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This is about implementing a new API for printing on the web. It's a "low level" API that allows web developers to have rich control about printing output.
Defining the PrintSetting API as used in PrintDocument.print(printSetting) is out of the scope of this document. == Proposed API Notes ==
* Use points as metric for printing (72 points per inch)
* Open Questions
** What is (0,0)? The top left corner of the physical page OR of the page taking into account the print margin?
** Should there be different color spaces then RGB? How to make them work, as there are no CSS colors defined for CMYK.
** Should the browser display a progress view while the pages are drawn (this doesn't mean the actual printing output progress)?
** Lot more... TBD
=== Possible values for the 'scale' property (see below) ===
* 'scale': Scales the drawing while keeping the ration to to fit on the print paper size
* 'fit': Scales the drawing while not taking the ration of the printer paper size in account
* 'center': No scaling, just placing the center of the drawing onto the center of the printer paper.
== Example ==
var pDoc = new PrintDocument(
'documentTitle', // Title
'letter', // Paper size
'scale', // optional: see notes about "scale"
false // optional: isLandscape?
// ---
// Following things functions MUST be defined/set by the developer.
// ---
// ..
fontCtx.font = '...';
fontCtx.measureText(...);
};
// Actually drawing function. Each page is painted drawn individually. This is
// handy for page preview or if the user picks only a subset of the total
// pages.
// ...
}
// Render the page <pageNumber> to the ctx.
setTimeout(function() {
// Continue drawing...
// This page is done drawing.
ctx.endPage();
// ---
// Other APIsProvided API functions
// ---
pDoc.getPageSize = function() {
}
pDoc.getUnwriteableMargin = function() {
return {
top: <inch>,
bottom: <inch>,
left: <inch>,
right: <inch>
}
}
// Was the printing started but is not finished yet?
pDoc.isPrinting;
// Are all the pages drawn?
pDoc.isFinished;
// Start the printing progress. This opens the print dialog.
// The passed in `printSetting` is not defined yet and is outside of the scope // of this proposal/API. pDoc.print(printSetting);
// Stops the print process. Once all data is created, there is no way to stop
// the printing anymore; that means, as soon as `pDoc.isFinished` is true,
// calling this function has no effect.
pDoc.abort();
== Proposed API ==
See the example to get an idea. More details coming soon!
== Implementation ==
