Webview文本选择不清除

Question

我已经实现了一个ActionMode.Callback自定义文本选择功能WebView.我遇到的问题是选择和操作模式状态不匹配.

当我长按时,一切都很好.

当我与其中一个按钮或WebView(不包括实际选择)进行交互时,ActionMode应该销毁它,并且选择应该消失.

在Android 4.4,KitKat中,这正是发生的事情.

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然而,这不是4.1.1 - 4.3,Jelly Bean中发生的情况.单击其中一个按钮时,不会删除选择.

当我在选择之外点击时,恰好相反.删除选择,但上下文操作栏仍保留在屏幕上.

正如上面的评论所示,我认为问题在于clearFocus()方法.当我删除该方法时,按下一个按钮会使选择落后于4.4,就像Jelly Bean中的行为一样.clearFocus()给出4.4中的预期行为,但不转移到早期的API.(请注意,这clearFocus()对KitKat来说并不陌生;自API 1以来一直在Android中.)

怎么解决这个问题？

Answer 1

经过多次尝试解决这个问题,我终于明白了!

重要的是要知道WebViewAndroid 4.4(KitKat)之前的s与典型的浏览器不同.有一些隐藏的类可以开始搞乱事情.有WebViewCore所有繁重的工作,实际上产生了结果WebViewClassic,这就是这个问题的罪魁祸首.

解决方案是半破解,因为您实际上不需要做任何操作来操作底层类,但您必须抓住问题场景.

WebViewClassic负责拦截长按并处理它们以进行文本选择,包括选择突出显示和选择控制柄的动画,以及启动ActionMode填充上下文操作栏(CAB).不幸的是,由于我们希望ActionMode用我们自己的方式覆盖它,因此文本选择和CAB变得不同步,因为它们彼此不相关.为了解决这个问题,随时跟踪自己的自定义的ActionMode.Callback,以及在ActionMode.Callback与选择动画制作相关的.然后,当你ActionMode.Callback被摧毁时,调用选择的finish()方法来销毁它ActionMode.Callback.

好的,说得够多; 这是代码.

public class CustomWebView extends WebView {

    private ActionMode mActionMode;
    private ActionMode.Callback mActionModeCallback;
    // Add this class variable
    private ActionMode.Callback mSelectActionModeCallback;

    @Override
    public ActionMode startActionMode(Callback callback) {
        /* When running Ice Cream Sandwich (4.0) or Jelly Bean (4.1 - 4.3), there
         * is a hidden class called 'WebViewClassic' that draws the selection.
         * In order to clear the selection, save the callback from Classic
         * so it can be destroyed later.
         */
        // Check the class name because WebViewClassic.SelectActionModeCallback
        // is not public API.
        String name = callback.getClass().toString();
        if (name.contains("SelectActionModeCallback")) {
            mSelectActionModeCallback = callback;
        }
        mActionModeCallback = new CustomActionModeCallback();
        // We haven't actually done anything yet. Send our custom callback 
        // to the superclass so it will be shown on screen.
        return super.startActionModeForChild(this, mActionModeCallback);
    }

    private class CustomActionModeCallback implements ActionMode.Callback {

        // Called when the action mode is created; startActionMode() was called
        @Override
        public boolean onCreateActionMode(ActionMode mode, Menu menu) {
            // This is important for part 2.
            mActionMode = mode;
            // Inflate a menu resource providing context menu items
            MenuInflater inflater = mode.getMenuInflater();
            inflater.inflate(R.menu.contextual_menu, menu);
            return true;
        }

        // Called each time the action mode is shown.
        // Always called after onCreateActionMode, but
        // may be called multiple times if the mode is invalidated.
        @Override
        public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
            // This method is called when the handlebars are moved.
            loadJavascript("javascript:getSelectedTextInfo()");
            return false; // Return false if nothing is done
        }

        // Called when the user selects a contextual menu item
        @Override
        public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
            switch(item.getItemId() {
            case R.id.button_1:
                // do stuff
                break;
            ...
            default:
                break;
            }

            mode.finish(); // Action picked, so close the CAB
            return true;
        }

        // Called when the user exits the action mode
        @Override
        public void onDestroyActionMode(ActionMode mode) {
            clearFocus(); // Remove the selection highlight and handles.

            // Semi-hack in order to clear the selection
            // when running Android earlier than KitKat.
            if (mSelectActionModeCallback != null) {
                mSelectActionModeCallback.onDestroyActionMode(mode);
            }
            // Relevant to part 2.
            mActionMode = null;
        }
    }
}

信不信由你,我们只完成了一半.上面的代码负责在CAB关闭时删除选择.要在触摸事件中关闭CAB,我们必须做更多的工作.这一次,它更加直截了当.我用a GestureDetector并听一个单击事件.当我得到那个事件,我呼吁finish()对mActionMode关闭CAB:

public class CustomWebView extends WebView {

    private ActionMode mActionMode; 
    private ActionMode.Callback mActionModeCallback;
    private ActionMode.Callback mSelectActionModeCallback;

    // Code from above segment
    ...

    private class CustomGestureListener extends GestureDetector.SimpleOnGestureListener {
        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            if (mActionMode != null) {
                mActionMode.finish();
                return true;
            }
            return false;
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // Send the event to our gesture detector
        // If it is implemented, there will be a return value
        this.mDetector.onTouchEvent(event);
        // If the detected gesture is unimplemented, send it to the superclass
        return super.onTouchEvent(event);
    }

}

这应该做到!我们做到了!

你不会WebViewClassic在其他任何地方找到这些材料; 这就是为什么我提供了很多关于发生了什么的细节.调试器花了很多时间来弄清楚发生了什么.幸运的是,GestureDetector该类已有详细记录,并包含多个教程.我从Android开发者网站上获取了我的信息.我希望这能帮助那些像我一样努力解决这个问题的人.:)