UIImage有关的几个方法

最新推荐文章于 2017-02-12 16:16:00 发布

最新推荐文章于 2017-02-12 16:16:00 发布 · 96 阅读

本文介绍了使用UIImage类进行图像处理的方法，包括使用imageNamed方法的注意事项、如何显示RGB24解码数据、保存UIImage到文件及截取UIView并保存的具体实现。

1） UIImage类imageNamed方法是便捷的便捷构造方法，使用了自动释放池，在需要频繁大量加载图片的场合请不要使用imageNamed, 而
imageWithContentsOfFile，

2）如何将解码后的RGB24数据显示到UIImage上
#define SCREEN_METRIC_WIDTH 176
#define SCREEN_METRIC_HEIGHT 144
int i = 0;

int bitsPerComponent = 8;
int bitsPerPixel = 24;
int bytesPerRow = 3 * SCREEN_METRIC_WIDTH;
NSInteger myLCDDataLength =
SCREEN_METRIC_WIDTH * SCREEN_METRIC_HEIGHT * 3;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bmpInof = kCGBitmapByteOrderDefault;
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
CGDataProviderRef provider = nil;

//rgb_image = malloc(SCREEN_METRIC_WIDTH*SCREEN_METRIC_HEIGHT*3)

provider = CGDataProviderCreateWithData(NULL, rgb_image, myLCDDataLength, NULL);

CGImageRef cgImage= CGImageCreate(SCREEN_METRIC_WIDTH,SCREEN_METRIC_HEIGHT,
bitsPerComponent,
bitsPerPixel,
bytesPerRow,
colorSpaceRef,
bmpInof,
provider,
NULL,
NO,
renderingIntent);

CGColorSpaceRelease(colorSpaceRef);
UIImage *image = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
CGDataProviderRelease(provider);

3）把UIImage数据保存文件

//get now time
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy_MMdd_HHMMSS"];
NSString *dateTime = [formatter stringFromDate:[NSDate date]];

NSString* filepath = [Utilities documentsPath:[NSString stringWithFormat:@"snapshot%@.png", dateTime]];

NSLog(@"save png, time:%@", filepath);

[formatter release];

//save UIImage to file in PNG format
NSData *imageData = NULL;

imageData = UIImagePNGRepresentation(cur_uiImage);
if ((imageData == nil) || ([imageData length] <= 0))
return 0;

[imageData writeToFile:filepath atomically:YES];
//直接保存图片到相册
//UIImageWriteToSavedPhotosAlbum(cur_uiImage, nil, nil, nil);

4）截取整个UIView并保存文件

UIView *view = [[[[[UIApplication sharedApplication] windows] objectAtIndex:1] subviews] lastObject];//获得某个window的某个subView

NSInteger index = 0;//用来给保存的png命名
for (UIView *subView in [view subviews]) {//遍历这个view的subViews
if ([subView isKindOfClass:NSClassFromString(@"UIImageView")] || [subView isKindOfClass:NSClassFromString(@"UIThreePartButton")]) {//找到自己需要的subView
//支持retina高分的关键
if(UIGraphicsBeginImageContextWithOpti***** != NULL)
{
UIGraphicsBeginImageContextWithOpti*****(subView.frame.size, NO, 0.0);
} else {
UIGraphicsBeginImageContext(subView.frame.size);
}

//获取图像
[subView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

//保存图像
NSString *path = [NSHomeDirectory() stringByAppendingFormat:@"/%d.png",index];
if ([UIImagePNGRepresentation(image) writeToFile:path atomically:YES]) {
index += 1;
NSLog(@"Succeeded!");
}
else {
NSLog(@"Failed!");
}
}
}