UIImage vs NSImage：在iOS中绘制为离屏图像 [英] UIImage vs NSImage: Drawing to an off screen image in iOS

问题描述

在mac osx（可可）中，很容易将特定大小的空白图片绘制到屏幕外：

  NSImage * image = [[NSImage alloc] initWithSize：NSMakeSize（64,64）]; 
 [image lockFocus]; 
 / *这里绘制代码* / 
 [image unlockFocus];然而，在iOS（可可触摸）中，似乎没有对UIImage的等效调用。
  

我想使用UIImage（或一些其他等效类）做同样的事情。也就是说，我想使用 UIRectFill（...）和 [UIBezierPath]这样的调用来创建一个显式大小的初始空图像

解决方案

/ div>

CoreGraphics在这里需要，因为UIImage没有像你解释的高级功能。

  UIGraphicsBeginImageContext （CGSizeMake（64,64））; 
 
 CGContextRef context = UIGraphicsGetCurrentContext（）; 
 //在这里绘制代码（使用上下文）
 
 UIImage * image = UIGraphicsGetImageFromCurrentImageContext（）; 
 UIGraphicsEndImageContext（）; 
  

In mac osx (cocoa), It is very easy to make a blank image of a specific size and draw to it off screen:

NSImage* image = [[NSImage alloc] initWithSize:NSMakeSize(64,64)];
[image lockFocus];
/* drawing code here */
[image unlockFocus];

However, in iOS (cocoa touch) there does not seem to be equivalent calls for UIImage. I want to use UIImage (or some other equivalent class) to do the same thing. That is, I want to make an explicitly size, initially empty image to which I can draw using calls like UIRectFill(...) and [UIBezierPath stroke].

How would I do this?

解决方案

CoreGraphics is needed here, as UIImage does not have high level functions like what you explained..

UIGraphicsBeginImageContext(CGSizeMake(64,64));

CGContextRef context = UIGraphicsGetCurrentContext();
// drawing code here (using context)

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

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