canvas

What JavaScript code would I use to plot a trend line?

由 只谈情不闲聊 提交于 2020-01-30 08:17:25
问题 Assuming that I have the following values that I'm going to plot on a Line chart (these are values and not coordinates - the coordinates are calculated by my software and are shown below): [4,4,3,2,5,5] How would I turn those values into a set of trendline values/coordinates? (BTW I don't really have any Maths expertise beyond school level - so no fancy Maths terminology please!). To add further details: These are a set of values that are spaced equally across a 500 pixel space (an HTML5

.drawImage function is throwing a “TypeError: Image or Canvas expected”, for canvas

由 被刻印的时光 ゝ 提交于 2020-01-30 07:44:04
问题 I am trying to add a rank card in my discord bot, and in order to do so I am trying to use canvas but when I use canvas everything works fine until I hit the .drawImage method. Where it gives me an error saying "TypeError: Image or Canvas expected". Although I've already require('canvas') globally, and everything else that has to do with canvas works properly as well. I've tried to require('canvas') inside the function but that doesn't fix the problem either. const canvas = Canvas

.drawImage function is throwing a “TypeError: Image or Canvas expected”, for canvas

由 帅比萌擦擦* 提交于 2020-01-30 07:42:57
问题 I am trying to add a rank card in my discord bot, and in order to do so I am trying to use canvas but when I use canvas everything works fine until I hit the .drawImage method. Where it gives me an error saying "TypeError: Image or Canvas expected". Although I've already require('canvas') globally, and everything else that has to do with canvas works properly as well. I've tried to require('canvas') inside the function but that doesn't fix the problem either. const canvas = Canvas

小程序利用canvas生成图片加文字，保存到相册

由 …衆ロ難τιáo~ 提交于 2020-01-30 06:53:16
<view class='poste_box' id='canvas-container'> <canvas canvas-id="myCanvas" style="width:100%;height:384px;" bindtap='saveShareImg'/> </view> /* pages/certificate/certificate.wxss */ page{ ">#fff; } .poste_box{ width: 100%; margin: auto; margin-top: 50rpx; ">#fff; } .savePoste{ ">#FF8427; width: 90%; margin-left: auto; margin-right: auto; margin-top:30rpx; color: #fff; } .saveTitle{ font-size: 25rpx; color: #666; width: 90%; margin-left: auto; margin-right: auto; margin-top: 20rpx; text-align: center; } //index.js //获取应用实例 const app = getApp() Page({ data: { cardInfo: { avater: "/media/zs.png"

使用canvas绘制小程序码

由 喜欢而已 提交于 2020-01-30 06:52:21
场景：使用小程序文档的API可以获取带参数的二维码和小程序码，但是小程序码中的图片默认都是小程序的头像（红框中的图片）。现在我们需要替换里面的图片，然后将小程序码保存成一张图片存入相册。 1.获取带参数的小程序码 小程序开发文档提供三种接口获取带参数的小程序码，根据自己的需求选择相应的接口。 https://developers.weixin.qq.com/miniprogram/dev/api/qrcode.html 2.将网络图片路径转换为本地图片路径。 使用wx.getImageInfo或者wx.downloadFile可以返回图片的本地路径。 用wx.setStorage将返回的本地路径存储在本地缓存中并指定key的值：path1，path2。 用wx.getStorageSync(KEY)从本地缓存中同步获取指定的key对应的内容。 备注：url1为第一步获取到的带参数的小程序码。url2为需要填入小程序码中间的图片。 const url1 = "https://images/ewm.jpg"; const url2 = "https://wx.qlogo.cn/mmopen/vi_32/DYAIOgq83epNAxDh5I0dQAQrNVs4pKWrYibfbA6Xw6lOJqqYic4qTFXt9tjbTJrgpusYy4KCEXnF3iaib8sdqP6CfQ

Python tkinter use canvas to create dynamically window with scroll bar

由 烂漫一生 提交于 2020-01-30 06:49:05
问题 My objective is to solve the problem of the grid exceeding the window(shown as figure.1) enter image description here My program function is creating a grid that number of columns defined by user. I tried using canvas to solve this problem, but it still doesn't work successfully. It doesn't show the full grid in the canvas.(shown as figure.2) enter image description here Below is my code, could you please help solve the problems or give me some advice. Thanks a lot. Code: import tkinter as tk

canvas performance drop after a few seconds

由 三世轮回 提交于 2020-01-30 04:03:16
问题 I wrote the following 1000 bounding squares demo as a test of the capabilities of HTML5 canvas. It runs fine at first but then a noticeable drop in fps after a few seconds. I am not sure why. Any pointers would be appreciated. var c = document.getElementById("canvas"); var context = c.getContext("2d"); var WIDTH = 600; var HEIGHT = 800; c.width = WIDTH; c.height = HEIGHT; image = loadImage("square.png"); function loadImage(imageName){ var i = new Image(); i.src = imageName; return i; }

canvas画的文字在ios移动设备上无法显示

由 五迷三道 提交于 2020-01-29 08:04:12
项目中做了移动端rem适配的，然而发现电脑上可行，在苹果手机上却无法显示， 查了一下，发现iOS Safari只支持标准的canvas，标准的canvas只支持px不支持rem。 上网找了一下，解决方法: 将rem转换回px //UI设计基础宽度：750px； ctx.font = 3*12.5+"px sans-serif"; 但是移动端有各种宽度的屏幕，为了适应各种屏幕是不能写死，所以最终下法应该如下： //获取设备宽度 let clientWidth = document.documentElement.clientWidth; //根据设计图中的canvas font字体的占比进行设置 let fontWidth = clientWidth*3*12.5/750; //设置自适应的字体大小 ctx.font = fontWidth+"px sans-serif"; 来源： CSDN 作者： gz-郭小敏 链接： https://blog.csdn.net/github_39570717/article/details/104059466

Drawing in JavaScript / HTML5 using XOR to remove old sprite

由 别来无恙 提交于 2020-01-29 05:39:09
问题 I'm building the engine for a tiny game, and right now I have just got a red circle with two little eyes as a main character. I have keyPress functions to detect movement, and that works, but I wanted to use something I used a long time ago in QBASIC to remove the character and redraw at a new location: XOR Basically, on keypress this happens: if (code == 39) { mainChar.drawChar(); mainChar.x += 1; mainChar.leftEye.x += 1; mainChar.rightEye.x += 1; mainChar.drawChar(); } I thought drawing the

Drawing in JavaScript / HTML5 using XOR to remove old sprite

由 a 夏天 提交于 2020-01-29 05:39:08
问题 I'm building the engine for a tiny game, and right now I have just got a red circle with two little eyes as a main character. I have keyPress functions to detect movement, and that works, but I wanted to use something I used a long time ago in QBASIC to remove the character and redraw at a new location: XOR Basically, on keypress this happens: if (code == 39) { mainChar.drawChar(); mainChar.x += 1; mainChar.leftEye.x += 1; mainChar.rightEye.x += 1; mainChar.drawChar(); } I thought drawing the
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