/// <summary>Performs a scroll to top action.</summary>
/// <remarks>
/// Performs a scroll to top action.
/// Scrolls to the top of the document.
/// </remarks>
/// <param name="widget">The text view.</param>
/// <param name="buffer">The text buffer.</param>
/// <returns>True if the event was handled.</returns>
/// <hide></hide>
protected internal virtual bool scrollTop(android.widget.TextView widget, android.text.Spannable
buffer)
{
android.text.Layout layout = widget.getLayout();
if (getTopLine(widget) >= 0)
{
android.text.method.Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop
(0));
return true;
}
return false;
}
/// <summary>Performs a scroll up action.</summary>
/// <remarks>
/// Performs a scroll up action.
/// Scrolls up by the specified number of lines.
/// </remarks>
/// <param name="widget">The text view.</param>
/// <param name="buffer">The text buffer.</param>
/// <param name="amount">The number of lines to scroll by. Must be at least 1.</param>
/// <returns>True if the event was handled.</returns>
/// <hide></hide>
protected internal virtual bool scrollUp(android.widget.TextView widget, android.text.Spannable
buffer, int amount)
{
android.text.Layout layout = widget.getLayout();
int top_1 = widget.getScrollY();
int topLine = layout.getLineForVertical(top_1);
if (layout.getLineTop(topLine) == top_1)
{
// If the top line is partially visible, bring it all the way
// into view; otherwise, bring the previous line into view.
topLine -= 1;
}
if (topLine >= 0)
{
topLine = System.Math.Max(topLine - amount + 1, 0);
android.text.method.Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop
(topLine));
return true;
}
return false;
}
/// <summary>Performs a scroll to bottom action.</summary>
/// <remarks>
/// Performs a scroll to bottom action.
/// Scrolls to the bottom of the document.
/// </remarks>
/// <param name="widget">The text view.</param>
/// <param name="buffer">The text buffer.</param>
/// <returns>True if the event was handled.</returns>
/// <hide></hide>
protected internal virtual bool scrollBottom(android.widget.TextView widget, android.text.Spannable
buffer)
{
android.text.Layout layout = widget.getLayout();
int lineCount = layout.getLineCount();
if (getBottomLine(widget) <= lineCount - 1)
{
android.text.method.Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop
(lineCount) - getInnerHeight(widget));
return true;
}
return false;
}
private void scroll()
{
Layout layout = deviceMessagesTextView.Layout;
if (layout != null)
{
int y = layout.getLineTop(deviceMessagesTextView.LineCount) - deviceMessagesTextView.Height;
if (y > 0)
{
deviceMessagesTextView.scrollTo(0, y);
deviceMessagesTextView.invalidate();
}
}
}
/// <summary>Performs a scroll page up action.</summary>
/// <remarks>
/// Performs a scroll page up action.
/// Scrolls up by one page.
/// </remarks>
/// <param name="widget">The text view.</param>
/// <param name="buffer">The text buffer.</param>
/// <returns>True if the event was handled.</returns>
/// <hide></hide>
protected internal virtual bool scrollPageUp(android.widget.TextView widget, android.text.Spannable
buffer)
{
android.text.Layout layout = widget.getLayout();
int top_1 = widget.getScrollY() - getInnerHeight(widget);
int topLine = layout.getLineForVertical(top_1);
if (topLine >= 0)
{
android.text.method.Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop
(topLine));
return true;
}
return false;
}
/// <summary>Performs a scroll page up action.</summary>
/// <remarks>
/// Performs a scroll page up action.
/// Scrolls down by one page.
/// </remarks>
/// <param name="widget">The text view.</param>
/// <param name="buffer">The text buffer.</param>
/// <returns>True if the event was handled.</returns>
/// <hide></hide>
protected internal virtual bool scrollPageDown(android.widget.TextView widget, android.text.Spannable
buffer)
{
android.text.Layout layout = widget.getLayout();
int innerHeight = getInnerHeight(widget);
int bottom_1 = widget.getScrollY() + innerHeight + innerHeight;
int bottomLine = layout.getLineForVertical(bottom_1);
if (bottomLine <= layout.getLineCount() - 1)
{
android.text.method.Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop
(bottomLine + 1) - innerHeight);
return true;
}
return false;
}
/// <summary>Performs a scroll down action.</summary>
/// <remarks>
/// Performs a scroll down action.
/// Scrolls down by the specified number of lines.
/// </remarks>
/// <param name="widget">The text view.</param>
/// <param name="buffer">The text buffer.</param>
/// <param name="amount">The number of lines to scroll by. Must be at least 1.</param>
/// <returns>True if the event was handled.</returns>
/// <hide></hide>
protected internal virtual bool scrollDown(android.widget.TextView widget, android.text.Spannable
buffer, int amount)
{
android.text.Layout layout = widget.getLayout();
int innerHeight = getInnerHeight(widget);
int bottom_1 = widget.getScrollY() + innerHeight;
int bottomLine = layout.getLineForVertical(bottom_1);
if (layout.getLineTop(bottomLine + 1) < bottom_1 + 1)
{
// Less than a pixel of this line is out of view,
// so we must have tried to make it entirely in view
// and now want the next line to be in view instead.
bottomLine += 1;
}
int limit = layout.getLineCount() - 1;
if (bottomLine <= limit)
{
bottomLine = System.Math.Min(bottomLine + amount - 1, limit);
android.text.method.Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop
(bottomLine + 1) - innerHeight);
return true;
}
return false;
}
private static int getCurrentLineTop(android.text.Spannable buffer, android.text.Layout
layout)
{
return(layout.getLineTop(layout.getLineForOffset(android.text.Selection.getSelectionEnd
(buffer))));
}