ios – 在UIImage周围添加透明空间

让我们说,我们有一个600X400的图像,我们想要一个1000X100的新图像,其中包含初始图像在中心和周围的透明空间.如何在代码中实现？

解决方法

您创建一个1000×1000的新图像上下文,在中间绘制您的旧图像,然后从上下文获取新的UI Image.

// Setup a new context with the correct size
CGFloat width = 1000;
CGFloat height = 1000;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(width,height),NO,0.0);        
CGContextRef context = UIGraphicsGetCurrentContext();       
UIGraphicsPushContext(context);                             

// Now we can draw anything we want into this new context.
CGPoint origin = CGPointMake((width - oldImage.size.width) / 2.0f,(height - oldImage.size.height) / 2.0f);
[oldImage drawAtPoint:origin];

// Clean up and get the new image.
UIGraphicsPopContext();                             
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();