iOS整个APP实现灰色主题的示例代码

灰色主题

背景

在一些哀悼日，清明节的时候app会实现一些灰色主题功能，部分app需求是tab首页实现灰色模式就可以，但一些需求是直接整个app都变为灰色模。

•  普通ui界面
• web页面
• xib界面
• attributetext加载的htmlstring页面
• attachment挂件页面

实现方式

基本的实现方式1，普通页面用hook颜色方式2.web页面用注入灰色js实现方式

图片变灰

重新绘制图片变为灰色代码实现

//image类别
- (uiimage *)getgrayimage {
    
  const int red =1;
  const int green =2;
  const int blue =3;
    
  uiimage *image = self;
    
  // create image rectangle with current image width/height
  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;
    
  // the pixels will be painted to this array
  uint32_t *pixels = (uint32_t*) malloc(width * height *sizeof(uint32_t));
    
  // clear the pixels so any transparency is preserved
  memset(pixels,0, width * height *sizeof(uint32_t));
    
  cgcolorspaceref colorspace = cgcolorspacecreatedevicergb();
    
  // create a context with rgba pixels
  cgcontextref context = cgbitmapcontextcreate(pixels, width, height,8, width *sizeof(uint32_t), colorspace, kcgbitmapbyteorder32little | kcgimagealphapremultipliedlast);
    
  // paint the bitmap to our context which will fill in the pixels array
  cgcontextdrawimage(context,cgrectmake(0,0, width, height), [image cgimage]);
    
  for(int y = 0; y < height; y++) {
    for(int x = 0; x < width; x++) {
      uint8_t *rgbapixel = (uint8_t*) &pixels[y * width + x];
        
      // convert to grayscale using recommended method: http://en.wikipedia.org/wiki/grayscale#converting_color_to_grayscale
      uint32_t gray = 0.3 * rgbapixel[red] +0.59 * rgbapixel[green] +0.11 * rgbapixel[blue];
        
      // set the pixels to gray
      rgbapixel[red] = gray;
      rgbapixel[green] = gray;
      rgbapixel[blue] = gray;
    }
  }
    
  // create a new cgimageref from our context with the modified pixels
  cgimageref imageref = cgbitmapcontextcreateimage(context);
    
  // we're done with the context, color space, and pixels
  cgcontextrelease(context);
  cgcolorspacerelease(colorspace);
  free(pixels);
    
  // make a new uiimage to return
  uiimage *resultuiimage = [uiimage imagewithcgimage:imageref scale:image.scale orientation:uiimageorientationup];
    
  // we're done with image now too
  cgimagerelease(imageref);
    
  return resultuiimage;
  
}

文本变灰

文本textcolor变为灰色 rgb的处理有很多这里简单提供一个

    [self swizzlemethod:self orgsel:@selector(initwithred:green:blue:alpha:) swizzsel:@selector(hdd_initwithred:green:blue:alpha:)];
+ (uicolor *)hdd_colorwithred:(cgfloat)red green:(cgfloat)green blue:(cgfloat)blue alpha:(cgfloat)a{
  cgfloat gray = red*0.299 + green*0.587 + blue*0.114;
  if ([csdarksitemanager islocalcachedarksitestatus]) {
    return [self hdd_colorwithred:gray green:gray blue:gray alpha:a];
  }
  else {
    return [self hdd_colorwithred:red green:green blue:blue alpha:a];
  }
}

文本变灰色还牵扯到系统颜色的灰色处理，例如[uicolor whitecolor],系统alertview弹框中的蓝色按钮颜色处理，都需要有专门的处理方法

xib图片变灰

由于xib读取图片不是直接通过[uiimageview imagename:@""] 加载方式 没办法直接通过hook setimage直接设置xib图片变为灰色

方法：重写uiimageview的awakefromnib，再去执行hook setimage的方法进行加载

webview的变灰

hook webview的初始化方法，注入js灰色

+ (void)swizzhook {
  static dispatch_once_t oncetoken;
  dispatch_once(&oncetoken, ^{
    method originalmethod = class_getinstancemethod([self class], @selector(initwithframe:configuration:));
    method swizzledmethod = class_getinstancemethod([self class], @selector(lg_initwithframe:configuration:));
    method_exchangeimplementations(originalmethod, swizzledmethod);
  });
}
- (instancetype)lg_initwithframe:(cgrect)frame configuration:(wkwebviewconfiguration *)configuration {
  class class = nsclassfromstring(@"airwkwebview");
  if ([csdarksitemanager islocalcachedarksitestatus] && ![self iskindofclass:class]) {
    nsstring *jscript = @"var filter = '-webkit-filter:grayscale(100%);-moz-filter:grayscale(100%); -ms-filter:grayscale(100%); -o-filter:grayscale(100%) filter:grayscale(100%);';document.getelementsbytagname('html')[0].style.filter = 'grayscale(100%)';";
    // 注入
    wkuserscript *wkuscript = [[wkuserscript alloc] initwithsource:jscript injectiontime:wkuserscriptinjectiontimeatdocumentend formainframeonly:yes];
    [configuration.usercontentcontroller adduserscript:wkuscript];
    wkwebview *webview = [self lg_initwithframe:frame configuration:configuration];
    return webview;
  }
  else {
    wkwebview *webview = [self lg_initwithframe:frame configuration:configuration];
    return webview;
  }
  
}

attributetext加载htmlstring变灰

attribute情况下加载html不是直接通过设置color来改变颜色的，需要通过遍历对应的属性进行重新颜色进行赋值

存在的问题

这样全局修改，可能会把键盘的颜色也改变了需要特殊处理

系统颜色中，alertview中的蓝色，不在定义的系统颜色范围之内需要重新加载

hook系统颜色的处理

完整性

需要完整的私发信息

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