CSS implements arrow code of any size, direction and angle

This article mainly introduces you to the relevant information about using css to realize arrow examples of any size, any direction and any angle. The editor thinks it is quite good. Now I will share it with you and give you a reference. I hope it can help. Everyone.

In web development, the drop-down arrow

is often used, and the right arrow

Such an arrow. It is generally implemented using css:

{  
        display: inline-block;  
        margin: 72px;  
        border-top: 24px solid;
        border-right: 24px solid;  
        width: 120px;
        height: 120px;  
        transform: rotate(45deg); 
    }

Because this is achieved by using the border-top and border-right of p, and then rotating the p.

Arrows at any angle

Here is a question: What if you need an arrow with an angle of 120 degrees? Since border-top and border-right are always 90 degrees, just rotation will not work. We can first rotate p 45 degrees to make it a rhombus, and then stretch it to reach any angle, so that we can get an arrow at any angle. Since two transformations, rotation and scaling, are used, you need to use the transformation matrix transform: matrix(a,b,c,d,e,f). The 6 variables here form a 3-dimensional transformation matrix

The translation, rotation, expansion transformation and various combinations of any point p(x,y) can be achieved through this transformation matrix:

Note: Homogeneous coordinates are used here to express a point. Simply put, p(x, y) is expressed as p'(x', y', 1)

Translation matrix

v(x, y) translates tx along the x-axis, along Translate ty along the y-axis. Then there is:

x' = x + tx
y' = y + ty

So the translation matrix:

Rotation Matrix

v(x, y) point is rotated θ around the origin to v'(x', y')

then there is:

x = r * cos(ϕ )
y = r * sin(ϕ )

x' = r * cos(θ + ϕ) = r * cos(θ ) * cos(ϕ) - r * sin(θ) * sin(ϕ ) // Cosine formula
y' = r * sin(θ + ϕ) = r * sin(θ) * cos(ϕ) + r * cos(θ) * sin(ϕ ) // Sine formula

So:

x' = x * cos(θ) - y * sin(θ)
y' = x * sin(θ) + y * cos(θ)

So the rotation matrix:

Stretching matrix

Assume that the expansion ratios of the x-axis and y-axis are kx and ky respectively. Then there is:

x' = x * kx
y' = y * ky

So:

Compound transformation

What if p(x, y) is first translated (transformation matrix A), then rotated (transformation matrix B), and then stretched (transformation matrix C)?

p' =C(B(Ap)) ==> p' = (CBA)p //Matrix multiplication combination rate

Now the arrow at any angle o is very simple:

First put p is rotated 45 degrees to become a rhombus, transformed into M1 Telescopic x-axis, y-axis:

x' = size * cos(o/2) = x * √2 *  cos(o/2)
y' = size * sin(o/2) = y *  √2  * sin(o/2)

That is: kx = √2 * cos(o/ 2); ky = √2 * sin(o/2) In this way, an arrow at any angle is obtained. Transform to M2

If the direction of the arrow is not pointing to the right, you can get an arrow in any direction by performing a rotation. Transformed to M3

, then since p' =C(B(Ap)) ==> p' = (CBA)p, we can calculate it first Extract M3 M2 M1, and then transform p accordingly, you can get arrows at any angle and direction.

The width and height of p are the side lengths of the arrow. By adjusting, you can get an arrow with any side length.

React component

For ease of use, this arrow is encapsulated into a React component.

Example

Simple arrow

##Simulate select

Divergent arrows

props

安装使用

npm install rc-arrow --save

import Arrow from 'rc-arrow'

class Hw extends Component {
    render() {
        return (
            <Arrow size="20px" color="red"/>
        )
    }
}

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