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Fixed transforms on Windows.

This commit is contained in:
Pietro Gagliardi 2015-10-12 12:16:44 -04:00
parent 5f2a8474d9
commit dac5eea07a
1 changed files with 11 additions and 2 deletions
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13
windows/draw.c
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@ -680,10 +680,19 @@ void uiDrawTransform(uiDrawContext *c, uiDrawMatrix *m)
{
D2D1_MATRIX_3X2_F dm;
uiDrawMatrix already;
uiDrawMatrix temp;
ID2D1RenderTarget_GetTransform(c->rt, &dm);
d2m(&dm, &already);
uiDrawMatrixMultiply(&already, m);
m2d(&already, &dm);
temp = *m; // don't modify m
// you would think we have to do already * m, right?
// WRONG! we have to do m * already
// why? a few reasons
// a) this lovely comment in cairo's source - http://cgit.freedesktop.org/cairo/tree/src/cairo-matrix.c?id=0537479bd1d4c5a3bc0f6f41dec4deb98481f34a#n330
// Direct2D uses column vectors and I don't know if this is even documented
// b) that's what Core Graphics does
// TODO see if Microsoft says to do this
uiDrawMatrixMultiply(&temp, &already);
m2d(&temp, &dm);
ID2D1RenderTarget_SetTransform(c->rt, &dm);
}