要應(yīng)用漸變到Canvas形狀上，需按以下步驟操作：1. 使用createLinearGradient()或createRadialGradient()創(chuàng)建漸變並定義其坐標(biāo)範(fàn)圍；2. 通過(guò)addColorStop()添加一個(gè)或多個(gè)顏色節(jié)點(diǎn)以設(shè)定漸變色彩；3. 將漸變對(duì)象賦值給fillStyle或strokeStyle屬性；4. 使用fillRect、arc等繪製方法創(chuàng)建形狀，漸變將自動(dòng)填充。注意漸變基於畫布坐標(biāo)系，移動(dòng)形狀時(shí)需重新調(diào)整漸變坐標(biāo)才能保持視覺(jué)一致，最終效果取決於坐標(biāo)設(shè)定與顏色過(guò)渡的精確控制。

Applying gradients to shapes on a canvas—especially in web development using HTML5 Canvas—requires a few clear steps. You create a gradient, assign it as the fill style, and then draw the shape. Here's how it works:

1. Create a Gradient with createLinearGradient() or createRadialGradient()

First, you need to define the type of gradient. The two main types are linear and radial.

• Linear Gradient : Flows in a straight line.
• Radial Gradient : Radiates outward from a central point.

 const canvas = document.getElementById('myCanvas');
const ctx = canvas.getContext('2d');

// Create a linear gradient from left to right
const linearGradient = ctx.createLinearGradient(0, 0, 200, 0);
linearGradient.addColorStop(0, 'red');
linearGradient.addColorStop(1, 'blue');

// Or create a radial gradient
const radialGradient = ctx.createRadialGradient(100, 100, 10, 100, 100, 50);
radialGradient.addColorStop(0, 'yellow');
radialGradient.addColorStop(1, 'transparent');

The parameters for createLinearGradient(x1, y1, x2, y2) define the start and end points of the gradient line. For createRadialGradient(x1, y1, r1, x2, y2, r2) , you define two circles: where the gradient starts and ends.

2. Assign the Gradient as the Fill Style

Once the gradient is defined, set it as the current fillStyle :

 ctx.fillStyle = linearGradient;
// or
ctx.fillStyle = radialGradient;

3. Draw the Shape

Now, when you draw a shape using methods like fillRect , fill , or arc , it will be filled with the gradient:

 // Draw a rectangle with linear gradient
ctx.fillRect(10, 10, 200, 100);

// Draw a circle with radial gradient
ctx.beginPath();
ctx.arc(100, 100, 50, 0, Math.PI * 2);
ctx.fillStyle = radialGradient;
ctx.fill();

Adding Multiple Color Stops

You can make gradients smoother or more complex by adding more color stops:

 const gradient = ctx.createLinearGradient(0, 0, 200, 0);
gradient.addColorStop(0, 'purple');
gradient.addColorStop(0.5, 'cyan');
gradient.addColorStop(1, 'orange');
ctx.fillStyle = gradient;
ctx.fillRect(10, 130, 200, 100);

This creates a smooth transition across three colors.

A few things to keep in mind:

• Gradients are tied to canvas coordinates, not shape positions. So if you move a shape, the gradient won't automatically reposition unless you recreate it.
• You can also apply gradients to strokes using strokeStyle instead of fillStyle .

Basically, it's about defining the gradient space, setting colors at key points, and using it like any other fill. Not hard once you get the coordinate logic down.

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