旋转 CGPDF 文档/页面

发布于 2024-10-20 10:25:10 字数 838 浏览 0 评论 0原文

我正在加载 CGPDFDocument，将其作为子层添加到 UIView (myContentView)，然后将 myContentView 添加到 UIScrollView。效果很好。现在我想允许用户旋转 PDF（如果他们选择）。让 PDF 最初通过一些旋转显示很容易 - 我只是在这里这样做：

- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx {
    CGContextSaveGState (ctx);
    CGContextSetRGBFillColor(ctx, 1.0, 1.0, 1.0, 1.0);
    CGContextFillRect(ctx, CGContextGetClipBoundingBox(ctx));
    CGContextTranslateCTM(ctx, 0.0, layer.bounds.size.height);
    CGContextScaleCTM(ctx, 1.0, -1.0);
    CGContextConcatCTM(ctx, CGPDFPageGetDrawingTransform(myPageRef, kCGPDFCropBox, layer.bounds, rotation, true));
    CGContextDrawPDFPage(ctx, myPageRef);
    CGContextRestoreGState (ctx);
}

但是，在初始加载后我该如何做呢？

注意：我尝试过旋转 myContentView，这似乎有效，但完成后，我无法再缩放/取消缩放 PDF...我认为我需要的是强制使用新值再次调用 drawLayer在“旋转”中......我该怎么做？

谢谢，史蒂夫

原文

I'm loading a CGPDFDocument, adding that as a sublayer to a UIView (myContentView), and then adding myContentView to a UIScrollView. That works fine. Now I want to allow the user to rotate the PDF if they choose to. It's easy to get the PDF to initially display with some rotation- I just do it here:

- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx {
    CGContextSaveGState (ctx);
    CGContextSetRGBFillColor(ctx, 1.0, 1.0, 1.0, 1.0);
    CGContextFillRect(ctx, CGContextGetClipBoundingBox(ctx));
    CGContextTranslateCTM(ctx, 0.0, layer.bounds.size.height);
    CGContextScaleCTM(ctx, 1.0, -1.0);
    CGContextConcatCTM(ctx, CGPDFPageGetDrawingTransform(myPageRef, kCGPDFCropBox, layer.bounds, rotation, true));
    CGContextDrawPDFPage(ctx, myPageRef);
    CGContextRestoreGState (ctx);
}

But, how can I do it after the initial load?

Note: I've tried just rotating myContentView, which seems like it works, but after doing it, I can no longer zoom/unzoom the PDF... I think what I need is to force drawLayer to be called again with a new value in "rotation"... how do I do that?

Thanks,
Steve

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