获取TextView(Android)上给定偏移的绝对位置

Question

我有一个TextView,我想在TextView的给定单词上放置一个纯色块,例如:

"这是一个文本字符串,我想在这个WORD上放一个矩形" - 所以,"WORD"会有一个纯色的矩形.

为此,我正在考虑重写onDraw(Canvas canvas)方法,以便在文本上绘制一个块.我唯一的问题是找到一种有效的方法来获得给定单词或字符的绝对位置.

基本上,我正在寻找与getOffsetForPosition(float x,float y)方法完全相反的东西

Answer 1

基于这篇文章:如何在TextView中获取ClickableSpan的坐标？,我设法使用此代码,以便在文本的顶部放置一个矩形:

protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Paint paint = new Paint();
    paint.setStyle(Paint.Style.FILL);
    paint.setColor(Color.WHITE);

    // Initialize global value
    TextView parentTextView = this;
    Rect parentTextViewRect = new Rect();

    // Find where the WORD is
    String targetWord = "WORD";
    int startOffsetOfClickedText = this.getText().toString().indexOf(targetWord);
    int endOffsetOfClickedText = startOffsetOfClickedText + targetWord.length();

    // Initialize values for the computing of clickedText position
    Layout textViewLayout = parentTextView.getLayout();

    double startXCoordinatesOfClickedText = textViewLayout.getPrimaryHorizontal((int)startOffsetOfClickedText);
    double endXCoordinatesOfClickedText = textViewLayout.getPrimaryHorizontal((int)endOffsetOfClickedText);

    // Get the rectangle of the clicked text
    int currentLineStartOffset = textViewLayout.getLineForOffset((int)startOffsetOfClickedText);
    int currentLineEndOffset = textViewLayout.getLineForOffset((int)endOffsetOfClickedText);
    boolean keywordIsInMultiLine = currentLineStartOffset != currentLineEndOffset;
    textViewLayout.getLineBounds(currentLineStartOffset, parentTextViewRect);

    // Update the rectangle position to his real position on screen
    int[] parentTextViewLocation = {0,0};
    parentTextView.getLocationOnScreen(parentTextViewLocation);

    double parentTextViewTopAndBottomOffset = (
        //parentTextViewLocation[1] - 
        parentTextView.getScrollY() + 
        parentTextView.getCompoundPaddingTop()
    );

    parentTextViewRect.top += parentTextViewTopAndBottomOffset;
    parentTextViewRect.bottom += parentTextViewTopAndBottomOffset;

    // In the case of multi line text, we have to choose what rectangle take
    if (keywordIsInMultiLine){

        WindowManager wm = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();

        int screenHeight = display.getHeight();
        int dyTop = parentTextViewRect.top;
        int dyBottom = screenHeight - parentTextViewRect.bottom;
        boolean onTop = dyTop > dyBottom;

        if (onTop){
            endXCoordinatesOfClickedText = textViewLayout.getLineRight(currentLineStartOffset);
        }
        else{
            parentTextViewRect = new Rect();
            textViewLayout.getLineBounds(currentLineEndOffset, parentTextViewRect);
            parentTextViewRect.top += parentTextViewTopAndBottomOffset;
            parentTextViewRect.bottom += parentTextViewTopAndBottomOffset;
            startXCoordinatesOfClickedText = textViewLayout.getLineLeft(currentLineEndOffset);
        }

    }

    parentTextViewRect.left += (
        parentTextViewLocation[0] +
        startXCoordinatesOfClickedText + 
        parentTextView.getCompoundPaddingLeft() - 
        parentTextView.getScrollX()
    );
    parentTextViewRect.right = (int) (
        parentTextViewRect.left + 
        endXCoordinatesOfClickedText - 
        startXCoordinatesOfClickedText
    );

    canvas.drawRect(parentTextViewRect, paint);
 }

Answer 2

您可以为此使用跨度。首先，为文本创建一个跨度，如下所示：

Spannable span = new SpannableString(text);

然后，在要突出显示的单词周围放置一个跨度，有点像这样：

span.setSpan(new UnderlineSpan(), start, end, 
                     Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

不幸的是，我不知道现有的跨度可以为单词添加边框。我找到了 UnderlineSpan 和BackgroundColorSpan，也许这些对你也有用，或者你可以看一下代码，看看是否可以基于其中之一创建一个 BorderSpan 。