How to use

vTranslateForSCenter

method

in

com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView

/**
 * Adjusts current scale and translate values to keep scale within the allowed range and the image on screen. Minimum scale
 * is set so one dimension fills the view and the image is centered on the other dimension.
 * @param center Whether the image should be centered in the dimension it's too small to fill. While animating this can be false to avoid changes in direction as bounds are reached.
 */
private void fitToBounds(boolean center) {
  boolean init = false;
  if (vTranslate == null) {
    init = true;
    vTranslate = new PointF(0, 0);
  }
  if (satTemp == null) {
    satTemp = new ScaleAndTranslate(0, new PointF(0, 0));
  }
  satTemp.scale = scale;
  satTemp.vTranslate.set(vTranslate);
  fitToBounds(center, satTemp);
  scale = satTemp.scale;
  vTranslate.set(satTemp.vTranslate);
  if (init && minimumScaleType != SCALE_TYPE_START) {
    vTranslate.set(vTranslateForSCenter(sWidth()/2, sHeight()/2, scale));
  }
}

/**
 * Given a requested source center and scale, calculate what the actual center will have to be to keep the image in
 * pan limits, keeping the requested center as near to the middle of the screen as allowed.
 */
@NonNull
private PointF limitedSCenter(float sCenterX, float sCenterY, float scale, @NonNull PointF sTarget) {
  PointF vTranslate = vTranslateForSCenter(sCenterX, sCenterY, scale);
  int vxCenter = getPaddingLeft() + (getWidth() - getPaddingRight() - getPaddingLeft())/2;
  int vyCenter = getPaddingTop() + (getHeight() - getPaddingBottom() - getPaddingTop())/2;
  float sx = (vxCenter - vTranslate.x)/scale;
  float sy = (vyCenter - vTranslate.y)/scale;
  sTarget.set(sx, sy);
  return sTarget;
}

/**
 * Adjusts current scale and translate values to keep scale within the allowed range and the image on screen. Minimum scale
 * is set so one dimension fills the view and the image is centered on the other dimension.
 * @param center Whether the image should be centered in the dimension it's too small to fill. While animating this can be false to avoid changes in direction as bounds are reached.
 */
private void fitToBounds(boolean center) {
  boolean init = false;
  if (vTranslate == null) {
    init = true;
    vTranslate = new PointF(0, 0);
  }
  if (satTemp == null) {
    satTemp = new ScaleAndTranslate(0, new PointF(0, 0));
  }
  satTemp.scale = scale;
  satTemp.vTranslate.set(vTranslate);
  fitToBounds(center, satTemp);
  scale = satTemp.scale;
  vTranslate.set(satTemp.vTranslate);
  if (init) {
    vTranslate.set(vTranslateForSCenter(sWidth()/2, sHeight()/2, scale));
  }
}

/**
 * Given a requested source center and scale, calculate what the actual center will have to be to keep the image in
 * pan limits, keeping the requested center as near to the middle of the screen as allowed.
 */
private PointF limitedSCenter(float sCenterX, float sCenterY, float scale, PointF sTarget) {
  PointF vTranslate = vTranslateForSCenter(sCenterX, sCenterY, scale);
  int vxCenter = getPaddingLeft() + (getWidth() - getPaddingRight() - getPaddingLeft())/2;
  int vyCenter = getPaddingTop() + (getHeight() - getPaddingBottom() - getPaddingTop())/2;
  float sx = (vxCenter - vTranslate.x)/scale;
  float sy = (vyCenter - vTranslate.y)/scale;
  sTarget.set(sx, sy);
  return sTarget;
}