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tableviewcell imageview改变图片大小方法

来源：互联网 发布：国外win10优化软件推荐 编辑：程序博客网 时间：2024/05/16 01:45

转自：http://blog.sina.com.cn/s/blog_5fb39f9101017n1v.html


UIGraphicsBeginImageContext

创建一个基于位图的上下文（context）,并将其设置为当前上下文(context)。方法声明如下：

void UIGraphicsBeginImageContext(CGSize size);

参数size为新创建的位图上下文的大小。它同时是由UIGraphicsGetImageFromCu

rrentImageContext函数返回的图形大小。

该函数的功能同UIGraphicsBeginImageContextWithOptions的功能相同，相当与

UIGraphicsBeginImageContextWithOptions的opaque参数为NO,scale因子为1.0。

UIGraphicsBeginImageContextWithOptions

函数原型为：

void UIGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque, CGFloat scale);

size——同UIGraphicsBeginImageContext

opaque—透明开关，如果图形完全不用透明，设置为YES以优化位图的存储。

scale—–缩放因子



默认创建一个透明的位图上下文

 

UIImageC处理

1、等比缩放

C代码 复制代码收藏代码
  1. - (UIImage *) scaleImage:(UIImage *)imagetoScale:(float)scaleSize {
  2. UIGraphicsBeginImageContext(CGSizeMake(image.size.width *scaleSize, image.size.height * scaleSize);
  3. [image drawInRect:CGRectMake(0, 0, image.size.width *scaleSize, image.size.height * scaleSize)];
  4. UIImage *scaledImage =UIGraphicsGetImageFromCurrentImageContext();
  5. UIGraphicsEndImageContext();
  6. returnscaledImage;
  7. }

 

2、自定义大小

C代码 复制代码收藏代码
  1. - (UIImage *) reSizeImage:(UIImage *)imagetoSize:(CGSize)reSize {
  2. UIGraphicsBeginImageContext(CGSizeMake(reSize.width,reSize.height));
  3. [image drawInRect:CGRectMake(0, 0, reSize.width,reSize.height)];
  4. UIImage *reSizeImage =UIGraphicsGetImageFromCurrentImageContext();
  5. UIGraphicsEndImageContext();
  6. returnreSizeImage;
  7. }

 

3、处理某个特定的view

只要是继承UIView的object 都可以处理
必须先import QuzrtzCore.framework

C代码 复制代码收藏代码
  1. -(UIImage*) captureView:(UIView *)theView{
  2. CGRect rect = theView.frame;
  3. UIGraphicsBeginImageContext(rect.size);
  4. CGContextRef context =UIGraphicsGetCurrentContext();
  5. [theView.layer renderInContext:context];
  6. UIImage *img =UIGraphicsGetImageFromCurrentImageContext();
  7. UIGraphicsEndImageContext();
  8. returnimg;
  9. }

 

4、存储图片

4.1、存储到app的文件里

把要处理的图片以image.png的名字存储到apphome地下的Document目录中

 

C代码 复制代码收藏代码
  1. NSString *path =[[NSHomeDirectory()stringByAppendingPathComponent:@"Documents"]stringByAppendingPathComponent:@"image.png"];
  2. [UIImagePNGRepresentation(image)writeToFile:pathatomically:YES];

4.2、存储到手机的图片库中

C代码 复制代码收藏代码
  1. CGImageRef screen =UIGetScreenImage();
  2. UIImage* image = [UIImageimageWithCGImage:screen];
  3. CGImageRelease(screen);
  4. UIImageWriteToSavedPhotosAlbum(image, self, nil,nil);

 

直接拨打有分机号的电话

 

C代码 复制代码收藏代码
  1. [[UIApplication sharedApplication] openURL:[NSURLURLWithString:@"tel://01011112222,3333"]];

 

一些有关图像处理的代码片段

- (UIImage *)rescaleImage:(UIImage *)img ToSize:(CGSize)size;//图片缩放裁剪

- (UIImage*)transformWidth:(CGFloat)widthheight:(CGFloat)height; //改变大小

+ (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage*)image2; //合并图片

+ (UIImage *)imageFromImage:(UIImage *)imageinRect:(CGRect)rect; //裁剪部分图片

+ (void)imageSavedToPhotosAlbum:(UIImage *)image

didFinishSavingWithError:(NSError *)error contextInfo:(void*)contextInfo; //保存图片到媒体库


零）重新设置图片的尺寸

- (UIImage *)rescaleImage:(UIImage *)img ToSize:(CGSize)size{

CGRect rect = CGRectMake(0.0, 0.0, size.width, size.height);

UIGraphicsBeginImageContext(rect.size);

[img drawInRect:rect]; // scales image to rect

UIImage *resImage =UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return resImage;

}

－）根据给定得图片，从其指定区域截取一张新得图片

-(UIImage *)getImageFromImage{

//大图bigImage

//定义myImageRect，截图的区域

CGRect myImageRect = CGRectMake(10.0, 10.0, 57.0, 57.0);

UIImage* bigImage= [UIImage imageNamed:@"k00030.jpg"];

CGImageRef imageRef = bigImage.CGImage;

CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef,myImageRect);

CGSize size;

size.width = 57.0;

size.height = 57.0;

UIGraphicsBeginImageContext(size);

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextDrawImage(context, myImageRect, subImageRef);

UIImage* smallImage = [UIImageimageWithCGImage:subImageRef];

UIGraphicsEndImageContext();

return smallImage;

}

二） 合并两张图片

- (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage*)image2 {

UIGraphicsBeginImageContext(image1.size);

// Draw image1

[image1 drawInRect:CGRectMake(0, 0, image1.size.width,image1.size.height)];

// Draw image2

[image2 drawInRect:CGRectMake(0, 0, image2.size.width,image2.size.height)];

UIImage *resultingImage =UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return resultingImage;

}


三） 捕捉屏幕截图

CALayer实例使用CoreGraphics的renderInContext方法可以将视图绘制到图像上下文中以便转化为其他UIImage实例。前提先#import

复制代码
+ (UIImage *) imageFromView: (UIView *)theView {    // draw a view's contents into an image context   UIGraphicsBeginImageContext(theView.frame.size);   CGContextRef  context = UIGraphicsGetCurrentContext();   [theView.layer  renderInContext:context];   UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();   UIGraphicsEndImageContext();    return theImage;}
复制代码

注：UIGraphicsBeginImageContext(CGSizesize)创建一个基于位图的上下文(context)，并将其设置为当前上下文。函数功能与UIGraphicsBeginImageContextWithOptions相同，相当于该方法的opaque参数为NO，scale因子为1.0。而UIGraphicsEndImageContext()方法是移除栈顶的基于当前位图的图形上下文。

视图添加倒影效果

复制代码
const CGFloat kReflectPercent = -0.25f;const CGFloat kReflectOpacity = 0.3f;const CGFloat kReflectDistance = 10.0f;+ (void)addSimpleReflectionToView:(UIView *)theView{     CALayer *reflectionLayer = [CALayer layer];     reflectionLayer.contents = [theView layer].contents;     reflectionLayer.opacity = kReflectOpacity;     reflectionLayer.frame = CGRectMake(0.0f,0.0f,theView.frame.size.width,theView.frame.size.height*kReflectPercent);  //倒影层框架设置，其中高度是原视图的百分比    CATransform3D stransform = CATransform3DMakeScale(1.0f,-1.0f,1.0f);     CATransform3D transform = CATransform3DTranslate(stransform,0.0f,-(kReflectDistance + theView.frame.size.height),0.0f);     reflectionLayer.transform = transform;     reflectionLayer.sublayerTransform = reflectionLayer.transform;     [[theView layer] addSublayer:reflectionLayer];}
复制代码

另一：使用Core Graphics创建倒影

复制代码
+ (CGImageRef) createGradientImage:(CGSize)size{      CGFloat colors[] = {0.0,1.0,1.0,1.0};      //在灰色设备色彩上建立一渐变     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();      CGContextRef context = CGBitmapContextCreate(nil,size.width,size.height,8,0,colorSpace,kCGImageAlphaNone);      CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace,colors,NULL,2);      CGColorSpaceRelease(colorSpace);      //绘制线性渐变     CGPoint p1 = CGPointZero;      CGPoint p2 = CGPointMake(0,size.height);      CGContextDrawLinearGradient(context,gradient,p1,p2,kCGGradientDrawsAfterEndLocation);      //Return the CGImage      CGImageRef theCGImage = CGBitmapContextCreateImage(context);      CFRelease(gradient);      CGContextRelease(context);      return theCGImage;}
复制代码

//Create a shrunken frame for the reflection

复制代码
+ (UIImage *) reflectionOfView:(UIView *)theView WithPercent:(CGFloat) percent{     //Retain the width but shrink the height     CGSize size = CGSizeMake(theView.frame.size.width, theView.frame.size.height * percent);     //Shrink the View     UIGraphicsBeginImageContext(size);     CGContextRef context = UIGraphicsGetCurrentContext();     [theView.layer renderInContext:context];     UIImage *partialimg = UIGraphicsGetImageFromCurrentImageContext();     UIGraphicsEndImageContext();     //build the mask     CGImageRef mask = [ImageHelper createGradientImage:size];     CGImageRef ref = CGImageCreateWithMask(partialimg.CGImage,mask);     UIImage *theImage = [UIImage imageWithCGImage:ref];     CGImageRelease(ref);     CGImageRelease(mask);     return theImage;}const CGFloat kReflectDistance = 10.0f;+ (void) addReflectionToView: (UIView *)theView{     theView.clipsToBounds = NO;     UIImageView *reflection = [[UIImageView alloc] initWithImage:[ImageHelper reflectionOfView:theView withPercent:0.45f]];     CGRect frame = reflection.frame;     frame.origin = CGPointMake(0.0f, theView.frame.size.height + kReflectDistance);     reflection.frame = frame;     // add the reflection as a simple subview     [theView addSubView:reflection];     [reflection release];}

关于图片缩放的线程安全和非线程安全操作.

非线程安全的操作只能在主线程中进行操作,对于大图片的处理肯定会消耗大量的时间,如下面的方法

方法1： 使用UIKit

+ (UIImage*)imageWithImageINCLUDEPICTURE"http://www.61ic.com/Mobile/UploadFiles_9667/201103/20110309123315372.gif"\* MERGEFORMATINET UIImage*)image scaledToSize INCLUDEPICTURE"http://www.61ic.com/Mobile/UploadFiles_9667/201103/20110309123315372.gif"\* MERGEFORMATINET CGSize)newSize;

{

// Create a graphics imagecontext

UIGraphicsBeginImageContext(newSize);

// Tell the old image to draw inthis new context, with the desired

// new size

[imagedrawInRect:CGRectMake(0,0,newSize.width,newSize.height)];

// Get the new image from thecontext

UIImage* newImage =UIGraphicsGetImageFromCurrentImageContext();

// End the context

UIGraphicsEndImageContext();

// Return the newimage.

return newImage;

}

此方法很简单，但是，这种方法不是线程安全的情况下.

方法2： 使用CoreGraphics

+ (UIImage*)imageWithImageINCLUDEPICTURE"http://www.61ic.com/Mobile/UploadFiles_9667/201103/20110309123315372.gif"\* MERGEFORMATINET UIImage*)sourceImage scaledToSize INCLUDEPICTURE"http://www.61ic.com/Mobile/UploadFiles_9667/201103/20110309123315372.gif"\* MERGEFORMATINET CGSize)newSize;

{

CGFloat targetWidth =targetSize.width;

CGFloat targetHeight =targetSize.height;

CGImageRef imageRef = [sourceImageCGImage];

CGBitmapInfo bitmapInfo =CGImageGetBitmapInfo(imageRef);

CGColorSpaceRef colorSpaceInfo =CGImageGetColorSpace(imageRef);

if (bitmapInfo ==kCGImageAlphaNone) {

bitmapInfo =kCGImageAlphaNoneSkipLast;

}

CGContextRef bitmap;

if (sourceImage.imageOrientation== UIImageOrientationUp ||sourceImage.imageOrientation ==UIImageOrientationDown) {

bitmap =CGBitmapContextCreate(NULL, targetWidth,targetHeight,CGImageGetBitsPerComponent(imageRef),CGImageGetBytesPerRow(imageRef),colorSpaceInfo, bitmapInfo);

} else {

bitmap =CGBitmapContextCreate(NULL, targetHeight,targetWidth,CGImageGetBitsPerComponent(imageRef),CGImageGetBytesPerRow(imageRef),colorSpaceInfo, bitmapInfo);

}

if (sourceImage.imageOrientation== UIImageOrientationLeft) {

CGContextRotateCTM (bitmap,radians(90));

CGContextTranslateCTM (bitmap, 0,-targetHeight);

} else if(sourceImage.imageOrientation ==UIImageOrientationRight){

CGContextRotateCTM (bitmap,radians(-90));

CGContextTranslateCTM (bitmap,-targetWidth, 0);

} else if(sourceImage.imageOrientation == UIImageOrientationUp) {

// NOTHING

} else if(sourceImage.imageOrientation ==UIImageOrientationDown){

CGContextTranslateCTM (bitmap,targetWidth, targetHeight);

CGContextRotateCTM (bitmap,radians(-180.));

}

CGContextDrawImage(bitmap,CGRectMake(0, 0, targetWidth,targetHeight), imageRef);

CGImageRef ref =CGBitmapContextCreateImage(bitmap);

UIImage* newImage = [UIImageimageWithCGImage:ref];

CGContextRelease(bitmap);

CGImageRelease(ref);

return newImage;

}

这种方法的好处是它是线程安全，加上它负责的（使用正确的颜色空间和位图信息，处理图像方向） 的小东西，UIKit 版本不会。

如何调整和保持长宽比 （如 AspectFill选项）？

它是非常类似于上述，方法，它看起来像这样：

+ (UIImage*)imageWithImageINCLUDEPICTURE"http://www.61ic.com/Mobile/UploadFiles_9667/201103/20110309123315372.gif"\* MERGEFORMATINET UIImage*)sourceImagescaledToSizeWithSameAspectRatio INCLUDEPICTURE"http://www.61ic.com/Mobile/UploadFiles_9667/201103/20110309123315372.gif"\* MERGEFORMATINET CGSize)targetSize;

{

CGSize imageSize =sourceImage.size;

CGFloat width =imageSize.width;

CGFloat height =imageSize.height;

CGFloat targetWidth =targetSize.width;

CGFloat targetHeight =targetSize.height;

CGFloat scaleFactor =0.0;

CGFloat scaledWidth =targetWidth;

CGFloat scaledHeight =targetHeight;

CGPoint thumbnailPoint =CGPointMake(0.0,0.0);

if (CGSizeEqualToSize(imageSize,targetSize) == NO) {

CGFloat widthFactor = targetWidth/ width;

CGFloat heightFactor =targetHeight / height;

if (widthFactor > heightFactor){

scaleFactor = widthFactor; //scale to fit height

}

else {

scaleFactor = heightFactor; //scale to fit width

}

scaledWidth = width *scaleFactor;

scaledHeight = height *scaleFactor;

// center the image

if (widthFactor > heightFactor){

thumbnailPoint.y = (targetHeight -scaledHeight) * 0.5;

}

else if (widthFactor <heightFactor) {

thumbnailPoint.x = (targetWidth -scaledWidth) * 0.5;

}

}

CGImageRef imageRef = [sourceImageCGImage];

CGBitmapInfo bitmapInfo =CGImageGetBitmapInfo(imageRef);

CGColorSpaceRef colorSpaceInfo =CGImageGetColorSpace(imageRef);

if (bitmapInfo ==kCGImageAlphaNone) {

bitmapInfo =kCGImageAlphaNoneSkipLast;

}

CGContextRef bitmap;

if (sourceImage.imageOrientation== UIImageOrientationUp ||sourceImage.imageOrientation ==UIImageOrientationDown) {

bitmap =CGBitmapContextCreate(NULL, targetWidth,targetHeight,CGImageGetBitsPerComponent(imageRef),CGImageGetBytesPerRow(imageRef),colorSpaceInfo, bitmapInfo);

} else {

bitmap =CGBitmapContextCreate(NULL, targetHeight,targetWidth,CGImageGetBitsPerComponent(imageRef),CGImageGetBytesPerRow(imageRef),colorSpaceInfo, bitmapInfo);

}

// In the right or left cases, weneed to switch scaledWidth and scaledHeight,

// and also the thumbnailpoint

if (sourceImage.imageOrientation== UIImageOrientationLeft) {

thumbnailPoint =CGPointMake(thumbnailPoint.y, thumbnailPoint.x);

CGFloat oldScaledWidth =scaledWidth;

scaledWidth =scaledHeight;

scaledHeight =oldScaledWidth;

CGContextRotateCTM (bitmap,radians(90));

CGContextTranslateCTM (bitmap, 0,-targetHeight);

} else if(sourceImage.imageOrientation ==UIImageOrientationRight){

thumbnailPoint =CGPointMake(thumbnailPoint.y, thumbnailPoint.x);

CGFloat oldScaledWidth =scaledWidth;

scaledWidth =scaledHeight;

scaledHeight =oldScaledWidth;

CGContextRotateCTM (bitmap,radians(-90));

CGContextTranslateCTM (bitmap,-targetWidth, 0);

} else if(sourceImage.imageOrientation == UIImageOrientationUp) {

// NOTHING

} else if(sourceImage.imageOrientation ==UIImageOrientationDown){

CGContextTranslateCTM (bitmap,targetWidth, targetHeight);

CGContextRotateCTM (bitmap,radians(-180.));

}

CGContextDrawImage(bitmap,CGRectMake(thumbnailPoint.x,thumbnailPoint.y, scaledWidth,scaledHeight), imageRef);

CGImageRef ref =CGBitmapContextCreateImage(bitmap);

UIImage* newImage = [UIImageimageWithCGImage:ref];

CGContextRelease(bitmap);

CGImageRelease(ref);

return newImage;

}


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