center vertically with vertical layout?

center vertically with vertical layout? 2 years 8 months ago #15562

arlomedia
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I'm currently using the vertical layout (Global.def_view = 0) to scroll long documents vertically, but if the document height is less than the viewer height, the document is top-aligned. I would like the document to be vertically centered if it is shorter than the viewer. I see that def_view = 3 uses vertical centering, but then longer documents scroll horizontally.

I tried calling Document.Open() first, then calling GetPageCount() on the Document object, then setting def_view to 3 if the page count is 1 or 0 if the page count is more than one, then calling PDFLayoutView.PDFOpen() (def_view has to be set before PDFOpen()). That seems to work, but I wanted to check and see if there is a better way?

BTW, this wouldn't work if the document has two pages and its height is still less than the viewer height, but it's not a priority to support that scenario. In most cases, only single-page documents will have a document height less than the viewer height.

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center vertically with vertical layout? 2 years 8 months ago #15564

radaee Offline Moderator Posts: 1123 Thank you received: 73	dear user: it can be checked, by aspect ratio of total height of all pages and max width. you may compare these 2 values: 1. (total height of all pages) / (max width) 2. (screen height) / (screen width).
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center vertically with vertical layout? 2 years 8 months ago #15568

arlomedia
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You're right, I can calculate the actual length of the document with Document.GetPageHeight() and Document.GetPageCount() rather than just assuming a multi-page document will be taller than the viewer.

The part I was concerned about was changing Global.def_view each time I load a document. Will that cause any problems, or is there a single view that will provide the two behaviors I'm looking for (vertically centering of short documents and vertical scrolling of long documents)?

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center vertically with vertical layout? 2 years 8 months ago #15569

radaee
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the perfect solution for you, shall not be change view mode by checking total height.
you shall always use PDFLayoutVert, and modify codes for method:
PDFLayoutVert.vLayout()
this method only has 30 lines, that set (x,y) and scale for each page.

you can calculate total height in a new loop, if total height less than member m_h, then adjust y offset for each page.

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Last edit: by radaee.

center vertically with vertical layout? 2 years 8 months ago #15570

arlomedia
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Okay, good. Here's what I came up with. Starting at the line that initializes y, I replaced the rest of the function with this:

for(cur = 0;cur < cnt;cur++){
   if(Global.fit_different_page_size && m_scales[cur] == 0) {
      m_scales[cur] = ((float)(m_w - m_page_gap)) / m_doc.GetPageWidth(cur);
      m_scales_min[cur] = ((float)(m_w - m_page_gap)) / m_doc.GetPageWidth(cur);
   }
   float pageScale = Global.fit_different_page_size ? m_scales[cur] : m_scale;
   int h = (int)(m_doc.GetPageHeight(cur) * pageScale);
   m_th += h + m_page_gap;
}
int y = m_page_gap>>1;
if (m_th < m_h) {
   y += (m_h - m_th) / 2;
}
boolean clip = m_scale / m_scale_min > m_zoom_level_clip;
for(cur = 0;cur < cnt;cur++)
{
          float pageScale = Global.fit_different_page_size ? m_scales[cur] : m_scale;
   int w = (int)(m_doc.GetPageWidth(cur) * pageScale);
   int h = (int)(m_doc.GetPageHeight(cur) * pageScale);
   int x = Global.fit_different_page_size ? m_page_gap >> 1:
         ((int)(m_page_maxw * pageScale) + m_page_gap - w)>>1;
   boolean clipPage = Global.fit_different_page_size ? pageScale / m_scales_min[cur] > m_zoom_level_clip : clip;
   m_pages[cur].vLayout(x, y, pageScale, clipPage);
   y += h + m_page_gap;
}

This also takes into account document zooming and documents with different-sized pages. And then def_view can stay at 0.

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TOPIC:

center vertically with vertical layout? 2 years 8 months ago #15562

center vertically with vertical layout? 2 years 8 months ago #15564

center vertically with vertical layout? 2 years 8 months ago #15568

center vertically with vertical layout? 2 years 8 months ago #15569

center vertically with vertical layout? 2 years 8 months ago #15570