我有一个基于图层的类,其中包含两个子精灵。让我们称它们为:背景和树。
在这个类中,我有一个方法来捕获该层的屏幕截图。该方法工作正常。每次我对该图层进行截图时,我都会获得背景上树的构成。美好的。在某一点上,我想获得没有树的那层的屏幕截图。所以我要做的是,隐藏树,截取屏幕截图并再次显示树......就像这样:
[myLayer hideTree];
UIImage *screenshot = [myLayer screenshot];
[myLayer showTree];
令我惊讶的是,以这种方式生成的屏幕截图总是包含树。
这是 hideTree 和 showTree:
- (void) hideTree {
[treeLayer setOpacity:0];
// I have also tried [treelayer setVisible:NO];
}
- (void) showTree {
[treeLayer setOpacity:255];
// I have also tried [treelayer setVisible:YES];
}
我正在使用这种方法进行截图,来自 cocos2d 论坛:
-(UIImage*) screenshot
{
CGSize displaySize = [[CCDirector sharedDirector] winSize];
CGSize winSize = [self winSize];
//Create buffer for pixels
GLuint bufferLength = displaySize.width * displaySize.height * 4;
GLubyte* buffer = (GLubyte*)malloc(bufferLength);
//Read Pixels from OpenGL
glReadPixels(0, 0, displaySize.width, displaySize.height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
//Make data provider with data.
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer, bufferLength, NULL);
//Configure image
int bitsPerComponent = 8;
int bitsPerPixel = 32;
int bytesPerRow = 4 * displaySize.width;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
CGImageRef iref = CGImageCreate(displaySize.width, displaySize.height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent);
uint32_t* pixels = (uint32_t*)malloc(bufferLength);
CGContextRef context = CGBitmapContextCreate(pixels, winSize.width, winSize.height, 8, winSize.width * 4, CGImageGetColorSpace(iref), kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGContextTranslateCTM(context, 0, displaySize.height);
CGContextScaleCTM(context, 1.0f, -1.0f);
UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
switch (orientation)
{
case UIDeviceOrientationPortrait: break;
case UIDeviceOrientationPortraitUpsideDown:
CGContextRotateCTM(context, CC_DEGREES_TO_RADIANS(180));
CGContextTranslateCTM(context, -displaySize.width, -displaySize.height);
break;
case UIDeviceOrientationLandscapeLeft:
CGContextRotateCTM(context, CC_DEGREES_TO_RADIANS(-90));
CGContextTranslateCTM(context, -displaySize.height, 0);
break;
case UIDeviceOrientationLandscapeRight:
CGContextRotateCTM(context, CC_DEGREES_TO_RADIANS(90));
CGContextTranslateCTM(context, displaySize.width * 0.5f, -displaySize.height);
break;
case UIDeviceOrientationUnknown:
break;
case UIDeviceOrientationFaceUp:
break;
case UIDeviceOrientationFaceDown:
break;
}
CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, displaySize.width, displaySize.height), iref);
CGImageRef imageRef = CGBitmapContextCreateImage(context);
UIImage *outputImage = [UIImage imageWithCGImage:imageRef];
//Dealloc
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGImageRelease(iref);
CGColorSpaceRelease(colorSpaceRef);
CGContextRelease(context);
free(buffer);
free(pixels);
return outputImage;
}
我错过了什么?为什么树总是出现?