The GINO driver is based on the work of the Independent JPEG Group for the software to carry out the actual compression.
Nomination Routines
Two nominations routines are provided for the JPEG driver. The first has no argument and uses a default resolution of 72 dpi for the interpretation of pixels to drawing units. The second uses a single argument where this mapping may be altered by specifying the required dots-per-inch setting.
Drawing Limits
The default drawing limits of the metafile is 960 by 720 pixels, which relates to a drawing area of 338mm by 254 mm (at 72dpi). For mechanisms to change the default drawing limits, refer to this section under Image File Formats (see Metafile Drawing Limits).
Image Size
The resulting image size can be enquired using the GINO routine gEnqDrawingLimits() with these values being returned in current drawing units. The pixel resolution of the image can be enquired by calling gEnqPixelResolution().
Image Quality
The IPAPTY argument to the routine gSetDrawingLimits() is used to set the compression quality. Quality can range from 1 (worst) to 100 (best) with a default setting of 75.
Multiple Frames
The driver does not recognise multiple images within the application so only the first image will be stored. (i.e. up to the first call to gNewDrawing() after any drawing routines).
Intermediate Vector File
This driver uses an internal GINO vector to raster pre-processor to create the output for the device which contains a fixed sized memory area into which the image is rasterized.
