canvas

问题 I have a method which renders a matrix of rectangles within a Canvas before the next repaint using requestAnimationFrame . I'm trying to achieve maximum performances. My first approach to this problem was to create rectangles in real-time within the Canvas . render(display: PanelDisplay): void { const ctx = this.parameters.canva.getContext("2d"); const widthEachBit = Math.floor(this.parameters.canva.width / display[0].length); const heightEachBit = Math.floor(this.parameters.canva.height /

问题 I have a React page that draw about 15K lines on a canvas. If I draw on a canvas that's not in the document.body, the UI is responsive. The moment I draw the lines on a canvas that's in the document.body, the UI is very slow. There's the code: render() { if (this.canvasRef.current && this.state.chartData) { const canvas = document.createElement("canvas") canvas.width = 1000; canvas.height = 800; drawChart(canvas, this.state.chartData); } return ( <div> <canvas ref={this.canvasRef} height={800

问题 Is is possible to use the particle effects system on your UI elements. For instance on the Canvas? I'd like to make some animations and whatnot for my UI elements and the particle system would be nice, but it doesn't seem to support this. Am I correct in assuming this? Is there another solution? 回答1: Well what you could do would be letting a Camera render the Particle effects on a different layer to a RenderTexture and show it in a RawImage in your UI. Combined with a hint from this answer:

问题 I use a canvas, in which I support mouse dragging by setting in Javascript: canvas.onmousedown canvas.onmouseup canvas.onmousemove This works.. I can support drag operations with the mouse. On iOS safari browser, though, dragging with a finger does not trigger the mouse functions. Instead, the entire webpage just scrolls up or down. At first I thought adding ontouchmove and others, would fix this. But it does not. How can the browser on a mobile device tell when touches are meant for the

问题 I'm trying to use canvg to draw a highchart inside a canvas. the problem I have is that the chart legends dont appear in the canvas and also the size and quality is reduced. $('#container').highcharts({ credits: { enabled: false }, xAxis: { categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'] }, series: [{ data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4] }] }); function exportChart() { var svg = canvg(document

问题 I have the following WPF Control, that should behave like, by e.g. GoogleMaps does(zoom on left double click, unzoom on right double click): <Grid> <ScrollViewer x:Name="scrollViewer"> <Canvas x:Name="myCanvas"/> </ScrollViewer> </Grid> And some code: void OnScrollViewerPreviewMouseDoubleClick(object sender, MouseButtonEventArgs e) { //this.myCanvas.ContextMenu = null; if (e.OriginalSource is Canvas) { // zoom on left doubleClick if (e.ChangedButton == MouseButton.Left) { ZoomOnMouseOnce(); }

问题 I have referred official document of skia: https://docs.microsoft.com/en-us/dotnet/api/skiasharp.skcanvas?view=skiasharp-1.68.1#constructing-a-pdf-document // create the document var stream = SKFileWStream.OpenStream("document.pdf"); var document = SKDocument.CreatePdf(stream); // get the canvas from the page var canvas = document.BeginPage(256, 256); // draw on the canvas ... // end the page and document document.EndPage(); document.Close(); As per the above code I'm getting canvas, but how

问题 I am trying to select a selection handle and then move it but the mouse handles are not in sync with the mouse pointer. when you select the rectangle and then try to move the middle selection handle to create a gap in the rectangle the mouse pointer is positioned away from the handle is. Fiddle is : http://jsfiddle.net/3PwWY/ case 8: if(mx > mySel.x + mySel.w/2) mySel.windowWidth = mx - (mySel.x + mySel.w/2); else mySel.windowWidth = (mySel.x + mySel.w/2) - mx; // Enforce limits on mx: //

问题 This question already has answers here : Canvas is stretched when using CSS but normal with “width” / “height” properties (7 answers) Closed 3 years ago . I have seen various answers on canvas resize but could not understand the problem I am facing. Following is the canvas element rendered on my web app. Before Rendering: <canvas id="g_5" resize></canvas> After Rendering: <canvas id="g_5" resize width="1076" height="306" style="-webkit-user-select: none; touch-action: none; -webkit-user-drag: