我想从我的iOS应用程序中的png图像资源中读取ARGB像素数据。 我使用CGDataProvider获得CFDataRef如下所述:CGDataProvider第一次工作,第二次返回空图像
http://developer.apple.com/library/ios/#qa/qa1509/_index.html
它完美,我第一次用它一定的图像上。但是第二次在同一个图像上使用它时,它返回一个长度为0的CFDataRef。
也许我没有发布什么?为什么会这样做?
- (GLuint)initWithCGImage:(CGImageRef)newImageSource
{
CGDataProviderRef dataProvider;
CFDataRef dataRef;
GLuint t;
@try {
// NSLog(@"initWithCGImage");
// report_memory2();
CGFloat widthOfImage = CGImageGetWidth(newImageSource);
CGFloat heightOfImage = CGImageGetHeight(newImageSource);
// pixelSizeOfImage = CGSizeMake(widthOfImage, heightOfImage);
// CGSize pixelSizeToUseForTexture = pixelSizeOfImage;
// CGSize scaledImageSizeToFitOnGPU = [GPUImageOpenGLESContext sizeThatFitsWithinATextureForSize:pixelSizeOfImage];
GLubyte *imageData = NULL;
//CFDataRef dataFromImageDataProvider;
// stbi stbiClass;
int x;
int y;
int comp;
dataProvider = CGImageGetDataProvider(newImageSource);
dataRef = CGDataProviderCopyData(dataProvider);
const unsigned char * bytesRef = CFDataGetBytePtr(dataRef);
// NSUInteger length = CFDataGetLength(dataRef);
//CGDataProviderRelease(dataProvider);
//dataProvider = nil;
/*
UIImage *tmpImage = [UIImage imageWithCGImage:newImageSource];
NSData *data2 = UIImagePNGRepresentation(tmpImage);
// if (data2==NULL)
// data2 = UIImageJPEGRepresentation(tmpImage, 1);
unsigned char *bytes = (unsigned char *)[data2 bytes];
NSUInteger length = [data2 length];*/
// stbiClass.img_buffer = bytes;
// stbiClass.buflen = length;
// stbiClass.img_buffer_original = bytes;
// stbiClass.img_buffer_end = bytes + length;
// unsigned char *data = stbi_load_main(&stbiClass, &x, &y, &comp, 0);
//unsigned char * data = bytesRef;
x = widthOfImage;
y = heightOfImage;
comp = CGImageGetBitsPerPixel(newImageSource)/8;
int textureWidth = [self CalcPow2: x];
int textureHeight = [self CalcPow2: y];
unsigned char *scaledData = [self scaleImageWithParams:@{@"x":@(x), @"y":@(y), @"comp":@(comp), @"targetX":@(textureWidth), @"targetY":@(textureHeight)} andData:(unsigned char *)bytesRef];
//CFRelease (dataRef);
// dataRef = nil;
// free (data);
glGenTextures(1, &t);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, t);
GLint format = (comp > 3) ? GL_RGBA : GL_RGB;
imageData = scaledData;
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, format, textureWidth, textureHeight, 0, format, GL_UNSIGNED_BYTE, imageData);
//GLenum err = glGetError();
}
@finally
{
CGDataProviderRelease(dataProvider);
// CGColorSpaceRelease(colorSpaceRef);
CGImageRelease(dataRef);
}
return t;
}
这就是所谓的一个CGImageRef第二次是从[UIImage的imageNamed:路径]起源与相同的路径,我第一次得到长度为0 的dataRef它虽然工作在第一时间。
一些代码将非常有帮助。 – trudyscousin
相关:http://stackoverflow.com/questions/12363801/ios-cgimagecreatewithpng-or-jpegdataprovider-causes-segmentation-fault – 2012-12-17 21:12:24
@ H2CO3:这似乎是关于创建一个数据提供商,然后从它创建一个图像,而不是创建一个图像并获取其数据提供者。或者我错过了什么? –