ViewerPreferences 完整参考

ViewerPreferences 允许控制 PDF 文档在支持它们的阅读器中的呈现方式，以及某些默认打印设置的初始化方式。当前 HotPDF 库支持 14 个 ViewerPreferences 值以及相关的 InitialZoom 属性

Current Data Types

THPDFDirection = (LeftToRight, RightToLeft);
THPDFNonFullScreenPageMode = (
  nfpmUseNone, nfpmUseOutlines, nfpmUseThumbs, nfpmUseOC, nfpmUseAttachments
);
THPDFPrintScaling = (psNone, psAppDefault);
THPDFDuplex = (dupSimplex, dupDuplexFlipShortEdge, dupDuplexFlipLongEdge);
THPDFPageBoundary = (pbMediaBox, pbCropBox, pbBleedBox, pbTrimBox, pbArtBox);
THPDFInitialZoom = (
  FitNone, FitPage, FitWidth, FitHeight, FitBox, FitBoxWidth, FitBoxHeight,
  Zoom50, Zoom75, Zoom100, Zoom125, Zoom150, Zoom200
);

THPDFViewerPreference = (
  vpHideToolbar, vpHideMenubar, vpHideWindowUI, vpFitWindow, vpCenterWindow,
  vpDisplayDocTitle, vpDirection, vpNonFullScreenPageMode, vpPrintScaling,
  vpDuplex, vpPickTrayByPDFSize, vpNumCopies, vpPrintArea, vpPrintClip,
  vpViewArea, vpViewClip
);

THPDFViewerPreferences = set of THPDFViewerPreference;

Supported ViewerPreferences

Option	Companion Property	说明
vpHideToolbar	None	Hide the viewer toolbar.
vpHideMenubar	None	Hide the viewer menu bar.
vpHideWindowUI	None	Hide UI elements such as scroll bars and navigation controls.
vpFitWindow	None	Resize the document window to fit the first displayed page.
vpCenterWindow	None	Center the document window on the screen.
vpDisplayDocTitle	Title	Display the document title instead of the file name in the viewer caption.
vpDirection	Direction	Store the predominant reading order using `LeftToRight` or `RightToLeft`.
vpNonFullScreenPageMode	NonFullScreenPageMode	Choose the page mode to use after leaving full-screen mode.
vpPrintScaling	PrintScaling	Choose `psNone` or `psAppDefault` for default print scaling.
vpDuplex	Duplex	Choose simplex or duplex printing behavior.
vpPickTrayByPDFSize	None	Request printer tray selection based on the PDF page size.
vpNumCopies	NumCopies	Store the suggested print copy count.
vpPrintArea	PrintArea	Select the page boundary used for print rendering.
vpPrintClip	PrintClip	Select the page boundary used for print clipping.
vpViewArea	ViewArea	Page boundary used for the on-screen view area (PDF 1.4 12.2). Available since HotPDF v2.29.0.
vpViewClip	ViewClip	Page boundary used for the on-screen view clipping (PDF 1.4 12.2). Available since HotPDF v2.29.0.

Companion Property Values

这些属性只会在匹配的 ViewerPreferences 标志启用时写入

属性	Values
Direction	LeftToRight, RightToLeft
NonFullScreenPageMode	nfpmUseNone, nfpmUseOutlines, nfpmUseThumbs, nfpmUseOC, nfpmUseAttachments
PrintScaling	psNone, psAppDefault
Duplex	dupSimplex, dupDuplexFlipShortEdge, dupDuplexFlipLongEdge
PrintArea / PrintClip / ViewArea / ViewClip	pbMediaBox, pbCropBox, pbBleedBox, pbTrimBox, pbArtBox

InitialZoom Integration

InitialZoom 补充 ViewerPreferences，用于控制文档打开时的初始页面显示模式

默认值：自 HotPDF v2.3.11 起，默认值为 FitHeight（PDF /FitV destination），因此生成的文档会以每页适配阅读器窗口高度的方式打开。将 InitialZoom 设为 FitNone 可省略 OpenAction，并让阅读器回退到自身默认缩放。若需要打开时跳到命名目标，请使用 THotPDF.SetOpenNamedDestinationAction

// Complete document presentation setup
HotPDF.ViewerPreferences := [vpFitWindow, vpCenterWindow, vpDisplayDocTitle];
HotPDF.InitialZoom := FitWidth;

// Technical document setup
HotPDF.ViewerPreferences := [vpDisplayDocTitle, vpPrintScaling];
HotPDF.InitialZoom := Zoom125;

// Presentation mode
HotPDF.ViewerPreferences := [vpFitWindow, vpHideToolbar, vpHideMenubar];
HotPDF.InitialZoom := FitPage;

Implementation Example

var
  VPref: THPDFViewerPreferences;
begin
  VPref := [vpFitWindow, vpCenterWindow, vpDisplayDocTitle];

  if EnableDirection then
  begin
    Include(VPref, vpDirection);
    HotPDF.Direction := RightToLeft;
  end;

  if EnablePrintScaling then
  begin
    Include(VPref, vpPrintScaling);
    HotPDF.PrintScaling := psNone;
  end;

  HotPDF.ViewerPreferences := VPref;
  HotPDF.InitialZoom := FitWidth;
end;

Compatibility Notes

通常 Adobe Reader/Acrobat 提供最完整的 ViewerPreferences 支持
其他阅读器：支持情况不同，因为这些值是偏好设置而非强制要求
合规阅读器应安全忽略不支持的设置

Demo Applications

以下 demo 已与当前库支持保持同步：

Demo\Delphi\ViewerPref
Demo\CBuilder\ViewerPref