android:自定义横向滑动的 ViewGroup
效果图:大概就是这样子的,然后可以左右滑动。原来是想做成ViewPager的那种效果的,但是感觉那种更不实用。这个效果很类似系统控件 HorizontalScrollView 了。关键代码还是测量,布局,触摸事件拦截,触摸滑动。完整代码:public class HorizontalView extends ViewGroup {private static final ...
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效果图:
大概就是这样子的,然后可以左右滑动。
原来是想做成ViewPager
的那种效果的,但是感觉那种更不实用。
这个效果很类似系统控件 HorizontalScrollView
了。
关键代码还是测量,布局,触摸事件拦截,触摸滑动。
完整代码:
public class HorizontalView extends ViewGroup {
private static final int DEFAULT_DP = 20;
int defaultSize;
private int touchSlop;
private float downInterceptX;
private float downInterceptY;
private int tapTimeout;
private Scroller mScroller;
private long elapsedRealtime;
private int goodSize;
public HorizontalView(Context context) {
super(context);
init(context);
}
public HorizontalView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public HorizontalView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
public HorizontalView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
init(context);
}
private void init(Context context) {
defaultSize = (int) ViewUtils.dp2px(context, DEFAULT_DP);
LogUtils.e("default size ========%s", defaultSize);
setWillNotDraw(false);
ViewConfiguration configuration = ViewConfiguration.get(context);
touchSlop = configuration.getScaledTouchSlop();
tapTimeout = ViewConfiguration.getTapTimeout();
mScroller = new Scroller(context);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
LogUtils.w(ViewUtils.logMeasureSpec(widthMeasureSpec, "1-w"));
LogUtils.w(ViewUtils.logMeasureSpec(heightMeasureSpec, "1-h"));
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
LogUtils.i(ViewUtils.logMeasureSpec(widthMeasureSpec, "2-w"));
LogUtils.i(ViewUtils.logMeasureSpec(heightMeasureSpec, "2-h"));
int wMode = MeasureSpec.getMode(widthMeasureSpec);
int wSize = MeasureSpec.getSize(widthMeasureSpec);
int hMode = MeasureSpec.getMode(heightMeasureSpec);
int hSize = MeasureSpec.getSize(heightMeasureSpec);
this.goodSize = wSize;
int childCount = getChildCount();
if (childCount == 0) {
LogUtils.e("no need to set wh, use super.");
return;
}
// measureChildren(widthMeasureSpec, heightMeasureSpec); // 必须要调用
int w = 0, h = defaultSize;
for (int i = 0; i < childCount; ++i) {
View child = getChildAt(i);
if (child == null || child.getVisibility() == GONE) {
continue;
}
measureChildWithMargins(child,
0, widthMeasureSpec,
0, heightMeasureSpec);
int measuredWidth = child.getMeasuredWidth();
int measuredHeight = child.getMeasuredHeight();
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
LogUtils.i("index=%s,wh=(%s,%s), lp:[%s,%s]", i,
measuredWidth, measuredHeight,
lp.leftMargin, lp.rightMargin);
h = Math.max(h, measuredHeight + lp.topMargin + lp.bottomMargin);
w += measuredWidth + lp.leftMargin + lp.rightMargin;
}
w += getPaddingStart() + getPaddingEnd();
h += getPaddingTop() + getPaddingBottom();
// w = Math.min(w, wSize); // 此时的 wSize 为 match_parent具体数值的大小
// 保证 w 不会超过 parent 预期大小
LogUtils.e("计算前的 ow,oh=(%s,%s),#,计算后的 wh(%s,%s)", wSize, hSize, w, h);
if (wMode == MeasureSpec.EXACTLY && hMode == MeasureSpec.EXACTLY) {
// LogUtils.e("no need to set wh, use super.");
LogUtils.e("m1");
setMeasuredDimension(w > wSize ? w : wSize, h > hSize ? h : hSize);
} else if (wMode == MeasureSpec.EXACTLY) {
LogUtils.e("m2");
setMeasuredDimension(wSize, h);
} else if (hMode == MeasureSpec.EXACTLY) {
LogUtils.e("m3");
setMeasuredDimension(w, hSize);
} else {
LogUtils.e("m4");
setMeasuredDimension(w, h);
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
LogUtils.i("- -onLayout(%s,%s,%s,%s)", l, t, r, b);
l += getPaddingStart();
r -= getPaddingEnd();
t += getPaddingTop();
b -= getPaddingBottom();
int childCount = getChildCount();
LogUtils.e("childCount = %s", childCount);
for (int i = 0; i < childCount; ++i) {
View child = getChildAt(i);
if (child == null || child.getVisibility() == GONE) {
continue;
}
int measuredWidth = child.getMeasuredWidth();
int measuredHeight = child.getMeasuredHeight();
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int w = measuredWidth + lp.leftMargin + lp.rightMargin;
l += lp.leftMargin;
t += lp.topMargin;
LogUtils.d("layout child:");
LogUtils.d("index=%s,#,l,t,r,b (%s,%s,%s,%s)",
i,
l, t,
l + measuredWidth, t + measuredWidth);
child.layout(l, t, l + measuredWidth, t + measuredHeight);
// for next child
l += measuredWidth + lp.rightMargin;
t -= lp.topMargin; // 下一个不能沿用上一个的 marginTop, 因为是横向排列,不是总纵向
// t += measuredHeight + lp.bottomMargin;
}
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
LogUtils.e("old(%s,%s), now(%s,%s)", oldw, oldh, w, h);
}
@Override
protected LayoutParams generateDefaultLayoutParams() {
LogUtils.e("generateDefaultLayoutParams");
return new MarginLayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
}
@Override
protected LayoutParams generateLayoutParams(LayoutParams p) {
LogUtils.e("generateLayoutParams p");
return new MarginLayoutParams(p);
}
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new MarginLayoutParams(getContext(), attrs);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
boolean intercept = false;
int actionMasked = ev.getActionMasked();
float x = ev.getX();
float y = ev.getY();
switch (actionMasked) {
case MotionEvent.ACTION_DOWN:
downInterceptX = x;
downInterceptY = y;
break;
case MotionEvent.ACTION_MOVE:
if (Math.abs(x - downInterceptX) > Math.abs(y - downInterceptY)
&& Math.abs(x - downInterceptX) > touchSlop) {
intercept = true;
}
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_CANCEL:
break;
}
return intercept || super.onInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
elapsedRealtime = SystemClock.elapsedRealtime();
break;
case MotionEvent.ACTION_MOVE:
float diffX = x - downInterceptX;
float diffY = y - downInterceptY;
scrollBy((int) -diffX, 0);
// 由于 move 会被多次调用
downInterceptX = x;
downInterceptY = y;
break;
case MotionEvent.ACTION_UP:
long realtime = SystemClock.elapsedRealtime();
if (Math.abs(y - downInterceptY) < touchSlop
&& Math.abs(x - downInterceptX) < touchSlop
&& realtime - elapsedRealtime < tapTimeout) {
LogUtils.e("click me....");
performClick();
}
break;
case MotionEvent.ACTION_CANCEL:
break;
}
return true;
}
@Override
public boolean performClick() {
return super.performClick();
}
@Override
public void computeScroll() {
// 没用上,没处理 ACTION_UP
super.computeScroll();
if (mScroller.computeScrollOffset()) {
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
}
}
@Override
public void scrollTo(int x, int y) {
// 重写 scrollTo 之后,不让其滑动超出边界
LogUtils.v("scrollTo(%s,%s)", x, y);
if (x > getWidth() - goodSize) {
LogUtils.v("getWidth(), goodSize=%s,%s", getWidth(), goodSize);
x = getWidth() - goodSize;
}
if (x < 0) {
x = 0;
}
if (x != getScrollX()) {
super.scrollTo(x, y);
}
}
}
主要步骤:
- 重写 generateLayoutParams 三个方法,让 child 支持 margin 属性
- 重写 onMeasure , 自己的宽度是 children 宽度总和
- 重写 onLayout , 自己的高度是 children 的最大值
- 重写 onIntercept, 是横向滑动就拦截
- 重写 onTouch, move 的时候,通过 scrollBy 进行滑动
- 重写 scrollTo, 不让其滑动超过自身的左右最大边界
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