Convert page size to pixels

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3 total messages Started by Steve_J_Willis Fri, 03 Apr 2009 16:23

#205

Author: Steve_J_Willis
Date: Fri, 03 Apr 2009 16:23

19 lines
1945 bytes

Two (possibly) related questions:

(1) I am drawing the image of a page to an offscreen bitmap using PDPageDrawContentsToWindow. I need to allocate a correct height and width for the page in pixels for the resulting bitmap. What I want is an image that represents the size of the page at 100% zoom. This is what I've tried:

ASFixedRect cropBox;
PDPageGetCropBox(AVPageViewGetPage(pageView), &cropBox);
AVDevRect pageRect;
AVPageViewRectToDevice(pageView, &cropBox, &pageRect);
double zoom = ASFixedToFloat(AVPageViewGetZoom(pageView));
int pageWidth = (int) (abs(pageRect.right - pageRect.left) / zoom);
int pageHeight = (int) (abs(pageRect.bottom - pageRect.top) / zoom);

The above width and height are too large for the image drawn to my bitmap by PDPageDrawContentsToWindow.

(2) I notice that when I select File | Export | Image in Acrobat and save the page as a JPEG, the resulting image width and height are substantially larger than the width and height calculated in #1 (which are themselves too large for the PDPageDrawContentsToWindow function). How does Acrobat choose an optimal width/height to avoid aliasing? The size of my output image is arbitrary; I want to choose a width and height that are optimal to capture the image data of the original page, and understand how to scale the output of PDPageDrawContentsToWindow to those values.

Thanks!

Steve

Re: Convert page size to pixels

#208

Author: Leonard_Rosenthol
Date: Fri, 03 Apr 2009 17:30

5 lines
754 bytes

You don't need to deal with the AV stuff here - just the page size...

BUT you need to remember to multiply by the resolution...

Leonard

Re: Convert page size to pixels

#210

Author: Steve_J_Willis
Date: Fri, 03 Apr 2009 18:14

7 lines
1169 bytes

Could you give me a more concrete example? I don't understand how to get the page size without dealing with the AV stuff.

My question is probably simpler than I stated above: PDPageDrawContentsToWindow will draw the page to a bitmap of some size, measured in pixels. I need to know what that size is in advance so I can create a correctly sized bitmap for it to draw on to hold the entire page. How do I determine the width and height of the page image PDPageDrawContentsToWindow will draw in pixels?

Your help is appreciated!

Steve

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