將多行文本區域添加到圖像

基本上，我想爲圖像添加一個任意文本的區域。所以之後圖像尺寸變大。這是我想出來的：將多行文本區域添加到圖像

public partial class ViewController : UIViewController 
{ 
    public override void ViewDidLoad() 
    { 
     base.ViewDidLoad(); 

     string filename = "TestImage.jpg"; 
     string bundlePath = NSBundle.MainBundle.BundlePath; 
     string sourcePath = Path.Combine(bundlePath, filename); 
     string docPath = Environment.GetFolderPath(Environment.SpecialFolder.Personal); 
     string destinationPath = Path.Combine(docPath, filename); 
     File.Copy(sourcePath, destinationPath, true); 

     string testString = "Lorem ipsum dolor sit amet"; 
     this.AddTextToImage(testString, destinationPath); 

     var imageView = new UIImageView(new CGRect(0, 0, 500, 500)); 
     imageView.ContentMode = UIViewContentMode.ScaleAspectFit; 
     imageView.Image = UIImage.FromFile(destinationPath); 
     this.View.AddSubview(imageView); 
     this.View.BackgroundColor = UIColor.Red; 
    } 


    public void AddTextToImage(string texttoadd, string filepath) 
    { 
     UIImage image = UIImage.FromFile(filepath); 
     nfloat fontSize = 16; 

     nfloat fWidth = image.Size.Width; 
     nfloat fHeight = image.Size.Height; 
     nfloat textWidth; 
     nfloat textHeight; 

     CGColorSpace colorSpace = CGColorSpace.CreateDeviceRGB(); 

     UIFont font = UIFont.FromName("Helvetica", fontSize); 
     NSParagraphStyle style = new NSMutableParagraphStyle(); 
     style.LineBreakMode = UILineBreakMode.WordWrap; 
     NSAttributedString attributedString = new NSAttributedString(texttoadd, font: font, foregroundColor: UIColor.Blue, paragraphStyle: style); 
     CGRect stringSize = attributedString.GetBoundingRect(new CGSize(fWidth, double.MaxValue), NSStringDrawingOptions.UsesLineFragmentOrigin | NSStringDrawingOptions.UsesFontLeading, null); 
     textWidth = (nfloat)Math.Ceiling(stringSize.Width); 
     textHeight = (nfloat)Math.Ceiling(stringSize.Height); 

     nfloat fullWidth = fWidth; 
     nfloat fullHeight = fHeight + textHeight; 
     UIImage composition; 

     using (CGBitmapContext ctx = new CGBitmapContext(IntPtr.Zero, (nint)fullWidth, (nint)fullHeight, 8, 4 * (nint)fullWidth, CGColorSpace.CreateDeviceRGB(), CGImageAlphaInfo.PremultipliedFirst)) 
     { 
      CGRect frameRect = new CGRect(0, 0, fullWidth, fullHeight); 

      ctx.SetFillColor(UIColor.Yellow.CGColor); 
      ctx.FillRect(frameRect); 

      CGRect imageRect = new CGRect(0, textHeight, (double)fWidth, (double)fHeight); 
      ctx.DrawImage(imageRect, image.CGImage); 

      CGPath stringPath = new CGPath(); 
      stringPath.AddRect(new CGRect(0, 0, textWidth, textHeight)); 
      CTFramesetter framesetter = new CTFramesetter(attributedString); 
      CTFrame frame = framesetter.GetFrame(new NSRange(0, attributedString.Length), stringPath, null); 
      frame.Draw(ctx); 

      using (var imageRef = ctx.ToImage()) 
       composition = new UIImage(imageRef); 
     } 

     NSData data = composition.AsJPEG(); 
     NSError error; 
     data.Save(filepath, NSDataWritingOptions.FileProtectionNone, out error); 
    } 
}

目前，我有以下問題：

文本被裁剪（例如fontSize = 160;）。多行文字似乎不起作用。
文本根本不顯示（例如fontSize = 16;）。

你可以在Objective-C，Swift或C＃中提供答案 - 我會試着翻譯它。

來源

2017-08-25 testing

似乎字體是問題。使用

UIFont font = UIFont.SystemFontOfSize(fontSize);

現在可以在不切斷文本的情況下完成任務。剩下的唯一問題是，爲什麼？

來源

2017-08-28 11:55:16 testing

將多行文本區域添加到圖像

回答

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