您好，能否提供个可运行的代码片段（https://developers.weixin.qq.com/miniprogram/dev/devtools/minicode.html）。

看了一下你的代码，有两个问题：

一个是因为你的格式有问题，改成以下代码即可：

var c2 = 'rgb(' + (c1) + ','+ (c1) +','+ (c1) + ")"

另外一个得把setFillStyle方法改成fillStyle，如：

context.fillStyle = c2

var canvas = wx.createCanvas("fore")

var scrw = 0

var scrh = 0

var minV = 0

wx.getSystemInfo

(

{

success: function (res)

{

scrh = res.windowHeight

scrw = res.windowWidth

minV = scrh

if (scrh > scrw)

minV = scrw

}

}

)

canvas.width = minV

canvas.height = minV

// console.log(canvas.width, canvas.height)

var context = canvas.getContext('2d')

var a = 10

var b = minV - 20

context.fillStyle = 'rgb(200,100,100)'

var i = 0

while (i < 20) {

var c1 = (20 - i) * 10

var c2 = "'"+'rgb(' + c1 + ','+ c1 +','+ c1 + ")'"

console.log(c2)

context.setFillStyle = c2

context.fillRect(a + i, a + i, b - i * 2, b - i * 2)

i = i + 1

}

var offScreenCanvas1 = wx.createCanvas()

var offContext1 = offScreenCanvas1.getContext('2d')

offContext1.fillStyle = 'blue'

offContext1.fillRect(0, 0, 100, 100)

context.drawImage(offScreenCanvas1, 100, 100);