/// <summary>
/// Scrolls the specified widget to the specified coordinates, except
/// constrains the X scrolling position to the horizontal regions of
/// the text that will be visible after scrolling to the specified
/// Y position.
/// </summary>
/// <remarks>
/// Scrolls the specified widget to the specified coordinates, except
/// constrains the X scrolling position to the horizontal regions of
/// the text that will be visible after scrolling to the specified
/// Y position.
/// </remarks>
public static void scrollTo(android.widget.TextView widget, android.text.Layout layout
, int x, int y)
{
int verticalPadding = widget.getTotalPaddingTop() + widget.getTotalPaddingBottom(
);
int top = layout.getLineForVertical(y);
int bottom = layout.getLineForVertical(y + widget.getHeight() - verticalPadding);
int left = int.MaxValue;
int right = 0;
android.text.Layout.Alignment?a = layout.getParagraphAlignment(top);
bool ltr = layout.getParagraphDirection(top) > 0;
{
for (int i = top; i <= bottom; i++)
{
left = (int)System.Math.Min(left, layout.getLineLeft(i));
right = (int)System.Math.Max(right, layout.getLineRight(i));
}
}
int hoizontalPadding = widget.getTotalPaddingLeft() + widget.getTotalPaddingRight
();
int availableWidth = widget.getWidth() - hoizontalPadding;
int actualWidth = right - left;
if (actualWidth < availableWidth)
{
if (a == android.text.Layout.Alignment.ALIGN_CENTER)
{
x = left - ((availableWidth - actualWidth) / 2);
}
else
{
if ((ltr && (a == android.text.Layout.Alignment.ALIGN_OPPOSITE)) || (a == android.text.Layout.Alignment
.ALIGN_RIGHT))
{
// align_opposite does NOT mean align_right, we need the paragraph
// direction to resolve it to left or right
x = left - (availableWidth - actualWidth);
}
else
{
x = left;
}
}
}
else
{
x = System.Math.Min(x, right - availableWidth);
x = System.Math.Max(x, left);
}
widget.scrollTo(x, y);
}
/// <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 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 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;
}