invalidate和requestLayout方法源码分析

/**
 * Mark the area defined by dirty as needing to be drawn. dirty代表需要重新绘制的脏的区域
 *  If the view is visible,  onDraw(Canvas) will be called at some point in the future.
 * This must be called from a UI thread. To call from a non-UI thread, call postInvalidate().
 * <b>WARNING:</b> In API 19 and below, this method may be destructive to dirty.
 * @param dirty the rectangle矩形 representing表示 the bounds of the dirty region地区
 */
public void invalidate(Rect dirty) {
	final int scrollX = mScrollX;
	final int scrollY = mScrollY;
	invalidateInternal(dirty.left - scrollX, dirty.top - scrollY,
			dirty.right - scrollX, dirty.bottom - scrollY, true, false);
}
public void invalidate(int l, int t, int r, int b) {
	final int scrollX = mScrollX;
	final int scrollY = mScrollY;
	//实质还是调用invalidateInternal方法
	invalidateInternal(l - scrollX, t - scrollY, r - scrollX, b - scrollY, true, false);
}
/**
 * Invalidate the whole view. 重新绘制整个View
 */
public void invalidate() {
	invalidate(true);
}
public void invalidate(boolean invalidateCache) {
	invalidateInternal(0, 0, mRight - mLeft, mBottom - mTop, invalidateCache, true);
}
//这是所有invalidate的终极调用方法
void invalidateInternal(int l, int t, int r, int b, boolean invalidateCache,	boolean fullInvalidate) {
	......
		// Propagate繁殖、传播 the damage损害的(只需要刷新的) rectangle to the parent view.
		final AttachInfo ai = mAttachInfo;
		final ViewParent p = mParent;
		if (p != null && ai != null && l < r && t < b) {
			final Rect damage = ai.mTmpInvalRect;
			damage.set(l, t, r, b);//将需要刷新的区域封装到damage中
			p.invalidateChild(this, damage);//调用Parent的invalidateChild方法，传递damage给Parent
		}
	......
}

public final void invalidateChild(View child, final Rect dirty) {
	ViewParent parent = this;
	......
	do {
		......
		//循环层层上级调用，直到ViewRootImpl会返回null
		parent = parent.invalidateChildInParent(location, dirty);
		......
	} while (parent != null);
}

@Override
public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
	......
	//View调用invalidate最终层层上传到ViewRootImpl后最终触发了该方法
	scheduleTraversals();
	......
	return null;
}

public void postInvalidate() {
	postInvalidateDelayed(0);
}
public void postInvalidateDelayed(long delayMilliseconds) {
	// We try only with the AttachInfo because there‘s no point in invalidating
	// if we are not attached to our window
	final AttachInfo attachInfo = mAttachInfo;
	//核心，实质就是调用了ViewRootImpl.dispatchInvalidateDelayed方法
	if (attachInfo != null) {
		attachInfo.mViewRootImpl.dispatchInvalidateDelayed(this, delayMilliseconds);
	}
}
public void dispatchInvalidateDelayed(View view, long delayMilliseconds) {
	Message msg = mHandler.obtainMessage(MSG_INVALIDATE, view);
	mHandler.sendMessageDelayed(msg, delayMilliseconds);
}

public void handleMessage(Message msg) {
    ......
    switch (msg.what) {
    case MSG_INVALIDATE:
        ((View) msg.obj).invalidate();
        break;
    ......
    }
    ......
}

@Override
public void setContentView(View view, ViewGroup.LayoutParams params) {
	......
	//如果mContentParent为空进行一些初始化
	if (mContentParent == null) {
		installDecor();
	} 
	......
	//把我们的view追加到mContentParent
	mContentParent.addView(view, params);
	......
}

public void addView(View child) {
	addView(child, -1);
}
public void addView(View child, int index) {
	......
	addView(child, index, params);
}
public void addView(View child, int index, LayoutParams params) {
	......
	//该方法稍后后面会详细分析
	requestLayout();
	//重点关注！！！
	invalidate(true);
	......
}

public void requestLayout() {
	......
	if (mParent != null && !mParent.isLayoutRequested()) {
		//从这个View开始向上一直requestLayout，最终到达ViewRootImpl的requestLayout
		mParent.requestLayout();
	}
	......
}

@Override
public void requestLayout() {
	if (!mHandlingLayoutInLayoutRequest) {
		checkThread();
		mLayoutRequested = true;
		//View调用requestLayout最终层层上传到ViewRootImpl后最终触发了该方法
		scheduleTraversals();
	}
}