What is the relationship between canvas scale and canvas size?

What's the relationship between canvas scale and canvas size? My ultimate goal is to change the scale by the user

P粉621033928 2023-07-25 12:33:23 0  1  537

Canvas appears blank?

I'm trying to render keys onto a canvas that I can get from BlazePose, but I can't seem to get them to draw to the canvas. I know the x and y of each keypoint and are retrieved, but I can't get them to display on the canvas. I've tried changing the style but so far no success. thanks for your help. ...

P粉147045274 2024-03-31 17:20:31 0  1  537

javascript - Use canvas to implement electronic signature, position the coordinates of the mouse in the canvas

When trying to use canvas to implement an electronic signature, the coordinates of the mouse in the canvas cannot be accurately obtained. {Code...} Use ev.clientY to obtain the coordinates of the mouse, but canvas.offsetTop obtains the height from the parent element. And canvas is in a form with scr...

巴扎黑 2017-05-16 13:36:00 0  1  571

javascript-canvas drawing

I wrote a function that calls canvas's drawImage for the first time to draw part of a local picture (it can succeed), and then calls toDataURL to convert the picture drawn by canvas into the src attribute of the image object, and then this Why does the picture drawn on canvas call the same method fo...

PHP中文网 2017-07-05 10:46:27 0  1  750

html5 - canvas sometimes cannot get toDataURL data

Questions: 1. I don’t know why, canvas sometimes cannot get the drawing data, but only gets “data:;”. Please tell me where I wrote this wrong. 2. I write canvas like this. Is there anything that needs to be optimized? Related code: {code...} {code...}

高洛峰 2017-06-06 09:53:01 0  2  885

javascript - canvas crop empty area

I used canvas to make an electronic signature, but there was too much space left after the user signed. Is there any way to capture the blank space? Original picture of the example: During the signing process, I obtained the area that the mouse passed through, and thus obtained the coordinates of th...

黄舟 2017-05-16 13:26:16 0  5  1032

javascript - Problems with canvas processing images

I need to use canvas to process a picture uploaded by the user. The size uploaded by the user may be very large, for example, it will exceed the width and height of the current browser window, so I scale it proportionally to the visible area of ​​the browser, and then Draw it onto the canvas, but th...

扔个三星炸死你 2017-06-10 09:49:16 0  3  985

javascript - Help canvas to draw translucent mosaic?

My requirement is to allow users to use the mouse to mosaic the uploaded documents. My idea is to bind mouse events to the canvas and draw a translucent png onto the document along the user's mouse pressing path. Now I don't want to use translucent Png overlay, I want to directly use canvas to gener...

仅有的幸福 2017-06-07 09:24:40 0  1  877

Get the *two* height values ​​of the canvas?

I'm trying to get two height values ​​of this canvas. <canvaswidth="886"height="792"style="display:block;opacity:0.5;width:834px;height:746px;"></canvas> I know that I can access the style using canvas.style.height; one of them, but how to get

P粉604848588 2024-04-05 09:32:33 0  1  1460

Problem with not getting accurate mouse coordinates: using HTML5 canvas when resizing the page

I want to create this pixel effect from a front-end expert. Although I can achieve the entire pixel effect on a full-screen canvas: constcanvas=getElementById('canvas');canvas.height=window.innerHeight;//Set the full-screen height to the canvas canvas.width=window.innerWidth;//Set the canvas to full...

P粉752290033 2023-09-12 12:20:33 0  1  731

javascript - How to get the coordinates of the touch event in the canvas in native canvas?

When canvas responds to the mousedown event, it can extract the internal coordinates of the element through event.offsetX and offsetY. Then I changed to touchstart and there is no offsetX and offsetY. Where should I find the internal coordinates of the element?

黄舟 2017-05-24 11:36:27 0  3  710

javascript - canvas design mouse drawing function draws multiple parallel colored lines in one stroke

1. The mouse drawing function of canvas design can draw multiple parallel colored lines in one stroke. 2. Tried adding drawing oCg.beginPath(); to the mouse event, but the event will be overwritten. 3. Add a duplicate canvas in the same way, but the canvas is covered.

PHP中文网 2017-06-13 09:24:08 0  1  1246

javascript - canvas uses toDataUrl() error, img setting img.crossOrigin = "*" is useless.

The page has a screenshot function, and a picture is generated locally, then converted to canvas, and then converted from canvas to png, but canvas.toDataUrl() keeps reporting an error: {code...} The code is as follows: {code... }

过去多啦不再A梦 2017-07-05 10:57:31 0  1  834

javascript - drag image into canvas

Can any expert help me to see this effect? ​​You can drag the picture on the right into the canvas and edit it. How is it achieved? Can you explain it in detail? Urgent.

phpcn_u1582 2017-06-14 10:52:41 0  2  896