在iOS上，在iPad上捏缩放图像移动到左上角？ [英] Pinch zoom shifting image to most left corner on iPad in iOS?

问题描述

我在iOS中有一张图片。当我捏住移动到左上角的图像时，我在图像上添加了捏合手势。我还在图像上添加了平移手势。当图像被缩放时，我在每个方向上滚动图像为此目的我已将平移手势添加到图像中。

I have a image in iOS. I have added pinch gesture on the image when i pinch the image it shifted to top left corner. I have also added pan gesture on image. When an image is zoomed then i am scrolling the image in every direction for that purpose i have added the pan gesture into the image.

我的代码是：

-(void)viewDidLoad
{
UIPinchGestureRecognizer *pinch=[[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(handlePinch:)];
            [self.zoom_image addGestureRecognizer:pinch];
            panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(moveImage:)];
            [panGesture setMinimumNumberOfTouches:1];
            [panGesture setMaximumNumberOfTouches:1];
            [self.zoom_image addGestureRecognizer:panGesture];

            img_center_x = self.zoom_image.center.x;
            img_center_y = self.zoom_image.center.y;

}

-(void)handlePinch:(UIPinchGestureRecognizer*)sender
{
    NSLog(@"latscale = %f",mLastScale);
    mCurrentScale += [sender scale] - mLastScale;
    mLastScale = [sender scale];
    NSLog(@"before ceneter x %f",img_center_x);
    NSLog(@"before ceneter x %f",img_center_y);
    CGPoint img_center = CGPointMake(img_center_x, img_center_y);
    self.zoom_image.center = img_center;
    if (sender.state == UIGestureRecognizerStateEnded)
    {
      mLastScale = 1.0;
    }
    if(mCurrentScale<1.0)
    {
        mCurrentScale=1.0;
    }
    if(mCurrentScale>3.0)
    {
        mCurrentScale=3.0;
    }
    CGAffineTransform currentTransform = CGAffineTransformIdentity;
    CGAffineTransform newTransform = CGAffineTransformScale(currentTransform,mCurrentScale, mCurrentScale);
    self.zoom_image.transform = newTransform;

}

平移手势

 UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(moveImage:)];
            [panGesture setMinimumNumberOfTouches:1];
            [panGesture setMaximumNumberOfTouches:1];
            [self.zoom_image addGestureRecognizer:panGesture];

move image:

- (void)moveImage:(UIPanGestureRecognizer *)recognizer
{
    CGPoint translation = [recognizer translationInView:self.zoom_image];
    CGPoint location = [recognizer locationInView:self.view];
    CGPoint initial=CGPointZero;
    NSLog(@"%f\n%f",translation.x,translation.y);
    NSLog(@"%f",self.zoom_image.frame.origin.y);
    CGPoint finalpoint = CGPointMake(self.zoom_image.center.x + translation.x, self.zoom_image.center.y+ translation.y);
    NSLog(@"%f",finalpoint.y);
    //limit the boundary
    if(recognizer.state==UIGestureRecognizerStateChanged)
    {
        if ((self.zoom_image.frame.origin.x>0 && translation.x > 0) || (self.zoom_image.frame.origin.x + self.zoom_image.frame.size.width<=self.view.frame.size.width && translation.x < 0))
            finalpoint.x = self.zoom_image.center.x;

        if ((self.zoom_image.frame.origin.y>100 && translation.y > 0) || (self.zoom_image.frame.origin.y + self.zoom_image.frame.size.height<=self.view.frame.size.height && translation.y < 0))
            finalpoint.y = self.zoom_image.center.y;
        //set final position
        NSLog(@"%f",finalpoint.y);
        self.zoom_image.center = finalpoint;
        [recognizer setTranslation:initial inView:self.zoom_image];
    }
}

推荐答案

这里是一种可能的解决方案。

Here is a possible solution.

•我已经通过contentView重命名了你的zoom_image，因为这个类可以操作任何视图，而不仅仅是图像。

• I've renamed your zoom_image by contentView, because this class can manipulate any view, not only images.

•我删除了绑定测试，并让比例为（0.01 - 10.0）

• I've removed the bound tests, and let the scale be in ( 0.01 - 10.0 )

•捏手柄最多三指，也充当了泛。可以在不中断收缩的情况下更改触摸次数。

• The pinch handle up to three fingers, and also acts as pan. Number of touches can be changed without interrupting the pinch.

还有很多事情需要改进，但主要原则在于：）

There is still many things to improve, but the main principle is here :)

界面（minScale，maxScale，minMargin等属性仍然需要添加 - 为什么不是代表）

Interface ( properties like minScale,maxScale, minMargin and so are still to be added - why not a delegate )

@interface PinchViewController : UIViewController

@property(nonatomic,strong) IBOutlet UIView* contentView;

@end

实施

@implementation PinchViewController
{
    CGPoint translation;
    CGFloat scale;

    CGAffineTransform scaleTransform;
    CGAffineTransform translateTransform;

    CGPoint     previousTranslation;
    CGFloat     previousScale;
    NSUInteger  previousNumTouches;
}

-(void)viewDidLoad
{
    scale = 1.0f;
    scaleTransform = CGAffineTransformIdentity;
    translateTransform = CGAffineTransformIdentity;
    previousTranslation = CGPointZero;
    previousNumTouches = 0;

    UIPinchGestureRecognizer *pinch=[[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(handlePinch:)];
    [self.view addGestureRecognizer:pinch];

    UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
    [panGesture setMinimumNumberOfTouches:1];
    [panGesture setMaximumNumberOfTouches:1];
    [self.view addGestureRecognizer:panGesture];

}

-(void)handlePinch:(UIPinchGestureRecognizer*)recognizer
{
    // 1 - find pinch center
    CGPoint mid = [self computePinchCenter:recognizer];
    mid.x-= recognizer.view.bounds.size.width / 2.0f;
    mid.y-= recognizer.view.bounds.size.height / 2.0f;

    // 2 - compute deltas
    NSUInteger numTouches = recognizer.numberOfTouches;
    if ( (recognizer.state==UIGestureRecognizerStateBegan)  || ( previousNumTouches != numTouches ) ) {
        previousScale = recognizer.scale;
        previousTranslation = mid;
        previousNumTouches = numTouches;
    }

    CGFloat deltaScale = ( recognizer.scale - previousScale ) * scale;
    previousScale = recognizer.scale;

    CGPoint deltaTranslation = CGPointMake(mid.x-previousTranslation.x, mid.y-previousTranslation.y);
    previousTranslation = mid;

    deltaTranslation.x/=scale;
    deltaTranslation.y/=scale;

    // 3 - apply
    scale+=deltaScale;

    if (scale<0.01) scale = 0.01; else if (scale>10) scale = 10;

    scaleTransform = CGAffineTransformMakeScale(scale, scale);
    [self translateBy:deltaTranslation];

    NSLog(@"Translation : %.2f,%.2f - Scale Center : %.2f,%.2f - Scale : %.2f",deltaTranslation.x,deltaTranslation.y,mid.x,mid.y,scale);
}

- (void)handlePan:(UIPanGestureRecognizer *)recognizer
{
    if (recognizer.state==UIGestureRecognizerStateBegan) previousTranslation = CGPointZero;
    CGPoint recognizerTranslation = [recognizer translationInView:self.contentView];
    CGPoint deltaTranslation = CGPointMake(recognizerTranslation.x - previousTranslation.x,recognizerTranslation.y - previousTranslation.y);
    previousTranslation = recognizerTranslation;
    [self translateBy:deltaTranslation];

    NSLog(@"Translation : %.2f,%.2f - Scale : %.2f",deltaTranslation.x,deltaTranslation.y,scale);
}


-(void)translateBy:(CGPoint)delta
{
    translation.x+=delta.x;
    translation.y+=delta.y;
    translateTransform = CGAffineTransformMakeTranslation(translation.x,translation.y);
    self.contentView.transform = CGAffineTransformConcat(translateTransform,scaleTransform);
}

-(CGPoint)computePinchCenter:(UIPinchGestureRecognizer*)recognizer
{
    // 1 - handle up to 3 touches
    NSUInteger numTouches = recognizer.numberOfTouches;
    if (numTouches>3) numTouches = 3;

    // 2 - Find fingers middle point - with (0,0) being the center of the view
    CGPoint pt1,pt2,pt3,mid;
    switch (numTouches) {
        case 3:
            pt3 = [recognizer locationOfTouch:2 inView:recognizer.view];
        case 2:
            pt2 = [recognizer locationOfTouch:1 inView:recognizer.view];
        case 1:
            pt1 = [recognizer locationOfTouch:0 inView:recognizer.view];
    }
    switch (numTouches) {
        case 3:
            mid = CGPointMake( ( ( pt1.x + pt2.x ) / 2.0f + pt3.x ) / 2.0f, ( ( pt1.y + pt2.y ) / 2.0f + pt3.y ) / 2.0f );
            break;
        case 2:
            mid = CGPointMake( ( pt1.x + pt2.x ) / 2.0f, ( pt1.y + pt2.y ) / 2.0f  );
            break;
        case 1:
            mid = CGPointMake( pt1.x, pt1.y);
            break;
    }
    return mid;
}

@end

希望它会有所帮助:)干杯

Hope it will help :) Cheers

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