iPhone certa renderização de PDFs como imagem preta
Pergunta
Estou tentando desenhar as páginas de um pdf usando o código abaixo. Alguns renderizam corretamente, mas outros simplesmente mostram uma imagem completamente preta ou têm partes parciais renderizadas e o restante preto. Ao comparar o que está acontecendo, os que mostram ok parecem sempre ter texto "regular", juntamente com alguns gráficos (diagramas etc.), enquanto os que saem pretos são normalmente todos gráficos (como uma página de folha música, por exemplo). Alguém pode me apontar na direção certa sobre isso? Eu construindo isso no novo 3.2 SDK.
Obrigado!
// PDF page drawing expects a Lower-Left coordinate system, so we flip the coordinate system
// before we start drawing.
CGContextTranslateCTM(context, 0.0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// Grab the first PDF page
CGPDFPageRef page = CGPDFDocumentGetPage(myPDF, pageNo);
// We're about to modify the context CTM to draw the PDF page where we want it, so save the graphics state in case we want to do more drawing
CGContextSaveGState(context);
// CGPDFPageGetDrawingTransform provides an easy way to get the transform for a PDF page. It will scale down to fit, including any
// base rotations necessary to display the PDF page correctly.
CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, self.bounds, 0, true);
// And apply the transform.
CGContextConcatCTM(context, pdfTransform);
// Finally, we draw the page and restore the graphics state for further manipulations!
CGContextDrawPDFPage(context, page);
CGContextRestoreGState(context);
Solução
CGPDFDocumentRef mygetpdfdocumentRef (const char *nome do arquivo) {CfStringRef Path; Url cfurlref; Documento CGPDFDocumentRef; Path = CfStringCreateWithCString (NULL, FILENAME, KCFSTRINGENCODINGF8); url = cfurlcreatewithfilesystempath (null, path, kcfurlposixPathStyle, 0); Cfrelease (caminho); document = cgpdfdocumentCreateWithurl (url); // 2 cfrelease (URL); int conting = cgpdfdocumentGetNumberOfPages (document); // 3 if (count == 0) {printf ("` `%s 'precisa de pelo menos uma página!", nome do arquivo); retornar nulo; } retornar documento; }
void MyDisplayPDFPage (CGContextRef myContext,size_t pageNumber,const char *filename) {
CGPDFDocumentRef document;
CGPDFPageRef page;
document = MyGetPDFDocumentRef (filename);// 1
page = CGPDFDocumentGetPage (document, pageNumber);// 2
CGContextDrawPDFPage (myContext, page);// 3
CGContextTranslateCTM(myContext, 0, 20);
CGContextScaleCTM(myContext, 1.0, -1.0);
CGPDFDocumentRelease (document);// 4
}
#import "DashBoard.h"
#import <QuartzCore/QuartzCore.h>
@interface UIImage (WBImage)
// rotate UIImage to any angle
-(UIImage*)rotate:(UIImageOrientation)orient;
@end
@implementation UIImage (WBImage)
static inline CGFloat degreesToRadians(CGFloat degrees)
{
return M_PI * (degrees / 180.0);
}
static inline CGSize swapWidthAndHeight(CGSize size)
{
CGFloat swap = size.width;
size.width = size.height;
size.height = swap;
return size;
}
-(UIImage*)rotate:(UIImageOrientation)orient
{
CGRect bnds = CGRectZero;
UIImage* copy = nil;
CGContextRef ctxt = nil;
CGRect rect = CGRectZero;
CGAffineTransform tran = CGAffineTransformIdentity;
bnds.size = self.size;
rect.size = self.size;
switch (orient)
{
case UIImageOrientationUp:
return self;
case UIImageOrientationUpMirrored:
tran = CGAffineTransformMakeTranslation(rect.size.width, 0.0);
tran = CGAffineTransformScale(tran, -1.0, 1.0);
break;
case UIImageOrientationDown:
tran = CGAffineTransformMakeTranslation(rect.size.width,
rect.size.height);
tran = CGAffineTransformRotate(tran, degreesToRadians(180.0));
break;
case UIImageOrientationDownMirrored:
tran = CGAffineTransformMakeTranslation(0.0, rect.size.height);
tran = CGAffineTransformScale(tran, 1.0, -1.0);
break;
case UIImageOrientationLeft:
bnds.size = swapWidthAndHeight(bnds.size);
tran = CGAffineTransformMakeTranslation(0.0, rect.size.width);
tran = CGAffineTransformRotate(tran, degreesToRadians(-90.0));
break;
case UIImageOrientationLeftMirrored:
bnds.size = swapWidthAndHeight(bnds.size);
tran = CGAffineTransformMakeTranslation(rect.size.height,
rect.size.width);
tran = CGAffineTransformScale(tran, -1.0, 1.0);
tran = CGAffineTransformRotate(tran, degreesToRadians(-90.0));
break;
case UIImageOrientationRight:
bnds.size = swapWidthAndHeight(bnds.size);
tran = CGAffineTransformMakeTranslation(rect.size.height, 0.0);
tran = CGAffineTransformRotate(tran, degreesToRadians(90.0));
break;
case UIImageOrientationRightMirrored:
bnds.size = swapWidthAndHeight(bnds.size);
tran = CGAffineTransformMakeScale(-1.0, 1.0);
tran = CGAffineTransformRotate(tran, degreesToRadians(90.0));
break;
default:
// orientation value supplied is invalid
assert(false);
return nil;
}
UIGraphicsBeginImageContext(bnds.size);
ctxt = UIGraphicsGetCurrentContext();
switch (orient)
{
case UIImageOrientationLeft:
case UIImageOrientationLeftMirrored:
case UIImageOrientationRight:
case UIImageOrientationRightMirrored:
CGContextScaleCTM(ctxt, -1.0, 1.0);
CGContextTranslateCTM(ctxt, -rect.size.height, 0.0);
break;
default:
CGContextScaleCTM(ctxt, 1.0, -1.0);
CGContextTranslateCTM(ctxt, 0.0, -rect.size.height);
break;
}
CGContextConcatCTM(ctxt, tran);
CGContextDrawImage(ctxt, rect, self.CGImage);
copy = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return copy;
}
@end
@implementation DashBoard
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
filePath=[[NSString alloc] initWithString:[[NSBundle mainBundle] pathForResource:@"roadie" ofType:@"pdf"]];
// an IBOutlet UIScrollView
[scrMain setContentSize:CGSizeMake(720, 720)];
// an IBOutlet UIImageView
[imgV setFrame:CGRectMake(0, 0, 720, 720)];
UIGraphicsBeginImageContext(CGSizeMake(720, 720));
// initial page is an size_t variable
initialPage=1;
MyDisplayPDFPage(UIGraphicsGetCurrentContext(), initialPage, [filePath UTF8String],myTable,mainString);
imgV.image=UIGraphicsGetImageFromCurrentImageContext();
imgV.image=[imgV.image rotate:UIImageOrientationDownMirrored];
}
Basta copiar e colar o código acima. Vai funcionar para você.
Outras dicas
O problema era a cor de fundo - especificamente, os PDFs com os quais eu estava tendo problemas não tinham um fundo branco. Ao preencher a vista com um retângulo branco, meu problema foi resolvido.