在winforms中高亮显示换行文本

Question

我正在尝试突出显示给定范围内的换行文本。我可以实现预期的行为。如果搜索文本是单行，并且搜索文本以两行（换行）呈现，如下所示，我将面临问题，

我使用了字符范围和MeasureCharacterRanges方法来查找文本区域的区域，并排除了与给定搜索文本不匹配的文本区域，但我找不到没有文本的空白区域的区域渲染后，空白区域也会与给定的搜索文本一起突出显示。

StringFormat stringFormat = new StringFormat(StringFormat.GenericDefault);
Font font = new Font("Segoe UI", 9F, FontStyle.Regular);

var searchText = string.IsNullOrEmpty(SearchText) ? string.Empty : SearchText;
int matchIndex = Text.IndexOf(searchText);
if (matchIndex != -1 && searchText.Length > 0)
{
    CharacterRange[] characterRange = new CharacterRange[]
    {
            new CharacterRange(0, matchIndex),
            new CharacterRange(matchIndex, searchText.Length),
            new CharacterRange(matchIndex + searchText.Length , Text.Length - matchIndex - searchText.Length),
    };


    //Set the range of characters to be measured.
    stringFormat.SetMeasurableCharacterRanges(characterRange);

    //Gets the regions of the measurable characters applied to the string format for the given text with in the text bounds.
    Region[] regions = e.Graphics.MeasureCharacterRanges(Text, font, e.ClipRectangle, stringFormat);

    var clipBounds = e.Graphics.ClipBounds;

    for (int i = 0; i < regions.Length; i++)
    {
        RectangleF bound = regions[i].GetBounds(e.Graphics);
        e.Graphics.SetClip(Rectangle.Ceiling(bound));
        for (int j = 0; j < regions.Length; j++)
        {
            if (j != i)
                e.Graphics.ExcludeClip(regions[j]);
        }

        Rectangle rbound = new Rectangle((int)bound.X, (int)bound.Y, (int)bound.Width, (int)bound.Height);
        Brush brush = new SolidBrush(Color.Yellow);
        if (i == 1)
            e.Graphics.FillRectangle(brush, rbound);
     }

    e.Graphics.SetClip(clipBounds);
}


// Paints the text.
e.Graphics.DrawString(Text, font, Brushes.Black, e.ClipRectangle);

上面是用于突出显示搜索文本的代码。

我找不到用 MeasureCharacterRanges 概念排除空白区域的方法。 任何人都可以分享排除剩余空白区域的想法吗？

Answer 1

此代码将帮助您

        if (SelectionLength > 0 && Focused)
        {

            // Get the starting index and length of the selection
            int selectionStartIndex = SelectionStart;
            int selectionEndIndex = selectionStartIndex + SelectionLength; // Calculate the end index of the selection
            int selectedTextLength = this.SelectionLength;
            int OneCharSize = (int)TextRenderer.MeasureText("..", Font).Width;
            //  int OneCharSize = (int)TextRenderer.MeasureText("..", new Font("Tahoma", Font.Size)).Width;

            // Loop through each selected character to draw the background
            for (int i = selectionStartIndex; i < selectionEndIndex; i++)
            {
                // Check if the current character is a newline character
                if (Text[i] == '\n' || Text[i] == '\r')
                {
                    continue; // Skip drawing for newline characters
                }


                // Get the position of the character at the current index
                Point charPosition = GetPositionFromCharIndex(i);

                // Get the size of the character at the current index
                Size charSize = TextRenderer.MeasureText(Text[i].ToString(), Font);


                // Create a rectangle using the position and size of the character
                Rectangle charRect = new Rectangle(charPosition.X, charPosition.Y, charSize.Width - OneCharSize / 2, charSize.Height);


                // Draw the selection background for the current character
                //using (SolidBrush selectionBrush = new SolidBrush(Color.FromArgb(100, SystemColors.Highlight)))
                using (SolidBrush selectionBrush = new SolidBrush(highlightColor))

                {
                    e.Graphics.FillRectangle(selectionBrush, charRect);
                   
                }
            }


        }