** ScrollView下拉頭部縮放 **
用法和ScrollView一樣
public class PersonalScrollView extends ScrollView {
private static final String TAG = "BounceScrollView";
//----頭部收縮屬性--------
// 記錄首次按下位置
private float mFirstPosition = 0;
// 頭部圖片是否正在放大
private Boolean mScaling = false;
private View dropZoomView;//需要被放大的view
private int dropZoomViewWidth;
private int dropZoomViewHeight;
//----頭部收縮屬性end--------
//------尾部收縮屬性--------
private View inner;// 子View
private float y;// 點(diǎn)擊時(shí)y坐標(biāo)
private Rect normal = new Rect();// 矩形(這里只是個(gè)形式，只是用于判斷是否需要?jiǎng)赢?)
private boolean isCount = false;// 是否開始計(jì)算
//最后的坐標(biāo)
private float lastX = 0;
private float lastY = 0;
//當(dāng)前坐標(biāo)
private float currentX = 0;
private float currentY = 0;
//移動(dòng)的坐標(biāo)量
private float distanceX = 0;
private float distanceY = 0;
private boolean upDownSlide = false; //判斷上下滑動(dòng)的flag
//------尾部收縮屬性end--------
public PersonalScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
//初始化
private void init() {
setOverScrollMode(OVER_SCROLL_NEVER);
if (getChildAt(0) != null) {
inner = getChildAt(0);//這個(gè)是底部收縮的view
//頭部收縮的
ViewGroup vg = (ViewGroup) getChildAt(0);
if (vg.getChildAt(0) != null) {
dropZoomView = vg.getChildAt(0);
}
}
}
/***
* 生成視圖工作完成.該函數(shù)在生成視圖的最后調(diào)用，在所有子視圖添加完之后. 即使子類覆蓋了 onFinishInflate
* 方法，也應(yīng)該調(diào)用父類的方法，使該方法得以執(zhí)行.
*/
@Override
protected void onFinishInflate() {
//初始化
init();
super.onFinishInflate();
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
//這里只是計(jì)算尾部坐標(biāo)
currentX = ev.getX();
currentY = ev.getY();
switch (ev.getAction()) {
case MotionEvent.ACTION_MOVE:
distanceX = currentX - lastX;
distanceY = currentY - lastY;
if (Math.abs(distanceX) < Math.abs(distanceY) && Math.abs(distanceY) > 12) {
upDownSlide = true;
}
break;
}
lastX = currentX;
lastY = currentY;
if (upDownSlide && inner != null) commOnTouchEvent(ev);
return super.dispatchTouchEvent(ev);
}
/***
* 觸摸事件
*
* @param ev
*/
public void commOnTouchEvent(MotionEvent ev) {
//頭部縮放計(jì)算
if (dropZoomViewWidth <= 0 || dropZoomViewHeight <= 0) {
dropZoomViewWidth = dropZoomView.getMeasuredWidth();
dropZoomViewHeight = dropZoomView.getMeasuredHeight();
}
switch (ev.getAction()) {
case MotionEvent.ACTION_UP:
//手指離開后頭部恢復(fù)圖片
mScaling = false;
replyImage();
// 手指松開尾部恢復(fù)
if (isNeedAnimation()) {
animation();
isCount = false;
}
clear0();
break;
//這里頭尾分開處理，互不干擾
case MotionEvent.ACTION_MOVE:
//尾部處理
final float preY = y;// 按下時(shí)的y坐標(biāo)
float nowY = ev.getY();// 時(shí)時(shí)y坐標(biāo)
int deltaY = (int) (preY - nowY);// 滑動(dòng)距離
if (!isCount) {
deltaY = 0; // 在這里要?dú)w0.
}
y = nowY;
// 當(dāng)滾動(dòng)到最上或者最下時(shí)就不會(huì)再滾動(dòng)，這時(shí)移動(dòng)布局
if (isNeedMove()) {
// 初始化頭部矩形
if (normal.isEmpty()) {
// 保存正常的布局位置
normal.set(inner.getLeft(), inner.getTop(),
inner.getRight(), inner.getBottom());
}
// 移動(dòng)布局
inner.layout(inner.getLeft(), inner.getTop() - deltaY / 2,
inner.getRight(), inner.getBottom() - deltaY / 2);
}
isCount = true;
//尾部處理end
//頭部處理
if (!mScaling) {
if (getScrollY() == 0) {
mFirstPosition = ev.getY();// 滾動(dòng)到頂部時(shí)記錄位置，否則正常返回
} else {
break;
}
}
int distance = (int) ((ev.getY() - mFirstPosition) * 0.6); // 滾動(dòng)距離乘以一個(gè)系數(shù)
if (distance < 0) { // 當(dāng)前位置比記錄位置要小，正常返回
break;
}
// 處理放大
mScaling = true;
setZoom(1 + distance);
//頭部處理end
break;
}
}
/***
* 回縮動(dòng)畫,尾部往下縮動(dòng)畫
*/
public void animation() {
// 開啟移動(dòng)動(dòng)畫
TranslateAnimation ta = new TranslateAnimation(0, 0, inner.getTop(),
normal.top);
ta.setDuration(200);
inner.startAnimation(ta);
// 設(shè)置回到正常的布局位置
inner.layout(normal.left, normal.top, normal.right, normal.bottom);
normal.setEmpty();
}
// 是否需要開啟動(dòng)畫
public boolean isNeedAnimation() {
return !normal.isEmpty();
}
// 回彈動(dòng)畫，header往上縮動(dòng)畫 (使用了屬性動(dòng)畫)
public void replyImage() {
final float distance = dropZoomView.getMeasuredWidth() - dropZoomViewWidth;
// 設(shè)置動(dòng)畫
ValueAnimator anim = ObjectAnimator.ofFloat(0.0F, 1.0F).setDuration((long) (distance * 0.7));
anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
float cVal = (Float) animation.getAnimatedValue();
setZoom(distance - ((distance) * cVal));
}
});
anim.start();
}
//頭部縮放
public void setZoom(float s) {
if (dropZoomViewHeight <= 0 || dropZoomViewWidth <= 0) {
return;
}
ViewGroup.LayoutParams lp = dropZoomView.getLayoutParams();
lp.width = (int) (dropZoomViewWidth + s);
lp.height = (int) (dropZoomViewHeight * ((dropZoomViewWidth + s) / dropZoomViewWidth));
dropZoomView.setLayoutParams(lp);
}
/***
* 是否需要移動(dòng)布局 inner.getMeasuredHeight():獲取的是控件的總高度
*
* getHeight()：獲取的是屏幕的高度
*
* @return
*/
public boolean isNeedMove() {
int offset = inner.getMeasuredHeight() - getHeight();
int scrollY = getScrollY();
// 0是頂部，后面那個(gè)是底部
if (scrollY == 0 || scrollY == offset) {
return true;
}
return false;
}
//清理尾部屬性值
private void clear0() {
lastX = 0;
lastY = 0;
distanceX = 0;
distanceY = 0;
upDownSlide = false;
}
}
