2019.2

scale
Scale at which to draw. To draw at the 100% size, use a scale of device_dpi / 72. Do not use
the DC to do the scaling; this will result in scaling artifacts being drawn.
offsetX
Horizontal offset from the left edge of the DC surface, in *device* units, at which to start the
drawing.
offsetY
Vertical offset from the top edge of the DC surface, in *device* units, at which to start the
drawing.
The drawing is done in PDF user space units (72th of an inch). In order to have a smooth
drawing of the page, the device context must have its mapping mode set to MM_TEXT with a
1:1 mapping between logical space (SetWindowExtEx) and device space (SetViewportExtEx).
Since MM_TEXT has its origin at the top instead of the bottom, the drawing is done vertically
mirrored; this means that the other mapping modes may not work because they are based at
the bottom. A 100% zoom is obtained by setting the scale to the ratio of the device dpi divided
by 72.
The Acrobat library automatically clips the drawing based on the viewable portion of the DC. If
the DC is translated or scaled, either by a world transform (SetWorldTransform) or a logical-to-
device space transform (SetWindowOrgEx or SetViewportOrgEx ), the *untransformed* space
is used. As a result, all scaling and translation operation must be done by the library itself to
work correctly. Otherwise, unwanted scaling artifacts or clipping will occur.
As such, the drawing code of the caller should look similar to this to obtain the same result as
what Acrobat does:
1. Fill the entire drawing area with gray.
2. Determine the origin (orgx, orgy) (for example, at (0, 0), or as indicated by scroll bars).
3. Draw a white rectangle of size (CropBox.width * zoom, CropBox.height * zoom) at (orgx,
orgy) representing the page (optional; Acrobat does not do that, and this method already
draws the white page background).
4. Call the IPage.Draw() method to draw the page at (orgx, orgy).
Note that extra care must be taken when filling rectangles as to whether the boundary pixel will
be inside or outside the region.
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