html5-canvas

问题 I'm making a simple engine for isometric games to use in the future. The thing is i'm having trouble drawing on the canvas. Take for instance this code: function pre_load() { var imgs = ['1', '1000','1010','1011','1012','1013']; var preload_image_object = new Image(); $.each(imgs,function(i,c){ preload_image_object.src='img/sprites/'+c.logo+'.png'; }) } function GameWorld() { //[...] this.render = function() { this.draw(1000, this.center); this.draw(1013, this.center); this.draw(1010, this

问题 I'm working on a project in which i need to draw an image on a canvas and rectangles also to mention the objects present on that image. Rectangles are drawing correct positions if the image is not scaling to fit to the canvas. But if i scaled the image, Rectangles are not getting scaled to meet the correct positions. I have already gone through similar questions/answers present on stackoverflow, but none of them are working in my case or may be i'm not much educated to understand and

问题 I'm working on a project in which i need to draw an image on a canvas and rectangles also to mention the objects present on that image. Rectangles are drawing correct positions if the image is not scaling to fit to the canvas. But if i scaled the image, Rectangles are not getting scaled to meet the correct positions. I have already gone through similar questions/answers present on stackoverflow, but none of them are working in my case or may be i'm not much educated to understand and

问题 I want to record a video from a HTML <canvas> element at a specific frame rate. I am using CanvasCaptureMediaStream with canvas.captureStream(fps) and also have access to the video track via const track = stream.getVideoTracks()[0] so I create track.requestFrame() to write it to the output video buffer via MediaRecorder . I want to precisely capture one frame at a time and then change the canvas content. Changing the canvas content can take some time (as images need to be loaded etc). So I

问题 How I clean text from canvas shape ? this my code: <div id="ways" style="width:1000px;margin:0 auto;height:100%;"> <canvas id="canvas" width="1000" height="1000"></canvas> and fiddle 回答1: Just refactor the code a bit - Extract the lines which draws the circle into a single function which takes one of those circle objects as an argument: function drawCircle(circle) { context.beginPath(); context.arc(circle.x, circle.y, circle.radius, 0, 2 * Math.PI, false); context.fillStyle = 'green'; context

问题 I'm trying to use a smaller canvas as a viewport for another much bigger canvas. I really like the approach used in this the solution on a similar question. He basically uses CanvasRenderingContext2D.drawImage() to "crop" the buffer/offset canvas and then displays that portion of the image on the smaller canvas (viewport). I'm trying to implement a simpler version of the given solution in this fiddle: https://jsfiddle.net/avvac0x8/2/. But as you can see the viewport is not entirely in sync

问题 i made 2 deference size html canvas to drawing First canvas = width : 400px,height:200px Second canvas = width : 200px,height :100px Now when i drawing in first html canvas i send that coordinates(x1,y1,x2,y2) to second canvas. When first canvas coordinates send in second canvas it's not drawing in same place as first canvas. is there way to equal first canvas coordinates to second one without changing canvas width and height . ctx.beginPath(); ctx.lineWidth = 5; ctx.lineCap = 'round'; ctx

问题 i made 2 deference size html canvas to drawing First canvas = width : 400px,height:200px Second canvas = width : 200px,height :100px Now when i drawing in first html canvas i send that coordinates(x1,y1,x2,y2) to second canvas. When first canvas coordinates send in second canvas it's not drawing in same place as first canvas. is there way to equal first canvas coordinates to second one without changing canvas width and height . ctx.beginPath(); ctx.lineWidth = 5; ctx.lineCap = 'round'; ctx

问题 I have an animated canvas to create a noise effect on the background. Short explanation of my code is following: using for loop I am drawing 1px X 1px squares (dots) around canvas at random. It creates a static noise (grain). Later, I animate it with requestAnimationFrame . My problem is that if I set the original size of the canvas to whole viewport, the browser can not handle huge drawing space and animation becomes extremely sluggish. So I need to keep the original size of canvas small,

问题 I have an animated canvas to create a noise effect on the background. Short explanation of my code is following: using for loop I am drawing 1px X 1px squares (dots) around canvas at random. It creates a static noise (grain). Later, I animate it with requestAnimationFrame . My problem is that if I set the original size of the canvas to whole viewport, the browser can not handle huge drawing space and animation becomes extremely sluggish. So I need to keep the original size of canvas small,