Revealing the secrets of canvas properties

To explore the secrets of the canvas attribute, specific code examples are required

Canvas is a very powerful graphics drawing tool in HTML5, through which we can easily draw on web pages Create complex graphics, dynamic effects, games, etc. However, in order to use it, we must be familiar with the related properties and methods of Canvas and master how to use them. In this article, we will explore some of the core properties of Canvas and provide specific code examples to help readers better understand how these properties should be used.

1. canvas attributes

1. width and height

The width and height attributes of the Canvas element determine the size of the drawing surface. Both properties default to 300, and you can change the canvas size by setting them. It should be noted that setting these two properties will cause the canvas content to be cleared.

Code example:

<canvas id="myCanvas" width="500" height="500"></canvas>

2. getContext()

getContext() is one of the core methods of Canvas. It returns an object that provides Various methods and properties for drawing on Canvas. This method has only one parameter, which specifies the context type (2d, webgl, etc.).

Code example:

let canvas = document.getElementById("myCanvas");
let ctx = canvas.getContext("2d");

3. style attribute

The style attribute is used to set the style of the Canvas element, including background color, border style, width, etc. It should be noted that this property does not affect the drawn content.

Code example:

<canvas id="myCanvas" width="500" height="500" style="background-color: #f2f2f2; border: 1px solid #000;"></canvas>

2. Drawing properties

1. fillStyle and strokeStyle

The fillStyle property is used to set the fill color, strokeStyle Property is used to set the line color.

Code example:

ctx.fillStyle = "#FF0000";
ctx.strokeSytle = "#000000";

2. lineWidth

The lineWidth property is used to set the line width.

Code example:

ctx.lineWidth = 5;

3. lineCap and lineJoin

The lineCap property is used to set the style of the line endpoints. There are three optional values: butt (flat head ), round (round head) and square (square head). The lineJoin attribute is used to set the style of line intersections. It has three optional values: miter (miter), round (round connection) and bevel (direct).

Code example:

ctx.lineCap = "round";
ctx.lineJoin = "round";

3. Drawing method

1. fillRect and strokeRect

The fillRect method is used to draw a filled rectangle, strokeRect Method used to draw a hollow rectangle.

Code example:

ctx.fillRect(50, 50, 100, 100);
ctx.strokeRect(50, 50, 100, 100);

2. fillText and strokeText

The fillText method is used to draw filled text, and the strokeText method is used to draw hollow text.

Code example:

ctx.font = "30px Arial";
ctx.fillStyle = "#000000";
ctx.fillText("Hello World!", 100, 100);
ctx.strokeStyle = "#FF0000";
ctx.strokeText("Hello World!", 100, 100);

3. beginPath, moveTo, lineTo, arc and closePath

These methods can be combined to draw any complex graphics. The beginPath method is used to start drawing a path, the moveTo method is used to move the brush to the specified coordinates, the lineTo method is used to draw a straight line based on the coordinates, the arc method is used to draw an arc, and the closePath method is used to end the path.

Code example:

ctx.beginPath();
ctx.moveTo(100, 100);
ctx.lineTo(200, 200);
ctx.arc(100, 200, 50, 0, 2 * Math.PI, false);
ctx.closePath();
ctx.fillStyle = "#FF0000";
ctx.fill();

4. Summary

Through the introduction of this article, readers should have a deeper understanding of some core properties of Canvas and be able to use the code Examples are drawn expertly using them. Of course, this is just the tip of the iceberg of Canvas. In future use, we still need to continue to learn, explore and practice to better utilize its power.

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