html5-canvas

问题 Is it possible to write image on canvas and write text with background? For example like this: 回答1: How text works in canvas Unfortunately no, you can't produce text with background with the text methods - only fill or outline the text itself. This is because the glyphs from the typeface (font) are converted to individual shapes or paths if you want, where the background of it would be the inner part of the glyph itself (the part you see when using fill). There is no layer for the black-box

问题 I'm having problems with Canvas gradient it only shows the last color that I set on gradient.__addColorStop__(offset,color) method. For example here is a piece of my code to understand better: let canvas = document.getElementById('canvas'); let ctx = canvas.getContext('2d'); let gradient = ctx.createLinearGradient(10, 90, 200, 90); gradient.addColorStop(1 / 10, "black"); gradient.addColorStop(1 / 5, "yellow"); gradient.addColorStop(1 / 1, "red"); let circle1 = new Circle(300, 250, 50,

问题 I want to give my users an easy way to visually trace a route on a map or a picture. The solution must let the users add control points that they can use to put bends into the route. It should work with html5 canvas - I currently use the Konvajs library so a solution that uses this would be good. In the interests of sharing & learning, if you can suggest solutions using other HTML5 canvas libraries that would be good to see too. Note: This is not the original question posed. However it

问题 I want to give my users an easy way to visually trace a route on a map or a picture. The solution must let the users add control points that they can use to put bends into the route. It should work with html5 canvas - I currently use the Konvajs library so a solution that uses this would be good. In the interests of sharing & learning, if you can suggest solutions using other HTML5 canvas libraries that would be good to see too. Note: This is not the original question posed. However it

问题 I want to give my users an easy way to visually trace a route on a map or a picture. The solution must let the users add control points that they can use to put bends into the route. It should work with html5 canvas - I currently use the Konvajs library so a solution that uses this would be good. In the interests of sharing & learning, if you can suggest solutions using other HTML5 canvas libraries that would be good to see too. Note: This is not the original question posed. However it

问题 How do i bind onclick event to piechart segment? https://github.com/sauminkirve/HTML5/blob/master/PieChart/piechart.html 回答1: A pie chart segment is really a wedge. You have several ways to hit-test a wedge. One way is the math way: Test if the mouse is within the radius of a circle created by the wedges. If the radius test is true, then calculate the angle of the mouse versus the circle's centerpoint. Compare that angle to each wedge. If the angle is between the starting and ending angle of

问题 How do i bind onclick event to piechart segment? https://github.com/sauminkirve/HTML5/blob/master/PieChart/piechart.html 回答1: A pie chart segment is really a wedge. You have several ways to hit-test a wedge. One way is the math way: Test if the mouse is within the radius of a circle created by the wedges. If the radius test is true, then calculate the angle of the mouse versus the circle's centerpoint. Compare that angle to each wedge. If the angle is between the starting and ending angle of

问题 Hey guys so I have a sprite sheet with multiple sprites that I want to use to animate a website using canvas. However the problem I am having is I don't know how to go about reading in only the frames that I need. Example: 1 1 1 2 2 2 2 2 3 3 4 4 4 4 4 4 Here I have 4 different sprites that I want to animate. How would I go about retrieving and animating the correct frames? P.S I'm using javascript. 回答1: Retrieving and Playing multiple sprites on a spritesheet Retrieving: Create an object

问题 I'm trying to make a simple game (view from above) on canvas. Please tell me, which is faster: 1) Draw everything on one <canvas> and calculate the areas that need to be redrawn. 2) Draw certain parts of the scene on different <canvas> elements and update each only if necessary. In the it variant, probably, I can also use a partial redraw. For example, I could draw a map on one element, enemies on the second, and a cursor and etc on the third. When moving enemies, I could only redraw the

问题 I want to have it so that when i create a "component" i can set its radius to make it curved. Below is my code for component create: function component(width, height, color, x, y) { this.width = width; this.height = height; this.speedX = 0; this.speedY = 0; this.x = x; this.y = y; this.color = color; this.update = function() { ctx = GameArena.context; ctx.fillStyle = this.color; ctx.fillRect(this.x, this.y, this.width, this.height); } } as you can see it specifies the width height, color and