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实现步骤:
arcTo 可以根据控制点和半径绘制圆弧路径
// 绘制圆角矩形(使用 arcTo) function drawRoundedRect(ctx, x, y, width, height, radius) { // 重置当前路径 ctx.beginPath() // 移动到左上角 ctx.moveTo(x + radius, y) // 绘制右上角 ctx.arcTo(x + width, y, x + width, y + radius, radius) // 绘制右下角 ctx.arcTo(x + width, y + height, x + width - radius, y + height, radius) // 绘制左下角 ctx.arcTo(x, height, x, height - radius, radius) // 绘制左上角 ctx.arcTo(x, y, x + radius, y, radius) // 填充当前路径 ctx.fill() }
quadraticCurveTo 用于创建二次贝塞尔曲线
// 绘制圆角矩形(使用二次贝塞尔曲线 quadraticCurveTo) function drawRoundedRect(ctx, x, y, width, height, radius) { // 重置当前路径 ctx.beginPath() // 移动到右上角 ctx.moveTo(x + width - radius, y) // 绘制右上角曲线 ctx.quadraticCurveTo(x + width, y, x + width, y + radius) // 绘制右边线 ctx.lineTo(x + width, y + height - radius) // 绘制右下角曲线 ctx.quadraticCurveTo(x + width, y + height, x + width - radius, y + height) // 绘制下边线 ctx.lineTo(x + radius, y + height) // 绘制左下角曲线 ctx.quadraticCurveTo(x, y + height, x, y + height - radius) // 绘制左边线 ctx.lineTo(x, y + radius) // 绘制左上角曲线 ctx.quadraticCurveTo(x, y, x + radius, y) // 绘制上边线(创建从当前点回到起始点的路径) ctx.closePath() // 填充当前路径 ctx.fill() }
不得不说贝塞尔曲线真烦人,圆角矩形还是 arcTo 香
clip 可以从原始画布剪切任意形状和尺寸的区域。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Canvas 绘制带圆角的矩形图 — clip</title> </head> <body> <div> <img id="img" src="https://mms1.baidu.com/it/u=181635795,1817021705&fm=253&app=138&f=JPEG&fmt=auto&q=75?w=500&h=284" alt="" /> </div> <canvas id="canvas" width="500" height="284"></canvas> <script> // 绘制圆角矩形(使用 arcTo) function drawRoundedRect(ctx, x, y, width, height, radius) { // 保存当前环境的状态 ctx.save() // 重置当前路径 ctx.beginPath() // 移动到左上角 ctx.moveTo(x + radius, y) // 绘制右上角 ctx.arcTo(x + width, y, x + width, y + radius, radius) // 绘制右下角 ctx.arcTo(x + width, y + height, x + width - radius, y + height, radius) // 绘制左下角 ctx.arcTo(x, height, x, height - radius, radius) // 绘制左上角 ctx.arcTo(x, y, x + radius, y, radius) // 填充当前路径 ctx.fill() } const img = document.getElementById('img') const canvas = document.getElementById('canvas') const ctx = canvas.getContext('2d') window.onload = function () { const x = 0 const y = 0 const width = canvas.width const height = canvas.height let radius = 50 // 处理圆角边界值 radius = Math.min(radius, Math.min(width, height) / 2) // 绘制圆角矩形 drawRoundedRect(ctx, x, y, width, height, radius) // 对矩形进行剪切 ctx.clip() // 绘制图片 ctx.drawImage(img, x, y, width, height) } </script> </body> </html>
CodeSandbox: Canvas 绘制带圆角的矩形图 — clip
globalCompositeOperation 可以设置要在绘制新形状时应用的合成操作的类型
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Canvas 绘制带圆角的矩形图 — globalCompositeOperation</title> </head> <body> <div> <img id="img" src="https://mms1.baidu.com/it/u=181635795,1817021705&fm=253&app=138&f=JPEG&fmt=auto&q=75?w=500&h=284" alt="" /> </div> <canvas id="canvas" width="500" height="284"></canvas> <script> // 绘制圆角矩形(使用 arcTo) function drawRoundedRect(ctx, x, y, width, height, radius) { // 保存当前环境的状态 ctx.save() // 重置当前路径 ctx.beginPath() // 移动到左上角 ctx.moveTo(x + radius, y) // 绘制右上角 ctx.arcTo(x + width, y, x + width, y + radius, radius) // 绘制右下角 ctx.arcTo(x + width, y + height, x + width - radius, y + height, radius) // 绘制左下角 ctx.arcTo(x, height, x, height - radius, radius) // 绘制左上角 ctx.arcTo(x, y, x + radius, y, radius) // 填充当前路径 ctx.fill() } const img = document.getElementById('img') const canvas = document.getElementById('canvas') const ctx = canvas.getContext('2d') window.onload = function () { const x = 0 const y = 0 const width = canvas.width const height = canvas.height let radius = 600 // 处理圆角边界值 radius = Math.min(radius, Math.min(width, height) / 2) // 绘制圆角矩形 drawRoundedRect(ctx, x, y, width, height, radius) // 只在新图形和目标画布重叠的地方绘制图形 ctx.globalCompositeOperation = 'source-in' // 绘制图片 ctx.drawImage(img, x, y, width, height) } </script> </body> </html>
CodeSandbox: Canvas 绘制带圆角的矩形图 — globalCompositeOperation
这是李总教我的方案,再次膜拜一下大佬
The text was updated successfully, but these errors were encountered:
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Canvas 绘制带圆角的矩形图
实现步骤:
绘制圆角矩形
arcTo 方案
arcTo 可以根据控制点和半径绘制圆弧路径
quadraticCurveTo 二次贝塞尔曲线方案
quadraticCurveTo 用于创建二次贝塞尔曲线
不得不说贝塞尔曲线真烦人,圆角矩形还是 arcTo 香
绘制图片
clip 方案
clip 可以从原始画布剪切任意形状和尺寸的区域。
CodeSandbox: Canvas 绘制带圆角的矩形图 — clip
globalCompositeOperation 方案
globalCompositeOperation 可以设置要在绘制新形状时应用的合成操作的类型
CodeSandbox: Canvas 绘制带圆角的矩形图 — globalCompositeOperation
这是李总教我的方案,再次膜拜一下大佬
相关资料
The text was updated successfully, but these errors were encountered: