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iOS,图片处理
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1.旋转图片
2.缩放图片
3.截取图片指定区域
4.祛除图片白色背景，弄成透明png
5.将UIView转化为UIImage，并转化为data和base64
6.将视频一帧(CMSampleBufferRef)转换为UIImage
7.使用UIWebView加载gif动态图
8.实现图片(UIImage)圆角
9.图片加印章图
10.图片压缩到指定大小
旋转图片
//给定角度旋转图片
-(UIImage *)image:(UIImage *)image rotation:(UIImageOrientation)orientation
{
long double rotate = 0.0;
CGRect rect;
float translateX = 0;
float translateY = 0;
float scaleX = 1.0;
float scaleY = 1.0;
switch (orientation) {
case UIImageOrientationLeft:
rotate = M_PI_2;
rect = CGRectMake(0, 0, image.size.height, image.size.width);
translateX = 0;
translateY = -rect.size.width;
scaleY = rect.size.width/rect.size.height;
scaleX = rect.size.height/rect.size.width;
break;
case UIImageOrientationRight:
rotate = 3 * M_PI_2;
rect = CGRectMake(0, 0, image.size.height, image.size.width);
translateX = -rect.size.height;
translateY = 0;
scaleY = rect.size.width/rect.size.height;
scaleX = rect.size.height/rect.size.width;
break;
case UIImageOrientationDown:
rotate = M_PI;
rect = CGRectMake(0, 0, image.size.width, image.size.height);
translateX = -rect.size.width;
translateY = -rect.size.height;
break;
default:
rotate = 0.0;
rect = CGRectMake(0, 0, image.size.width, image.size.height);
translateX = 0;
translateY = 0;
break;
}
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
//做CTM变换
CGContextTranslateCTM(context, 0.0, rect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextRotateCTM(context, rotate);
CGContextTranslateCTM(context, translateX, translateY);
CGContextScaleCTM(context, scaleX, scaleY);
//绘制图片
CGContextDrawImage(context, CGRectMake(0, 0, rect.size.width, rect.size.height), image.CGImage);
UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext();
return newPic;
}
缩放图片
//按比例缩放,size 是你要把图显示到 多大区域 CGSizeMake(980, 560)
-(UIImage *) imageCompressForSize:(UIImage *)sourceImage targetSize:(CGSize)size{
UIImage *newImage = nil;
CGSize imageSize = sourceImage.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = size.width;
CGFloat targetHeight = size.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0, 0.0);
if(CGSizeEqualToSize(imageSize, size) == NO){
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if(widthFactor > heightFactor){
scaleFactor = widthFactor;
}
else{
scaleFactor = heightFactor;
}
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
if(widthFactor > heightFactor){
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}else if(widthFactor < heightFactor){
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
UIGraphicsBeginImageContext(size);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
if(newImage == nil){
NSLog(@"scale image fail");
}
UIGraphicsEndImageContext();
return newImage;
}
截取图片指定区域
CGRect rect=CGRectMake(0, 0, 100, 100);
//截取图片指定区域
img=[UIImage imageWithCGImage:CGImageCreateWithImageInRect(img.CGImage, rect)];
祛除图片白色背景，弄成透明png
//颜色变化
void ProviderReleaseData (void *info, const void *data, size_t size)
{
free((void*)data);
}
//将签名不要的背景色转换
- (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++)
{
//把绿色变成黑色，把背景色变成透明
if ((*pCurPtr & 0x65815A00) == 0x65815a00) // 将背景变成透明
{
uint8_t* ptr = (uint8_t*)pCurPtr;
ptr[0] = 0;
}
else if ((*pCurPtr & 0x00FF0000) == 0x00ff0000) // 将绿色变成黑色
{
uint8_t* ptr = (uint8_t*)pCurPtr;
ptr[3] = 0; //0~255
ptr[2] = 0;
ptr[1] = 0;
}
else if ((*pCurPtr & 0xFFFFFF00) == 0xffffff00) // 将白色变成透明
{
uint8_t* ptr = (uint8_t*)pCurPtr;
ptr[0] = 0;
}
else
{
// 改成下面的代码，会将图片转成想要的颜色
uint8_t* ptr = (uint8_t*)pCurPtr;
ptr[3] = 0; //0~255
ptr[2] = 0;
ptr[1] = 0;
}
}
// 将内存转成image
CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, ProviderReleaseData);
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);
return resultUIImage;
}
将UIView转化为UIImage，并转化为data和base64
//将UIView转化为UIImage
-(UIImage *)createImageFromView:(UIView *)view{
//屏幕密度
CGFloat scale=[UIScreen mainScreen].scale;
//开始绘图，区域大小，半透明效果，屏幕密度
UIGraphicsBeginImageContextWithOptions(self.view.frame.size, NO, scale);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
//开始生成图片
UIImage *image=UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
//确定签名事件
-(void)okAction:(UIButton *)sender{
[self.touchView.cleanBtn removeFromSuperview];
//将有签名的视图转化为img并获取data
UIImage *img=[self createImageFromView:self.touchView];
NSData *data=UIImageJPEGRepresentation(img, 80.0f);
//将data转化为base64字符串
NSString *base64Str=[data base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
NSString *utf8Str=[NSString stringWithUTF8String:[base64Str UTF8String]];
//base64转UIImage
NSData *dataUtf8=[[NSData alloc] initWithBase64EncodedString:utf8Str options:NSDataBase64DecodingIgnoreUnknownCharacters];
UIImage *base64Image=[UIImage imageWithData:dataUtf8];
}
将视频一帧(CMSampleBufferRef)转换为UIImage
//用AVFoundation捕捉视频帧，很多时候需要把某一帧转换成UIImage，用此函数：
- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer {
// 为媒体数据设置一个CMSampleBuffer的Core Video图像缓存对象
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
// 锁定pixel buffer的基地址
CVPixelBufferLockBaseAddress(imageBuffer, 0);
// 得到pixel buffer的基地址
void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
// 得到pixel buffer的行字节数
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
// 得到pixel buffer的宽和高
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
// 创建一个依赖于设备的RGB颜色空间
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// 用抽样缓存的数据创建一个位图格式的图形上下文（graphics context）对象
CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8,
bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
// 根据这个位图context中的像素数据创建一个Quartz image对象
CGImageRef quartzImage = CGBitmapContextCreateImage(context);
// 解锁pixel buffer
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
// 释放context和颜色空间
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
// 用Quartz image创建一个UIImage对象image
UIImage *image = [UIImage imageWithCGImage:quartzImage];
// 释放Quartz image对象
CGImageRelease(quartzImage);
return (image);
}
当然，先不要急，因为捕捉到得帧是YUV颜色通道的，这种颜色通道无法通过以上函数转换，RGBA颜色通道才可以成功转换，所以，先需要把视频帧的输出格式设置一下：
[videoOutput setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey]];
使用UIWebView加载gif动态图
//使用UIWebView加载gif动态图
UIWebView *webView=[[UIWebView alloc] initWithFrame:self.view.frame];
//读取图片
NSString *retinaPath = [[NSBundle mainBundle] pathForResource:@"ker" ofType:@"gif"];
//图片转换为data
NSData *data = [NSData dataWithContentsOfFile:retinaPath];
[webView loadData:data MIMEType:@"image/gif" textEncodingName:nil baseURL:nil];
[self.view addSubview:webView];
实现图片(UIImage)圆角
/**
设置图片圆角方法
@param image 原图片
@param radius 圆角度数
@param rect 新图片frame
@return 返回圆角图片
*/
-(UIImage *)makeRoundedImage:(UIImage *) image
radius: (float) radius cgRect:(CGRect)rect;
{
CALayer *imageLayer = [CALayer layer];
imageLayer.frame = CGRectMake(0, 0, rect.size.width, rect.size.height);
imageLayer.contents = (id) image.CGImage;
imageLayer.masksToBounds = YES;
imageLayer.cornerRadius = radius;
UIGraphicsBeginImageContext(rect.size);
[imageLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *roundedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return roundedImage;
}
图片加印章图
#pragma mark - 加图片印章(可以用半透明图片形成水印效果)
- (UIImage *)imageWithTransImage:(UIImage *)useImage addtransparentImage:(UIImage *)transparentimg
{
UIGraphicsBeginImageContext(useImage.size);
[useImage drawInRect:CGRectMake(0, 0, useImage.size.width, useImage.size.height)];
//印章图片位置大小
[transparentimg drawInRect:CGRectMake(useImage.size.width - useImage.size.width*0.18 - 10, 10, useImage.size.width*0.18, useImage.size.height*0.26)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}
图片压缩到指定大小
#pragma mark -压缩图片到指定大小(单位KB)
- (NSData *)compressImage:(UIImage *)image toMaxFileSize:(NSInteger)maxFileSize{
CGFloat compression = 0.9f;
CGFloat maxCompression = 0.1f;
NSData *imageData = UIImageJPEGRepresentation(image, compression);
while ([imageData length] / 1000 > maxFileSize && compression > maxCompression) {
compression -= 0.1;
imageData = UIImageJPEGRepresentation(image, compression);
}
return imageData;
}
