Question

我在View Controller中有View Controller我已经放置了一个UIImageView我试图以这种方式在UIImageView中显示图像。

- (void)viewDidLoad {
 [super viewDidLoad];
 [self.drawImageView setImage:editableImage];
 UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(drawingViewDidPan:)];
 panGesture.maximumNumberOfTouches = 1;
 self.drawImageView.userInteractionEnabled = YES;
 [self.drawImageView addGestureRecognizer:panGesture];
}

其中drawImageView是我的UIImageView，editableImage是我试图绘制的UIImage。

我正在实施绘图部分如下

- (void)drawingViewDidPan:(UIPanGestureRecognizer*)sender
{
  CGPoint currentDraggingPosition = [sender locationInView:drawImageView];

  if(sender.state == UIGestureRecognizerStateBegan){
     prevDraggingPosition = currentDraggingPosition;
  }

  if(sender.state != UIGestureRecognizerStateEnded){
      [self drawLine:prevDraggingPosition to:currentDraggingPosition];
  }
  prevDraggingPosition = currentDraggingPosition;
}

-(void)drawLine:(CGPoint)from to:(CGPoint)to
{
  CGSize size = drawImageView.frame.size;
  UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);

  CGContextRef context = UIGraphicsGetCurrentContext();

  [drawImageView.image drawAtPoint:CGPointZero];

  CGFloat strokeWidth = 5.0;
  UIColor *strokeColor = [UIColor redColor];

  CGContextSetLineWidth(context, strokeWidth);
  CGContextSetStrokeColorWithColor(context, strokeColor.CGColor);
  CGContextSetLineCap(context, kCGLineCapRound);


  CGContextMoveToPoint(context, from.x, from.y);
  CGContextAddLineToPoint(context, to.x, to.y);
  CGContextStrokePath(context);

  drawImageView.image = UIGraphicsGetImageFromCurrentImageContext();

  UIGraphicsEndImageContext();
}

问题是，一旦我用手指画出UIImage调整大小并变得小休息一切都很好

我该如何解决这个问题？

我的editableImage来自另一个viewcontroller，它有一个名为draw

的按钮

-(IBAction)drawOnOmage:(id)sender {
    [self performSegueWithIdentifier:@"MySegue1" sender:self];
}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
  ThirdViewController *destinationController = (ThirdViewController *)segue.destinationViewController;
  destinationController->editableImage = self.editImage.image;
}

Answer 1

我刚刚将您的代码复制到一个新项目中，它似乎对我有用。我唯一注意到的是你没有对@property使用prevDraggingPosition声明 - 也许这就是问题所在？你能告诉我们你如何申报prevDraggingPosition吗？

看看我的示例（对我有用，我只添加了self.）：

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong) IBOutlet UIImageView *drawImageView;
@property (nonatomic, assign) CGPoint prevDraggingPosition;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(drawingViewDidPan:)];
    panGesture.maximumNumberOfTouches = 1;
    self.drawImageView.userInteractionEnabled = YES;
    [self.drawImageView addGestureRecognizer:panGesture];

}

- (void)drawingViewDidPan:(UIPanGestureRecognizer*)sender
{
    CGPoint currentDraggingPosition = [sender locationInView:self.drawImageView];

    if(sender.state == UIGestureRecognizerStateBegan){
        self.prevDraggingPosition = currentDraggingPosition;
    }

    if(sender.state != UIGestureRecognizerStateEnded){
        [self drawLine:self.prevDraggingPosition to:currentDraggingPosition];
    }
    self.prevDraggingPosition = currentDraggingPosition;
}

-(void)drawLine:(CGPoint)from to:(CGPoint)to
{
    CGSize size = self.drawImageView.frame.size;
    UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);

    CGContextRef context = UIGraphicsGetCurrentContext();

    [self.drawImageView.image drawAtPoint:CGPointZero];

    CGFloat strokeWidth = 5.0;
    UIColor *strokeColor = [UIColor redColor];

    CGContextSetLineWidth(context, strokeWidth);
    CGContextSetStrokeColorWithColor(context, strokeColor.CGColor);
    CGContextSetLineCap(context, kCGLineCapRound);


    CGContextMoveToPoint(context, from.x, from.y);
    CGContextAddLineToPoint(context, to.x, to.y);
    CGContextStrokePath(context);

    self.drawImageView.image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();
}

@end

UIImage意外调整大小

1 个答案: