自定义View selector无效

一个自定义的View 继承自 RelativeLayout

重写了 onTouchEvent()后 使用 selector 无效

selector很简单，放在普通view上是正常的：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true" android:drawable="@mipmap/ibtn_guide_bg_pressed"/>
    <item android:state_pressed="false" android:drawable="@mipmap/ibtn_guide_bg" />
</selector>

自定义view在使用时加上了 android:clickable="true" 

代码里也设置了 setOnClickListener()

最后发现问题出在 onTouchEvent() 的返回值上

为了实现我要的功能，这里我返回的是 true

返回 true：selector无效

返回 false： 无法响应点击事件，selector无效

返回 super.onTouchEvent(ev)： 无法实现我想要的功能，selector有效（测试发现返回值其实是 true）

实测在返回 true 时，MotionEvent.ACTION_DOWN这一步中 isPressed() 为 false，说明控件这时是未按压状态

所以解决方法很直接，就在这一步调用 setPressed(true)，然后在 ACTION_UP 时 setPressed(false)

具体事件处理的内部逻辑没有搞明白，不过看看 View 的 onTouchEvent 方法，其中有调用 setPressed() 

if (((viewFlags & CLICKABLE) == CLICKABLE ||
        (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE) ||
        (viewFlags & CONTEXT_CLICKABLE) == CONTEXT_CLICKABLE) {
    switch (action) {
        case MotionEvent.ACTION_UP:
            boolean prepressed = (mPrivateFlags & PFLAG_PREPRESSED) != 0;
            if ((mPrivateFlags & PFLAG_PRESSED) != 0 || prepressed) {
                // take focus if we don't have it already and we should in
                // touch mode.
                boolean focusTaken = false;
                if (isFocusable() && isFocusableInTouchMode() && !isFocused()) {
                    focusTaken = requestFocus();
                }

                if (prepressed) {
                    // The button is being released before we actually
                    // showed it as pressed.  Make it show the pressed
                    // state now (before scheduling the click) to ensure
                    // the user sees it.
                    setPressed(true, x, y);
               }

                if (!mHasPerformedLongPress && !mIgnoreNextUpEvent) {
                    // This is a tap, so remove the longpress check
                    removeLongPressCallback();

                    // Only perform take click actions if we were in the pressed state
                    if (!focusTaken) {
                        // Use a Runnable and post this rather than calling
                        // performClick directly. This lets other visual state
                        // of the view update before click actions start.
                        if (mPerformClick == null) {
                            mPerformClick = new PerformClick();
                        }
                        if (!post(mPerformClick)) {
                            performClick();
                        }
                    }
                }

                if (mUnsetPressedState == null) {
                    mUnsetPressedState = new UnsetPressedState();
                }

                if (prepressed) {
                    postDelayed(mUnsetPressedState,
                            ViewConfiguration.getPressedStateDuration());
                } else if (!post(mUnsetPressedState)) {
                    // If the post failed, unpress right now
                    mUnsetPressedState.run();
                }

                removeTapCallback();
            }
            mIgnoreNextUpEvent = false;
            break;

        case MotionEvent.ACTION_DOWN:
            mHasPerformedLongPress = false;

            if (performButtonActionOnTouchDown(event)) {
                break;
            }

            // Walk up the hierarchy to determine if we're inside a scrolling container.
            boolean isInScrollingContainer = isInScrollingContainer();

            // For views inside a scrolling container, delay the pressed feedback for
            // a short period in case this is a scroll.
            if (isInScrollingContainer) {
                mPrivateFlags |= PFLAG_PREPRESSED;
                if (mPendingCheckForTap == null) {
                    mPendingCheckForTap = new CheckForTap();
                }
                mPendingCheckForTap.x = event.getX();
                mPendingCheckForTap.y = event.getY();
                postDelayed(mPendingCheckForTap, ViewConfiguration.getTapTimeout());
            } else {
                // Not inside a scrolling container, so show the feedback right away
                setPressed(true, x, y);
                checkForLongClick(0, x, y);
            }
            break;

其中最外层的 if 条件说明了为什么有些解决方案中 需要给View设置 clickable=“true” 属性