领悟自定义风采，ScrollView源码完全解析

Posted 2020-08-17 Mero技术博客

今天给大家带来这篇源码解读，首先很感谢大家能"赏脸。本文秉着思路清晰，细致分析源码脉络。从根本上带领大家学会自定义控件和分析源码，学会举一反三。"自定义，何等熟悉的名词。到底，它有多深奥，其实不然，咱们github千万自定义控件让人眼花缭乱，先克服恐惧。拒绝一味"承袭"人家控件。毕竟，人家的始终是人家的，自己的才是根本。好了，开篇不说多，咱们进入正题吧！分析源码第一要点，切入继承图，分析继承关系(快捷键F4)。我们通过图3可以看见ScrollView继承自FrameLayout布局。

一：继承关系

然后我们先大致了解一下ScrollView中所有的方法。该部分为读者自己回顾整体查询，为节省篇幅，所以比较紧凑。先请大家快速地大致预览一下方法名，有个大致过目。为后面的讲解做准备。

二：所有方法预览

public ScrollView(Context context) {...}  


public ScrollView(Context context, AttributeSet attrs) {...}  

public ScrollView(Context context, AttributeSet attrs, int defStyleAttr) {...}  

public (Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {...}  

public boolean shouldDelayChildPressedState() {...}  

protected float getTopFadingEdgeStrength() {...}  

protected float getBottomFadingEdgeStrength() {...}  

public int getMaxScrollAmount() {...}  

private void initScrollView() {...}  

public void addView(View child) {...}  

public void addView(View child, int index) {...}  

public void addView(View child, ViewGroup.LayoutParams params) {...}  

public void addView(View child, int index, ViewGroup.LayoutParams params) {... }  

private boolean canScroll() {...}  

public boolean isFillViewport() {...}  

public void setFillViewport(boolean fillViewport) {... }  

public boolean isSmoothScrollingEnabled() {...}  

public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {...}  

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {... }  

public boolean  dispatchKeyEvent(KeyEvent event) {... }  

public boolean executeKeyEvent(KeyEvent event) {...}  

private boolean inChild(int x, int y) {...}  

private void initOrResetVelocityTracker() {...}  

private void initVelocityTrackerIfNotExists() {...}  

private void recycleVelocityTracker() {...}  

public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {...}  

public boolean onInterceptTouchEvent(MotionEvent ev) {...}  

public boolean onTouchEvent(MotionEvent ev) {... }  

private void onSecondaryPointerUp(MotionEvent ev) {...}  

public boolean onGenericMotionEvent(MotionEvent event) {...}  

protected void onOverScrolled(int scrollX, int scrollY,boolean clampedX, boolean clampedY){...}  

public boolean performAccessibilityActionInternal(int action, Bundle arguments) {...}  

public CharSequence getAccessibilityClassName() {...}  

public void onInitializeAccessibilityNodeInfoInternal(AccessibilityNodeInfo info) {...}  

public void onInitializeAccessibilityEventInternal(AccessibilityEvent event) {...}  

private int getScrollRange() {... }  

private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) {...}  

public boolean (int direction) {...}  

public boolean (int direction) {...}  

private boolean (int direction, int top, int bottom) {...}  

public boolean (int direction) {... }  

private boolean (View descendant) {...}  

private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) {... }  

private void doScrollY(int delta) {...}      

public final void smoothScrollBy(int dx, int dy) {... }  

public final void smoothScrollTo(int x, int y) {...}  

protected int computeVerticalScrollRange() {...}  

  
protected int computeVerticalScrollOffset() {...}  

protected void measureChild(View child, int parentWidthMeasureSpec,  

int parentHeightMeasureSpec) {...}  

protected voidmeasureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,  

int parentHeightMeasureSpec, int heightUsed) {...}  
  
oid computeScroll() {...}  

private void scrollToChild(View child) {...}  

private boolean scrollToChildRect(Rect rect, boolean immediate) {...}  

protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) {...}  

public void requestChildFocus(View child, View focused) {...}  

protected boolean onRequestFocusInDescendants(int direction,  
        Rect previouslyFocusedRect) {...}  

public boolean requestChildRectangleOnScreen(View child, Rect rectangle,  
        boolean immediate) {...}  

public void requestLayout() {...}  

protected void onDetachedFromWindow() {...}  

protected void onLayout(boolean changed, int l, int t, int r, int b) {...}  

protected void onSizeChanged(int w, int h, int oldw, int oldh) {...}  

private static boolean isViewDescendantOf(View child, View parent) {... }  

public void fling(int velocityY) {...}  

private void flingWithNestedDispatch(int velocityY) {...}  

private void endDrag() {...}  

public void scrollTo(int x, int y) {...}  

public void setOverScrollMode(int mode) {...}  

public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {...}  

public voidonNestedScrollAccepted(View child, View target, int axes) {...}  

public void onStopNestedScroll(View target) {...}  

public void onNestedScroll(View target, int dxConsumed, int dyConsumed,  
        int dxUnconsumed, int dyUnconsumed) {...}  

public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) {...}  

public void (Canvas canvas) {...}  

private static int clamp(int n, int my, int child) {...}  

protected void onRestoreInstanceState(Parcelable state) {... }  

protected void encodeProperties(@NonNull ViewHierarchyEncoder encoder) {...}  

以上是关于领悟自定义风采，ScrollView源码完全解析的主要内容，如果未能解决你的问题，请参考以下文章

JVM源码分析之堆外内存完全解读

大数据技术之_03_Hadoop学习_02_入门_Hadoop运行模式+本地运行模式+伪分布式运行模式+完全分布式运行模式(开发重点)+Hadoop编译源码(面试重点)+常见错误及解决方案(示例代(代

素材下载网站代下源码

SPRING_应用程序框架源码解析目录

Swift - Alamofire源码解析

Swift - Alamofire源码解析