获取当前显示屏幕某一点的颜色

获取当前显示屏幕某一点的颜色

1、 获取当前屏幕的截图

-(UIImage *)fullScreenshots{    UIWindow *screenWindow = [[UIApplication sharedApplication] keyWindow];    UIGraphicsBeginImageContext(screenWindow.frame.size);//全屏截图，包括window    [screenWindow.layer renderInContext:UIGraphicsGetCurrentContext()];    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();    return viewImage;}

2、 通过图片获取点颜色

- (UIColor*) getPixelColorAtLocation:(CGPoint)point withImage:(UIImage*) image {    UIColor* color = nil;    CGImageRef inImage = image.CGImage;    // Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue    CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];    if (cgctx == NULL) { return nil;  }    size_t w = CGImageGetWidth(inImage);    size_t h = CGImageGetHeight(inImage);    CGRect rect = {{0,0},{w,h}};    // Draw the image to the bitmap context. Once we draw, the memory    // allocated for the context for rendering will then contain the    // raw image data in the specified color space.    CGContextDrawImage(cgctx, rect, inImage);    // Now we can get a pointer to the image data associated with the bitmap    // context.    unsigned char* data = CGBitmapContextGetData (cgctx);    if (data != NULL) {        //offset locates the pixel in the data from x,y.        //4 for 4 bytes of data per pixel, w is width of one row of data.        @try {            int offset = 4*((w*round(point.y))+round(point.x));            NSLog(@"offset: %d", offset);            int alpha =  data[offset];            int red = data[offset+1];            int green = data[offset+2];            int blue = data[offset+3];            NSLog(@"offset: %i colors: RGB A %i %i %i  %i",offset,red,green,blue,alpha);            color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)];        }        @catch (NSException * e) {            NSLog(@"%@",[e reason]);        }        @finally {        }    }    return color;}- (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) inImage {    CGContextRef    context = NULL;    CGColorSpaceRef colorSpace;    void *          bitmapData;    int             bitmapByteCount;    int             bitmapBytesPerRow;    // Get image width, height. We'll use the entire image.    size_t pixelsWide = CGImageGetWidth(inImage);    size_t pixelsHigh = CGImageGetHeight(inImage);    // Declare the number of bytes per row. Each pixel in the bitmap in this    // example is represented by 4 bytes; 8 bits each of red, green, blue, and    // alpha.    bitmapBytesPerRow   = (pixelsWide * 4);    bitmapByteCount     = (bitmapBytesPerRow * pixelsHigh);    // Use the generic RGB color space.    colorSpace = CGColorSpaceCreateDeviceRGB();    if (colorSpace == NULL)    {        fprintf(stderr, "Error allocating color spacen");        return NULL;    }    // Allocate memory for image data. This is the destination in memory    // where any drawing to the bitmap context will be rendered.    bitmapData = malloc( bitmapByteCount );    if (bitmapData == NULL)    {        fprintf (stderr, "Memory not allocated!");        CGColorSpaceRelease( colorSpace );        return NULL;    }    // Create the bitmap context. We want pre-multiplied ARGB, 8-bits    // per component. Regardless of what the source image format is    // (CMYK, Grayscale, and so on) it will be converted over to the format    // specified here by CGBitmapContextCreate.    context = CGBitmapContextCreate (bitmapData,                                     pixelsWide,                                     pixelsHigh,                                     8,      // bits per component                                     bitmapBytesPerRow,                                     colorSpace,                                     kCGImageAlphaPremultipliedFirst);    if (context == NULL)    {        free (bitmapData);        fprintf (stderr, "Context not created!");    }    // Make sure and release colorspace before returning    CGColorSpaceRelease( colorSpace );    return context;}

3、 使用方法

- (void)webViewDidFinishLoad:(UIWebView *)webView {        if (_backView) {        [self performSelector:@selector(changeColor) withObject:nil afterDelay:.5];    }}- (void) changeColor {    UIColor* color = [self getPixelColorAtLocation:CGPointMake(4, 22) withImage:[self fullScreenshots]];    if (color && !CGColorEqualToColor(color.CGColor, _backView.backgroundColor.CGColor)) {        _backView.backgroundColor = color;    }}

在url加载完成后，根据webview的navigationbar颜色确定状态栏背景颜色，保持一致风格