canvas

Chart.js not working properly to draw lines when is only 1 bar

由 匆匆过客 提交于 2019-12-25 09:06:28
问题 I want to do this chart: As you can see the lines ( Meta and Rango de aceptación ) were drawed like a points. I believe this is because I only have one bar and in another charts I was made with 2 bars I get the lines drawed like a line. This is the code, what I'm doing wrong? <canvas id="myChart2016_5857751099b04" width="500" height="500" style="display: block; width: 500px; height: 500px;"></canvas> <script style="text/javascript"> var ctx2016_5857751099b04 = document.getElementById(

Zoom/scale from different point of image in canvas

由 半城伤御伤魂 提交于 2019-12-25 09:04:22
问题 I have made a canvas in html5. I'm using it to show parts of a bigger image that you can move and I want to make it possible to zoom both in and out. But I do not know how to make the image scale from a certain point. When I increase the size of the image the part which is shown by the canvas is moved, I want the part in the center of the canvas to be the focus point when the scaling is complete, but no matter how I try it gets distorted some how. It seems like depending on which part of the

onclick function button change canvas

由 百般思念 提交于 2019-12-25 08:56:36
问题 I have the following code creating an animated series of lines in canvas. I would like to change the context being drawn in the canvas depending on certain DOM elements being clicked. I have the following html: <style> *{ overflow: hidden; margin: 0; width: 100%; height: 100%; } .c{ background: black;} </style> <canvas class='c'>waves</canvas> <div style="width:100%; height:100%; position:absolute; top:0; left:0;"> <center> <img id="click" style="margin:0 auto; position:relative; top:20%;

Canvas resizes on width but not height

由 可紊 提交于 2019-12-25 08:54:25
问题 When I create a canvas such as: <!DOCTYPE html> <html> <body> <canvas style="background-color: #FF0000; width: 100%; height: 100%></canvas> </body> </html> I've found that if I make the window small enough, the width will be scaled but not the height. That is, the canvas resizes proportionally but only enough so that the width fits in completely --- the height may need scrolling. I would like instead to have the entire canvas resized proportionally so that it fits all on the page (both

Scrollable Toplevel Window (tkinter)

由 房东的猫 提交于 2019-12-25 08:22:46
问题 I'm pretty new to Python and have delopped a little program. In that program the user is able to open a Toplevel window as a popup which shows a map as an image file. I've managed to add a scrollbar to it and make the image scrollable. The reason for the scrollbar is to support different screen resolutions so that if the shown image is too big, the user can scroll the content of the popup. I now would like to ensure that the scrollbar changes size, when the popup window changes size or isn't

Adding multiple touch listeners inside canvas Android

由 让人想犯罪 __ 提交于 2019-12-25 08:15:46
问题 Suppose I have multiple drawings in my canvas, how can I add touch listener for each of the drawings seperately inside that canvas? I will be having different drawings like star, circle, rectangle etc etc added dynamically how can I handle each of them ? I couldn find ans in SO the very close question was this Set touch listeners on canvas drawings but it has no ans. Help and suggestions will be appreciated. Thanks in advance :) 回答1: Actually you can't add any touch listener on the drawings

Android undo drawing method on canvas

由 你说的曾经没有我的故事 提交于 2019-12-25 08:15:13
问题 I created some code that takes a picture and displays the picture, then the user is able to draw on the picture. I want to implement an undo method. I based my code on many examples I've read. The problem is in my onDraw method - the examples don't use drawBitmap but for me I have to draw the bitmap on the canvas in order for the image to show up. The code shown displays the image, allows drawing on the image, but does not undo the drawings. I can't figure out what's wrong/how to fix it.

How to convert RGBA style color to canvas friendly color?

由 无人久伴 提交于 2019-12-25 08:08:37
问题 I am trying to draw on canvas with the same colour as a computed style. for colours like so it is fine: rgb(0, 255, 255)" but for something like rgba(0, 0, 0, 0) is is black on the canvas but white in the browser 回答1: Matching DOM colour blending Red, Green, Blue and the Alpha channel For the most part all the graphics you see in your browser is comprised of 4 channels. The first 3 are colour channels and represent the intensity of each component colour, red, green, and blue. The fourth

canvas fillrect and drawimage combination doesn't work

由 拟墨画扇 提交于 2019-12-25 08:07:20
问题 As you see on the code below I added a fillrect called "red_rec" below the img and images variables, because I need a red rectangle with color-dodge blending applied to the two images, I mean (globalCompositeOperation = "color-dodge") but running it along with the two images variables just makes dissapear both images and blend, I don't know what I am doing wrong. so as a resume... I Want a red rectangle with globalCompositeOperation = "color-dodge" blending with the two images. var canvas =

How to recognize an area in an canvas via javascript [duplicate]

由 最后都变了- 提交于 2019-12-25 07:58:42
问题 This question already has answers here : How can I perform flood fill with HTML Canvas? (3 answers) Closed 4 years ago . This image is loaded in an html5 canvas. If a user presses at any point inside the square, I want to fill this area with a color. But just inside, the color stops at the black lines. You can think about the fill tool like in Windows Paint. How can I solve this? Are there libraries for javascript for such a function to start with? 回答1: What you are looking for is called a
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