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Scale down a Konvajs stage without losing quality

Consider having a large (2000x1000) stage with some text in it. The stage gets downscaled to 1000x500 making the text unreadable. Then we try to enlarge the text by zooming it in.
Expected: the text should become readable again at some point.
Actual: the text remains unreadable (blurred) no matter how much we zoom in.
Try zooming the page in (with native browser zoom on desktop) after running the snippet:
const stage = new Konva.Stage({
container: 'container',
width: 2000,
height: 1000,
});
const layer = new Konva.Layer();
stage.add(layer);
const rect = new Konva.Text({
x : 50, y : 50, width: 100, height: 100,
fontSize: 12,
text: "This text should be readable when the viewport gets downscaled"
});
layer.add(rect).draw();
stage.scale({x: 0.5, y: 0.5});
stage.setAttrs({width: 1000, height: 500});
stage.draw();
<script src="https://cdnjs.cloudflare.com/ajax/libs/konva/2.6.0/konva.js"></script>
<div id="container"></div>
The quality loss can be avoided by downscaling with CSS only, like this:
const stage = new Konva.Stage({
container: 'container',
width: 2000,
height: 1000,
});
const layer = new Konva.Layer();
stage.add(layer);
const rect = new Konva.Text({
x : 50, y : 50, width: 100, height: 100,
fontSize: 12,
text: "This text should be readable when the viewport gets downscaled"
});
layer.add(rect).draw();
stage.getChildren().forEach(function(layer) {
layer.canvas._canvas.style.width = "1000px";
layer.canvas._canvas.style.height = "500px";
layer.hitCanvas.setSize(1000, 500);
layer.hitCanvas.context.scale(0.5, 0.5);
});
stage.draw();
<script src="https://cdnjs.cloudflare.com/ajax/libs/konva/2.6.0/konva.js"></script>
<div id="container"></div>
Note how text becomes readable at a certain level of zooming.
The workaround breaks Konvajs abstraction. What problems it can potentially cause? Is there a better way, which uses only public methods exposed by Konvajs?
In fabric.js it can be done like this (complete example here):
canvas.setDimensions({width: '1000px', height: '500px'}, {cssOnly: true});

Konva is a canvas framework. Canvas is a bitmap image unlike vector elements like SVG. So that "blur" should be expected. Technically to fix the issue you can redraw stage with higher pixelRatio on zoom event:
Konva.pixelRatio = 4
stage.draw();
That code will generate more pixels for canvas element. But the page may be very heavy in RAM in this case because Konva will have to produce very large canvas. In most of the mobile apps, you don't need native zooming and you can use responsive design. For zooming the stage, you can use Konva methods.

Fabricjs Textbox make the text shrink to fit

I would define a text box (single-line)
By default, with a character size of 16 (for example)
When the text gets bigger than the text box, I do not want it to wrap or the text box gets bigger, I want the text size to fit the maximum size of the text box. text. When the text returns to a smaller size, it can resume its initial size (in our example 16). Possibly manage a minimum size
If you have an idea, I take :)
thanks in advance
Test Case : http://jsfiddle.net/Da7SP/273/
// initialize fabric canvas and assign to global windows object for debug
var canvas = window._canvas = new fabric.Canvas('c');
// ADD YOUR CODE HERE
var canvas = window._canvas = new fabric.Canvas('c');
var t1 = new fabric.Textbox('My Text', {
width: 200,
top: 5,
left: 5,
fontSize: 16,
textAlign: 'center'
});
var t2 = new fabric.Textbox('My text is longer, but I do not want the box to grow, or the text to wrap. I only want the text to fit the available size', {
width: 200,
height: 200,
top: 250,
left: 5,
fontSize: 16,
textAlign: 'center'
});
canvas.add(t1);
canvas.add(t2);
A small video to explain what I want :
When the text gets bigger than the text box, I want the text size fit the maximum size of the text box.

This is a basic fiddle that can replicate your idea.
The point is that you have an event that fires on every text change and that can be used to do something before the textbox is rendered.
In this case i m shrinking font size based on a non standard parameter i added to textbox called fixedWidth
// ADD YOUR CODE HERE
var canvas = new fabric.Canvas('c');
var t1 = new fabric.Textbox('MyText', {
width: 150,
top: 5,
left: 5,
fontSize: 16,
textAlign: 'center',
fixedWidth: 150
});
canvas.on('text:changed', function(opt) {
var t1 = opt.target;
if (t1.width > t1.fixedWidth) {
t1.fontSize *= t1.fixedWidth / (t1.width + 1);
t1.width = t1.fixedWidth;
}
});
canvas.add(t1);
canvas {
border: 1px solid #999;
}
<script src="https://rawgithub.com/kangax/fabric.js/master/dist/fabric.js"></script>
<canvas id="c" width="600" height="600"></canvas>

Here's a similar answer to https://stackoverflow.com/a/41335051/1469525 but this example modifies the fontSize up to a maxFontSize (the initial fontSize). This allows the text to shrink and then grow back to the original size, as well as preventing line wraps.
(Note, if you use this, you'll have to find a way to prevent the user from using the enter key. I put in a check that basically cancels it if an enter key is detected. My app actually has a separate form to enter the text, so I can control prevention through normal javascript. I'm not quite sure how to do that directly on a canvas element when it is editable like here...)
var canvas = new fabric.Canvas('c');
var t1 = new fabric.Textbox('MyText', {
width: 150,
top: 5,
left: 5,
fontSize: 16,
textAlign: 'center',
maxFontSize: 16,
});
canvas.on('text:changed', function(opt) {
var t1 = opt.target;
if (t1.text.match(/[\r\n]/)) return;
t1.set({
fontSize: t1.maxFontSize,
});
while (t1._textLines.length > 1) {
t1.set({
fontSize: t1.fontSize - 1,
});
}
});
canvas.add(t1);
canvas {
border: 1px solid #999;
}
<script src="https://rawgithub.com/kangax/fabric.js/master/dist/fabric.js"></script>
<canvas id="c" width="600" height="600"></canvas>

Kinetic canvas with user text field input

I've pulled out most of my hair trying to find a solution to no avail.
I know this must be easy but being a javascript neophyte I can't seem to wrap my head around it and am hoping someone can help me out!!!
I'm trying to create a simple canvas element that has an image with text (with wrapping) on top of it. The text will come from a text field outside of the canvas (nothing fancy). I've seen where the canvas populates with the text as it is input into the text field which is what I'm looking for (no submit button). Eventually, I will need to add 2 additional text fields with different information, doing the same thing but for right now I'd be happy to get one to work!
The kinetic text tutorial found here (http://www.html5canvastutorials.com/kineticjs/html5-canvas-kineticjs-text-tutorial/ - code below) would be perfect if I could only figure out how to get the "complex text" to be pulled from a regular text input field instead of being hard coded!
Any help would be greatly appreciated!
Working code without input text field:
<!DOCTYPE HTML>
<html>
<head>
<style>
body {
margin: 0px;
padding: 0px;
}
</style>
</head>
<body>
<div id="container"></div>
<script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.7.4.min.js"></script>
<script defer="defer">
var stage = new Kinetic.Stage({
container: 'container',
width: 578,
height: 220
});
var layer = new Kinetic.Layer();
var simpleText = new Kinetic.Text({
x: stage.getWidth() / 2,
y: 15,
text: 'Simple Text',
fontSize: 30,
fontFamily: 'Calibri',
fill: 'green'
});
// to align text in the middle of the screen, we can set the
// shape offset to the center of the text shape after instantiating it
simpleText.setOffset({
x: simpleText.getWidth() / 2
});
// since this text is inside of a defined area, we can center it using
// align: 'center'
var complexText = new Kinetic.Text({
x: 100,
y: 60,
text: 'COMPLEX TEXT\n\nAll the world\'s a stage, and all the men and women merely players. They have their exits and their entrances.',
fontSize: 18,
fontFamily: 'Calibri',
fill: '#555',
width: 380,
padding: 20,
align: 'center'
});
var rect = new Kinetic.Rect({
x: 100,
y: 60,
stroke: '#555',
strokeWidth: 5,
fill: '#ddd',
width: 380,
height: complexText.getHeight(),
shadowColor: 'black',
shadowBlur: 10,
shadowOffset: [10, 10],
shadowOpacity: 0.2,
cornerRadius: 10
});
// add the shapes to the layer
layer.add(simpleText);
layer.add(rect);
layer.add(complexText);
stage.add(layer);
</script>
</body>
</html>

Possible solution: to add one input field, set up event listener which fire on change of its value and then start drawing.
<body>
<div id="container"></div>
<input type="text" id='complexText' size="20"/>
<script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.7.4.min.js"></script>
<script defer="defer">
var inputField = document.getElementById('complexText');
inputField.addEventListener('change', function() {
var inputText = this.value;
showText(inputText);
}, false);
function showText(inputText) {
*** here goes all your 'Kinetic' code ***
}
See example at jsBin.

How do I 'forward' (mouse) events to a node/shape on a lower Zindex in kineticjs

I'm working with kineticjs where I have a stage with one layer in it. This layer has multiple shapes on it who react on a mouseover event (they show a tooltip)
besides these shapes I also have some text nodes on a higher ZIndex (so they are above the shapes).
This all works fine with one exception, when a text is on top of a shape, the shape doesn't show a tooltip I assume it's because the textnode uses the event, rather than 'forward' it, eventhough I haven't bound anything to the text node.
How can I propagate events to nodes on a lower ZIndex?

Personally I'd create a separate layer to put anything you dont want to register mouse events on and when you create the layer set its listening property to false.
You could also set the this property for the individual elements.
Here's an example using layers...
var stage = new Kinetic.Stage({
container: 'container',
width: 578,
height: 200
});
var normalLayer = new Kinetic.Layer();
var textLayer = new Kinetic.Layer({listening :false});
var rect = new Kinetic.Rect({
x: 20,
y: 20,
width: 100,
height: 50,
fill: 'green',
stroke: 'black',
strokeWidth: 4
});
rect.on('click', function(evt) {
this.setFill('blue');
normalLayer.draw();
});
normalLayer.add(rect);
var simpleText = new Kinetic.Text({
x: 40,
y: 40,
text: 'Simple Text',
fontSize: 30,
fontFamily: 'Calibri',
textFill: 'yellow'
});
textLayer.add(simpleText);
stage.add(normalLayer);
stage.add(textLayer);
http://jsfiddle.net/MT435/
Remember the listening property can be set for individual elements aswell.

how to pull Line/Polygon by one of the points in kineticjs?

Some part of my code here:
var stage = new Kinetic.Stage({
container: "canvas",
width: 300,
height: 200
});
var layer = new Kinetic.Layer({
});
var line = new Kinetic.Polygon({
id: 'wall',
points: [50, 50, 100, 50, 100, 100, 50, 100],
stroke: "black",
strokeWidth: 4,
draggable: true
});
line.on('dragmove', function(mouseEvent) {
line.getPoints()[2] = {x:mouseEvent.x, y:mouseEvent.y};
layer.draw();
});
stage.add(layer);
layer.add(line);
layer.draw();
​The task is to drag polygon by one of the corners (in example by right-bottom). But actually result is not that I expected. What is wrong in my code? or what is correct way of moving elemten by one of the points?

Check out this post iOS6 pull/drag border on circle
The effects are similar, I think, to what you're looking for. You could animate the drag on any of your corners by detecting the click/touch location.
Let me know if you need another example.