+ /**
+ * Value that corresponds to being on the bottom edge of the scroll bar.
+ */
+ private int bottomValue = 100;
+
+ /**
+ * Current value of the scroll.
+ */
+ private int value = 0;
+
+ /**
+ * The increment for clicking on an arrow.
+ */
+ private int smallChange = 1;
+
+ /**
+ * The increment for clicking in the bar between the box and an arrow.
+ */
+ private int bigChange = 20;
+
+ /**
+ * When true, the user is dragging the scroll box.
+ */
+ private boolean inScroll = false;
+
+ // ------------------------------------------------------------------------
+ // Constructors -----------------------------------------------------------
+ // ------------------------------------------------------------------------
+
+ /**
+ * Public constructor.
+ *
+ * @param parent parent widget
+ * @param x column relative to parent
+ * @param y row relative to parent
+ * @param height height of scroll bar
+ */
+ public TVScroller(final TWidget parent, final int x, final int y,
+ final int height) {
+
+ // Set parent and window
+ super(parent, x, y, 1, height);
+ }
+
+ // ------------------------------------------------------------------------
+ // Event handlers ---------------------------------------------------------
+ // ------------------------------------------------------------------------
+
+ /**
+ * Handle mouse button releases.
+ *
+ * @param mouse mouse button release event
+ */
+ @Override
+ public void onMouseUp(final TMouseEvent mouse) {
+ if (bottomValue == topValue) {
+ return;
+ }
+
+ if (inScroll) {
+ inScroll = false;
+ return;
+ }
+
+ if ((mouse.getX() == 0)
+ && (mouse.getY() == 0)
+ ) {
+ // Clicked on the top arrow
+ decrement();
+ return;
+ }
+
+ if ((mouse.getX() == 0)
+ && (mouse.getY() == getHeight() - 1)
+ ) {
+ // Clicked on the bottom arrow
+ increment();
+ return;
+ }
+
+ if ((mouse.getX() == 0)
+ && (mouse.getY() > 0)
+ && (mouse.getY() < boxPosition())
+ ) {
+ // Clicked between the top arrow and the box
+ value -= bigChange;
+ if (value < topValue) {
+ value = topValue;
+ }
+ return;
+ }
+
+ if ((mouse.getX() == 0)
+ && (mouse.getY() > boxPosition())
+ && (mouse.getY() < getHeight() - 1)
+ ) {
+ // Clicked between the box and the bottom arrow
+ value += bigChange;
+ if (value > bottomValue) {
+ value = bottomValue;
+ }
+ return;
+ }
+ }
+
+ /**
+ * Handle mouse movement events.
+ *
+ * @param mouse mouse motion event
+ */
+ @Override
+ public void onMouseMotion(final TMouseEvent mouse) {
+ if (bottomValue == topValue) {
+ return;
+ }
+
+ if ((mouse.isMouse1())
+ && (inScroll)
+ && (mouse.getY() > 0)
+ && (mouse.getY() < getHeight() - 1)
+ ) {
+ // Recompute value based on new box position
+ value = (bottomValue - topValue)
+ * (mouse.getY()) / (getHeight() - 3) + topValue;
+ if (value > bottomValue) {
+ value = bottomValue;
+ }
+ if (value < topValue) {
+ value = topValue;
+ }
+ return;
+ }
+
+ inScroll = false;
+ }
+
+ /**
+ * Handle mouse press events.
+ *
+ * @param mouse mouse button press event
+ */
+ @Override
+ public void onMouseDown(final TMouseEvent mouse) {
+ if (bottomValue == topValue) {
+ return;
+ }
+
+ if ((mouse.getX() == 0)
+ && (mouse.getY() == boxPosition())
+ ) {
+ inScroll = true;
+ return;
+ }
+ }
+
+ // ------------------------------------------------------------------------
+ // TWidget ----------------------------------------------------------------
+ // ------------------------------------------------------------------------
+
+ /**
+ * Draw a vertical scroll bar.
+ */
+ @Override
+ public void draw() {
+ CellAttributes arrowColor = getTheme().getColor("tscroller.arrows");
+ CellAttributes barColor = getTheme().getColor("tscroller.bar");
+ getScreen().putCharXY(0, 0, GraphicsChars.CP437[0x1E], arrowColor);
+ getScreen().putCharXY(0, getHeight() - 1, GraphicsChars.CP437[0x1F],
+ arrowColor);
+
+ // Place the box
+ if (bottomValue > topValue) {
+ getScreen().vLineXY(0, 1, getHeight() - 2,
+ GraphicsChars.CP437[0xB1], barColor);
+ getScreen().putCharXY(0, boxPosition(), GraphicsChars.BOX,
+ arrowColor);
+ } else {
+ getScreen().vLineXY(0, 1, getHeight() - 2, GraphicsChars.HATCH,
+ barColor);
+ }
+
+ }
+
+ // ------------------------------------------------------------------------
+ // TVScroller -------------------------------------------------------------
+ // ------------------------------------------------------------------------
+