Pdf Configuration
The parameters pageSize
, pageFit
, dpi
and resamplingMethod
interact in a complex way when adding bitmap images (JPEG, PNG, or raw) to the PDF. There are three cases to consider:
pageSize
isCUSTOM
: in this casedpi
is used as the conversion ratio to calculate both the physical page and image sizes in inches from the bitmap dimensions.resamplingMethod
is ignored.pageSize
is notCUSTOM
ANDpageFit
isNONE
: in this casedpi
is used as the conversion ratio to calculate only the physical image size in inches from the bitmap dimensions. The image is centered onto the page.resamplingMethod
is ignored.pageSize
is notCUSTOM
ANDpageFit
is notNONE
: in this case the page has a pre-determined physical size and we want to stretch the image to fit the page in one of the ways described bypageFit
. The image DPI is automatically calculated for each image from the given physical page size, page fit setting and image dimensions. There are two sub-cases to consider: a.resamplingMethod
is NONE OR the calculated DPI is less than or equal todpi
: in this case the image is added to the PDF without resampling, which means that the image rectangle is simply rescaled to fit into the page as specified bypageFit
andpageSize
. b.resamplingMethod
is not NONE AND the calculated DPI is greater thandpi
: in this case the bitmap of the image is resampled to matchdpi
using the selected method before adding it to the PDF. This will result in a bitmap that is smaller than the original image and hence, the resulting PDF will be smaller in size.
Constructors
Properties
Attributes.
The dpi
parameter has two different meanings depending on the value of pageSize
and pageFit
. If pageSize is CUSTOM or pageFit is NONE, then dpi
is the conversion ratio used to convert from units of pixels to physical inches when adding bitmap images (JPEG, PNG, or raw) to the PDF. Otherwise, if resamplingMethod
is not NONE, then the image is downscaled if necessary (if the image after being fit to the page has a higher calculated DPI than dpi
) to match dpi
before adding it to the PDF. Otherwise, the setting is ignored and the calculated image DPI is used instead.
JPEG quality for images. Applies if an image is added as a cv::Mat and therefore needs to be encoded. Also applies if resamplingMethod
not NONE and the image being added needs to be downscaled. Otherwise, when adding JPEG files to the PDF, the files are copied directly into the PDF and not re-encoded, which is many times faster and also preserves the quality of the original.
Page direction.
Resampling method.