iPad (muy) simple dibujo

Question

Estoy tratando de implementar una vista de dibujo muy simple en mi aplicación. Esta es solo una pequeña parte de mi aplicación, pero se está convirtiendo en una verdadera molestia. Esto es lo que tengo hasta ahora, pero todo lo que muestra ahora es código morse como puntos y líneas.

- (void)viewDidLoad { 
     [super viewDidLoad]; 
    self.view.backgroundColor = [UIColor whiteColor]; 
    NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 
                 NSUserDomainMask, YES); 
    NSString *docsPath = [paths objectAtIndex:0]; 

    NSString *savePath = [NSString stringWithFormat:@"%@/notePadImage.jpg",docsPath]; 

    NSData *data = [NSData dataWithContentsOfFile:savePath]; 

    UIImage *image = [UIImage imageWithData:data]; 

    if (image == nil) { 
     NSString *pathToBlank = [[NSBundle mainBundle]pathForResource:@"blankNotePadPage" ofType:@"png"]; 
     NSData *data = [NSData dataWithContentsOfFile:pathToBlank]; 
     image = [UIImage imageWithData:data]; 
    } 
    arrayOfTouches = [[NSMutableArray alloc] initWithCapacity:10]; 
    self.drawImage.image = image; 

    mouseMoved = 0; 
    [self.view bringSubviewToFront:closeButton]; 
    [self.view bringSubviewToFront:clearButton]; 
    self.timer = [NSTimer scheduledTimerWithTimeInterval:.02 target:self selector:@selector(drawIt) userInfo:nil repeats:YES]; 

    } 

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


    UITouch *touch = [touches anyObject]; 

    [arrayOfTouches addObject:touch]; 




    } 


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

    UITouch *touch = [touches anyObject]; 
    [arrayOfTouches addObject:touch]; 


    } 

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

    } 

    -(void) drawIt { 

    NSMutableArray *tempArray = [NSMutableArray arrayWithArray:arrayOfTouches]; 
    [arrayOfTouches removeAllObjects]; 
    if ([tempArray count]>1) { 

     [arrayOfTouches removeAllObjects]; 
     CGPoint point1 = [[tempArray objectAtIndex:0] previousLocationInView:self.view];; 
     CGPoint point2; 
     CGPoint point3; 

     for (int i = 0; i < [tempArray count]-1;i = i+1) { 




      UIGraphicsBeginImageContext(self.view.frame.size); 
      [drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)]; 
      CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); 
      CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 3.0); 
      CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 1.0); 
      CGContextMoveToPoint(UIGraphicsGetCurrentContext(), point1.x, point1.y); 
      CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), point2.x, point2.y); 

      CGContextStrokePath(UIGraphicsGetCurrentContext()); 
      CGContextFlush(UIGraphicsGetCurrentContext()); 
      drawImage.image = UIGraphicsGetImageFromCurrentImageContext(); 
      UIGraphicsEndImageContext(); 
      [self.view bringSubviewToFront:closeButton]; 
      [self.view bringSubviewToFront:clearButton]; 
      point1 = point2; 

     } 

     } 
    } 

Answer 1

Una de mis aplicaciones también necesitaba un dibujo simple. Aquí hay una versión ligeramente modificada de esto. Funciona básicamente como lo describe hotpaw2. Creé una vista de "lienzo" que maneja todo el dibujo y simplemente lo agrego donde sea necesario.

La velocidad está bien para mis propósitos.

CanvasView.h:

@interface CanvasView : UIView { 
    NSMutableArray *points; 
} 
@property (nonatomic, retain) NSMutableArray *points; 
@end 

CanvasView.m:

#import "CanvasView.h" 

@implementation CanvasView 

@synthesize points; 

- (id) initWithFrame:(CGRect)frame { 
    if (self = [super initWithFrame:frame]) { 
     self.backgroundColor = [UIColor blueColor]; 
    } 
    return self; 
} 

-(void)drawRect:(CGRect)rect 
{ 
    if (self.points.count == 0) 
     return; 

    CGContextRef context = UIGraphicsGetCurrentContext(); 
    CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); //white 
    CGContextSetLineWidth(context, 1.0); 

    CGPoint firstPoint = [[self.points objectAtIndex:0] CGPointValue]; 
    CGContextBeginPath(context); 
    CGContextMoveToPoint(context, firstPoint.x, firstPoint.y); 

    int i = 1; 
    while (i < self.points.count) 
    { 
     CGPoint nextPoint = [[self.points objectAtIndex:i] CGPointValue]; 

     if (nextPoint.x < 0 && nextPoint.y < 0) 
     { 
      CGContextDrawPath(context, kCGPathStroke); 

      if (i < (self.points.count-1)) 
      { 
       CGContextBeginPath(context); 
       CGPoint nextPoint2 = [[self.points objectAtIndex:i+1] CGPointValue];     
       CGContextMoveToPoint(context, nextPoint2.x, nextPoint2.y); 
       i = i + 2; 
      } 
      else 
       i++; 
     } 
     else 
     { 
      CGContextAddLineToPoint(context, nextPoint.x, nextPoint.y); 
      i++; 
     } 
    } 

    CGContextDrawPath(context, kCGPathStroke); 
} 

-(void)dealloc 
{ 
    [points release]; 
    [super dealloc]; 
} 

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

    if (self.points == nil) 
    { 
     NSMutableArray *newPoints = [[NSMutableArray alloc] init]; 
     self.points = newPoints; 
     [newPoints release]; 
    } 

    [self.points addObject:[NSValue valueWithCGPoint:(location)]]; 
} 

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    UITouch *touch = [[event touchesForView:self] anyObject]; 
    CGPoint location = [touch locationInView:self]; 
    [self.points addObject:[NSValue valueWithCGPoint:(location)]]; 

    [self setNeedsDisplay]; 
} 

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    UITouch *touch = [[event touchesForView:self] anyObject]; 
    CGPoint location = [touch locationInView:self]; 
    [self.points addObject:[NSValue valueWithCGPoint:(location)]]; 

    CGPoint endPoint = CGPointMake(-99, -99); //"end of path" indicator 
    [self.points addObject:[NSValue valueWithCGPoint:(endPoint)]]; 

    [self setNeedsDisplay]; 
} 

@end 

Adición de la canvasView donde se necesita:

CanvasView *cv = [[CanvasView alloc] initWithFrame:CGRectMake(0, 0, 320, 640)]; 
[self.view addSubview:cv]; 
[cv release]; 

Answer 2

No dibujar mientras se tocan. Disminuirá la velocidad del manejador táctil tanto que podría obtener el efecto de conectar los puntos que está viendo.

Guarde las coordenadas táctiles en una matriz y planee dibujarlas más tarde.

Observe algunos tutoriales de animación simples sobre cómo dibujar en un drawRect basado en un setNeedsDisplay llamado por una animación UITimer o CADisplayLink. Dibuja todos tus segmentos de línea a una velocidad más adecuada.