iOS 手写签名的简单实用封装

简介

现在很多项目在完善信息或者注册信息的时候,或者支付这一方面,都希望用户手写签名,这样既可以保证是用户亲自签名的,保证该记录是用用户操作的,而不是别人操作的.所以手写签字这个还是比较重要的.下面就是通过QuartzCore来绘制签名.QuartzCore是iOS的核心动画框架.

绘制

• 1定义一个结构体

static CGPoint midpoint(CGPoint p0,CGPoint p1) {
    return (CGPoint) {
        (p0.x + p1.x) /2.0,
        (p0.y + p1.y) /2.0
    };
}

• 2添加手势

UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    pan.maximumNumberOfTouches = pan.minimumNumberOfTouches =1;
    [self addGestureRecognizer:pan];

• 3开始绘制

  CGPoint currentPoint = [pan locationInView:self];
    CGPoint midPoint = midpoint(previousPoint, currentPoint);
    NSLog(@"获取到的触摸点的位置为--currentPoint:%@",NSStringFromCGPoint(currentPoint));
    [self.currentPointArr addObject:[NSValue valueWithCGPoint:currentPoint]];
    self.hasSignatureImg = YES;
    CGFloat viewHeight = self.frame.size.height;
    CGFloat currentY = currentPoint.y;
    if (pan.state ==UIGestureRecognizerStateBegan) {
        [path moveToPoint:currentPoint];
        
    } else if (pan.state ==UIGestureRecognizerStateChanged) {
        [path addQuadCurveToPoint:midPoint controlPoint:previousPoint];
        
        
    }
    
    if(0 <= currentY && currentY <= viewHeight)
    {
        if(max == 0&&min == 0)
        {
            max = currentPoint.x;
            min = currentPoint.x;
        }
        else
        {
            if(max <= currentPoint.x)
            {
                max = currentPoint.x;
            }
            if(min>=currentPoint.x)
            {
                min = currentPoint.x;
            }
        }
        
    }
    
    previousPoint = currentPoint;
    //记得调用,及时刷新视图
    [self setNeedsDisplay];

• 4获取绘制视图,在进行一系列处理就好

 if(UIGraphicsBeginImageContextWithOptions !=NULL)
    {
        UIGraphicsBeginImageContextWithOptions(self.bounds.size,NO, [UIScreen mainScreen].scale);
    }else {
        UIGraphicsBeginImageContext(self.bounds.size);
        
    }
    
    [self.layer renderInContext:UIGraphicsGetCurrentContext()];
    
    UIImage *image =UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    //绘制成图
    image = [self imageBlackToTransparent:image];
    NSLog(@"width:%f,height:%f",image.size.width,image.size.height);
    //截取图片
    UIImage *img = [self cutImage:image];
    //压缩图片
    self.SignatureImg = [self scaleToSize:img];

• 5附上处理的方法

1.绘制成图

- (UIImage*) imageBlackToTransparent:(UIImage*) image
{
    // 分配内存
    const int imageWidth = image.size.width;
    const int imageHeight = image.size.height;
    size_t      bytesPerRow = imageWidth * 4;
    uint32_t* rgbImageBuf = (uint32_t*)malloc(bytesPerRow * imageHeight);
    
    // 创建context
    CGColorSpaceRef colorSpace =CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace,
                                                 kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
    
    CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage);
    
    // 遍历像素
    int pixelNum = imageWidth * imageHeight;
    uint32_t* pCurPtr = rgbImageBuf;
    for (int i =0; i < pixelNum; i++, pCurPtr++)
    {
        //        if ((*pCurPtr & 0xFFFFFF00) == 0)    //将黑色变成透明
        if (*pCurPtr == 0xffffff)
        {
            uint8_t* ptr = (uint8_t*)pCurPtr;
            ptr[0] =0;
        }
        
        //改成下面的代码，会将图片转成灰度
        /*uint8_t* ptr = (uint8_t*)pCurPtr;
         // gray = red * 0.11 + green * 0.59 + blue * 0.30
         uint8_t gray = ptr[3] * 0.11 + ptr[2] * 0.59 + ptr[1] * 0.30;
         ptr[3] = gray;
         ptr[2] = gray;
         ptr[1] = gray;*/
    }
    
    // 将内存转成image
    CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight,/*ProviderReleaseData**/NULL);
    CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8,32, bytesPerRow, colorSpace,
                                        kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider,
                                        NULL, true,kCGRenderingIntentDefault);
    CGDataProviderRelease(dataProvider);
    
    UIImage* resultUIImage = [UIImage imageWithCGImage:imageRef];
    
    // 释放
    CGImageRelease(imageRef);
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);
    // free(rgbImageBuf) 创建dataProvider时已提供释放函数，这里不用free
    
    return resultUIImage;
}

2.截图图片

CGRect rect ;
    //签名事件没有发生
    if(min == 0&&max == 0)
    {
        rect =CGRectMake(0,0, 0, 0);
    }
    else//签名发生
    {
        rect =CGRectMake(min-3,0, max-min+6,self.frame.size.height);
    }
    CGImageRef imageRef =CGImageCreateWithImageInRect([image CGImage], rect);
    UIImage * img = [UIImage imageWithCGImage:imageRef];
    //添加水印
    UIImage *lastImage = [self addText:img text:self.showMessage];
    CGImageRelease(imageRef);
    [self setNeedsDisplay];

3.压缩

//压缩图片,最长边为128(根据不同的比例来压缩)
- (UIImage *)scaleToSize:(UIImage *)img {
    CGRect rect ;
    CGFloat imageWidth = img.size.width;
    //判断图片宽度
    if(imageWidth >= 128)
    {
        rect =CGRectMake(0,0, 128, self.frame.size.height);
    }
    else
    {
        rect =CGRectMake(0,0, img.size.width,self.frame.size.height);
        
    }
    CGSize size = rect.size;
    UIGraphicsBeginImageContext(size);
    [img drawInRect:rect];
    UIImage* scaledImage =UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    //此处注释是为了防止该签名图片被保存到本地
    //    UIImageWriteToSavedPhotosAlbum(scaledImage,nil, nil, nil);
    [self setNeedsDisplay];
    return scaledImage;
}

剩下的,都是一些细节问题,根据不同的项目进行不同的修改就好.

自己做的demo效果

image

附上demo