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Avoid overflows when calculating metafile coordinates in wxMSW.

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Use MulDiv() instead of naive multiplication followed by division as this
could overflow, and did when large paper sizes were used in print preview.

Closes #16138.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76219 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 2014-03-29 16:53:57 +00:00
parent 9a5d02f2c3
commit ddd7ce624a
1 changed files with 5 additions and 8 deletions
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13
src/msw/utilsgui.cpp
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@ -257,10 +257,9 @@ void PixelToHIMETRIC(LONG *x, LONG *y, HDC hdcRef)
iWidthPels = GetDeviceCaps(hdcRef, HORZRES),
iHeightPels = GetDeviceCaps(hdcRef, VERTRES);
*x *= (iWidthMM * 100);
*x /= iWidthPels;
*y *= (iHeightMM * 100);
*y /= iHeightPels;
// Take care to use MulDiv() here to avoid overflow.
*x = ::MulDiv(*x, iWidthMM * 100, iWidthPels);
*y = ::MulDiv(*y, iHeightMM * 100, iHeightPels);
}
void HIMETRICToPixel(LONG *x, LONG *y, HDC hdcRef)
@ -270,10 +269,8 @@ void HIMETRICToPixel(LONG *x, LONG *y, HDC hdcRef)
iWidthPels = GetDeviceCaps(hdcRef, HORZRES),
iHeightPels = GetDeviceCaps(hdcRef, VERTRES);
*x *= iWidthPels;
*x /= (iWidthMM * 100);
*y *= iHeightPels;
*y /= (iHeightMM * 100);
*x = ::MulDiv(*x, iWidthPels, iWidthMM * 100);
*y = ::MulDiv(*y, iHeightPels, iHeightMM * 100);
}
void HIMETRICToPixel(LONG *x, LONG *y)