uiimageview上的Alpha蒙版漸變

Question

我希望能夠在圖像的邊緣添加Alpha漸變以使其「淡入」到下一個圖像中。下面的圖片解釋了我想要做的事情。

如何做到這一點任何想法？我沒有太多的圖形背景經驗，這就是爲什麼我在這裏尋求幫助。

Answer 1

您可以查看本代碼並張貼結果。

UIImage* first = [[UIImage alloc]initWithContentsOfFile:@"firstImagePath"]; 
UIImage* second = [[UIImage alloc]initWithContentsOfFile:@"secondImagePath"]; 
CGSize sizeToSet; 
int mergeArea = 200; 
sizeToSet.width = first.size.width + second.size.width - mergeArea; 
sizeToSet.height = first.size.height; 

UIGraphicsBeginImageContext(sizeToSet); 

[first drawAtPoint:CGPointMake(0, 0)]; 
[second drawAtPoint:CGPointMake(first.size.width - mergeArea, 0) blendMode:kCGBlendModeLuminosity alpha:1.0f]; 

UIImageView* imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 300, 300)]; 
[imageView setCenter:self.view.center]; 
[imageView setImage:UIGraphicsGetImageFromCurrentImageContext()]; 

UIGraphicsEndImageContext(); 

[[self view]addSubview:imageView]; 

[imageView release]; 
[first release]; 
[second release];