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win32: adjust printing-dc% scale to simulate screen DPI

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This is questionable; it might be better to set up a printing
 context with 72 DPI and adjust the resolution of the Pango
 font map associated with the DC to be 72 DPI; matching the
 screen is easier, and it provides the benefit that font metrics
 (based on fonts with point sizes rather than pixel sizes) are
 consistent across drawing contexts
This commit is contained in:
Matthew Flatt 2011-01-13 20:05:34 -07:00
parent 559f756374
commit 0d36dbefb8
1 changed files with 17 additions and 9 deletions
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26
collects/mred/private/wx/win32/printer-dc.rkt
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@ -78,6 +78,11 @@
(define-gdi32 EndPage (_wfun _HDC -> (r : _int) -> (unless (positive? r) (failed 'EndPage))))
(define-gdi32 EndDoc (_wfun _HDC -> (r : _int) -> (unless (positive? r) (failed 'EndDoc))))
(define-gdi32 GetDeviceCaps (_wfun _HDC _int -> _int))
(define LOGPIXELSX 88)
(define LOGPIXELSY 90)
(define needs-delete ((allocator DeleteDC) values))
(define (clone-page-setup p)
@ -111,6 +116,14 @@
;; the hDevModes and hDevNames fields
r)))))
;; Pango uses the resolution of the screen to make point<->pixel
;; decisions for all devices (by default). So, we make on drawing unit in
;; a printing context match the relative drawing unit for the screen.
(define SCREEN-DPI (let ([hdc (GetDC #f)])
(begin0
(exact->inexact (GetDeviceCaps hdc LOGPIXELSX))
(ReleaseDC #f hdc))))
(define printer-dc%
(class (record-dc-mixin (dc-mixin bitmap-dc-backend%))
(init [parent #f])
@ -134,9 +147,9 @@
(let ([scale (if (zero? (bitwise-and (PAGESETUPDLG-Flags page-setup)
PSD_INTHOUSANDTHSOFINCHES))
;; 100ths of mm
(/ 72.0 (/ 10.0 2.54))
(/ SCREEN-DPI (/ 10.0 2.54))
;; 1000ths of in
(/ 72.0 1000.0))])
(/ SCREEN-DPI 1000.0))])
(values
(* scale (POINT-x (PAGESETUPDLG-ptPaperSize page-setup)))
(* scale (POINT-y (PAGESETUPDLG-ptPaperSize page-setup))))))
@ -206,14 +219,9 @@
(EndDoc hdc))
(DeleteDC hdc))))))))
(define-gdi32 GetDeviceCaps (_wfun _HDC _int -> _int))
(define LOGPIXELSX 88)
(define LOGPIXELSY 90)
(define (set-point-scale hdc cr)
(let* ([lpx (GetDeviceCaps hdc LOGPIXELSX)]
[lpy (GetDeviceCaps hdc LOGPIXELSY)]
[lx (/ (if (zero? lpx) 300 lpx) 72.0)]
[ly (/ (if (zero? lpy) 300 lpy) 72.0)])
[lx (/ (if (zero? lpx) 300 lpx) SCREEN-DPI)]
[ly (/ (if (zero? lpy) 300 lpy) SCREEN-DPI)])
(cairo_scale cr lx ly)))