如何计算索引在文本框的查看区域中垂直居中的 VerticalOffset? [英] How can I calculate the VerticalOffset at which an index would be vertically centered in the viewing area of a textbox?

问题描述

我正在为我正在构建的文本编辑器添加查找和替换功能，我希望能够滚动文本框，以便所选匹配项在屏幕上垂直居中.

I am working on adding find and replace functionality to a text editor that I am building and I would like to be able to scroll the textbox so that the selected match is vertically centered on the screen.

推荐答案

您可以使用 GetRectFromCharacterIndex 将字符索引转换为屏幕上的矩形.这将考虑滚动，因此您需要添加当前的 VerticalOffset:

You can use GetRectFromCharacterIndex to convert from a character index to a rectangle on the screen. This will account for scrolling, so you'll need to add the current VerticalOffset:

var start = textBox.GetRectFromCharacterIndex(textBox.SelectionStart);
var end = textBox.GetRectFromCharacterIndex(textBox.SelectionStart + textBox.SelectionLength);
textBox.ScrollToVerticalOffset((start.Top + end.Bottom - textBox.ViewportHeight) / 2 + textBox.VerticalOffset);

如果您有 RichTextBox，则可以使用 TextPointer.GetCharacterRect:

If you have a RichTextBox, you would use TextPointer.GetCharacterRect:

var start = textBox.Selection.Start.GetCharacterRect(LogicalDirection.Forward);
var end = textBox.Selection.End.GetCharacterRect(LogicalDirection.Forward);
textBox.ScrollToVerticalOffset((start.Top + end.Bottom - textBox.ViewportHeight) / 2 + textBox.VerticalOffset);

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