我想，当我在 iPad 模拟器和设备上使用 iOS 4.3 时，为什么我的应用程序会出现图像失真。看截图。在 iOS 5.1 模拟器和设备上正常显示相同的图像。看第二张截图......我应该如何管理这个？是否可以在显示 JPEG 之前编写一些代码？
不幸的是，我必须修复它，因为我的应用程序必须以某种方式在 iOS 4.3 上运行。
这是一种用于生成拇指的方法：
- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
UIImage *sourceImage = self;
UIImage *newImage = nil;
CGSize imageSize = sourceImage.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
if (CGSizeEqualToSize(imageSize, targetSize) == NO)
{
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if (widthFactor > heightFactor)
scaleFactor = widthFactor; // scale to fit height
else
scaleFactor = heightFactor; // scale to fit width
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
// center the image
if (widthFactor > heightFactor)
{
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}
else
if (widthFactor < heightFactor)
{
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
UIGraphicsBeginImageContext(targetSize); // this will crop
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
if(newImage == nil)
NSLog(@"could not scale image");
//pop the context to get back to the default
UIGraphicsEndImageContext();
return newImage;
}
但是，如果我不使用它来准备我的图像，它仍然是负面的，但工作更慢，因为图像会自动调整大小。
此方法用于显示图像：
-(void) setImage:(UIImage*)image forState:(UIControlState) state
{
[self.buttonView setImage:image forState:state];
}
这边走：
[current setImage:thumb forState:UIControlStateNormal];
是的，我忘了提，这些家伙只是视图控制器的自定义按钮。