tableviewcell imageview改变图片大小方法
2015-03-16 15:44
330 查看
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：
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：
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
1、等比缩放
C代码
- (UIImage *) scaleImage:(UIImage *)imagetoScale:(float)scaleSize {
UIGraphicsBeginImageContext(CGSizeMake(image.size.width *scaleSize, image.size.height * scaleSize);
[image drawInRect:CGRectMake(0, 0, image.size.width *scaleSize, image.size.height * scaleSize)];
UIImage *scaledImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
returnscaledImage;
}
2、自定义大小
C代码
- (UIImage *) reSizeImage:(UIImage *)imagetoSize:(CGSize)reSize {
UIGraphicsBeginImageContext(CGSizeMake(reSize.width,reSize.height));
[image drawInRect:CGRectMake(0, 0, reSize.width,reSize.height)];
UIImage *reSizeImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
returnreSizeImage;
}
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
-(UIImage*) captureView:(UIView *)theView{
CGRect rect = theView.frame;
UIGraphicsBeginImageContext(rect.size);
CGContextRef context =UIGraphicsGetCurrentContext();
[theView.layer renderInContext:context];
UIImage *img =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
returnimg;
}
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
NSString *path =[[NSHomeDirectory()stringByAppendingPathComponent:@"Documents"]stringByAppendingPathComponent:@"image.png"];
[UIImagePNGRepresentation(image)writeToFile:pathatomically:YES];
4.2、存储到手机的图片库中
C代码
CGImageRef screen =UIGetScreenImage();
UIImage* image = [UIImageimageWithCGImage:screen];
CGImageRelease(screen);
UIImageWriteToSavedPhotosAlbum(image, self, nil,nil);
C代码
[[UIApplication sharedApplication] openURL:[NSURLURLWithString:@"tel://01011112222,3333"]];
- (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
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
另一：使用Core Graphics创建倒影
//Create a shrunken frame for the reflection
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;
}
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
- (UIImage *) scaleImage:(UIImage *)imagetoScale:(float)scaleSize {
UIGraphicsBeginImageContext(CGSizeMake(image.size.width *scaleSize, image.size.height * scaleSize);
[image drawInRect:CGRectMake(0, 0, image.size.width *scaleSize, image.size.height * scaleSize)];
UIImage *scaledImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
returnscaledImage;
}
2、自定义大小
C代码
- (UIImage *) reSizeImage:(UIImage *)imagetoSize:(CGSize)reSize {
UIGraphicsBeginImageContext(CGSizeMake(reSize.width,reSize.height));
[image drawInRect:CGRectMake(0, 0, reSize.width,reSize.height)];
UIImage *reSizeImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
returnreSizeImage;
}
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
-(UIImage*) captureView:(UIView *)theView{
CGRect rect = theView.frame;
UIGraphicsBeginImageContext(rect.size);
CGContextRef context =UIGraphicsGetCurrentContext();
[theView.layer renderInContext:context];
UIImage *img =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
returnimg;
}
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
NSString *path =[[NSHomeDirectory()stringByAppendingPathComponent:@"Documents"]stringByAppendingPathComponent:@"image.png"];
[UIImagePNGRepresentation(image)writeToFile:pathatomically:YES];
4.2、存储到手机的图片库中
C代码
CGImageRef screen =UIGetScreenImage();
UIImage* image = [UIImageimageWithCGImage:screen];
CGImageRelease(screen);
UIImageWriteToSavedPhotosAlbum(image, self, nil,nil);
直接拨打有分机号的电话
C代码[[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
+ (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;
}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
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];
}另一：使用Core Graphics创建倒影
+ (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;
}//Create a shrunken frame for the reflection
+ (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;
}
内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理 
相关文章推荐
- Android 改变ImageView图片的Bitmap大小
- 改变cell的imageview的大小
- Swift中tableViewCelll和ImageView中图片背景显示的问题
- Android ImageView设置图片的可见性,设置颜色的不同方法，设置图片指定大小
- iOS开发中tableview中cell图片大小自定义方法
- 解决关于图片大小不一导致Cell的imageView无法显示为圆形
- 使用image drawInRect: 方法改变图片大小后，图片画质变差了--（头像修改时）
- 改变UITableViewCell的imageView的大小（cell.imageView）
- android 通过uri截取指定大小的图片显示在imageview上
- 如何动态改变ImageView大小 -- 方案之二
- 【Android 开发】：UI控件之显示图片控件 ImageView 的使用方法
- [转]当图片源大小大于ImageView大小时的处理方式（缩放）
- 点击tableview里的cell后改变cell的背景图片
- ImageVIew 设置图片大小
- Android Smart Image View使用方法--从url获取图片或从通讯录获取图片，支持缓存
- 图片不能显示： [cell.imageView setImageWithURL:imageUrl placeholderImage:nil options:SDWebImageLowPriority
- imageView代码实现设置图片大小
- ios 改变图片大小缩放方法
- ImageVIew 设置图片大小
- Android里同一个ImageView显示不同的图片的方法