使用 UIGraphicsImageRenderer 时如何设置比例

How to set the scale when using UIGraphicsImageRenderer(使用 UIGraphicsImageRenderer 时如何设置比例)

问题描述

默认情况下 UIGraphicsImageRenderer 将比例设置为设备的屏幕比例，在 iPhone 6s 上它是 2x 和 iPhone 6s Plus 3x，因此即使你给它一个尺寸为 300 的尺寸，它也会创建它600 或 900 取决于正在使用的设备.当你想确保它始终是 300 时，你如何设置比例?

By default UIGraphicsImageRenderer sets the scale to the device's screen scale, on iPhone 6s it's 2x and iPhone 6s Plus 3x, therefore even though you've given it a size with dimension 300 it's creating it at either 600 or 900 depending on which device is being used. When you want to ensure it's always 300, how do you set the scale?

let outputBounds = CGRect(x: 0, y: 0, width: 300, height: 300)
let renderer = UIGraphicsImageRenderer(bounds: outputBounds)
let image = renderer.image { context in
     //...
}

之前您可以通过此处的最后一个参数设置比例:UIGraphicsBeginImageContextWithOptions(bounds.size, false, 1)

Previously you would set the scale via the last parameter here: UIGraphicsBeginImageContextWithOptions(bounds.size, false, 1)

推荐答案

您应该在创建 UIGraphicsImageRenderer 时使用 UIGraphicsImageRendererFormat 类.如果您想写入精确的像素而不是缩放点，请使用以下内容:

You should use the UIGraphicsImageRendererFormat class when creating your UIGraphicsImageRenderer. If you want to write exact pixels rather than scaled points, use something like this:

let format = UIGraphicsImageRendererFormat()
format.scale = 1

let renderer = UIGraphicsImageRenderer(size: yourImageSize, format: format)
let image = renderer.image { ctx in
    // etc
}

我保留了一份iOS 10 代码示例列表，并将在此基础上添加一个.

I'm keeping a list of iOS 10 code examples and will add one based on this.

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