UIView塗鴉 - ios開發

你好，我正在這個項目上工作，以允許用戶在UIView上的塗鴉。我的方法是創建一個CGMutablePathRef路徑，並在TouchMoved中添加新行。UIView塗鴉 - ios開發

下面列出了相關的代碼，它們在UIView的類中。

static CGMutablePathRef path; //create it as static value. 
//I got this habit from java coding but actually not sure 
//if it's a good way to do it in objective-c. 


//draw the path 

-(void)drawRect:(CGRect)rect{ 
    CGContextRef context = UIGraphicsGetCurrentContext(); 
    CGContextBeginPath(context); 
    CGContextAddPath(context, path); 
    CGContextStrokePath(context); 
    CGPathRelease(path); 
} 

//touch began. create the path and add point. 
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{ 

    path = CGPathCreateMutable(); 
    UITouch *touch = [touches anyObject]; 
    CGPoint point = [touch locationInView:self]; 
    CGPathMoveToPoint(path, NULL, point.x, point.y); 
    [self setNeedsDisplay];    
} 


//add points when touch moved 
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ 

    UITouch *touch = [touches anyObject]; 
    CGPoint point = [touch locationInView:self]; 

    CGPathAddLineToPoint(path, NULL, point.x, point.y); 
    [self setNeedsDisplay]; 

} 

//last points when touch ends 
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{ 
    UITouch *touch = [touches anyObject]; 
    CGPoint point = [touch locationInView:self]; 
    CGPathAddLineToPoint(path, NULL, point.x, point.y); 
    [self setNeedsDisplay]; 
}

然而，我的錯誤，我不很懂...我想這件事情與UIGestureRecognizer，這是我從其他塗鴉代碼看見。是否有必要添加UIGestureRecognizer？我還沒有學到任何東西，所以我試圖避免使用它。但如果這是必須的，我會試一試。

我想到的另一種方法是將所有點位置存儲到可變數組中，因爲我必須將這些點位置值存儲在某處。但是，我不知道數組是否合適，因爲我沒有找到將浮點值存儲到數組的方法。如果有人能幫助我，這將是非常有幫助的。謝謝！

來源

2012-03-28 user1299082

沒有必要使用UIGestureRecognizers。至於存儲浮動到NSMutableArray看看[[NSNumber]（http://developer.apple.com/library/ios/#documentation/Cocoa/Reference/Foundation/Classes/NSNumber_Class/Reference/Reference.html）numberWithFloat： ]。也看看這個問題：http://stackoverflow.com/questions/7393058/how-do-i-use-uibezierpath-to-draw-a-line-that-follows-a-touch-event – 2012-03-28 20:10:59

我' d建議使用手勢識別器。它使你的代碼更簡單，更容易擴展。 – Sven 2012-03-28 20:26:48

@rokjarc是鏈接的問題是非常有幫助的。還有一個小問題：該答案中使用的類是UIImageView，因此在它調用的方法中[self.image drawInRect：CGRectMake（0，0，self.frame.size.width，self.frame.size.height）]。但在我的情況下，它是UIView，所以我應該調用什麼方法來繪製？（對不起，我猜這是一個愚蠢的問題，我真的是一個新手），謝謝！ – user1299082 2012-03-31 00:14:50

感謝給我幫助的人。通過一堆代碼和方法後，幸運的是我找到了解決這個問題的有效方法！

通常，當我繪圖時，我的SketchView中的imageView會動態更新。也就是說，每次繪製更多像素時，都會將一行添加到該新像素中，更改UIImageView，然後將其設置爲UIView的背景圖像。

SketchView.h

@property (assign, nonatomic) CGPoint CurrentPoint; 
@property (assign, nonatomic) CGPoint PreviousPoint; 
@property (assign, nonatomic) CGPoint InitialPoint;

SketchView.m

@synthesize CurrentPoint; 
@synthesize PreviousPoint; 
@synthesize InitialPoint; 


//begin the touch. store the initial point because I want to connect it to the last 
//touch point 
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{ 
    UITouch *touch = [touches anyObject]; 
    CGPoint point = [touch locationInView:image]; 
    InitialPoint = point; 

    } 


//When touch is moving, draw the image dynamically 
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ 

UITouch *touch = [touches anyObject]; 
PreviousPoint = [touch previousLocationInView:image]; 
CurrentPoint = [touch locationInView:image]; 
UIGraphicsBeginImageContext(image.frame.size); 
CGContextRef ctx = UIGraphicsGetCurrentContext(); 
[image.image drawInRect:CGRectMake(0, 0, image.frame.size.width, image.frame.size.height)]; 
CGContextSetLineCap(ctx, kCGLineCapRound); 
CGContextSetLineWidth(ctx, 5.0); 
CGContextSetRGBStrokeColor(ctx, 1.0, 0.0, 0.0, 1.0); 
CGContextBeginPath(ctx); 
CGContextMoveToPoint(ctx, PreviousPoint.x, PreviousPoint.y); 
CGContextAddLineToPoint(ctx, CurrentPoint.x, CurrentPoint.y); 
CGContextStrokePath(ctx); 
image.image = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext(); 
} 



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

UITouch *touch = [touches anyObject]; 
PreviousPoint = [touch previousLocationInView:image]; 
CurrentPoint = [touch locationInView:image]; 
UIGraphicsBeginImageContext(image.frame.size); 
CGContextRef ctx = UIGraphicsGetCurrentContext(); 
[image.image drawInRect:CGRectMake(0, 0, image.frame.size.width, image.frame.size.height)]; 
CGContextSetLineCap(ctx, kCGLineCapRound); 
CGContextSetLineWidth(ctx, 5.0); 
CGContextSetRGBStrokeColor(ctx, 1.0, 0.0, 0.0, 1.0); 
CGContextBeginPath(ctx); 
CGContextMoveToPoint(ctx, PreviousPoint.x, PreviousPoint.y); 
CGContextAddLineToPoint(ctx, CurrentPoint.x, CurrentPoint.y); 

//I connected the last point to initial point to make a closed region 
CGContextMoveToPoint(ctx, CurrentPoint.x, CurrentPoint.y); 
CGContextAddLineToPoint(ctx, InitialPoint.x, InitialPoint.y); 
CGContextStrokePath(ctx); 
image.image = UIGraphicsGetImageFromCurrentImageContext(); 


UIGraphicsEndImageContext(); 
}

和它的作品！

p.s.我發現

PreviousPoint = [touch previousLocationInView:image];

非常有幫助，雖然在代碼中我沒有提到太多塗鴉...我希望這有助於。 :)

來源

2012-04-09 03:29:31 user1299082

UIView塗鴉 - ios開發

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