I'm pretty close to have `async` support done for the mozPrintCallback, but I'm stuck with a problem that I don't know how to solve best.
Here is some very basic background to understand my problem: - I've implemented a new function `nsSimplePageSequenceFrame::PrePrintNextPage()` that is called from the nsPrintEngine/nsPagePrintTimer to deter if the current page is ready for printing. If the function returns `true`, nsSimplePageSequenceFrame::PrintNextPage() is executed that does the actual printing to the page. - PrePrintNextPage does the canvas-surface-replacement to replace the pixel based surface by a vector one that is used for printing. If there are no canvas with a mozPrintCallback or the page doesn't get printed, it returns true. Otherwise, it waits until on all canvas with a mozPrintCallback the `done()` function is called. [I have the two current function PrePrintNextPage() and PrintNextPage() here: https://gist.github.com/2483955#L611] The problem is now in the "canvas-surface-replacement": The "renderingSurface->CreateSimilarSurface()" function call only returns a vector-based surface iff "dc->BeginPage()" was called at least once before. However, for the first page, this is not the case (as "PrePrintNextPage()" is called before "PrintNextPage()", which does the call to dc->BeginPage()). An easy solution might be to "move all the code from the beginning of `PrintNextPage` until the dc->BeginPage() into the "PrePrintNextPage()" function. Then, before a similar surface is created, a dc->BeginPage() call already happened. To do this, I need some more clarification on this code: http://mxr.mozilla.org/mozilla-central/source/layout/generic/nsSimplePageSequence.cpp#620 * can PresContext()->IsRootPaginatedDocument() be false at any time? The `PrintNextPage()` function is only called for printing to paper - it's not called for preview. Therefore, the PresContext is always a paginatedDocument? * the function might call `dc->BeginPage()` multiple times. Shouldn't this function add only one page to the output? Is this a bug or a feature? * was this code in "PrintNextPage()" used once for rendering the preview window output as well (which is longer the case if I read the code right)? Are the two points I've listed above left over from sharing the same function and can be removed now? Best, Julian _______________________________________________ dev-tech-layout mailing list [email protected] https://lists.mozilla.org/listinfo/dev-tech-layout
