iOS 手写签名的简单实用封装

2017 年 11 月 10 日 CocoaChina lxiaokai

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;

}