public void StartPinchToZoom(float x0, float y0, float x1, float y1)
{
// update previous distance
previousDist = LineUtil.Distance(x0, y0, x1, y1);
if (previousDist > minPinchToZoomDistance)
{
savedMatrix.Set(matrix);
LineUtil.Middle(ref middle, x0, y0, x1, y1);
}
}
public void PinchToZoom(float x0, float y0, float x1, float y1)
{
float currentDist = LineUtil.Distance(x0, y0, x1, y1);
if (currentDist > minPinchToZoomDistance)
{
float scale = currentDist / previousDist;
matrix.Set(savedMatrix);
matrix.PostScale(scale, scale, middle.X, middle.Y);
matrix.GetValues(matrixValues);
zoom = matrixValues[Matrix.MscaleX];
translate.Set(matrixValues[Matrix.MtransX], matrixValues[Matrix.MtransY]);
}
}