BAD_ACCESS當時的UIView到的UIImage

Question

我打算採取UIView是drawed通過OpenGL ES到UIImage的快照，這裏是我使用的代碼：

if(context){ 
    [EAGLContext setCurrentContext:context]; 
    glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebuffer); 
    NSInteger dataLength = framebufferWidth * framebufferHeight * 4; 

    GLubyte* data = (GLubyte*)malloc(dataLength) ; // malloc(myDataLength); 
    glReadPixels(0, 0, framebufferWidth, framebufferHeight, GL_RGBA, GL_UNSIGNED_BYTE, data); 

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

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

    // make the cgimage 
    CGImageRef result = CGImageCreate(framebufferWidth, framebufferHeight, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent); 

    // then make the uiimage from that 
    UIImage *image = [UIImage imageWithCGImage:result]; 
    CGImageRelease(result); 
    CGColorSpaceRelease(colorSpaceRef); 
    CGDataProviderRelease(provider); 
    //free(data); 

    return image; 
} 

我打算用free(data);在return之前，但會引起BAD_ACCESS運行時錯誤。

所以我的問題是，如何free正確？或者我應該free他們在圖像發佈後？

Answer 1

這是我當前的代碼，它工作得很好。

if(context){ 
    [EAGLContext setCurrentContext:context]; 
    glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebuffer); 
    NSInteger dataLength = width * height * 4; 
    int bitsPerComponent = 8; 
    int bitsPerPixel = 32; 
    int bytesPerRow = 4 * width; 
    GLubyte* data = (GLubyte*)malloc(dataLength) ; 
    glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data); 

    // make upside down 
    GLubyte* swp = (GLubyte*)malloc(width * 4); 
    for (int h = 0; h < height/2; h++) { 
     memcpy(swp, data + (height - 1 - h) * bytesPerRow, bytesPerRow); 
     memcpy(data + (height - 1 - h) * bytesPerRow, data + h * bytesPerRow, bytesPerRow); 
     memcpy(data + h * bytesPerRow, swp, bytesPerRow); 
    } 

    NSData* nsData = [NSData dataWithBytesNoCopy:data length:dataLength freeWhenDone:YES]; 
    // make data provider with data. 
    CGDataProviderRef provider = CGDataProviderCreateWithCFData((CFDataRef)nsData); 

    // prep the ingredients 
    CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB(); 
    CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault; 
    CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault; 

    // make the cgimage 
    CGImageRef result = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent); 
    CGColorSpaceRelease(colorSpaceRef); 
    CGDataProviderRelease(provider); 

    // then make the uiimage from that 
    UIImage *image = [UIImage imageWithCGImage:result]; 
    CGImageRelease(result); 

    return image; 
} 

Answer 2

您應該使用CGDataProviderCreateWithData'sCGDataProviderReleaseDataCallback如here所述。

只需添加freeData回調函數：

void freeData(void *info, const void *data, size_t size) 
{ 
    free((void*)data); 
} 

，並把它傳遞給CGDataProviderCreateWithData：

CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, data, dataLength, freeData);