代碼iphone圖像繪製線

Question

大家好我是法國人，所以我嘲笑我的英語。所以我想製作一個像飛行控制的遊戲。當我從一個像飛機這樣的圖像畫線時，我希望飛機跟着那條線。我該怎麼做？

Answer 1

1. 劃清界線，實施touchesBegan:，touchedMove:，touchedEnded，touchesCancelled:在您的視圖或視圖控制器，並建立使用觸摸點的路徑（CGPathRef）。
2. 要使對象沿着線條移動，請創建CAKeyframeAnimation，設置路徑並將其分配給對象的圖層。

編輯：示例代碼

當你有一個CGPathRef path，創建動畫一樣簡單：

CAKeyframeAnimation* animation = [CAKeyframeAnimation animation]; 
animation.path = thePath; 
animation.duration = 2; 
animation.rotationMode = kCAAnimationRotateAuto; // object auto rotates to follow the path 
animation.removedOnCompletion = NO; 
animation.fillMode = kCAFillModeForwards; 

最後，分配動畫層：

[layer1 addAnimation:animation forKey:@"position"]; 

編輯2：示例應用程序：

我爲您構建了一個名爲PathAnimation的整個項目。

編輯3：這是我在PathAnimation項目中使用的代碼：

// 
// CustomView.m 
// PathAnimation 
// 
// Created by Dominique d'Argent on 19.04.11. 
// Copyright 2011 Nicky Nubbel. All rights reserved. 
// 

#import "CustomView.h" 


@implementation CustomView 

- (id)initWithFrame:(CGRect)frame 
{ 
    self = [super initWithFrame:frame]; 
    if (self) { 
     object = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"arrow"]]; 
     object.frame = CGRectMake(10.0, 30.0, 20.0, 20.0); 

     [self addSubview:object]; 

     [self createPath]; 
    } 
    return self; 
} 


- (void)dealloc 
{ 
    [object release]; 

    [super dealloc]; 
} 

#pragma mark - Custom drawing 

// Only override drawRect: if you perform custom drawing. 
// An empty implementation adversely affects performance during animation. 
- (void)drawRect:(CGRect)rect { 
    CGContextRef g = UIGraphicsGetCurrentContext(); 
    CGFloat bgColor[4] = {1.0f, 1.0f, 1.0f, 1.0f}; 

    CGContextSetFillColor(g, bgColor); 
    CGContextFillRect(g, self.frame); 

    CGFloat color[4] = {1.0f, 0.0f, 0.0f, 1.0f}; 
    CGContextAddPath(g,path); 
    CGContextSetStrokeColor(g, color); 
    CGContextDrawPath(g, kCGPathStroke); 

    CGPoint position = CGPathGetCurrentPoint(path); 
    CGContextAddArc(g, position.x, position.y, 5.0f, 0.0f, 2 * M_PI, 0); 
    CGContextSetFillColor(g, color); 
    CGContextDrawPath(g, kCGPathFill); 
} 

#pragma mark - Path creation 
- (void)createPath { 
    path = CGPathCreateMutable(); 
    CGPathMoveToPoint(path, NULL, object.center.x, object.center.y); 
} 

#pragma mark - Touch handling 

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = [touches anyObject]; 
    CGPoint position = [touch locationInView:self]; 

    if (CGRectContainsPoint(object.frame, position)) { 
     // start animation 
     [self go]; 
    } 
    else { 
     CGPoint lastPosition = CGPathGetCurrentPoint(path); 

     if (CGPointEqualToPoint(lastPosition, object.center)) { 
      CGFloat angle = -atan2f(position.x - lastPosition.x, position.y - lastPosition.y); 
      angle += M_PI_2; 

      object.layer.transform = CATransform3DMakeRotation(angle, 0.0, 0.0, 1.0); 
     } 

     CGPathAddLineToPoint(path, NULL, position.x, position.y); 

     [self setNeedsDisplay]; 
    } 
} 

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 
} 

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { 
} 

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { 
} 

#pragma mark - Animations 

- (void) go { 
    NSLog(@"go"); 

    object.layer.transform = CATransform3DIdentity; 

    CAKeyframeAnimation* animation = [CAKeyframeAnimation animation]; 
    animation.path = path; 
    animation.duration = 5.0; 
    animation.rotationMode = kCAAnimationRotateAuto; // object auto rotates to follow the path 
    animation.removedOnCompletion = NO; 
    animation.fillMode = kCAFillModeForwards; 

    [object.layer addAnimation:animation forKey:@"position"]; 
    object.center = CGPathGetCurrentPoint(path); 

    [self createPath]; 
} 

@end 

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