UIImage PNG 着色

Question

我想在用户点击 PNG 时为其着色。

我在 Xcode here 中找到了一个示例，但是当我在 C# 中尝试时，我无法检索图像。

这是我写的代码：

public UIImage DrawSelectedBorder(UIImage image)
{
    UIGraphics.BeginImageContextWithOptions(image.Size, false, image.CurrentScale); // for correct resolution on retina, thanks @MobileVet
    CGContext context = UIGraphics.GetCurrentContext();

    context.TranslateCTM(0, image.Size.Height);
    context.ScaleCTM((System.nfloat)1.0, (System.nfloat)(-1.0));

    CGRect rect = new CGRect(0, 0, image.Size.Width, image.Size.Height);

    context.SetBlendMode(CGBlendMode.Normal);
    context.SetFillColor(UIColor.Black.CGColor);
    context.FillRect(rect);


    // draw original image
    context.SetBlendMode(CGBlendMode.Normal);
    context.DrawImage(rect,image.CGImage);

    // tint image (losing alpha) - the luminosity of the original image is preserved
    context.SetBlendMode(CGBlendMode.Color);
    context.FillRect(rect);

    // mask by alpha values of original image
    context.SetBlendMode(CGBlendMode.DestinationIn);
    context.DrawImage(rect, image.CGImage);

    UIImage coloredImage = UIGraphics.GetImageFromCurrentImageContext();
    UIGraphics.EndImageContext();

    return coloredImage;
}

Answer 1

刚刚尝试了您的代码。一切都正确，但您没有选择要填充 PNG 的颜色。

变化：

// tint image (losing alpha) - the luminosity of the original image is preserved
context.SetBlendMode(CGBlendMode.Color);
context.FillRect(rect);

到：

// tint image (losing alpha) - the luminosity of the original image is preserved
context.SetBlendMode(CGBlendMode.Color);
context.SetFillColor(UIColor.Red.CGColor);
context.FillRect(rect);