手写板制作----UITouch

先写一下UITouch的功能和用法:

UITouch是view本身存在的协议。只需实现它的具体方法就行了。还有就是UIScrollView中没有UITouch这个事件，要想在UIScrollView中实现这个触摸事件，方法就是重写UIScrollView：

//手指接触到屏幕时触发

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

//手指在屏幕上移动的时候触发

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

//一次接触完成 手指离开屏幕的时候触发

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

//突然强制接触终止时触发(比如：不小心按到锁屏键，或者突然来电话了)

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

有了这些监听手指在屏幕上的位置的方法，就可以得到手指在屏幕上某个view中的位置

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
   UITouch *touch = [touches anyObject];
   CGPoint point = [touch  locationInView:self];//self 指一个view  现在是自动一个view
}

在手指接触屏幕的时候就创建好用于装接下来记录点的容器

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    if (!m_pointArr)
    {
         m_pointArr = [NSMutableArray arrayWithCapacity:50];
    }
    NSMutableArray *mArr = [NSMutableArray arrayWithCapacity:100];
    [m_pointArr addObject:mArr];
}

（每接触一次就创建一个动态数组用于装接下来手指划过的点）

在手指在屏幕上移动的时候将手指经过的点全部记录下来

-(void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint point = [touch  locationInView:self];
    PointObj *pObj = [[PointObj alloc]initWithX:point.x Y:point.y];
    NSMutableArray *currentArr = [m_pointArr lastObject];
    [currentArr addObject:pObj];
    [self setNeedsDisplay];//这个方法的调用和让view自动调用他的 - (void)drawRect:(CGRect)rect
}　　　　　　

　　　(这里的PointObj类  就是一个点类  生成一个点对象便于放在数组中/* 蛋疼得很这个 数组中只让方对象!!*/)

#import <Foundation/Foundation.h>

@interface PointObj : NSObject
@property(nonatomic,assign)float x,y;
-(instancetype)initWithX:(float)P_X Y:(float)P_Y;
@end

#import "PointObj.h"

@implementation PointObj
-(instancetype)initWithX:(float)P_X Y:(float)P_Y
{
    if (self = [super init])
    {
        _x = P_X;
        _y = P_Y;
    }
    return self;
}
@end

记录的点有了，下面就是将记录下来的点绘成图形啦  这里要用到quarz2d绘图那里的知识!!

- (void)drawRect:(CGRect)rect
{
    if (m_pointArr && m_pointArr.count > 0)
    {
        for (NSMutableArray *item in m_pointArr)
        {
            if (item.count > 2)
            {
                PointObj *firstObj = [item firstObject];
                CGContextRef ctf = UIGraphicsGetCurrentContext();
                CGContextMoveToPoint(ctf, firstObj.x, firstObj.y);
                for (int i = 1; i < item.count; i++)
                {
                    PointObj *oneObj = [item objectAtIndex:i];
                    CGContextAddLineToPoint(ctf, oneObj.x, oneObj.y);
                }
                
                CGContextSetFillColorWithColor(ctf, [UIColor blackColor].CGColor);
                CGContextSetLineWidth(ctf, 5.0); //线条的宽度
                //将会出的线渲染出来
                CGContextStrokePath(ctf);

            }
        }
    }
}

到此为止  手写的功能已经实现啦！！

绘制的图形有了之后只需要通过截屏  或者区域截取又或者对一个View截取  得到一个Image的对象  

下面介绍一些截屏的方法

1.直接截取一个view中的一部分区域 (如果直接传入view.bounds那就是直接截取这个view)

- (UIImage *)screenshotWithRect:(CGRect)rect;
{
    UIGraphicsBeginImageContextWithOptions(rect.size, NO, [UIScreen mainScreen].scale);
    
    CGContextRef context = UIGraphicsGetCurrentContext();
    if (context == NULL)
    {
        return nil;
    }
    CGContextSaveGState(context);
    CGContextTranslateCTM(context, -rect.origin.x, -rect.origin.y);
    if( [self respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)])
    {
        [self drawViewHierarchyInRect:self.bounds afterScreenUpdates:NO];
    }
    else
    {
        [self.layer renderInContext:context];
    }
    CGContextRestoreGState(context);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

2.对手机屏幕截屏

- (UIImage *)getImageWithFullScreenshot
{
    // Source (Under MIT License): https://github.com/shinydevelopment/SDScreenshotCapture/blob/master/SDScreenshotCapture/SDScreenshotCapture.m#L35
    
    BOOL ignoreOrientation = [[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0?YES:NO;
    UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
    
    CGSize imageSize = CGSizeZero;
    if (UIInterfaceOrientationIsPortrait(orientation) || ignoreOrientation)
        imageSize = [UIScreen mainScreen].bounds.size;
    else
        imageSize = CGSizeMake([UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width);
    
    UIGraphicsBeginImageContextWithOptions(imageSize, NO, [UIScreen mainScreen].scale);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    for (UIWindow *window in [[UIApplication sharedApplication] windows])
    {
        CGContextSaveGState(context);
        CGContextTranslateCTM(context, window.center.x, window.center.y);
        CGContextConcatCTM(context, window.transform);
        CGContextTranslateCTM(context, -window.bounds.size.width * window.layer.anchorPoint.x, -window.bounds.size.height * window.layer.anchorPoint.y);
        
        // Correct for the screen orientation
        if(!ignoreOrientation)
        {
            if(orientation == UIInterfaceOrientationLandscapeLeft)
            {
                CGContextRotateCTM(context, (CGFloat)M_PI_2);
                CGContextTranslateCTM(context, 0, -imageSize.width);
            }
            else if(orientation == UIInterfaceOrientationLandscapeRight)
            {
                CGContextRotateCTM(context, (CGFloat)-M_PI_2);
                CGContextTranslateCTM(context, -imageSize.height, 0);
            }
            else if(orientation == UIInterfaceOrientationPortraitUpsideDown)
            {
                CGContextRotateCTM(context, (CGFloat)M_PI);
                CGContextTranslateCTM(context, -imageSize.width, -imageSize.height);
            }
        }
        
        if([window respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)])
            [window drawViewHierarchyInRect:window.bounds afterScreenUpdates:NO];
        else
            [window.layer renderInContext:UIGraphicsGetCurrentContext()];
        
        CGContextRestoreGState(context);
    }
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return image;
}

  

文章到此就结束了,希望对路过的人有所帮助!!!!!