Objective-C图片处理
2017-02-03 本文已影响937人
朱思明
背景
1.在我们的实际开发工作中随着项目的深入对于图片得要求越来高，考虑的外在条件也越来越多
2.我们不在满足于UI给我图片我们直接加载显示在视图上，我们需要考虑资源包的大小，图片的可扩展性（机型的适配）
3.所以在这里给大家分享图片一些关于图片处理的技术
一、图片截屏处理
1.获取某个视图的截屏
- (UIImage *)getScreenRecordingImageWithView:(UIView *)view
{
// 1.设置获取画布大小
UIGraphicsBeginImageContextWithOptions(CGSizeMake(view.frame.size.width, view.frame.size.height), YES, [UIScreen mainScreen].scale);
// [self.layer renderInContext:UIGraphicsGetCurrentContext()];
[view drawViewHierarchyInRect:view.bounds afterScreenUpdates:true];
UIImage *screenshotImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return screenshotImage;
}
二、视图的颜色处理
1.设置视图渐变色效果
- (void)setGradientLayerWithView:(UIView *)view {
// 创建 CAGradientLayer 对象
CAGradientLayer *gradientLayer = [CAGradientLayer layer];
// 设置 gradientLayer 的 Frame
gradientLayer.frame = view.bounds;
// 创建渐变色数组，需要转换为CGColor颜色
gradientLayer.colors = @[(__bridge id)[UIColor redColor].CGColor, [UIColor yellowColor].CGColor, (__bridge id)[UIColor redColor].CGColor];
// 设置三种颜色变化点，取值范围 0.0~1.0
gradientLayer.locations = @[@(0.0f) ,@(0.2f) ,@(1.0f)];
// 设置渐变颜色方向，左上点为(0,0), 右下点为(1,1)
gradientLayer.startPoint = CGPointMake(0, 0);
gradientLayer.endPoint = CGPointMake(0, 1);
// 添加渐变色到创建的 UIView 上去
[view.layer addSublayer:gradientLayer];
}
2.视图渐隐效果设置
// 在很多时候我们为了增强我们的视觉交互效果，往往让一些视图在边界位置有一个渐隐,效果，
// 例如：很多音乐播放器中歌词滚出屏幕或者进入屏幕时，文字会像切掉一样很生硬，如果能让文字出现渐隐效果会更好一些
// 实现思虑：1.UIView的蒙版效果，蒙版视图实体和视图重叠位置显示，蒙版视图透明位置和视图重叠位置隐藏，蒙版视图有透明效果位置和视图重叠位置alpha = 1.0 - 蒙版视图.alpha
// 2.使用渐变视图作为蒙版视图
- (void)setBoundaryFadeWithView:(UIView *)view {
// 1.获取一个黑色到透明色渐变色蒙版
UIView *maskView = [[UIView alloc] initWithFrame:view.bounds];
// 创建 CAGradientLayer 对象
CAGradientLayer *gradientLayer = [CAGradientLayer layer];
// 设置 gradientLayer 的 Frame gradientLayer.frame = view.bounds;
// 创建渐变色数组，需要转换为CGColor颜色
gradientLayer.colors = @[[UIColor colorWithWhite:0 alpha:0].CGColor, [UIColor blackColor].CGColor, [UIColor blackColor].CGColor, [UIColor colorWithWhite:0 alpha:0].CGColor];
// 设置三种颜色变化点，取值范围 0.0~1.0
gradientLayer.locations = @[@(0.0f) ,@(0.1f) ,@(0.9f) ,@(1.0f)];
// 设置渐变颜色方向，左上点为(0,0), 右下点为(1,1)
gradientLayer.startPoint = CGPointMake(0, 0);
gradientLayer.endPoint = CGPointMake(0, 1);
// 添加渐变色到创建的 UIView 上去
[maskView.layer addSublayer:gradientLayer];
// 2.把maskView作为view的蒙版视图
view.maskView = maskView;
}
3.获取任意颜色色的png图片视图
- (void)setPNGColorView:(UIView *)view pngImage:(UIImage *)pngImage color:(UIColor *)color {
// 1.设置视图的颜色
view.backgroundColor = color;
// 2.创建蒙版
UIImageView *maskView = [[UIImageView alloc] initWithFrame:view.bounds];
maskView.image = pngImage;
view.maskView = maskView;
}
三、iOS绘制镂空的图片
// 获取镂空的背景图片，例如我们在日常开发中添加的各种功能引导视图，需要遮罩中漏出需要看到的按钮或者图片
- (UIImage*)drawHollowPicture
{
// 01 创建画布
CGFloat width = [UIScreen mainScreen].bounds.size.width;
CGFloat height = [UIScreen mainScreen].bounds.size.height;
CGRect frame = CGRectMake(0, 0, width, height);
UIGraphicsBeginImageContextWithOptions(frame.size, false, [UIScreen mainScreen].nativeScale);
CGContextRef context = UIGraphicsGetCurrentContext();
// 02 绘制背景颜色
UIColor *bgColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.7];
CGContextSetFillColorWithColor(context, bgColor.CGColor);
CGContextAddRect(context, frame);
CGContextDrawPath(context, kCGPathFill);
// 03 裁剪圆形
// 设置绘制模式
CGContextSetBlendMode(context, kCGBlendModeClear);
// 画椭圆
CGContextAddEllipseInRect(context, CGRectMake(10, 10, 60, 60)); //椭圆
CGContextSetFillColorWithColor(context, [UIColor clearColor].CGColor);
CGContextDrawPath(context, kCGPathFill);
// 04 获取绘制图片
UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return theImage;
}
四、iOS中对图片进行数字处理的方式
// 1.灰度处理
- (UIImage*)getNewImageWithOldImage:(UIImage*)image {
// 1.定义色值的索引位置
const int RED =0;
const int GREEN =1;
const int BLUE =2;
const int ALPHA =3;
// 2.定义图片的大小
CGRect imageRect = CGRectMake(0,0, image.size.width* image.scale, image.size.height* image.scale);
int width = imageRect.size.width;
int height = imageRect.size.height;
// 3.创建图片像素数组的内存大小
uint32_t *pixels = (uint32_t*) malloc(width * height *sizeof(uint32_t));
// 清空像素组里面的内容
memset(pixels,0, width * height *sizeof(uint32_t));
// 4.创建色系对象
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// 5.创建一个rgba像素的画布对象，像素存放在pixels中
// create a context with RGBA pixels
CGContextRef context = CGBitmapContextCreate(pixels, width, height,8, width *sizeof(uint32_t), colorSpace,kCGImageAlphaPremultipliedLast);
// 6.把图片绘制到画布上，并且同步到存放像素内容的数组中
// paint the bitmap to our context which will fill in the pixels array
CGContextDrawImage(context,CGRectMake(0,0, width, height), [image CGImage]);
// 7.遍历所有的像素点进行处理
for(int y = 0; y < height; y++) {
for(int x = 0; x < width; x++) {
// 01 每一个像素点的颜色数组
uint8_t *rgbaPixel = (uint8_t*) &pixels[y * width + x];
// 02 色彩灰度处理
uint32_t gray = 0.3 * rgbaPixel[RED] +0.59 * rgbaPixel[GREEN] +0.11 * rgbaPixel[BLUE];
// rgbaPixel[RED] = gray;
// rgbaPixel[GREEN] = gray;
// rgbaPixel[BLUE] = gray;
// 03 单一颜色替换成红色
if (rgbaPixel[RED] == 239 && rgbaPixel[GREEN] == 60 && rgbaPixel[BLUE] == 153) {
rgbaPixel[RED] = 255;
rgbaPixel[GREEN] = 0;
rgbaPixel[BLUE] = 0;
}
}
}
// 8.获取画布中的图片对象
CGImageRef imageRef = CGBitmapContextCreateImage(context);
UIImage *resultImage = [UIImage imageWithCGImage:imageRef scale:image.scale orientation:UIImageOrientationUp];
// 9.释放对象
// we're done with the context, color space, and pixels
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
free(pixels);
CGImageRelease(imageRef);
return resultImage;
}
// 2.亮度和对比度处理
/*
对比度： contrast -1～1
亮度： brightness -1～1
亮度公式：Gray = 0.3*R + 0.59*G + 0.11*B
*/
- (UIImage*)getNewImageWithOldImage:(UIImage*)image
contrast:(CGFloat)contrast
brightness:(CGFloat)brightness {
// 1.定义色值的索引位置
const int RED =0;
const int GREEN =1;
const int BLUE =2;
const int ALPHA =3;
// 2.定义图片的大小
CGRect imageRect = CGRectMake(0,0, image.size.width* image.scale, image.size.height* image.scale);
int width = imageRect.size.width;
int height = imageRect.size.height;
// 3.创建图片像素数组的内存大小
uint32_t *pixels = (uint32_t*) malloc(width * height *sizeof(uint32_t));
// 清空像素组里面的内容
memset(pixels,0, width * height *sizeof(uint32_t));
// 4.创建色系对象
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// 5.创建一个rgba像素的画布对象，像素存放在pixels中
// create a context with RGBA pixels
CGContextRef context = CGBitmapContextCreate(pixels, width, height,8, width *sizeof(uint32_t), colorSpace,kCGImageAlphaPremultipliedLast);
// 6.把图片绘制到画布上，并且同步到存放像素内容的数组中
// paint the bitmap to our context which will fill in the pixels array
CGContextDrawImage(context,CGRectMake(0,0, width, height), [image CGImage]);
// 7.设置亮度和对比度
// 如果当前亮度或者对比度发生变化时修改图片参数
if (contrast != 0 && brightness == 0) {
// 01 当前只修改了对比度
float ta = 0, tr = 0, tg = 0, tb = 0;
for(int y = 0; y < height; y++) {
for(int x = 0; x < width; x++) {
// 01 每一个像素点的颜色数组
uint8_t *rgbaPixel = (uint8_t*) &pixels[y * width + x];
ta = rgbaPixel[ALPHA];
tr = rgbaPixel[RED];
tg = rgbaPixel[GREEN];
tb = rgbaPixel[BLUE];
tr = (tr - 127.5) * arctan(contrast) + 127.5;
tg = (tg - 127.5) * arctan(contrast) + 127.5;
tb = (tb - 127.5) * arctan(contrast) + 127.5;
rgbaPixel[RED] = clamp(tr);
rgbaPixel[GREEN] = clamp(tg);
rgbaPixel[BLUE] = clamp(tb);
}
}
} else if (contrast == 0 && brightness != 0) {
// 02 当前只修改了亮度
float ta = 0, tr = 0, tg = 0, tb = 0;
for(int y = 0; y < height; y++) {
for(int x = 0; x < width; x++) {
// 01 每一个像素点的颜色数组
uint8_t *rgbaPixel = (uint8_t*) &pixels[y * width + x];
ta = rgbaPixel[ALPHA];
tr = rgbaPixel[RED];
tg = rgbaPixel[GREEN];
tb = rgbaPixel[BLUE];
tr = tr + 255 * brightness;
tg = tg + 255 * brightness;
tb = tb + 255 * brightness;
rgbaPixel[RED] = clamp(tr);
rgbaPixel[GREEN] = clamp(tg);
rgbaPixel[BLUE] = clamp(tb);
}
}
} else if (contrast != 0 && brightness != 0) {
// 03 当前对比度和亮度
float ta = 0, tr = 0, tg = 0, tb = 0;
for(int y = 0; y < height; y++) {
for(int x = 0; x < width; x++) {
// 01 每一个像素点的颜色数组
uint8_t *rgbaPixel = (uint8_t*) &pixels[y * width + x];
ta = rgbaPixel[ALPHA];
tr = rgbaPixel[RED];
tg = rgbaPixel[GREEN];
tb = rgbaPixel[BLUE];
tr = (tr - 127.5 * (1 - brightness)) * arctan(contrast) + 127.5 * (1 + brightness);
tg = (tg - 127.5 * (1 - brightness)) * arctan(contrast) + 127.5 * (1 + brightness);
tb = (tb - 127.5 * (1 - brightness)) * arctan(contrast) + 127.5 * (1 + brightness);
rgbaPixel[RED] = clamp(tr);
rgbaPixel[GREEN] = clamp(tg);
rgbaPixel[BLUE] = clamp(tb);
}
}
}
// 8.获取画布中的图片对象
CGImageRef imageRef = CGBitmapContextCreateImage(context);
UIImage *resultImage = [UIImage imageWithCGImage:imageRef scale:image.scale orientation:UIImageOrientationUp];
// 9.释放对象
// we're done with the context, color space, and pixels
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
free(pixels);
CGImageRelease(imageRef);
return resultImage;
}
// 获取对比度系数
float arctan(float value) {
return tan( (45 + 44 * value) / 180 * M_PI);
}
float clamp(float value) {
return value > 255 ? 255 :(value < 0 ? 0 : value);
}
五、多张图片合成视频文件
1.有多张UIImage对象合成视频文件
- (void)getVideoWithImages:(NSArray *)images
{
// 1.视频输出设置
NSError *error = nil;
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:[NSURL fileURLWithPath:kMoviePath] fileType:AVFileTypeMPEG4 error:&error];
NSParameterAssert(videoWriter);
// 2.视频写入设置
NSDictionary *videoSettings = @{AVVideoCodecKey: AVVideoCodecH264, AVVideoWidthKey: [NSNumber numberWithInt:inRect.size.width], AVVideoHeightKey: [NSNumber numberWithInt:inRect.size.height]};
AVAssetWriterInput* writerInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
sourcePixelBufferAttributes:nil];
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];
// 3.允许开始写入视频
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
// 4.多张图片写入视频文件
int __block frame = 0;
[writerInput requestMediaDataWhenReadyOnQueue:dispatch_queue_create("mediaInputQueue", NULL) usingBlock:^{
@autoreleasepool {
while ([writerInput isReadyForMoreMediaData]) {
@autoreleasepool {
if ([self isRecording] == NO) {
[writerInput markAsFinished];
[videoWriter finishWritingWithCompletionHandler:^{
NSLog(@"Successfully closed video writer");
if (videoWriter.status == AVAssetWriterStatusCompleted) {
NSLog(@"成功");
} else {
NSLog(@"失败");
}
}];
CVPixelBufferPoolRelease(adaptor.pixelBufferPool);
break;
}
CGImageRef imageRef = [self getScreenRecordingImage];
CVPixelBufferRef buffer = (CVPixelBufferRef)[self pixelBufferFromCGImage:imageRef size:inRect.size];
dispatch_async(dispatch_get_global_queue(0, 0), ^{
if (buffer) {
if(![adaptor appendPixelBuffer:buffer withPresentationTime:CMTimeMake(frame, 20)])
NSLog(@"FAIL");
else
CFRelease(buffer);
}
});
frame++;
NSLog(@"%d",frame);
}
}
}
}];
}
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