canvas

问题 I am working with clip() in canvas. I have made a region to clip() , as specified below this.svgRenderer.ctx.rect(positionX, positionY, Width, Height); this.svgRenderer.ctx.clip(); After few drawing on the same canvas, I am trying to remove the clip for that region by using save() and restore() . But I am making mistakes and can't get that. So suggest any other way to remove the clip for the specified region without using save() and restore() 回答1: .clip is a permanent context state change. It

问题 Rotation of rectangles within an html5 canvas is being stored in radians. In order to find whether subsequent mouse clicks are within any given rectangle, I am translating the mouse x and y to the origin of rotation for the rectangle, applying the reverse of the rotation to the mouse coordinates, and then translating the mouse coordinates back. This simply isn't working - mouse coordinates are not being transformed as expected (that is, not within the bounds of the original rectangle when

问题 Rotation of rectangles within an html5 canvas is being stored in radians. In order to find whether subsequent mouse clicks are within any given rectangle, I am translating the mouse x and y to the origin of rotation for the rectangle, applying the reverse of the rotation to the mouse coordinates, and then translating the mouse coordinates back. This simply isn't working - mouse coordinates are not being transformed as expected (that is, not within the bounds of the original rectangle when

问题 As the title states. Is this possible? Edit: When i say doughnut I mean a top, 2D view Is the only option to draw a segment of a circle, then draw a segment of a smaller circle with the same origin and smaller radius over the top, with the colour of the background? That would be crap if so :( 回答1: You do it by making a single path with two arcs. You draw one circle clockwise, then draw a second circle going counter-clockwise. I won't go into the detail of it, but the way paths are constructed

问题 I am working on a canvas video player with some special features based on frames of the video. To overcome the unreliable timing in the video HTML5 tag the videos we are using have a barcode embedded in each frame indicating the current frame number. Using the canvas getImageData method I can grab the pixels and read the barcode to get the frame number. This works great and I have a JSFiddle demonstrating that it works (I couldn't get around CORS in this fiddle to serve the video to the

问题 So i want a tool that generates a .ico file from a jpg/png. I have generated the jpg from a canvas using this code: var img = c.toDataURL("image/png"); document.write('<img src="'+img+'"/>'); Which takes from this canvas: <canvas id="myCanvas" width="16" height="16"> So the qustion is; is it possible to convert the generated png to a ico? 回答1: In Firefox you can do this directly from canvas: // Make ICO files (Firefox only) var ctx = c.getContext("2d"); ctx.arc(c.width>>1, c.height>>1, c

问题 I' m building a page loader with canvas, and using the es6 classes... ALthough at the moment I can't make it work properly.. one of the reason is that I can't find a way to clear the canvas in progression. This is my code so far : class Loader { constructor (width, height) { this.width = width this.height = height } _init() { this._createCanvas() this._bindEvents() } // create canvas _createCanvas () { this.canvas = document.createElement("canvas") document.body.appendChild(this.canvas) this

问题 I'd like to implement click detection for multiple complex shapes on a single canvas element similar to that as realized by CanvasRenderingContext2D.isPointInPath() . Obligatory example code below. HTML: <canvas id="canvas"></canvas> <p>In path: <code id="result">false</code></p> JS: const canvas = document.getElementById('canvas'); const ctx = canvas.getContext('2d'); const result = document.getElementById('result'); ctx.beginPath(); ctx.moveTo(25, 25); ctx.lineTo(105, 25); ctx.lineTo(25,

问题 I found a lot on this subject for HTML 5 JavaScript (like so), but I have found nothing over WPF. I have a canvas that we are creating for selecting points over a image in that canvas. The canvas element in XAML is very simple: <Canvas x:Name="Cnv" Grid.Column="1" Grid.Row="1" /> We are getting the coordinates from mouse click like so: Point p = Mouse.GetPosition(Cnv); Then, we draw something on that point: ellipse = new Ellipse(); ellipse.Fill = Brushes.Transparent; ellipse.Width = 20;

问题 I found a lot on this subject for HTML 5 JavaScript (like so), but I have found nothing over WPF. I have a canvas that we are creating for selecting points over a image in that canvas. The canvas element in XAML is very simple: <Canvas x:Name="Cnv" Grid.Column="1" Grid.Row="1" /> We are getting the coordinates from mouse click like so: Point p = Mouse.GetPosition(Cnv); Then, we draw something on that point: ellipse = new Ellipse(); ellipse.Fill = Brushes.Transparent; ellipse.Width = 20;