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我尝试使用 UIActivityViewController 创建屏幕截图并保存到 iPhone/iPad 设备中的照片中。但是,在模拟器中,一切都正确显示,但是当我切换到设备时,它只显示了一部分。这是屏幕截图:

  1. 在模拟器中(你可以看到有一个背景,一个绿线和一个星图)

在此处输入图像描述

  1. 在真实设备中(您可以看到只有一个星图,其他一切都没有了)

在此处输入图像描述

我将所有这三个不同的 UIImage 合并到一个图像中,以便我可以截屏。

  1. 我首先将背景图像(桥 UIImage)与星形图像合并。

    -(UIImage*)mergeUIImageView:(UIImage*)bkgound
                       FrontPic:(UIImage*)fnt
                      FrontPicX:(CGFloat)xPos
                      FrontPicY:(CGFloat)yPos
                  FrontPicWidth:(CGFloat)picWidth
                 FrontPicHeight:(CGFloat)picHeight
                      FinalSize:(CGSize)finalSize
      {
         UIGraphicsBeginImageContext(CGSizeMake([UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width));
    
         // bkgound - is the bridge image
         [bkgound drawInRect:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width)];
    
         // fnt - is the star image
         [fnt drawInRect:CGRectMake(xPos, yPos, picWidth, picHeight)];
    
         // merged image
         UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    
         UIGraphicsEndImageContext();
         return newImage;
      }
    
  2. 然后我将这张图片与绿线的opengl渲染图片合并。

a) 我首先使用这个函数将 opengGL 图像更改为 UIImage

    -(UIImage *) glToUIImage {

     float scaleFactor = [[UIScreen mainScreen] scale];
     CGRect screen = [[UIScreen mainScreen] bounds];
     CGFloat image_height = screen.size.width * scaleFactor;
     CGFloat image_width = screen.size.height * scaleFactor;

     NSInteger myDataLength = image_width * image_height * 4;

     // allocate array and read pixels into it.
     GLubyte *buffer = (GLubyte *) malloc(myDataLength);
     glReadPixels(0, 0, image_width, image_height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);

     // gl renders "upside down" so swap top to bottom into new array.
     // there's gotta be a better way, but this works.
     GLubyte *buffer2 = (GLubyte *) malloc(myDataLength);
     for(int y = 0; y < image_height; y++)
     {
        for(int x = 0; x < image_width * 4; x++)
        {
           buffer2[(int)((image_height - 1 - y) * image_width * 4 + x)] = buffer[(int)(y * 4 * image_width + x)];
         }
      }

      // make data provider with data.
      CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer2, myDataLength, NULL);

      // prep the ingredients
      int bitsPerComponent = 8;
      int bitsPerPixel = 32;
      int bytesPerRow = 4 * image_width;
      CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
      CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
      CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;

      // make the cgimage
      CGImageRef imageRef = CGImageCreate(image_width, image_height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent);

       // then make the uiimage from that
       UIImage *myImage = [UIImage imageWithCGImage:imageRef];

       return myImage;
     }

b)然后我通过使用上面相同的功能将这个opengl图像与我上面的图像(桥+星)合并

    -(UIImage*)screenshot
    {
        // get opengl image from above function
        UIImage *image = [self glToUIImage];

        CGRect pos = CGRectMake(0, 0, image.size.width, image.size.height);
        UIGraphicsBeginImageContext(image.size);
        [image drawInRect:pos];
        [self.background.image drawInRect:pos];
        UIImage* final = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

        return final;
     }

它在(iPhone、iPad、带有视网膜的 iPhone 和带有视网膜的 iPad)模拟器(6.0 版)中运行良好。但是,当我切换到真实设备(iPhone 4/4s/5、iPad (2/mini/retina))时,它只显示星形图像。xcode 版本是 4.6.3,基础 SDK 是最新的 IOS(IOS 6.1),IOS 部署目标是 5.0。你们能告诉我如何解决它吗?谢谢。

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1 回答 1

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问题是 IOS 6.0 不会一直保留缓冲区,它会擦除​​它。但是,当您进行屏幕截图时,您会从缓冲区中获取数据,这就是我不断获得黑色背景的原因。所以添加类别让设备保留缓冲图像将解决这个问题。

 @interface CAEAGLLayer (Retained)
 @end

 @implementation CAEAGLLayer (Retained)
 - (NSDictionary*) drawableProperties
 {
    return @{kEAGLDrawablePropertyRetainedBacking : @(YES)};
 }
 @end
于 2013-09-17T15:34:11.117 回答