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backported high-quality wxMSW printing to 2.8 (disabled by default, has to be enabled by changing wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW to 1 in prntbase.cpp

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@54409 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Václav Slavík
2008-06-28 20:52:59 +00:00
parent c6b44b6c88
commit d9f3bf6e1b
1 changed files with 308 additions and 0 deletions
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308
src/common/prntbase.cpp
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@@ -18,6 +18,17 @@
#if wxUSE_PRINTING_ARCHITECTURE
// change this to 1 to use experimental high-quality printing on Windows
// (NB: this can't be in msw/printwin.cpp because of binary compatibility)
#define wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW 0
#if wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW
#if !defined(__WXMSW__) || !wxUSE_IMAGE || !wxUSE_WXDIB
#undef wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW
#define wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW 0
#endif
#endif
#include "wx/dcprint.h"
#ifndef WX_PRECOMP
@@ -65,6 +76,19 @@
#endif
#endif // __WXMSW__
#if wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW
#include "wx/msw/dib.h"
#include "wx/image.h"
typedef bool (wxPrintPreviewBase::*RenderPageIntoDCFunc)(wxDC&, int);
static bool RenderPageIntoBitmapHQ(wxPrintPreviewBase *preview,
RenderPageIntoDCFunc RenderPageIntoDC,
wxPrinterDC& printerDC,
wxBitmap& bmp, int pageNum,
int pageWidth, int pageHeight);
#endif // wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW
//----------------------------------------------------------------------------
// wxPrintFactory
//----------------------------------------------------------------------------
@@ -1503,6 +1527,29 @@ bool wxPrintPreviewBase::RenderPageIntoDC(wxDC& dc, int pageNum)
bool wxPrintPreviewBase::RenderPageIntoBitmap(wxBitmap& bmp, int pageNum)
{
#if wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW
// try high quality rendering first:
static bool s_hqPreviewFailed = false;
if ( !s_hqPreviewFailed )
{
wxPrinterDC printerDC(m_printDialogData.GetPrintData());
if ( RenderPageIntoBitmapHQ(this,
&wxPrintPreviewBase::RenderPageIntoDC,
printerDC,
bmp, pageNum,
m_pageWidth, m_pageHeight) )
{
return true;
}
else
{
wxLogTrace(_T("printing"),
_T("high-quality preview failed, falling back to normal"));
s_hqPreviewFailed = true; // don't bother re-trying
}
}
#endif // wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW
wxMemoryDC memoryDC;
memoryDC.SelectObject(bmp);
memoryDC.Clear();
@@ -1770,4 +1817,265 @@ void wxPrintPreview::DetermineScaling()
m_pimpl->DetermineScaling();
}
//----------------------------------------------------------------------------
// experimental backport of high-quality preview on Windows
//----------------------------------------------------------------------------
#if wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW
// The preview, as implemented in wxPrintPreviewBase (and as used prior to wx3)
// is inexact: it uses screen DC, which has much lower resolution and has
// other properties different from printer DC, so the preview is not quite
// right.
//
// To make matters worse, if the application depends heavily on GetTextExtent()
// or does text layout itself, the output in preview and on paper can be very
// different. In particular, wxHtmlEasyPrinting is affected and the preview
// can be easily off by several pages.
//
// To fix this, we attempt to render the preview into high-resolution bitmap
// using DC with same resolution etc. as the printer DC. This takes lot of
// memory, so the code is more complicated than it could be, but the results
// are much better.
//
// Finally, this code is specific to wxMSW, because it doesn't make sense to
// bother with it on other platforms. Both OSX and modern GNOME/GTK+
// environments have builtin accurate preview (that applications should use
// instead) and the differences between screen and printer DC in wxGTK are so
// large than this trick doesn't help at all.
namespace
{
// If there's not enough memory, we need to render the preview in parts.
// Unfortunately we cannot simply use wxMemoryDC, because it reports its size
// as bitmap's size, and we need to use smaller bitmap while still reporting
// original ("correct") DC size, because printing code frequently uses
// GetSize() to determine scaling factor. This DC class handles this.
class PageFragmentDC : public wxMemoryDC
{
public:
PageFragmentDC(wxDC *printer, wxBitmap& bmp, const wxRect& rect)
: wxMemoryDC(printer),
m_rect(rect)
{
SetDeviceOrigin(0, 0);
SelectObject(bmp);
}
virtual void SetDeviceOrigin(wxCoord x, wxCoord y)
{
wxMemoryDC::SetDeviceOrigin(x - m_rect.x, y - m_rect.y);
}
virtual void DoGetDeviceOrigin(wxCoord *x, wxCoord *y) const
{
wxMemoryDC::DoGetDeviceOrigin(x, y);
if ( x ) *x += m_rect.x;
if ( x ) *y += m_rect.y;
}
virtual void DoGetSize(int *width, int *height) const
{
if ( width )
*width = m_rect.width;
if ( height )
*height = m_rect.height;
}
private:
wxRect m_rect;
};
// estimate how big chunks we can render, given available RAM
long ComputeFragmentSize(long printerDepth,
long width,
long height)
{
// Compute the amount of memory needed to generate the preview.
// Memory requirements of RenderPageFragment() are as follows:
//
// (memory DC - always)
// width * height * printerDepth/8
// (wxImage + wxDIB instance)
// width * height * (3 + 4)
// (this could be reduced to *3 if using wxGraphicsContext)
//
// So, given amount of memory M, we can render at most
//
// height = M / (width * (printerDepth/8 + F))
//
// where F is 3 or 7 depending on whether wxGraphicsContext is used or not
wxMemorySize memAvail = wxGetFreeMemory();
if ( memAvail == -1 )
{
// we don't know; 10meg shouldn't be a problem hopefully
memAvail = 10000000;
}
else
{
// limit ourselves to half of available RAM to have a margin for other
// apps, for our rendering code, and for miscalculations
memAvail /= 2;
}
const float perPixel = float(printerDepth)/8 + (3 + 4);
const long perLine = long(width * perPixel);
const long maxstep = (memAvail / perLine).GetValue();
const long step = wxMin(height, maxstep);
wxLogTrace(_T("printing"),
_T("using %liMB of RAM (%li lines) for preview, %li %lipx fragments"),
long((memAvail >> 20).GetValue()),
maxstep,
(height+step-1) / step,
step);
return step;
}
} // anonymous namespace
static bool RenderPageFragment(wxPrintPreviewBase *preview,
RenderPageIntoDCFunc RenderPageIntoDC,
float scaleX, float scaleY,
int *nextFinalLine,
wxPrinterDC& printer,
wxMemoryDC& finalDC,
const wxRect& rect,
int pageNum)
{
// compute 'rect' equivalent in the small final bitmap:
const wxRect smallRect(wxPoint(0, *nextFinalLine),
wxPoint(int(rect.GetRight() * scaleX),
int(rect.GetBottom() * scaleY)));
wxLogTrace(_T("printing"),
_T("rendering fragment of page %i: [%i,%i,%i,%i] scaled down to [%i,%i,%i,%i]"),
pageNum,
rect.x, rect.y, rect.GetRight(), rect.GetBottom(),
smallRect.x, smallRect.y, smallRect.GetRight(), smallRect.GetBottom()
);
// create DC and bitmap compatible with printer DC:
wxBitmap large(rect.width, rect.height, printer);
if ( !large.IsOk() )
return false;
// render part of the page into it:
{
PageFragmentDC memoryDC(&printer, large, rect);
if ( !memoryDC.IsOk() )
return false;
memoryDC.Clear();
if ( !(preview->*RenderPageIntoDC)(memoryDC, pageNum) )
return false;
} // release bitmap from memoryDC
// now scale the rendered part down and blit it into final output:
wxImage img;
{
wxDIB dib(large);
if ( !dib.IsOk() )
return false;
large = wxNullBitmap; // free memory a.s.a.p.
img = dib.ConvertToImage();
} // free the DIB now that it's no longer needed, too
if ( !img.IsOk() )
return false;
img.Rescale(smallRect.width, smallRect.height, wxIMAGE_QUALITY_HIGH);
if ( !img.IsOk() )
return false;
wxBitmap bmp(img);
if ( !bmp.IsOk() )
return false;
img = wxNullImage;
finalDC.DrawBitmap(bmp, smallRect.x, smallRect.y);
if ( bmp.IsOk() )
{
*nextFinalLine += smallRect.height;
return true;
}
return false;
}
static bool RenderPageIntoBitmapHQ(wxPrintPreviewBase *preview,
RenderPageIntoDCFunc RenderPageIntoDC,
wxPrinterDC& printerDC,
wxBitmap& bmp, int pageNum,
int pageWidth, int pageHeight)
{
wxLogTrace(_T("printing"), _T("rendering HQ preview of page %i"), pageNum);
if ( !printerDC.IsOk() )
return false;
// compute scale factor
const float scaleX = float(bmp.GetWidth()) / float(pageWidth);
const float scaleY = float(bmp.GetHeight()) / float(pageHeight);
wxMemoryDC bmpDC;
bmpDC.SelectObject(bmp);
bmpDC.Clear();
const int initialStep = ComputeFragmentSize(printerDC.GetDepth(),
pageWidth, pageHeight);
wxRect todo(0, 0, pageWidth, initialStep); // rect to render
int nextFinalLine = 0; // first not-yet-rendered output line
while ( todo.y < pageHeight )
{
todo.SetBottom(wxMin(todo.GetBottom(), pageHeight - 1));
if ( !RenderPageFragment(preview, RenderPageIntoDC,
scaleX, scaleY,
&nextFinalLine,
printerDC,
bmpDC,
todo,
pageNum) )
{
if ( todo.height < 20 )
{
// something is very wrong if we can't render even at this
// slow space, let's bail out and fall back to low quality
// preview
wxLogTrace(_T("printing"),
_T("it seems that HQ preview doesn't work at all"));
return false;
}
// it's possible our memory calculation was off, or conditions
// changed, or there's not enough _bitmap_ resources; try if using
// smaller bitmap would help:
todo.height /= 2;
wxLogTrace(_T("printing"),
_T("preview of fragment failed, reducing height to %ipx"),
todo.height);
continue; // retry at the same position again
}
// move to the next segment
todo.Offset(0, todo.height);
}
return true;
}
#endif // wxUSE_HIGH_QUALITY_PREVIEW_IN_WXMSW
#endif // wxUSE_PRINTING_ARCHITECTURE