canvas

uni app canvas 不生效

由 不羁的心 提交于 2020-01-14 16:21:31
canvas 创建canvas绘图上下文。 <canvas style="width: 300px; height: 200px;" canvas-id="firstCanvas"></canvas> uni.createCanvasContext(canvasId, this) uni.createCanvasContext(firstCanvas, this) 注意：在自定义组件下，第二个参数传入组件实例this，若不传，则无法显示 来源： https://www.cnblogs.com/lww-3018/p/12192560.html

canvas使用

由 风流意气都作罢 提交于 2020-01-14 16:12:58
基本步骤类似于 步骤1准备画布 准备画布 <canvas></canvas>标签就是画布 canvas画布有默认大小 默认350X150 设置canvas画布大小 通常canvas是一个标签，可以在style canvas{width:xxxpx; height:xxpx} 但是不建议这样写 不建议在样式设置尺寸 我们可以在元素本身来设置 <canvas width="600" height="400"></canvas> 解释：不在样式表中设置canvas画布大小的原因 在css中设置canvas尺寸 canvas{ border:1px solid black; width: 600px; height: 400px; } 同样类似下面在(100,100)的位置绘制一条直线 此时可以发现 原来300X150的框拉伸到600X400，同样原来100X100的点距离左边和上边同比例放大了。就好比于拉伸了图片，点的相对比例没变，而实际位置改变。 所以在css样式中我们设置canvas的样式，而不是canvas的大小 步骤2准备绘制工具，利用工具绘图 <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width,

Canvas has inconsistent pixel grid across browsers when using drawImage()

由 隐身守侯 提交于 2020-01-14 14:45:09
问题 I recognize that Canvas drawImage is inexplicably offset by 1 Pixel is a very similar issue, but I was already applying the advice given in that question's answer before I even came across this problem. I'm implementing a sprite sheet system for an HTML5-based game. Individual frames are defined simply: frame = new AnimationFrame(img, x, y, w, h); Inside the AnimationFrame constructor, all of the numeric parameters are truncated to integers. Then when I go to draw it on the canvas, I use what

Canvas eyeDropper

由 ╄→尐↘猪︶ㄣ 提交于 2020-01-14 14:16:48
问题 I need to implement an eyedropper tool. I want it so you click the eyedropper button to make it active, then using a onmove it will change the colour of my colour picker and when you click using onclick it will set the colour to the colour picker using: $('#colorpickerHolder').ColorPickerSetColor(eyeDropperColour); The variable eyeDropperColour would be set using the onlick based on what colour pixel you are over. I am wondering would I have to do it based on what layer as I have: canvas and

Overlap image2 on image1

由 ℡╲_俬逩灬. 提交于 2020-01-14 13:43:09
问题 We are displaying image1 in site as below : Now we are giving an option to upload image2, and what we want is uploaded image2 should overlap on existed image1 like here. but now when we upload image2, image1 is overlapping on image2. var canvas = new fabric.Canvas('canvas'); document.getElementById('file').addEventListener("change", function (e) { var file = e.target.files[0]; var reader = new FileReader(); reader.onload = function (f) { var data = f.target.result; fabric.Image.fromURL(data,

Upload image thumbnail to server, without uploading whole image

由 折月煮酒 提交于 2020-01-14 12:58:29
问题 As far as I know, what I ask here isn't possible, but I thought I'd ask anyway in case I'm missing something. Suppose you want to let users upload JPG images, and these images are scaled into smaller icons and the original images are always discarded and never required again. Is there any way that would commonly work in most modern browsers that would let the user select a single image on their hard drive, have that LOCALLY turned into a thumbnail and upload the created thumbnail to a server?

text is grainy/blurry when drawing text on a canvas via onload

由 六眼飞鱼酱① 提交于 2020-01-14 12:35:47
问题 If I try to draw text to my canvas at the onload event, the text shows up blurry. I draw to the same canvas later via a button click from another function and it's fine. But if I call this function from the button, it's still blurry. Can anybody see something wrong in this code? window.onload = initCanvasRender; function initCanvasRender() { var c = document.getElementById("canvas"); var ctx = c.getContext('2d'); ctx.setTransform(1, 0, 0, 1, 0, 0); ctx.textAlign = 'center'; ctx.textBaseline =

text is grainy/blurry when drawing text on a canvas via onload

由 我的梦境 提交于 2020-01-14 12:35:07
问题 If I try to draw text to my canvas at the onload event, the text shows up blurry. I draw to the same canvas later via a button click from another function and it's fine. But if I call this function from the button, it's still blurry. Can anybody see something wrong in this code? window.onload = initCanvasRender; function initCanvasRender() { var c = document.getElementById("canvas"); var ctx = c.getContext('2d'); ctx.setTransform(1, 0, 0, 1, 0, 0); ctx.textAlign = 'center'; ctx.textBaseline =

Drawing a Region with CSS -fx-shape. How it is possible?

由 久未见 提交于 2020-01-14 10:37:29
问题 I'm looking a way to draw shapes in a Region (JavaFX8) I've seen some examples that set the region style like this: -fx-shape : "M 3.0313 0 L 0 74 L 7.9688 74 L 4.9375 0 L 3.0313 0 Z"; Can anyone give an explanation of the meaning of this string? Is there any way to create this type of string using Visual Software? 回答1: The shape string is an SVG Path. Note the shape string for a region is the shape of the region, not a shape in a region. If you want to create shapes based on paths to put in

Chartjs - keeping 2 graphs aligned side by side

由 别来无恙 提交于 2020-01-14 10:17:19
问题 Jsfiddle: http://jsfiddle.net/8gvkmLxL/ I have 2 bar graphs that are next to each other and I want them to be aligned relative to their x-axis. I'm having trouble achieving this as the graph height changes according to the length of the labels (see jsfiddle link). What's the best way to maintain consistency of height of the actual charts (as opposed to the canvas) var data,ctx,mychart; data = { labels: ["Iantojones","Jackharkness","Owenharper"], datasets: [ { label: "My First dataset",
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