我正在尝试使用以下代码绘制PDF页面。某些PDF正确渲染,但其他PDF只显示为完全黑色的图像,或者部分渲染部分,其余部分为黑色。在比较正在发生的事情时,显示OK的那些似乎总是在其中有“常规”文本以及一些图形(图表等),而出现黑色的那些通常是所有图形(如页面的一页)音乐,例如)。有人能指出我正确的方向吗? 我在新的3.2 SDK上构建它。
谢谢!
// 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);
答案 0 :(得分:4)
CGPDFDocumentRef MyGetPDFDocumentRef(const char * filename){ CFStringRef路径; CFURLRef url; CGPDFDocumentRef文件; path = CFStringCreateWithCString(NULL,filename,kCFStringEncodingUTF8); url = CFURLCreateWithFileSystemPath(NULL,path,kCFURLPOSIXPathStyle,0); CFRelease(路径); document = CGPDFDocumentCreateWithURL(url); // 2 CFRelease(URL); int count = CGPDFDocumentGetNumberOfPages(document); // 3 if(count == 0){ printf(“`%s'至少需要一个页面!”,文件名); 返回NULL; } 退货文件; }
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];
}
只需复制&amp;粘贴上面的代码。它会对你有用。
答案 1 :(得分:3)
问题是背景颜色 - 特别是,我遇到麻烦的pdf没有白色背景。通过用白色矩形填充视图,我的问题就解决了。