按下时更改单个 ClickableSpan 的文本颜色，而不影响同一 TextView 中的其他 ClickableSpan [英] Change the text color of a single ClickableSpan when pressed without affecting other ClickableSpans in the same TextView

问题描述

我有一个 TextView，里面有多个 ClickableSpan.当按下 ClickableSpan 时，我希望它改变其文本的颜色.

I have a TextView with multiple ClickableSpans in it. When a ClickableSpan is pressed, I want it to change the color of its text.

我尝试将颜色状态列表设置为 TextView 的 textColorLink 属性.这不会产生预期的结果，因为当用户在 TextView 上单击 anywhere 时，这会导致 所有跨度改变颜色.

I have tried setting a color state list as the textColorLink attribute of the TextView. This does not yield the desired result because this causes all the spans to change color when the user clicks anywhere on the TextView.

有趣的是，使用 textColorHighlight 更改背景颜色可以按预期工作:单击 span 只会更改该 span 的背景颜色，而单击 TextView 中的其他任何地方都不会执行任何操作.

Interestingly, using textColorHighlight to change the background color works as expected: Clicking on a span changes only the background color of that span and clicking anywhere else in the TextView does nothing.

我还尝试将 ForegroundColorSpans 设置为与 ClickableSpans 相同的边界，在其中我传递与上面相同的颜色状态列表作为颜色资源.这也不起作用.span 始终保持颜色状态列表中默认状态的颜色，永远不会进入按下状态.

I have also tried setting ForegroundColorSpans with the same boundaries as the ClickableSpans where I pass the same color state list as above as the color resource. This doesn't work either. The spans always keep the color of the default state in the color state list and never enter the pressed state.

有人知道怎么做吗?

这是我使用的颜色状态列表:

This is the color state list I used:

<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:state_pressed="true" android:color="@color/pressed_color"/>
  <item android:color="@color/normal_color"/>
</selector>

推荐答案

我终于找到了一个可以满足我所有需求的解决方案.它基于this answer.

I finally found a solution that does everything I wanted. It is based on this answer.

这是我修改后的 LinkMovementMethod，它在触摸事件 (MotionEvent.ACTION_DOWN) 开始时将跨度标记为按下，并在触摸结束或触摸位置移出跨度时取消标记.

This is my modified LinkMovementMethod that marks a span as pressed on the start of a touch event (MotionEvent.ACTION_DOWN) and unmarks it when the touch ends or when the touch location moves out of the span.

public class LinkTouchMovementMethod extends LinkMovementMethod {
    private TouchableSpan mPressedSpan;

    @Override
    public boolean onTouchEvent(TextView textView, Spannable spannable, MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            mPressedSpan = getPressedSpan(textView, spannable, event);
            if (mPressedSpan != null) {
                mPressedSpan.setPressed(true);
                Selection.setSelection(spannable, spannable.getSpanStart(mPressedSpan),
                        spannable.getSpanEnd(mPressedSpan));
            }
        } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
            TouchableSpan touchedSpan = getPressedSpan(textView, spannable, event);
            if (mPressedSpan != null && touchedSpan != mPressedSpan) {
                mPressedSpan.setPressed(false);
                mPressedSpan = null;
                Selection.removeSelection(spannable);
            }
        } else {
            if (mPressedSpan != null) {
                mPressedSpan.setPressed(false);
                super.onTouchEvent(textView, spannable, event);
            }
            mPressedSpan = null;
            Selection.removeSelection(spannable);
        }
        return true;
    }

    private TouchableSpan getPressedSpan(
            TextView textView,
            Spannable spannable,
            MotionEvent event) {

            int x = (int) event.getX() - textView.getTotalPaddingLeft() + textView.getScrollX();
            int y = (int) event.getY() - textView.getTotalPaddingTop() + textView.getScrollY();

            Layout layout = textView.getLayout();
            int position = layout.getOffsetForHorizontal(layout.getLineForVertical(y), x);

            TouchableSpan[] link = spannable.getSpans(position, position, TouchableSpan.class);
            TouchableSpan touchedSpan = null;
            if (link.length > 0 && positionWithinTag(position, spannable, link[0])) {
                touchedSpan = link[0];
            }

            return touchedSpan;
        }

        private boolean positionWithinTag(int position, Spannable spannable, Object tag) {
            return position >= spannable.getSpanStart(tag) && position <= spannable.getSpanEnd(tag);
        }
    }

这需要像这样应用于 TextView:

This needs to be applied to the TextView like so:

    yourTextView.setMovementMethod(new LinkTouchMovementMethod());

这是修改后的 ClickableSpan，它根据 LinkTouchMovementMethod 设置的按下状态编辑绘制状态:(它还删除了链接中的下划线)

And this is the modified ClickableSpan that edits the draw state based on the pressed state set by the LinkTouchMovementMethod: (it also removes the underline from the links)

public abstract class TouchableSpan extends ClickableSpan {
    private boolean mIsPressed;
    private int mPressedBackgroundColor;
    private int mNormalTextColor;
    private int mPressedTextColor;

    public TouchableSpan(int normalTextColor, int pressedTextColor, int pressedBackgroundColor) {
        mNormalTextColor = normalTextColor;
        mPressedTextColor = pressedTextColor;
        mPressedBackgroundColor = pressedBackgroundColor;
    }

    public void setPressed(boolean isSelected) {
        mIsPressed = isSelected;
    }

    @Override
    public void updateDrawState(TextPaint ds) {
        super.updateDrawState(ds);
        ds.setColor(mIsPressed ? mPressedTextColor : mNormalTextColor);
        ds.bgColor = mIsPressed ? mPressedBackgroundColor : 0xffeeeeee;
        ds.setUnderlineText(false);
    }
}

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