ios - CGBitmapContextCreate : invalid data bytes/row

Question

我试图在将图像显示给用户之前调整图像的大小。

我得到的错误是错误:CGBitmapContextCreate:无效数据字节/行:对于 8 个整数位/组件、3 个组件、kCGImageAlphaNoneSkipFirst，应该至少为 5504。

我还收到错误:CGContextDrawImage:无效上下文 0x0。

这是我正在使用的代码:

    -(UIImage*)imageByScalingToSize:(CGRect)target :(UIImage*)old
{
    UIImage* sourceImage = old;
    CGFloat targetWidth = target.size.width + 10;
    CGFloat targetHeight = target.size.height;
    CGFloat x = target.origin.x;
    CGFloat y = target.origin.y - 105;

    CGImageRef imageRef = [sourceImage CGImage];
    CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
    CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);

    if (bitmapInfo == kCGImageAlphaNone) {
        bitmapInfo = kCGImageAlphaNoneSkipLast;
    }   CGContextRef bitmap;

    if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
        bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);    
    } 
    else {
        bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);      
    }

    if (sourceImage.imageOrientation == UIImageOrientationLeft) {
        CGContextRotateCTM (bitmap, radians(90));
        CGContextTranslateCTM (bitmap, 0, -targetHeight);     
    } 
    else if (sourceImage.imageOrientation == UIImageOrientationRight) {
        CGContextRotateCTM (bitmap, radians(-90));
        CGContextTranslateCTM (bitmap, -targetWidth, 0);     
    } 
    else if (sourceImage.imageOrientation == UIImageOrientationUp) {
        // NOTHING
    } 
    else if (sourceImage.imageOrientation == UIImageOrientationDown) {
        CGContextTranslateCTM (bitmap, targetWidth, targetHeight);
        CGContextRotateCTM (bitmap, radians(-180.));
    }

    CGContextDrawImage(bitmap, CGRectMake(x, y, targetWidth, targetHeight), imageRef);
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage* newImage = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return newImage; 
}

Answer 1

试试这个:

bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), 0, colorSpaceInfo, bitmapInfo);    

bitsPerComponent

The number of bits to use for each component of a pixel in memory. For example, for a 32-bit pixel format and an RGB color space, you would specify a value of 8 bits per component. For the list of supported pixel formats, see “Supported Pixel Formats” in the “Graphics Contexts” chapter of Quartz 2D Programming Guide.

如果这不能改善情况，请发布 CGImageGetBitsPerComponent(imageRef) 和 CGImageGetBytesPerRow(imageRef) 的值。