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Bug 173051. Do transforms consistently. r+sr=dbaron

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roc+%cs.cmu.edu 2005-03-28 21:03:01 +00:00
parent 34a19db7c3
commit 7718916c29
1 changed files with 8 additions and 87 deletions
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95
gfx/src/nsTransform2D.cpp
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@ -432,14 +432,8 @@ void nsTransform2D :: TransformCoord(nscoord *ptX, nscoord *ptY)
break;
case MG_2DSCALE | MG_2DTRANSLATION:
// You can not use a translation that is not rounded to calculate a
// final destination and get consistent results. The translation is rounded
// separately only for the final coordinate location. Its ok
// to keep the tranlation in floating for the matrix.. just don't use it
// pre-rounded for coordinate locations. Its not valid to translate 1.333 pixels for example
// on output since .33 pixel is not a valid output unit and can cause inconsistencies. (dcone)
*ptX = NSToCoordRound(*ptX * m00) + NSToCoordRound(m20);
*ptY = NSToCoordRound(*ptY * m11) + NSToCoordRound(m21);
*ptX = NSToCoordRound(*ptX * m00 + m20);
*ptY = NSToCoordRound(*ptY * m11 + m21);
break;
default:
@ -517,85 +511,12 @@ void nsTransform2D :: Transform(float *aX, float *aY, float *aWidth, float *aHei
void nsTransform2D :: TransformCoord(nscoord *aX, nscoord *aY, nscoord *aWidth, nscoord *aHeight)
{
float x, y;
float ex,ey;
switch (type)
{
case MG_2DIDENTITY:
break;
case MG_2DTRANSLATION:
*aX += NSToCoordRound(m20);
*aY += NSToCoordRound(m21);
break;
case MG_2DSCALE:
*aX = NSToCoordRound(*aX * m00);
*aY = NSToCoordRound(*aY * m11);
*aWidth = NSToCoordRound(*aWidth * m00);
*aHeight = NSToCoordRound(*aHeight * m11);
break;
case MG_2DGENERAL:
x = (float)*aX;
y = (float)*aY;
*aX = NSToCoordRound(x * m00 + y * m10);
*aY = NSToCoordRound(x * m01 + y * m11);
x = (float)*aWidth;
y = (float)*aHeight;
*aWidth = NSToCoordRound(x * m00 + y * m10);
*aHeight = NSToCoordRound(x * m01 + y * m11);
break;
case MG_2DSCALE | MG_2DTRANSLATION:
// first transform the X and Y locations
x = *aX * m00 + NSToCoordRound(m20);
y = *aY * m11 + NSToCoordRound(m21);
*aX = NSToCoordRound(x);
*aY = NSToCoordRound(y);
// the starting locations have a direct effect on the width and height if and only if
// the width and height are used to calculate positions relative to these locations.
// The layout engine does count on the width and height to be so many units away, so an
// error can be introduced if you round and then add a rounded width. To compensate, this error
// should be added to the width or height before rounding. If the width or height is used as a
// measurment, or distance, then use the direct floating point number. This width and height
// has an error adjustment for the starting locations inorder to calculate the ending positions.
// The error is the fractional difference between the transformed point and the next pixel
// calculate the error
ex = x - float(NSToCoordRound(x));
ey = y - float(NSToCoordRound(y));
// now you can transform with the error added in
*aWidth = NSToCoordRound(*aWidth * m00 + ex);
*aHeight = NSToCoordRound(*aHeight * m11 + ey);
break;
default:
case MG_2DGENERAL | MG_2DTRANSLATION:
x = (float)*aX;
y = (float)*aY;
x = x * m00 + y * m10 + m20;
y = x * m01 + y * m11 + m21;
ex = x - float(NSToCoordRound(x));
ey = y - float(NSToCoordRound(y));
*aX = NSToCoordRound(x);
*aY = NSToCoordRound(y);
x = (float)*aWidth;
y = (float)*aHeight;
*aWidth = NSToCoordRound((x * m00 + y * m10)+ex);
*aHeight = NSToCoordRound((x * m01 + y * m11)+ey);
break;
}
nscoord x2 = *aX + *aWidth;
nscoord y2 = *aY + *aHeight;
TransformCoord(aX, aY);
TransformCoord(&x2, &y2);
*aWidth = x2 - *aX;
*aHeight = y2 - *aY;
}
void nsTransform2D :: AddTranslation(float ptX, float ptY)