获取触摸坐标时出现严重问题
我有一个简单的应用程序,向用户显示图像(在 UIImageView 中),用户触摸屏幕的一部分,然后在下一个屏幕上显示相同的图像(在 UIImageView 中),但现在有一个“签名”覆盖在它。我遇到的问题是,从触摸返回的 x,y 坐标似乎没有正确映射到第二个屏幕上的 UIImageView 上。
例如,当我触摸屏幕底部时,我得到: X: 157.000000 Y: 358.000000
但屏幕底部应该是 480 ?因为我的屏幕尺寸是:X 处的屏幕高度和宽度:320.000000 Y:480.000000。这会导致签名放置在与用户预期不同的位置。
我使用以下代码来获取触摸坐标:
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
NSLog(@"TOUCH HAPPENED");
UITouch *touch = [touches anyObject];
CGPoint touchCoordinates = [touch locationInView:self.view];
NSLog(@"X: %f Y: %f",touchCoordinates.x, touchCoordinates.y);
}
我使用以下代码将“签名”与从触摸获得的值放在一起:
CGRect screenRect = [[UIScreen mainScreen] bounds];
UIGraphicsBeginImageContext(screenRect.size);
[pageImage drawInRect:CGRectMake(0, 0, screenRect.size.width, screenRect.size.height)]; // this is the original image
NSLog(@"SCREEN HEIGHT AND WIDTH AT X: %f Y: %f",screenRect.size.width, screenRect.size.height);
NSLog(@"PLACING IT AT TOUCH COORDINATES X: %f Y: %f",sigLocation.x, sigLocation.y);
UIImage *shieldLogo = [UIImage imageNamed:@"shield_bw.gif"];
[shieldLogo drawInRect:CGRectMake(sigLocation.x, sigLocation.y, shieldLogo.size.width/2, shieldLogo.size.height/2)];
[theSignature drawAtPoint:CGPointMake(sigLocation.x+24.000000, sigLocation.y) withFont:[UIFont fontWithName:@"Arial" size:8.0]];
[theSignature2 drawAtPoint:CGPointMake(sigLocation.x+24.000000, sigLocation.y+ 8.000000) withFont:[UIFont fontWithName:@"Arial" size:8.0]];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[image setImage:resultingImage];
I have a simple application that shows the user an image (in a UIImageView) whereby they touch on a part of the screen and then on the next screen the same image is shown (in a UIImageView) but now has a "signature" overlayed on it. The issue I am having is that it seems that the x,y coordinates returned from the touches do not seem to map properly on the UIImageView on the second screen.
For instance when I touch the bottom of the screen I get: X: 157.000000 Y: 358.000000
but the bottom of the screen should be 480 ? since my screen dimensions are: SCREEN HEIGHT AND WIDTH AT X: 320.000000 Y: 480.000000. This causes the signature to be placed at a DIFFERENT spot than what the user intended.
I use the following code to get my touch coordinates:
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
NSLog(@"TOUCH HAPPENED");
UITouch *touch = [touches anyObject];
CGPoint touchCoordinates = [touch locationInView:self.view];
NSLog(@"X: %f Y: %f",touchCoordinates.x, touchCoordinates.y);
}
I am using the following code to place the "signature" with the values I get from the touch:
CGRect screenRect = [[UIScreen mainScreen] bounds];
UIGraphicsBeginImageContext(screenRect.size);
[pageImage drawInRect:CGRectMake(0, 0, screenRect.size.width, screenRect.size.height)]; // this is the original image
NSLog(@"SCREEN HEIGHT AND WIDTH AT X: %f Y: %f",screenRect.size.width, screenRect.size.height);
NSLog(@"PLACING IT AT TOUCH COORDINATES X: %f Y: %f",sigLocation.x, sigLocation.y);
UIImage *shieldLogo = [UIImage imageNamed:@"shield_bw.gif"];
[shieldLogo drawInRect:CGRectMake(sigLocation.x, sigLocation.y, shieldLogo.size.width/2, shieldLogo.size.height/2)];
[theSignature drawAtPoint:CGPointMake(sigLocation.x+24.000000, sigLocation.y) withFont:[UIFont fontWithName:@"Arial" size:8.0]];
[theSignature2 drawAtPoint:CGPointMake(sigLocation.x+24.000000, sigLocation.y+ 8.000000) withFont:[UIFont fontWithName:@"Arial" size:8.0]];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[image setImage:resultingImage];
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问题可能在于用户正在触摸的视图。您可以尝试(如 此链接)
这应该给出触摸相对于屏幕的位置。
The issue might be with the view that the user is touching. You might try (as seen in this link)
This should give the location of the touch relative to the screen.