can do the add and remove function. How can I go about it?
function Add() {
var id = Math.floor(Math.random()*101+1);
x = Math.random() * 550;
y = Math.random() * 250;
if (document.getElementById('amount').value < 50){
document.getElementById('amount').value++;
svg = document.getElementById("main");
// construct uniqueid for the images
uniqueid = "frog" + document.getElementById('amount').value;
//namespaces for SVG
svgNS="http://www.w3.org/2000/svg";
xlinkNS="http://www.w3.org/1999/xlink";
// create a image element
image = document.createElementNS(svgNS, 'image');
// set id and other attributes
image.setAttributeNS(null, "id", uniqueid);
image.setAttributeNS(xlinkNS, "href","jef-frog.gif");
image.setAttributeNS(null, "x", x);
image.setAttributeNS(null, "y", y);
image.setAttributeNS(null, "width", "50");
image.setAttributeNS(null, "height", "50");
// append to svg
svg.appendChild(image);
} else {
alert("we got 50");
}
}

Assuming you are asking about transparency in SVG <image> elements, I'm pleased to say that it works just fine:
Demo: http://jsfiddle.net/XBCEK/
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xl="http://www.w3.org/1999/xlink">
<image xl:href="http://phrogz.net/tmp/alphaball.png"
x="20" y="30" width="128" height="128" />
<image xl:href="http://phrogz.net/tmp/hand.gif"
x="220" y="30" width="32" height="32" />
</svg>​
If you embed that SVG on a page along with the following CSS:
body { background:url(http://phrogz.net/tmp/grid.gif) }
svg { background:rgba(255,0,0,0.3) /*…*/ }
…then you will see that:
The background of the SVG is transparent by default. We can even provide a low-opacity color background that lets the background of the page (the grid) show through.
The background of both 8-bit-transparency PNG (the ball) and 1-bit transparency GIF (the hand) allow the background of the SVG/page to shine through correctly.
​

Related

Node JS Sharp - Maintain SVG Font When Converting To JPG

I am using the sharp library to create dynamic JPEG license plate images.
Basically, I have a PNG that is a vanity license plate with no numbers. Then I create an svg in code like so
const svg = new Buffer(
`<svg xmlns="http://www.w3.org/2000/svg" width="${width}" height="${height}" viewBox="${x} ${y} 500 40">
<defs>
<style type="text/css">
<![CDATA[
#font-face {
font-family: LicensePlate;
src: url('LicensePlate.ttf');
}
svg {
width: 100%;
height: 100%;
}
]]>
</style>
</defs>
<text x="0" y="0" font-family="LicensePlate" font-size="${fontsize}" letter-spacing="${letterspace}">
${platenumber.toUpperCase()}
</text>
</svg>`
);
Passing in the desired width, height, and license plate number. Then I use the sharp library to overlay my SVG in the middle of the license plate. This all works just fine.
However, I have imported a custom license plate font (LicensePlate.ttf). In order to debug my in-code SVG image I made an actual svg image file that I open in the browser to make sure that it all looks correct, which it does.
The problem is that when the final JPEG file is created it does not contain my custom font. Instead it falls back on Verdana.
My question is, is there any way I can maintain the SVG font while creating the image with sharp?
Thanks!
Full Code
function createImage(platenumber) {
//Trying to create some sort of responsiveness
let fontsize = 80;
let letterspace = 10;
let width = 300;
let height = 90;
let x = 0;
let y = -45;
const inputlength = platenumber.length;
//Minumum Length
if (inputlength == 2) {
x = -200;
}
if (inputlength == 3) {
x = -150;
}
if (inputlength == 4) {
x = -130;
}
if (inputlength == 5) {
x = -105;
}
if (inputlength == 6) {
x = -65;
}
try {
console.log('stream is duplex, ', pipe instanceof stream.Duplex);
//Read the svg code into a buffer with a passed in plate number
const svg = new Buffer(
`<svg xmlns="http://www.w3.org/2000/svg" width="${width}" height="${height}" viewBox="${x} ${y} 500 40">
<defs>
<style type="text/css">
<![CDATA[
#font-face {
font-family: LicensePlate;
src: url('LicensePlate.ttf');
}
svg {
width: 100%;
height: 100%;
}
]]>
</style>
</defs>
<text x="0" y="0" font-family="LicensePlate" font-size="${fontsize}" letter-spacing="${letterspace}">
${platenumber.toUpperCase()}
</text>
</svg>`
);
const plateid = rand.generate(10);
//Create a write stream to a randomly generated file name
const write = new fs.createWriteStream(`plates/${plateid}.jpg`);
//Create the sharp pipeline
const pipeline = pipe
.overlayWith(svg, { gravity: sharp.gravity.center })//we center the svg image over the top of whatever image gets passed into the pipeline
.jpeg();//we convert to JPG because it is a compressed file format and will save space (we could also do webp if we really want to be slick about it)
//Create the read stream from the license plate template
const read = new fs.createReadStream('plate-2.png')
.pipe(pipeline)//pipe out sharp pipeline
.pipe(write);//add the write stream so that our sharp pipeline knows where to put the image
return plateid;
} catch (e) {
console.log(e);
return null;
}
}
SVG Image
<svg xmlns="http://www.w3.org/2000/svg" width="200" height="90" viewBox="0 -50 500 40">
<defs>
<style type="text/css">
<![CDATA[
#font-face {
font-family: LicensePlate;
src: url('LicensePlate.ttf');
}
]]>
</style>
</defs>
<text x="0" y="0" font-family="LicensePlate" font-size="150" letter-spacing="10">
Pl#T3#
</text>
</svg>
Exact Font
Here is a link to the exact font I used
http://www.fontspace.com/dave-hansen/license-plate
I dealt with this problem by installing the font in my OS, when the file is being converted, the libraries can only access OS fonts.

Download svg including it's text tag value

I'm working on a way to download svg from a webpage.
I have pretty much everything working apart from the last part:
Downloading the svg including the text tag included in it.
Now, to give a better background:
I will need to download images out of an svg using fontawesome icon as text.
The svg is properly downloaded, hower the text tag is not (it's downloaded as a broken image "square")
Here's a simplified version of my code:
function triggerDownload(imgURI, name, format) {
let evt = new MouseEvent('click', {
view: window,
bubbles: false,
cancelable: true
});
let a = document.createElement('a');
a.setAttribute('download', name + '.' + format);
a.setAttribute('href', imgURI);
a.setAttribute('target', '_blank');
a.dispatchEvent(evt);
}
function clickSVG(event) {
const dd = 300;
const format = "png"
let canvas = document.getElementById('canvas'),
target = event.currentTarget;
canvas.width = dd;
canvas.height = dd;
debugger
let newImage = target.cloneNode(true),
circle = newImage.getElementsByClassName('svgCircle-test') ? newImage.getElementsByClassName('svgCircle-test') : null,
image = newImage.getElementsByClassName('svgImage-test');
newImage.height.baseVal.value = dd;
newImage.width.baseVal.value = dd;
if (circle.length > 0) {
circle[0].cx.baseVal.value = dd / 2;
circle[0].cy.baseVal.value = dd / 2;
circle[0].r.baseVal.value = dd / 2;
}
let ctx = canvas.getContext('2d'),
data = (new XMLSerializer()).serializeToString(newImage),
DOMURL = window.URL || window.webkitURL || window,
name = newImage.getAttribute('data-name'),
img = new Image(),
svgBlob = new Blob([data], {type: 'image/svg+xml;charset=utf-8'}),
url = DOMURL.createObjectURL(svgBlob);
img.onload = function () {
ctx.drawImage(img, 0, 0);
DOMURL.revokeObjectURL(url);
let imgURI = canvas
.toDataURL(`image/${format}`)
.replace(`image/${format}`, 'image/octet-stream');
triggerDownload(imgURI, name, format);
};
img.src = url;
}
document.getElementById("svg").addEventListener("click", clickSVG)
The html looks like this:
<svg id="svg" height="200" width="200" data-name="test">
<circle cx="100" cy="100" r="100" fill="#faa" class="svgCircle-test" />
<text x="0" y="120" width="200" height="200" class="svgImage-test"></text>
</svg>
<canvas id="canvas" />
And here's the CSS:
svg {
margin-top:10px;
cursor: pointer;
display: inline-block;
padding: 5px;
}
svg text{
font-family:'FontAwesome';
font-size: 100px;
}
#canvas {
display: none;
}
A codepen to help you understand the issue and help me out a bit better can be found here: https://codepen.io/NickHG/pen/QMmJvd
To see the issue, click on the circle (this will download the svg as a png image).
NB: If the download doesn't start, it's probably your browser blocking popups. Just allow it to see the downloaded image.
Thanks
There are a couple of things going on here.
Once you "convert" the SVG file to an HTMLImageElement (<image>), as you are doing here onto the canvas, things change:
the styling you have applied to the <text> no longer applies. That's because it is in the HTML file, not the SVG "file". You need to add the styling it to the SVG itself.
SVGs rendered as an <image> need to be self contained. They can't reference external files such as the Font Awesome font.
To make it self contained, you need to embed the font file in the SVG itself using a Data URL.
You'll need to add a <style> element to the SVG, and include a #font-face rule that specifies a Base64 encoded font file (or files).
See this question for an example

Drawing an SVG Selection Box with Batik

I notice on many SVG builder tools that almost each element can be resized and rotated. As shown below
What is the most common way to implement that whenever an element whenever is clicked, a bordering line will appear a long side with the small rectangles used for resizing as well as rotating ?
Are these objects "hidden" by default and only visible during mouse click ? Or they have to be drawn on every mousedown and removed on every mouseup ?
Are these objects "hidden" by default and only visible during mouse
click ?
Unless you're using a library that provides that functionality i.e FabricJS, then no you have to draw that selection rectangle yourself.
All the tools you see floating around essentially have code somewhere to create this rectangle you see exactly on top of the selected item - this rectangle is called the visible Bounding Box of the element - in modern browsers this is fetched using the el.getBBox() method.
The returned bounding box gives you all the information you need(x, y , width, height) to draw that selection rectangle yourself.
Typically you have a canvas on which you work (might be a <div>, might be an SVG rectangle etc...) - the concept is not exclusive to HTML5 canvas.
You draw the selection rectangle when clicking an element.
You remove the selection rectangle when clicking on a canvas empty area.
Here is a snippet I've made for this which also allows multi-selection by holding 'Shift'.
const svgns = 'http://www.w3.org/2000/svg'
// Draw selection box if we click on one or more elements.
$('.element').click(function() {
const bbox = $(this)[0].getBBox()
if (shiftKeyDown) {
drawSelectionRect(bbox.x, bbox.y, bbox.width, bbox.height)
return
}
$('.selectionRect').remove()
drawSelectionRect(bbox.x, bbox.y, bbox.width, bbox.height)
})
// Remove selection box(es) if we click on empty area.
$('#svgCanvas').click(() => {
$('.selectionRect').remove()
})
// Helper function which draws a selection box.
const drawSelectionRect = (x, y, width, height) => {
var rect = document.createElementNS(svgns, 'rect')
rect.setAttributeNS(null, 'x', x)
rect.setAttributeNS(null, 'y', y)
rect.setAttributeNS(null, 'height', height)
rect.setAttributeNS(null, 'width', width)
rect.setAttributeNS(null, 'stroke-width', '2px')
rect.setAttributeNS(null, 'stroke', 'red')
rect.setAttributeNS(null, 'fill', 'none')
rect.setAttributeNS(null, 'stroke-dasharray', '5,1')
rect.setAttributeNS(null, 'class', 'selectionRect')
document.getElementById('workarea').appendChild(rect)
}
// Determine if Shift key is being pressed.
let shiftKeyDown = false
$(document).keydown(e => {
if (e.keyCode == 16) {
shiftKeyDown = true
}
})
$(document).keyup(e => {
shiftKeyDown = false
})
#container {
display: block;
height: 320px;
background-color: #eee;
}
.element {
cursor: pointer;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<ul>
<li>Click on any element to draw it's selection box.</li>
<li>Hold down "Shift" to allow multi-selection.</li>
<li>Click anywhere else on the canvas to remove selections.</li>
</ul>
<div id="container">
<svg id="workarea" width="100%" height="100%">
<rect id="svgCanvas" width="100%" height="100%" x="0" y="0" style="fill:transparent"/>
<rect class="element" width="100" height="100" x="50" y="100" style="fill:#009688;" />
<rect class="element" width="75" height="100" x="250" y="150" style="fill:#009688;" />
</svg>
</div>

Pure SVG way to fit text to a box

Box size known. Text string length unknown. Fit text to box without ruining its aspect ratio.
After an evening of googling and reading the SVG spec, I'm pretty sure this isn't possible without JavaScript. The closest I could get was using the textLength and lengthAdjust text attributes, but that stretches the text along one axis only.
<svg width="436" height="180"
style="border:solid 6px"
xmlns="http://www.w3.org/2000/svg">
<text y="50%" textLength="436" lengthAdjust="spacingAndGlyphs">UGLY TEXT</text>
</svg>
I am aware of SVG Scaling Text to fit container and fitting text into the box
I didn't find a way to do it directly without Javascript, but I found a JS quite easy solution, without for loops and without modify the font-size and fits well in all dimensions, that is, the text grows until the limit of the shortest side.
Basically, I use the transform property, calculating the right proportion between the desired size and the current one.
This is the code:
<?xml version="1.0" encoding="UTF-8" ?>
<svg version="1.2" viewBox="0 0 1000 1000" width="1000" height="1000" xmlns="http://www.w3.org/2000/svg" >
<text id="t1" y="50" >MY UGLY TEXT</text>
<script type="application/ecmascript">
var width=500, height=500;
var textNode = document.getElementById("t1");
var bb = textNode.getBBox();
var widthTransform = width / bb.width;
var heightTransform = height / bb.height;
var value = widthTransform < heightTransform ? widthTransform : heightTransform;
textNode.setAttribute("transform", "matrix("+value+", 0, 0, "+value+", 0,0)");
</script>
</svg>
In the previous example the text grows until the width == 500, but if I use a box size of width = 500 and height = 30, then the text grows until height == 30.
first of all: just saw that the answer doesn't precisely address your need - it might still be an option, so here we go:
you are rightly observing that svg doesn't support word-wrapping directly. however, you might benefit from foreignObject elements serving as a wrapper for xhtml fragments where word-wrapping is available.
have a look at this self-contained demo (available online):
<?xml version="1.0" encoding="utf-8"?>
<!-- SO: http://stackoverflow.com/questions/15430189/pure-svg-way-to-fit-text-to-a-box -->
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:xhtml="http://www.w3.org/1999/xhtml"
xmlns:xlink="http://www.w3.org/1999/xlink"
version="1.1"
width="20cm" height="20cm"
viewBox="0 0 500 500"
preserveAspectRatio="xMinYMin"
style="background-color:white; border: solid 1px black;"
>
<title>simulated wrapping in svg</title>
<desc>A foreignObject container</desc>
<!-- Text-Elemente -->
<foreignObject
x="100" y="100" width="200" height="150"
transform="translate(0,0)"
>
<xhtml:div style="display: table; height: 150px; overflow: hidden;">
<xhtml:div style="display: table-cell; vertical-align: middle;">
<xhtml:div style="color:black; text-align:center;">Demo test that is supposed to be word-wrapped somewhere along the line to show that it is indeed possible to simulate ordinary text containers in svg.</xhtml:div>
</xhtml:div>
</xhtml:div>
</foreignObject>
<rect x="100" y="100" width="200" height="150" fill="transparent" stroke="red" stroke-width="3"/>
</svg>
I've developed #Roberto answer, but instead of transforming (scaling) the textNode, we simply:
give it font-size of 1em to begin with
calculate the scale based on getBBox
set the font-size to that scale
(You can also use 1px etc.)
Here's the React HOC that does this:
import React from 'react';
import TextBox from './TextBox';
const AutoFitTextBox = TextBoxComponent =>
class extends React.Component {
constructor(props) {
super(props);
this.svgTextNode = React.createRef();
this.state = { scale: 1 };
}
componentDidMount() {
const { width, height } = this.props;
const textBBox = this.getTextBBox();
const widthScale = width / textBBox.width;
const heightScale = height / textBBox.height;
const scale = Math.min(widthScale, heightScale);
this.setState({ scale });
}
getTextBBox() {
const svgTextNode = this.svgTextNode.current;
return svgTextNode.getBBox();
}
render() {
const { scale } = this.state;
return (
<TextBoxComponent
forwardRef={this.svgTextNode}
fontSize={`${scale}em`}
{...this.props}
/>
);
}
};
export default AutoFitTextBox(TextBox);
This is still an issue in 2022. There is no way to define bounds and get text to scale in a pure scalable vector graphic. Adjusting the font size manually is still the only solution it seems, and the examples given are quite buggy. Has anybody figured out a clean solution that works? Judging by the svg spec it looks like a pure solution doesn't exist.
And to provide some sort of answer myself, this resource is the best I've found, is hacky, but works much more robustly: fitrsvgtext - storybook | fitrsvgtext - GitHub
I don't think its the solution for what you want to do but you can use textLength
with percentage ="100%" for full width.
<svg width="436" height="180"
style="border:solid 6px"
xmlns="http://www.w3.org/2000/svg">
<text x="0%" y="50%" textLength="100%">blabla</text>
</svg>
you can also add text-anchor="middle" and change the x position to center perfectly your text
this will not change the fontsize and you will have weird space letterspacing...
JSFIDDLE DEMO

How to get a view based on coordinate in openlaszlo?

In JavaScript we have document.elementfrompoint to get an element based on coordinates.
Is there any thing like that in Openlaszlo to get a view based on coordinate?
There is no direct support for that functionality in OpenLaszlo, but for ActionScript 3 based runtimes you can utilize the flash.display.DisplayObjectContainer#getObjectsUnderPoint() method. In the DHTML runtime, you can use the document.elementFromPoint(x, y), and based on Quirksmode that should be supported by all modern browsers.
Here is an example program implementing an canvas.elementFromPoint() method:
<canvas debug="true">
<passthrough when="$as3">
import flash.geom.Point;
</passthrough>
<view id="background" width="100%" height="100%" bgcolor="#eeeeee" clickable="true"/>
<view id="red" x="200" y="100" width="200" height="200" bgcolor="#ff0000" opacity="0.3" clickable="true" />
<view id="green" x="150" y="200" width="200" height="200" bgcolor="#00ff00" opacity="0.3" clickable="true"/>
<view id="blue" x="250" y="200" width="200" height="200" bgcolor="#0000ff" opacity="0.3" clickable="true"/>
<handler name="onclick" reference="lz.GlobalMouse">
canvas.elementFromPoint();
</handler>
<method name="elementFromPoint"><![CDATA[
var mouseX = canvas.getMouse('x'),
mouseY = canvas.getMouse('y'),
objects = null, // array of objects at mouse pointer in SWF runtime
element = null; // The element we are looking for
Debug.info( 'mouse position: x=' + mouseX + ' / mouseY=' + mouseY );
if ($as3) {
// in SWF runtime, use the DisplayObjectContainer.getObjectsUnderPoint() method
objects = canvas.getDisplayObject().getObjectsUnderPoint(new Point(mouseX, mouseY));
element = objects[objects.length-1].owner;
} else {
// in DHTML, we can use elementFromPoint, and need to retrieve the owner view of the div
element = document.elementFromPoint(mouseX, mouseY).owner.owner;
}
Debug.info('View under mousecursor:', element);
return element;
]]></method>
</canvas>
There are 4 views, one background view scaled to 100% x 100%. And three color views: red, green and blue - with the blue one being the top one. When clicking on the view, the correct view object is returned.
The code has been tested in the DHTML runtime with Chrome 22.0, Firefox 16.0.1, and Opera 12.02. Flash should work in every browser, I haven't tested with IE.
I don't think so.
You will have to build your own custom array or observer object, collect all views and then loop through all items and do a check if the coordinates are inside the bounding box of the view.
In Flash there is also something like "hitTest", that might be similar to JavaScript's "document.elementfrompoint" to get the exact pixel matching, in case the bounding box is not enough for you.
Sebastian

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