如何转换单个UIView，以便可以在现有PDF中绘制它？

Question

I am creating a PDF with labels, tables, and charts. I have no problem drawing images and text, but I have PDF charts that are custom UIViews .

The current context is set initially for drawing the PDF, and most of the questions here are relating to that. But I am talking about, once you're already drawing a PDF, how do you add a single additional view like you would add a line of text or an image. ie I want to add a UIView that contains a pie chart to a PDF I am creating.

I tried converting the view to an image, but it ends up pretty low resolution and you can seed the pixelation, whereas if you draw it directly it uses vector graphics and comes out much crisper.

PieChartView is from an open source github library. The manager is a simple custom class I wrote to manage it.

CGRect frame = CGRectMake(PAGE_WIDTH/2 - pieWidth/2, origin.y, pieWidth, pieHeight);
PieChartView* pie = [[PieChartView alloc] initWithFrame:frame];
PieChartManager* pieManager = [[BPPieChartManager alloc] initWithData:data];
pie.delegate = pieManager;
pie.datasource = pieManager;
[pie.layer drawInContext:UIGraphicsGetCurrentContext()];

This results in the pie chart filling the entire page of the PDF. This isn't surprising, since its layer doesn't contain information about the frame.

I guess I am supposed to use CGContextTranslateCTM and CGContextScaleCTM to reposition, but I'm not sure if there isn't a simpler way, plus I'm not sure how to use them to get what I want.

Thanks for your help

EDIT: I tried just drawing the pie this way:

[pie drawRect: frame];

That draws the pie in the top left of the page, in the size that's expected. How do I get it where I want it? The frame contains the origin of where I want it, so why is it putting it in the top left?

Answer 1

It appears as if the custom UIView which renders inside the pdf will always start from (0,0). You can add the your pie view for the entire frame of the pdf page and draw the actual pie chart at a custom smaller frame in your UIView's drawRect function and make the remaining area transparent.