最近项目中碰到一个问题，由于背景图片太白，掩盖了视图中button的位置，造成了很不好的用户体验。
消失了的按钮.png
很显然，用户很难发现在左下角竟然隐藏了一个按钮。
- 解决方案一：
1.取背景图片的主色
2.判断主色是否是白色，如果是白色则改变按钮的颜色
//获取图片的主色
+ (UIColor *)mainColor:(UIImage *)image{
int bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;
//把图片缩小
CGSize thumbSize = CGSizeMake(image.size.width/2, image.size.height/2);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, thumbSize.width, thumbSize.height, 8, thumbSize.width*4, colorSpace, bitmapInfo);
CGRect drawRect = CGRectMake(0, 0, thumbSize.width, thumbSize.height);
CGContextDrawImage(context, drawRect, image.CGImage);
CGColorSpaceRelease(colorSpace);
//获取每个点的像素
unsigned char* data = CGBitmapContextGetData (context);
if (data == NULL) return nil;
NSCountedSet *cls=[NSCountedSet setWithCapacity:thumbSize.width*thumbSize.height];
for (int x=0; x<thumbSize.width; x++) {
for (int y=0; y<thumbSize.height; y++) {
int offset = 4*(x*y);
int red = data[offset];
int green = data[offset+1];
int blue = data[offset+2];
int alpha = data[offset+3];
if (alpha>0) {//去除透明
if (red==255&&green==255&&blue==255) {//去除白色
}else{
NSArray *clr=@[@(red),@(green),@(blue),@(alpha)];
[cls addObject:clr];
}
}
}
}
CGContextRelease(context);
//第三步 找到出现次数最多的那个颜色
NSEnumerator *enumerator = [cls objectEnumerator];
NSArray *curColor = nil;
NSArray *MaxColor=nil;
NSUInteger MaxCount=0;
while ( (curColor = [enumerator nextObject]) != nil )
{
NSUInteger tmpCount = [cls countForObject:curColor];
if ( tmpCount < MaxCount ) continue;
MaxCount=tmpCount;
MaxColor=curColor;
}
return [UIColor colorWithRed:([MaxColor[0] intValue]/255.0f) green:([MaxColor[1] intValue]/255.0f) blue:([MaxColor[2] intValue]/255.0f) alpha:([MaxColor[3] intValue]/255.0f)];
}
这种方案解决了背景颜色主色是白色的掩盖问题，可是如果图片的主色不是白色，但是白色的位置刚好和按钮的位置重合了呢？
于是，
- 方案二：
去除图片的白色背景，替换成其他颜色，或者透明
//去除图片的白色背景
+ (UIImage*) imageToTransparent:(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++)
{
// //去除白色...将0xFFFFFF00换成其它颜色也可以替换其他颜色。
// if ((*pCurPtr & 0xFFFFFF00) >= 0xffffff00) {
//
// uint8_t* ptr = (uint8_t*)pCurPtr;
// ptr[0] = 0;
// }
//接近白色
//将像素点转成子节数组来表示---第一个表示透明度即ARGB这种表示方式。ptr[0]:透明度,ptr[1]:R,ptr[2]:G,ptr[3]:B
//分别取出RGB值后。进行判断需不需要设成透明。
uint8_t* ptr = (uint8_t*)pCurPtr;
if (ptr[1] > 240 && ptr[2] > 240 && ptr[3] > 240) {
//当RGB值都大于240则比较接近白色的都将透明度设为0.-----即接近白色的都设置为透明。某些白色背景具有杂质就会去不干净，用这个方法可以去干净
ptr[0] = 0;
}
}
// 将内存转成image
CGDataProviderRef dataProvider =CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, nil);
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;
}
如此以来又出现了新的问题，直接破坏了原有的背景图片，可行性为0
虽然，还没有找到更好的可行的办法，但是不知不觉的竟然让我找到了几个不错的图片和颜色的方法。
etc.
- func1
//取图片的反色
+ (UIImage *)applyColorInvertFilter:(UIImage *)image{
GPUImageColorInvertFilter *filter = [[GPUImageColorInvertFilter alloc] init];
[filter forceProcessingAtSize:image.size];
GPUImagePicture *pic = [[GPUImagePicture alloc] initWithImage:image];
[pic addTarget:filter];
[pic processImage];
[filter useNextFrameForImageCapture];
return [filter imageFromCurrentFramebuffer];
}
- func2
//图片的灰度处理
+ (UIImage *)applySepiaFilter:(UIImage *)image
{
GPUImageSepiaFilter *filter = [[GPUImageSepiaFilter alloc] init];
[filter forceProcessingAtSize:image.size];
GPUImagePicture *pic = [[GPUImagePicture alloc] initWithImage:image];
[pic addTarget:filter];
[pic processImage];
[filter useNextFrameForImageCapture];
return [filter imageFromCurrentFramebuffer];
}
- func3
//高斯模糊(周围没有白边)
+ (UIImage *)imageWithGaussianBlur:(UIImage *)image float:(CGFloat)blur{
if (blur < 0.f || blur > 1.f) {
blur = 0.5f;
}
int boxSize = (int)(blur * 40);
boxSize = boxSize - (boxSize % 2) + 1;
CGImageRef img = image.CGImage;
vImage_Buffer inBuffer, outBuffer;
vImage_Error error;
void *pixelBuffer;
//从CGImage中获取数据
CGDataProviderRef inProvider = CGImageGetDataProvider(img);
CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);
//设置从CGImage获取对象的属性
inBuffer.width = CGImageGetWidth(img);
inBuffer.height = CGImageGetHeight(img);
inBuffer.rowBytes = CGImageGetBytesPerRow(img);
inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);
pixelBuffer = malloc(CGImageGetBytesPerRow(img) *
CGImageGetHeight(img));
if(pixelBuffer == NULL)
NSLog(@"No pixelbuffer");
outBuffer.data = pixelBuffer;
outBuffer.width = CGImageGetWidth(img);
outBuffer.height = CGImageGetHeight(img);
outBuffer.rowBytes = CGImageGetBytesPerRow(img);
error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
if (error) {
NSLog(@"error from convolution %ld", error);
}
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(
outBuffer.data,
outBuffer.width,
outBuffer.height,
8,
outBuffer.rowBytes,
colorSpace,
kCGImageAlphaNoneSkipLast);
CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
UIImage *returnImage = [UIImage imageWithCGImage:imageRef];
//clean up
CGContextRelease(ctx);
CGColorSpaceRelease(colorSpace);
free(pixelBuffer);
CFRelease(inBitmapData);
CGColorSpaceRelease(colorSpace);
CGImageRelease(imageRef);
return returnImage;
}
特别提醒的是，我试过使用CoreImage，发现它的渲染阻塞主进程，最关键的是还有白边，所以，我比较偏向鱼vImage，他的算法也更加高效，效果更加完美。
- func4
//判断颜色深浅
+ (BOOL)isDarkColor:(UIColor *)newColor{
const CGFloat *componentColors = CGColorGetComponents(newColor.CGColor);
CGFloat colorBrightness = ((componentColors[0] * 299) + (componentColors[1] * 587) + (componentColors[2] * 114)) / 1000;
if (colorBrightness < 0.5){
NSLog(@"Color is dark");
return YES;
}
else{
NSLog(@"Color is light");
return NO;
}
}
- func5
//毛玻璃(ios8)
UIBlurEffect *effect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:effect];
effectView.alpha = 0.9;
effectView.frame = CGRectMake(0, 0, imageView.frame.size.width*0.5, imageView.frame.size.height);
imageView.image = image;
[imageView addSubview:effectView];
- func6
//颜色转换为图片
+ (UIImage *)imageWithColor:(UIColor *)color {
CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
此外还用到到了一个大家都再熟悉不过的库GPUImage。相信做过滤镜的朋友大家都很熟悉，在这里我就不去班门弄斧了。
