javascript canvas draw

Draw a rectangle for HTML5 canvas Basic Drawing, html5canvas It is just a container for drawing graphics. In addition to attributes such as id, class, and style, there are also attributes of height and width. There are three steps to draw an element on the 1. Obtain the DOM object corresponding to the 2. Call the getContext () method of the

In general, there are two ways to draw, that is, fill and stroke, the previous article has described the stroke method of stroke, this article on the canvas to fill the method of graphics.Filling is fill (), is it straightforward? And as Strokestyle represents a stroke style, FillStyle represents a fill style.Ctx.fillstyle = ' color '; The default fill style is opaque blackquestion: Are unclosed paths popul

Comments: In html5, I think the most important thing is to introduce Canvas so that we can draw various images on the web, while Canvas is pixel-based. Canvas is an html node equivalent to a drawing board. We must operate the drawing using js. In html5, I think the most important thing is to introduce

SVG and Canvas are two completely different ways of drawing graphics applications on HTML5. Each of them has its own advantages and disadvantages, but they are not difficult to draw, in particular, the SVG content can be directly drawn on the Canvas, so that the two can be perfectly integrated, so that the Canvas can e

elliptic. // --------- Use cubic besell curves to simulate an elliptic 2 --------------------- // This method also produces when the lineWidth is wider and the ellipse is relatively flat. // The long axis is sharp and insmooth. // This method is more accurate than the previous besell method, but less efficient Function BezierEllipse2 (ctx, x, y, a, B) { Var k =. 5522848, Ox = a * k, // horizontal control point offset Oy = B * k; // Vertical Control Point offset Ctx. beginPath ()

Canvas provides 4 ways to draw a curve:arc (x,y,stratangle,endangle,true/false);//default = FalseArcTo (x1,y1,x2,y2,r);X1,y2 coordinates one, x2,y2 coordinates 2,r is the arc radiusQuadraticcurveto (dx,dy,x,y);Dx,dy control Point, X, Y is the end pointBeziercurveto (dx1,dy1,dx2,dy2,x,y);Dx1,dy1 is control point one, Dx2,dy2 is control point two, X, Y is the end point1, the use of Arc (X,y,startangle,endangl

First, use the canvas style defined. Here we mainly want to talk about width and height. do not define it in the style, otherwise it will be stretched. (For this, we recommend that you read the W3C documentation, not very familiar with it) The height and width attributes determine the coordinate system of the width and height of the canvas, while the CSS attribute only determines the size of the box, which

10 minutes, draw a small loading interface using canvas (by the way, we will discuss the problem of drawing efficiency), canvasloading First, use the canvas style defined. Here we mainly want to talk about width and height. do not define it in the style, otherwise it will be stretched. (For this, we recommend that you read the W3c documentation, not very familia

There are two forms: fill and stroke. The specific implementation code is as follows. For more information, see, I hope this will help you to put a canvas element on the html page. The canvas Element should have three attributes: ID, width, and height. The Code is as follows: Get the canvas object and obtain the context var cxt = document. getElementByI

Comments: There are two forms: fill and stroke. The specific implementation code is as follows. If you are interested, refer to the following, I hope this will help you to put a canvas element on the html page. The canvas Element should have three attributes: ID, width, and height.The Code is as follows:Get the canvas object and obtain the context var cxt = docum

In the canvas can be very convenient to draw a circle with the Arc method, the original circle can also be regarded as a wide and high equal ellipse, but there is no way to draw ellipse in the canvas, we have to use other methods to simulate.We first need to explicitly draw

(); Context.restore(); }//Draw motion ring function foregroundcircle (n) {context.save (); Context.strokestyle = ForeColor; Context.linewidth = 8; Context.linecap = "Round"; var radius = center_x-context.linewidth; Context.beginpath (); Context.arc (center_x, center_y, radius,-MATH.PI/2,-MATH.PI/2 +n*rad, false); Used to

Context : Always feel this translates into a "context", the context is an object that encapsulates a lot of drawing functions, and the method to get this object is var context =canvas. GetContext ("2d"); There are two ways that a canvas element paints an image, namelyContext.fill ()//FillContext.stroke ()//Draw BorderStyle: To set the drawing styles before

HTML5 applications that draw SVG content to Canvas, svghtml5 SVG and Canvas are two completely different ways of drawing graphics applications on HTML5. Each of them has its own advantages and disadvantages, but they are not difficult to draw, in particular, the SVG content can be directly drawn on the

After finding the node-canvas library, I simply used it and found it quite useful. Step 1 install You also need to install some dependencies before installing node-canvas. Linux and mac are used as examples to install different systems: Linux: sudo yum install cairo-devel cairomm-devel libjpeg-turbo-devel pango-devel pangomm-devel giflib-devel Mac: brew install pkg-config cairo pango libpng jpeg giflib For

Draw lines on canvasArticleIn, I talked about the method of drawing a straight line. The article on drawing a curve should have been published. However, because the canvas draw curve is special, I have not understood it yet, so I should try it step by step. One of the difficulties in drawing a curve in canvas is that