cocoa - 将 NSTextField 转换为 NSImage？

Question

有什么方法可以从 NSTextField 创建 NSImage 吗？我正在制作一个应该捕获用户文本并生成 PNG 文件的应用程序。

Answer 1

是的，让视图绘制成图像：

-(NSImage *)imageOfView:(NSView*)view
{
 NSRect myRect = view.bounds;
 NSSize imgSize = myRect.size;

 NSBitmapImageRep *bir = [view bitmapImageRepForCachingDisplayInRect:myRect];
 [bir setSize:mySize];
 [view cacheDisplayInRect:myRect toBitmapImageRep:bir];

 NSImage* image = [[[NSImage alloc]initWithSize:mySize] autorelease];
 [image addRepresentation:bir];
 return image;
}

来自http://www.stairways.com/blog/2009-04-21-nsimage-from-nsview

---

如果您只想要字符串，请使用 NSString 的 drawString 方法自己渲染它，如下所示：

-(NSImage *)imageWithText(NSString*)string:
{
 NSSize mySize = NSMakeSize(50,100); //or measure the string

 NSBitmapImageRep *bir = NSBitmapImageRep *bitmap = [[NSBitmapImageRep alloc]
    initWithBitmapDataPlanes:(unsigned char **)&bitmapArray
    pixelsWide:mySize.width pixelsHigh:mySize.height
    bitsPerSample:8
    samplesPerPixel:3  // or 4 with alpha
    hasAlpha:NO
    isPlanar:NO
    colorSpaceName:NSDeviceRGBColorSpace
    bitmapFormat:0
    bytesPerRow:0  // 0 == determine automatically
    bitsPerPixel:0];  // 0 == determine automatically

    //draw text using -(void)drawInRect:(NSRect)aRect withAttributes:(NSDictionary *)attributes

 NSImage* image = [[[NSImage alloc]initWithSize:mySize] autorelease];
 [image addRepresentation:bir];
 return image;
}

Answer 2

在 Swift 5 中：

  private func convertTextFieldToImage() -> NSImage? {
    let myRect = timerLabel.bounds
    let mySize = myRect.size

    guard let bitmapImageRepresentation = timerLabel.bitmapImageRepForCachingDisplay(in: myRect) else {
      return nil
    }
    bitmapImageRepresentation.size = mySize
    timerLabel.cacheDisplay(in: myRect, to: bitmapImageRepresentation)

    let image = NSImage(size: mySize)
    image.addRepresentation(bitmapImageRepresentation)

    return image
  }