將PDF加載到屏幕外層

Question

有沒有辦法將PDF加載到屏幕外的CALayer（或CATiledLayer）中，然後在需要時才顯示它？該解決方案還應支持所需分辨率的縮放。

更新
只是爲了澄清 - 我想要的PDF仍然基於矢量。

Answer 1

注意：您告訴您需要將PDF加載到CALayer中。但在這裏，我有解決方案將整個PDF頁面加載到圖像中。一旦圖像在數組中，您可以在需要時將其中任何一個視爲&。如果您有任何疑問，請添加評論。

• 你只需複製&粘貼以下代碼。它幾乎適合你。我測試過了。

首先把下面的方法放在你的視圖控制器的實現上面。

NSMutableArray *aRefImgs; // global variable. 
void setRefImgs(NSMutableArray *ref){ 
    aRefImgs=ref; 
} 

NSMutableArray* ImgArrRef(){ 
    return aRefImgs; 
} 
CGPDFDocumentRef MyGetPDFDocumentRef (const char *filename) { 
    CFStringRef path; 
    CFURLRef url; 
    CGPDFDocumentRef document; 
    path = CFStringCreateWithCString (NULL, filename,kCFStringEncodingUTF8); 
    url = CFURLCreateWithFileSystemPath (NULL, path, kCFURLPOSIXPathStyle, 0); 
    CFRelease (path); 
    document = CGPDFDocumentCreateWithURL (url);// 2 
    CFRelease(url); 
    int count = CGPDFDocumentGetNumberOfPages (document);// 3 
    if (count == 0) { 
     printf("`%s' needs at least one page!", filename); 
     return NULL; 
    } 
    return document; 
} 

void MyDisplayPDFPage (CGContextRef myContext,size_t pageNumber,const char *filename, CGPDFOperatorTableRef tblRef, NSMutableString *mainStr) { 
    CGPDFDocumentRef document; 
    CGPDFPageRef page; 
    document = MyGetPDFDocumentRef (filename);// 1 
    totalPages=CGPDFDocumentGetNumberOfPages(document); 
    page = CGPDFDocumentGetPage (document, pageNumber);// 2 
    CGContextDrawPDFPage (myContext, page);// 3 
    CGContextTranslateCTM(myContext, 0, 20); 
    CGContextScaleCTM(myContext, 1.0, -1.0); 
    CGPDFDocumentRelease (document);// 4 
} 

現在，將下面的代碼放在viewController.m文件中。

-(void)viewDidLoad { 
    filePath=[[NSString alloc] initWithString:[[NSBundle mainBundle] pathForResource:@"roadie" ofType:@"pdf"]]; 

    CGPDFDocumentRef d=MyGetPDFDocumentRef([filePath UTF8String]); 

    size_t nos=CGPDFDocumentGetNumberOfPages(d); 
    totalPages=nos; 
    arrImgs=[[NSMutableArray alloc] init]; // arrImgs variable declared in viewController.h file. 
setRefImgs(arrImgs); 
int i; 
for(i=0;i<nos;i++){ 
    UIGraphicsBeginImageContext(CGSizeMake(720, 720)); 
    MyDisplayPDFPage(UIGraphicsGetCurrentContext(), i+1, [filePath UTF8String],myTable,mainString); 
    UIImage *tmp=UIGraphicsGetImageFromCurrentImageContext(); 
    UIImage *t2=[tmp rotate:UIImageOrientationDownMirrored]; 
    [arrPDFImgs addObject:t2]; 
    UIImageView *imgV=[[UIImageView alloc] initWithFrame:CGRectMake(scrPDFImages.frame.size.width * i, 0, scrPDFImages.frame.size.width, scrPDFImages.frame.size.height)]; 
    [imgV setContentMode:UIViewContentModeScaleToFill]; 
    [imgV setImage:t2]; 
    [scrPDFImages addSubview:imgV]; 
      // scrPDFImages is an array that has all images 
      // per page one image from pdf document 
    [imgV release]; 
    UIGraphicsPopContext(); 
    } 
} 

您可能需要圖像方向 - 我也已將整個課程放在這裏。

@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