On Fri, 30 May 2025 06:40:40 GMT, Prasanta Sadhukhan <psadhuk...@openjdk.org> wrote:
>> The fix for the https://bugs.openjdk.org/browse/JDK-8251928. >> >> **Description**. >> This PR contains changes to be able to print with DPI higher than 72 on >> macOS, set default CPrinterJob DPI is 300 like in the PSPrinterJob. >> >> As described in the macOS drawing guide, the following steps are required to >> draw with high DPI >> (https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/CocoaDrawingGuide/Transforms/Transforms.html#//apple_ref/doc/uid/TP40003290-CH204-BCICIJAJ): >> 1. Convert the user-space point, size, or rectangle value to device space >> coordinates; >> 2. Normalize the value in device space so that it is aligned to the >> appropriate pixel boundary; >> 3. Convert the normalized value back to user space; >> 4. Draw your content using the adjusted value. >> >> The 1-st step is now implemented in the CPrinterJob, a Graphics provided to >> the print method adjusted to a printer's DPI. >> The 2-nd step is a drawing process in the java code (without changes). >> The 3-rd step is now implemented in the PrinterView.m, the drawing scaled >> back to the 72 DPI. >> The 4-th step is a drawing process in the native code (without changes). >> >> **Tests**. >> I run all tests from javax.print package and there is no any regression. >> New test covers macOS and Linux only because we know its default DPI - 300. > > While running PDFBOX4935PrintDpi testcase from the JBS, it is showing with > your fix > ScaleX: 4.166666 > ScaleY: 4.166666 > DPI = 300 > > while printing to pdf. Shouldn't the scale be shown as 2.0 for retina display > while doing pdf printing? @prsadhuk , no, the scale should be 4.166666. As described in the drawing guide https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/CocoaDrawingGuide/Transforms/Transforms.html#//apple_ref/doc/uid/TP40003290-CH204-SW6 > Units in the user space are based on the printer's point, which was used in > the publishing industry to measure the size of content on the printed page. A > single point is equivalent to 1/72 of an inch. Points were adopted by earlier > versions of Mac OS as the standard resolution for content on the screen. OS X > continues to use the same effective “resolution” for user-space drawing. > > Although a single point often corresponded directly to a pixel in the past, > in OS X, that may not be the case. Points are not tied to the resolution of > any particular device. If you draw a rectangle whose width and height are > exactly three points, that does not mean it will be rendered on the screen as > a three-pixel by three-pixel rectangle. On a 144 dpi screen, the rectangle > might be rendered using six pixels per side, and on a 600-dpi printer, the > rectangle would require 25 pixels per side. The actual translation from > points to pixels is device dependent and handled for you automatically by OS > X. So it does not matter what the actual device DPI is, we always use or see 72 on the java side. I set the default printing DPI for macOS to 300 in this PR, so if you do not provide different value using javax.print.attribute.standard.PrinterResolution then the scaling should be 300/72 = 4.16666. ------------- PR Comment: https://git.openjdk.org/jdk/pull/25489#issuecomment-2922481400
