iphone – iPad(非常)简单的绘图

我正在尝试在我的应用程序中实现一个非常简单的绘图视图.这只是我的应用程序的一小部分,但它变成了一个真正的麻烦.这是我到目前为止所拥有的,但它现在正在显示的是莫尔斯代码,如点和线.

- (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,self.view.frame.size.width,self.view.frame.size.height)];
            CGContextSetLineCap(UIGraphicsGetCurrentContext(),kCGLineCapRound);
            CGContextSetLineWidth(UIGraphicsGetCurrentContext(),3.0);
            CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(),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;

        }

        }   
    }

解决方法

我的一个应用程序也需要一些简单的绘图.这是它的略微修改版本.它的工作方式基本上与hotpaw2描述的一样.我创建了一个“画布”视图来处理所有绘图,我只需将它添加到任何需要的地方.

速度对我的目的来说很好.

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); //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

在需要的地方添加canvasView：

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