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。
好吧，然后我在UIImageView中显示第一个图像。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，我加载一个图像，如果向上拖动，我加载另一个图像，以及左右
。这一切都完成了。但我想实现缩放。这是我到目前为止的代码：
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 --> 为 0
y -->为 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 -
谢谢！！
PD：如果有一种方法可以使用UIScrollView，我可以在不同的图像之间移动，我也愿意看看。
好的。您可以考虑使用 UIScrollView，如果只是为了将其用于其缩放功能。
假设我们有一个scrollView和一个imageView，两者具有相同的边界。将imageView添加为scrollView的子视图。
[scrollView addSubview:imageView];
scrollView.contentSize = imageView.frame.size;
要仅支持缩放而不支持在scrollView中平移，您的viewController必须采用UIScrollViewDelegate协议。
// 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;
}
到目前为止，我们已经可以使用缩放。对于轻扫，您可以使用适当配置的 UISwipeGestureRecognizers。创建用于处理每个轻扫方向的手势，并将其添加到滚动视图中。
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。
最后，在 Deepak 的帮助下，我使用 UIImageView 的 transform 属性来制作缩放。
我在 CGAffineTransform 矩阵中的位置 [0,0] 处使用 CGFloat 来设置限制。我必须在放大时将 CGFloat 传递给一个字符串，因为当我将其与 0 进行比较时，这总是正确的。
最后，这是我的代码 touchesMoved，如果它对某人有用：
// comparo para saber si el usuario esta haciendo zoom in o zoom out
if(initialDistance < finalDistance) {
NSLog(@"Zoom Out");
CGAffineTransform transformer = CGAffineTransformScale(imagen.transform, 1.05, 1.05);
NSLog(@"transformer :: A: %.f, B: %.f, C: %.f, D: %.f", imagen.transform.a, imagen.transform.b, imagen.transform.c, imagen.transform.d);
if (transformer.a < 5) {
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration: 0.2];
imagen.transform = transformer;
[UIView setAnimationDelegate:self];
[UIView commitAnimations];
}
}
else {
NSLog(@"Zoom In");
CGAffineTransform transformer = CGAffineTransformScale(imagen.transform, 0.95, 0.95);
NSLog(@"transformer :: A: %.f, B: %.f, C: %.f, D: %.f", transformer.a, transformer.b, transformer.c, transformer.d);
NSString *num = [NSString stringWithFormat:@"%.f", transformer.a];
if (![num isEqualToString:@"0"]) {
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration: 0.2];
imagen.transform = transformer;
[UIView setAnimationDelegate:self];
[UIView commitAnimations];
}
}
当然，非常感谢迪帕克。