如何在没有 UIScrollView 的情况下放大和缩小 UIImageView?

How can i zoom in and out in a UIImageView without UIScrollView?(如何在没有 UIScrollView 的情况下放大和缩小 UIImageView?)

问题描述

我正在为 iOS 4.2、iPhone 开发一个应用程序，在这个应用程序中我下载图像并将它们保存在内部存储 (NSDocuments) 中.

I'm developing an app for iOS 4.2, iPhone, in this app I download images and I save them in the internal storage (NSDocuments).

那么，我在 UIImageView 中显示第一张图片.用户可以在 UIImageView (TouchesMoved) 上拖动手指，当用户这样做时，我会加载其他图像.如果用户向下拖动，我会加载一张图片，如果向上拖动，我会加载另一张图片，并且左右也可以.

Well, then I show the first image in a UIImageView. The user can drag their finger on the UIImageView (TouchesMoved), when the user do that, I load other image. If the user drag down, I load one image, if drag up, i load other, and also with right and left.

这一切都完成了.但我想实现缩放.到目前为止，这是我的代码:

This is all done. But I want to implement zooming. This is my code until now:

initialDistance --> 是第一次触摸时手指之间的距离
finalDistance --> 是手指每次移动时的距离
x --> 是 0
y --> 为 0

initialDistance --> is the distance between the fingers at first touch
finalDistance --> is the distance between the fingers each time they move
x --> is 0
y --> is 0

    // this method calculate the distance between 2 fingers
    - (CGFloat)distanceBetweenTwoPoints:(CGPoint)fromPoint toPoint:(CGPoint)toPoint {
        float xPoint = toPoint.x - fromPoint.x;
        float yPoint = toPoint.y - fromPoint.y;

        return sqrt(xPoint * xPoint + yPoint * yPoint);
     }

        //------------------- Movimientos con los dedos ------------------------------------
        #pragma mark -
        #pragma mark UIResponder

          // First Touch
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{

NSSet *allTouches = [event allTouches];

switch ([allTouches count]) {
    case 1: { //Single touch

        //Get the first touch.
        UITouch *touch1 = [[allTouches allObjects] objectAtIndex:0];

        switch ([touch1 tapCount])
        {
            case 1: //Single Tap.
            {
                // Guardo la primera localización del dedo cuando pulsa por primera vez
                //inicial = [touch1 locationInView:self.view];

            } break;
            case 2: {//Double tap. 
                //Track the initial distance between two fingers.
                //if ([[allTouches allObjects] count] >= 2) {

                // oculto/o no, la barra de arriba cuando se hace un dobleTap
                //[self switchToolBar];

            } break;
        }
    } break;
    case 2: { //Double Touch

        // calculo la distancia inicial que hay entre los dedos cuando empieza a tocar
        UITouch *touch1 = [[allTouches allObjects] objectAtIndex:0];
        UITouch *touch2 = [[allTouches allObjects] objectAtIndex:1];

        initialDistance = [self distanceBetweenTwoPoints:[touch1 locationInView:[self view]]
                                                 toPoint:[touch2 locationInView:[self view]]];
    }
    default:
        break;
}
}

// when the finger/s move to 
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{

NSSet *allTouches = [event allTouches];

switch ([allTouches count])
{
    case 1: {



    } break;
    case 2: {
        //The image is being zoomed in or out.

        UITouch *touch1 = [[allTouches allObjects] objectAtIndex:0];
        UITouch *touch2 = [[allTouches allObjects] objectAtIndex:1];

        //Calculate the distance between the two fingers.
        CGFloat finalDistance = [self distanceBetweenTwoPoints:[touch1 locationInView:[self view]]
                                                       toPoint:[touch2 locationInView:[self view]]];

        NSLog(@"Distancia Inicial :: %.f, Ditancia final :: %.f", initialDistance, finalDistance);

        float factorX = 20.0;
        float factorY = 11.0;

        // guardo la posicion de los 2 dedos
        //CGPoint dedo1 = [[[touches allObjects] objectAtIndex:0] locationInView:self.view];
        //CGPoint dedo2 = [[[touches allObjects] objectAtIndex:1] locationInView:self.view];

        // comparo para saber si el usuario esta haciendo zoom in o zoom out
        if(initialDistance < finalDistance) {
            NSLog(@"Zoom In");

            float newWidth = imagen.frame.size.width + (initialDistance - finalDistance + factorX);
            float newHeight = imagen.frame.size.height + (initialDistance - finalDistance + factorY);

            if (newWidth <= 960 && newHeight <= 640) {
                /*
                 if (dedo1.x >= dedo2.x) {
                 x = (dedo1.x + finalDistance/2); 
                 y = (dedo1.y + finalDistance/2);
                 } else {
                 x = (dedo2.x + finalDistance/2); 
                 y = (dedo2.y + finalDistance/2);
                 }
                 */

                //x = (dedo1.x);
                //y = (dedo1.y);

                imagen.frame = CGRectMake( x, y, newWidth, newHeight);
            } else {
                imagen.frame = CGRectMake( x, y, 960, 640);
            }



        }
        else {
            NSLog(@"Zoom Out");

            float newWidth = imagen.frame.size.width - (finalDistance - initialDistance + factorX);
            float newHeight = imagen.frame.size.height - (finalDistance - initialDistance + factorY);

            if (newWidth >= 480 && newHeight >= 320) { 
                /*
                 if (dedo1.x >= dedo2.x) {
                 x = (dedo1.x + finalDistance/2); 
                 y = (dedo1.y + finalDistance/2);
                 } else {
                 x = (dedo2.x + finalDistance/2); 
                 y = (dedo2.y + finalDistance/2);
                 }
                 */
                //x -= (finalDistance - initialDistance + factorX); 
                //y -= (finalDistance - initialDistance + factorX); 

                //x = (dedo1.x);
                //y = (dedo1.y);

                imagen.frame = CGRectMake( x, y, newWidth, newHeight);
            } else {
                imagen.frame = CGRectMake( 0, 0, 480, 320);
            }



        }

        initialDistance = finalDistance;

    } break;
}
}

#pragma mark -

非常感谢！！

PD:如果有 UIScrollView 的方法可以在不同的图像之间移动，我也愿意看看.

PD: If there is a method with UIScrollView whitch I can move between different images, I m open to take a look too.

推荐答案

好的.如果只是将它用于缩放功能，您可以考虑使用 UIScrollView.

Ok. You can consider using a UIScrollView if only to use it for its zoom functionality.

假设我们有一个 scrollView 和一个 imageView 两者具有相同的边界.添加 imageView 作为 scrollView 的子视图.

Say we have a scrollView and a imageView with both having the same bounds. Add the imageView as the subview of scrollView.

[scrollView addSubview:imageView];
scrollView.contentSize = imageView.frame.size;

要在 scrollView 中仅支持缩放而不支持平移，您的 viewController 必须采用 UIScrollViewDelegate 协议.

To support only zoom and not not panning in the scrollView your viewController will have to adopt the UIScrollViewDelegate protocol.

// Disabling panning/scrolling in the scrollView
scrollView.scrollEnabled = NO;

// For supporting zoom,
scrollView.minimumZoomScale = 0.5;
scrollView.maximumZoomScale = 2.0;

...

// Implement a single scroll view delegate method
- (UIView*)viewForZoomingInScrollView:(UIScrollView *)aScrollView {
    return imageView;
}

现在我们可以进行缩放了.对于滑动，您可以使用适当配置的 UISwipeGestureRecognizers.创建用于处理每个滑动方向的手势并将其添加到滚动视图.

By now we have zooming available. For swipes, you can use appropriately configured UISwipeGestureRecognizers. Create a gesture for handling each swipe direction and add it to scroll view.

UISwipeGestureRecognizer *rightSwipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self selector:@selector(handleRightSwipe:)];
rightSwipe.direction = UISwipeGestureRecognizerDirectionRight;
rightSwipe.numberOfTouchesRequired = 1;
[scrollView addGesture:rightSwipe];
[rightSwipe release];

并根据手势检索适当的图像并使用 imageView.image = yourImage; 进行设置.

And retrieve the appropriate image based on the gesture and set it using imageView.image = yourImage;.

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