攻略 10-4: 缩放图像

-(void)configureDetailsWithImage:(UIImage *)image label:(NSString *)label showsButtons:(BOOL)showsButton
{
    self.imageView.image = image;
    self.detailDescriptionLabel.text = label;
    if (showsButton == NO)
    {
        self.selectImageButton.hidden = YES;
        self.clearImageButton.hidden = YES;
    }
    else if (showsButton == YES)
    {
        self.selectImageButton.hidden = NO;
        self.clearImageButton.hidden = NO;
    }
}

-(void)setMainImage:(UIImage *)image
{
    [self.filteredImages removeAllObjects];
    if (image != nil)
    {
        [self populateImageViewWithImage:image];
    }
    
    _mainImage = image;
    NSIndexPath *currentIndexPath = self.tableView.indexPathForSelectedRow;
    [self.tableView reloadData];
    [self.tableView selectRowAtIndexPath:currentIndexPath animated:YES scrollPosition:UITableViewScrollPositionTop];
}

+ (UIImage *)scaleImage:(UIImage *)image toSize:(CGSize)size
{
    UIGraphicsBeginImageContext(size);
    [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return scaledImage;
}

+ (UIImage *)aspectScaleImage:(UIImage *)image toSize:(CGSize)size
{
    if (image.size.height < image.size.width)
    {
        float ratio = size.height / image.size.height;
        CGSize newSize = CGSizeMake(image.size.width * ratio, size.height);
        
        UIGraphicsBeginImageContext(newSize);
        [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    }
    else
    {
        float ratio = size.width / image.size.width;
        CGSize newSize = CGSizeMake(size.width, image.size.height*ratio);
        
        UIGraphicsBeginImageContext(newSize);
        [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    }
    UIImage *aspectScaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return aspectScaledImage;
}

+ (UIImage *)aspectFillImage:(UIImage *)image toSize:(CGSize)size
{
    UIGraphicsBeginImageContext(size);
    if (image.size.height< image.size.width)
    {
        float ratio = size.height/image.size.height;
        [image drawInRect:CGRectMake(0, 0, image.size.width*ratio, size.height)];
    }
    else
    {
        float ratio = size.width/image.size.width;
        [image drawInRect:CGRectMake(0, 0, size.width, image.size.height*ratio)];
    }
    UIImage *aspectScaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return aspectScaledImage;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (self.mainImage != nil)
    {
        UIImage *image;
        NSString *label;
        BOOL showsButtons = NO;
        if (indexPath.row == 0)
        {
            image = self.mainImage;
            label = @"Select an Image to Display";
            showsButtons = YES;
        }
        else if (indexPath.row == 1)
        {
            image = [MasterViewController scaleImage:self.mainImage toSize:self.detailViewController.imageView.frame.size];
            label = @"Chosen Image Resized";
        }
        else if (indexPath.row == 2)
        {
            image = [MasterViewController aspectScaleImage:self.mainImage toSize:self.detailViewController.imageView.frame.size];
            label = @"Chosen Image Scaled";
        }
        else if (indexPath.row == 3)
        {
            image = [self.filteredImages objectAtIndex:0];
            CGSize contentSize = self.detailViewController.imageView.frame.size;
            image = [MasterViewController aspectScaleImage:image toSize:contentSize];
            label = @"Hue Adjustment";
        }
        else if (indexPath.row == 4)
        {
            image = [self.filteredImages objectAtIndex:1];
            CGSize contentSize = self.detailViewController.imageView.frame.size;
            image = [MasterViewController aspectScaleImage:image toSize:contentSize];
            label = @"Straightening Filter";
        }
        else if (indexPath.row == 5)
        {
            image = [self.filteredImages objectAtIndex:2];
            CGSize contentSize = self.detailViewController.imageView.frame.size;
            image = [MasterViewController aspectScaleImage:image toSize:contentSize];
            label = @"Series Filter";
        }
        [self.detailViewController configureDetailsWithImage:image label:label showsButtons:showsButtons];
    }
}