I have 2 canvases, one uses HTML attributes width and height to size it, the other uses CSS:
<canvas id="compteur1" width="300" height="300" onmousedown="compteurClick(this.id);"></canvas>
<canvas id="compteur2" style="width: 300px; height: 300px;" onmousedown="compteurClick(this.id);"></canvas>
Compteur1 displays like it should, but not compteur2. The content is drawn using JavaScript on a 300x300 canvas.
Why is there a display difference?
It seems that the width and height attributes determine the width or height of the canvas’s coordinate system, whereas the CSS properties just determine the size of the box in which it will be shown.
This is explained in the HTML specification:
The canvas element has two attributes to control the size of the element’s bitmap: width and height. These attributes, when specified, must have values that are valid non-negative integers. The rules for parsing non-negative integers must be used to obtain their numeric values. If an attribute is missing, or if parsing its value returns an error, then the default value must be used instead. The width attribute defaults to 300, and the height attribute defaults to 150.
To set the width and height on a canvas, you may use:
canvasObject.setAttribute('width', '150');
canvasObject.setAttribute('height', '300');
For <canvas> elements, the CSS rules for width and height set the actual size of the canvas element that will be drawn to the page. On the other hand, the HTML attributes of width and height set the size of the coordinate system or 'grid' that the canvas API will use.
For example, consider this (jsfiddle):
var ctx = document.getElementById('canvas1').getContext('2d');
ctx.fillStyle = "red";
ctx.fillRect(10, 10, 30, 30);
var ctx2 = document.getElementById('canvas2').getContext('2d');
ctx2.fillStyle = "red";
ctx2.fillRect(10, 10, 30, 30);
canvas {
border: 1px solid black;
}
<canvas id="canvas1" style="width: 50px; height: 100px;" height="50" width="100"></canvas>
<canvas id="canvas2" style="width: 100px; height: 100px;" height="50" width="100"></canvas>
Both have had the same thing drawn on them relative to the internal coordinates of the canvas element. But in the second canvas, the red rectangle will be twice as wide because the canvas as a whole is being stretched across a bigger area by the CSS rules.
Note: If the CSS rules for width and/or height aren't specified then the browser will use the HTML attributes to size the element such that 1 unit of these values equals 1px on the page. If these attributes aren't specified then they will default to a width of 300 and a height of 150.
The canvas will be stretched if you set the width and height in your CSS. If you want to dynamically manipulate the dimension of the canvas you have to use JavaScript like so:
canvas = document.getElementById('canv');
canvas.setAttribute('width', '438');
canvas.setAttribute('height', '462');
The browser uses the css width and height, but the canvas element scales based on the canvas width and height. In javascript, read the css width and height and set the canvas width and height to that.
var myCanvas = $('#TheMainCanvas');
myCanvas[0].width = myCanvas.width();
myCanvas[0].height = myCanvas.height();
Shannimal correction
var el = $('#mycanvas');
el.attr('width', parseInt(el.css('width')))
el.attr('height', parseInt(el.css('height')))
Canvas renders image by buffer, so when you specify the width and height HTML attributes the buffer size and length changes, but when you use CSS, the buffer's size is unchanged. Making the image stretched.
Using HTML sizing.
Size of canvas is changed -> buffer size is changed -> rendered
Using CSS sizing
Size of canvas is changed -> rendered
Since the buffer length is kept unchanged, when the context renders the image,
the image is displayed in resized canvas (but rendered in unchanged buffer).
CSS sets the width and height of the canvas element so it affects the coordinate space leaving everything drawn skewed
Here's my way on how to set the width and height with Vanilla JavaScript
canvas.width = numberForWidth
canvas.height = numberForHeight
I believe CSS has much better machinery for specifying the size of the canvas and CSS must decide styling, not JavaScript or HTML. Having said that, setting width and height in HTML is important for working around the issue with canvas.
CSS has !important rule that allows to override other styling rules for the property, including those in HTML. Usually, its usage is frowned upon but here the use is a legitimate hack.
In Rust module for WebAssembly you can do the following:
fn update_buffer(canvas: &HtmlCanvasElement) {
canvas.set_width(canvas.client_width() as u32);
canvas.set_height(canvas.client_height() as u32);
}
//..
#[wasm_bindgen(start)]
pub fn start() -> Result<(), JsValue> {
// ...
let canvas: Rc<_> = document
.query_selector("canvas")
.unwrap()
.unwrap()
.dyn_into::<HtmlCanvasElement>()
.unwrap()
.into();
update_buffer(&canvas);
// ...
// create resizing handler for window
{
let on_resize = Closure::<dyn FnMut(_)>::new(move |_event: Event| {
let canvas = canvas.clone();
// ...
update_buffer(&canvas);
// ...
window.add_event_listener_with_callback("resize", on_resize.as_ref().unchecked_ref())?;
on_resize.forget();
}
}
There we update the canvas buffer once the WASM module is loaded and then whenever the window is resized. We do it by manually specifying width and height of canvas as values of clientWidth and clientHeight. Maybe there are better ways to update the buffer but I believe this solution is better than those suggested by #SamB, #CoderNaveed, #Anthony Gedeon, #Bluerain, #Ben Jackson, #Manolo, #XaviGuardia, #Russel Harkins, and #fermar because
The element is styled by CSS, not HTML.
Unlike elem.style.width & elem.style.height trick used by #Manolo or its JQuery equivalent used by #XaviGuardia, it will work for canvas whose size is specified by usage as flex or grid item.
Unlike the solution by #Russel Harkings, this also handles resizing. Though I like his answer because it is really clean and easy.
WASM is the future! Haha :D
P.S. there's a ton of .unwrap() because Rust explicitly handles possible failures.
P.P.S.
{
let on_resize = Closure::<dyn FnMut(_)>::new(move |_event: Event| {
let canvas = canvas.clone();
// ...
update_buffer(&canvas);
// ...
window.add_event_listener_with_callback("resize", on_resize.as_ref().unchecked_ref())?;
on_resize.forget();
}
can be done much cleaner with better libraries. E.g.
add_resize_handler(&window, move |e: ResizeEvent| {
let canvas = canvas.clone();
// ...
update_buffer(&canvas);
})
If you want a dynamic behaviour based on, e.g. CSS media queries, don't use canvas width and height attributes. Use CSS rules and then, before getting the canvas rendering context, assign to width and height attributes the CSS width and height styles:
var elem = document.getElementById("mycanvas");
elem.width = elem.style.width;
elem.height = elem.style.height;
var ctx1 = elem.getContext("2d");
...
I have a Zoom-able, dragable, tree graph which has thousands of nodes using inside my angular application.
Design referenced from here.
I can download/export SVG or any parent div of SVG from my d3 graph.
The issue is that only SVG elements can be downloaded which do not contain complete tree graphs because SVG gets overflow by its inner element "g". SVG has a inner group element "g" which is bigger than SVG's height and width, and it is dynamic (drag-able).
This "g" element has a complete tree graph that I am not able to export as image or pdf.
How do I export a complete graph?
If you're exporting an SVG file:
clone your original SVG node
append it to the document, so it has the bounding box calculated
clean the transform from the parent g node, where you're translating and scaling
set the cloned SVG with its width and height with the content bounding box dimension
serialize the SVG and download it as a document
You might need to add inline styles to SVG so it's rendered properly outside the original d3 application.
Example:
const svg = document.querySelector('svg').cloneNode(true); // clone your original svg
document.body.appendChild(svg); // append element to document
const g = svg.querySelector('g') // select the parent g
g.setAttribute('transform', '') // clean transform
svg.setAttribute('width', g.getBBox().width) // set svg to be the g dimensions
svg.setAttribute('height', g.getBBox().height)
const svgAsXML = (new XMLSerializer).serializeToString(svg);
const svgData = `data:image/svg+xml,${encodeURIComponent(svgAsXML)}`
const link = document.createElement("a");
document.body.appendChild(link);
link.setAttribute("href", svgData);
link.setAttribute("download", "image.svg");
link.click();
How to export the SVG from canvas.
http://bl.ocks.org/curran/7cf9967028259ea032e8
I have a rectangle and a text created through D3 which are grouped together like below.
<g>
<rect></rect>
<text></text>
</g>
In a javascript function I'm expanding this rectangle's width to allow the the value of text to be displayed in one go. (If the value is too long as the text value is set dynamically). This is working fine. However even though the rectangle width is expanding depending on the text value size , D3 text element is not showing the complete text value that is added, eventually the text is moved to left and the first bit of it can't be seen.
Do I need to increase the text element's width too or what would be the solution for this?
[UPDATE]
Following is the current code.
var elms = d3.selectAll("[id=s]"); // has the rectangle and text elements
var s = d3.selectAll("[id=s]").selectAll("text"); // just the text elements
var minimumValue = 100;
// updating rectangle width
elms.attr('width', function() { return dynamic < minimumValue ? minimumValue : dynamic;});
Now I need a way to update the position of the text element when the rectangle is expanded. Hope this is more clear. I just tried manually updating 'x' property of text element that works. But can I derive this value dynamically to set it within this function?
In case someone is looking for this, was able to get the text new 'x' value by x of rectangle + half of rectangle's width (and similar for y but with the height).
Got the answer from this link (How to place and center text in an SVG rectangle)
Is there a way in d3 to not draw overlapping tick labels? For example, if I have a bar chart, but the bars are only 5 pixels wide and the labels are 10 pixels wide, I end up with a cluttered mess. I'm currently working on an implementation to only draw the labels when they do not overlap. I can't find any existing way to do that, but wasn't sure if anyone else had dealt with this problem.
There is no way of doing this automatically in D3. You can set the number of ticks or the tick values explicitly (see the documentation), but you'll have to figure out the respective numbers/values yourself. Another option would be to rotate the labels such that there is less chance of them overlapping.
Alternatively, like suggested in the other answer, you could try using a force layout to place the labels. To clarify, you would use the force layout on the labels only -- this is completely independent of the type of chart. I have done this in this example, which is slightly more relevant than the one linked in the other answer.
Note that if you go with the force layout solution, you don't have to animate the position of the labels. You could simply compute the force layout until it converges and then plot the labels.
I've had a similar problem with multiple (sub-)axis, where the last tick overlaps my vertical axis in some situations (depending on the screen width), so I've just wrote a little function that compares the position of the end of the text label with the position of the next axis. This code is very specific to my use case, but could adapted easily to your needs:
var $svg = $('#svg');
// get the last tick of each of my sub-axis
$('.tick-axis').find('.tick:last-of-type').each(function() {
// get position of the end of this text field
var endOfTextField = $(this).offset().left + $(this).find('text').width();
// get the next vertical axis
var $nextAxis = $('line[data-axis="' + $(this).closest('.tick-axis').attr('data-axis') + '"]');
// there is no axis on the very right, so just use the svg width
var positionOfAxis = ($nextAxis.length > 0) ? $nextAxis.offset().left : $svg.offset().left + $svg.width();
// hide the ugly ones!
if (endOfTextField > positionOfAxis) {
$(this).attr('class', 'tick hide');
}
});
The ticks with color: aqua are the hidden ones:
What are the properties that control the width of the X-axis labels on a horizontal bar RadChart? Here's what it looks like now:
I need the labels on the left to be wider.
I actually, just needed to keep the auto layout doing its thing, and disable auto wrapping this way:
var item = new ChartAxisItem();
item.Appearance.RotationAngle = AutoTextWrap.False