将 zlib 压缩的 base 64 字符串覆盖到 Uiimage 中的问题 [英] Issue in Coverting zlib compressed base 64 string to Uiimage

问题描述

在我当前的一个项目中，我必须解析 base 64 字符串，该字符串由 flex(Adobe Flash) 应用程序编码和存储.通过与 flex 开发团队讨论，我发现他们以位图格式存储图像字符串，所以我认为它是像素表示.

In one my current project, I have to parse base 64 string, which is encoded and stored by flex(Adobe Flash) application. By discussing with flex dev team I found that they storing image string in bitmap format so I assumed it is a pixel representation.

所以，我的第一个问题是，在上述情况下，我可以使用 base64 解码类直接将原始数据转换为 UIimage 还是必须使用 CGBitmapContext ?

但是，目前我已经实现了下面提到的转换代码.

However, currently I have implemented below mentioned code for conversion.

`//转换为Base64数据

` //Convert to Base64 data

NSData *decodedData = [QSStrings decodeBase64WithString:_settingSerializedImage.currentValue];


NSError *error = nil;
NSData *unCompressedData = [decodedData bbs_dataByInflatingWithError:&error];



NSData *dataImage = [NSMutableData new];
NSUInteger bytePosition = 0;
uint8_t * bytes =  malloc(5);
[unCompressedData getBytes:&bytes range:NSMakeRange(unCompressedData.length-3, 3)];

bytes = OSSwapBigToHostInt16(bytes);
int width = (int)bytes;

[unCompressedData getBytes:&bytes range:NSMakeRange(unCompressedData.length-5, 5)];

bytes = OSSwapBigToHostInt16(bytes);dataImage = [unCompressedData subdataWithRange:NSMakeRange(0, (unCompressedData.length -5))];

NSUInteger length = [dataImage length];
unsigned char *bytesData = malloc( length * sizeof(unsigned char) ); [dataImage getBytes:bytesData length:length];UIImage *imgScreenShot = [ScreenshotPortlet convertBitmapRGBA8ToUIImage:bytesData withWidth:width withHeight:height];`

以下是使用核心图形转换图像中原始数据的方法

below is the method for converting raw data in image using core graphics

+ (UIImage *) convertBitmapRGBA8ToUIImage:(unsigned char *) buffer
                            withWidth:(int) width
                           withHeight:(int) height {

 char* rgba = (char*)malloc(width*height*4);
for(int i=0; i < width*height; ++i) {
    rgba[4*i] = buffer[4*i];
    rgba[4*i+1] = buffer[4*i+1];
    rgba[4*i+2] = buffer[4*i+2];
    rgba[4*i+3] = buffer[4*i+3];
}
//


size_t bufferLength = width * height * 4;
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, rgba, bufferLength, NULL);
size_t bitsPerComponent = 8;
size_t bitsPerPixel = 32;
size_t bytesPerRow = 4 * width;

CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
  if(colorSpaceRef == NULL) {
    NSLog(@"Error allocating color space");
    CGDataProviderRelease(provider);
    return nil;
}

CGBitmapInfo bitmapInfo = kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedFirst;

CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
CGImageRef iref = CGImageCreate(width,
                                height,
                                bitsPerComponent,
                                bitsPerPixel,
                                bytesPerRow,
                                colorSpaceRef,
                                bitmapInfo,
                                provider,
                                NULL,
                                YES,
                                renderingIntent);

uint32_t* pixels = (uint32_t*)malloc(bufferLength);

if(pixels == NULL) {
    NSLog(@"Error: Memory not allocated for bitmap");
    CGDataProviderRelease(provider);
    CGColorSpaceRelease(colorSpaceRef);
    CGImageRelease(iref);
    return nil;
}

CGContextRef context = CGBitmapContextCreate(pixels,
                                             width,
                                             height,
                                             bitsPerComponent,
                                             bytesPerRow,
                                             colorSpaceRef,
                                             bitmapInfo);

if(context == NULL) {
    NSLog(@"Error context not created");
    free(pixels);
}

UIImage *image = nil;
if(context) {

    CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, width, height), iref);

    CGImageRef imageRef = CGBitmapContextCreateImage(context);

    image = [UIImage imageWithCGImage:imageRef];

    CGImageRelease(imageRef);
    CGContextRelease(context);
}

CGColorSpaceRelease(colorSpaceRef);
CGImageRelease(iref);
CGDataProviderRelease(provider);


if(pixels) {
    free(pixels);
}   
return image;

}

这是我得到的输出，一个扭曲的图像:

那么任何人都可以建议我更好的解决方案或告诉我是否在正确的方向上?谢谢，提前:)

So can anyone suggest me better solution or tell if I'm on right direction in it or not? Thanks, in advance :)

参考这里你可以找到原始的base 64字符串

For reference here you can find original base 64 string

推荐答案

图片转base64string:

- (NSString *)imageToNSString:(UIImage *)image
{
    NSData *data = UIImagePNGRepresentation(image);

    return [data base64EncodedStringWithOptions:NSDataBase64EncodingEndLineWithLineFeed];
}

将base64string转换为图像:

- (UIImage *)stringToUIImage:(NSString *)string
{
    NSData *data = [[NSData alloc]initWithBase64EncodedString:string options:NSDataBase64DecodingIgnoreUnknownCharacters];

    return [UIImage imageWithData:data];
}

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