Android特效开发
本次我要向大家介绍一个Android特效，这个特效也是我在某款软件中看到的，至于软件叫什么，
好了，我来上一张动态效果图 在下面，屏幕小的请往下拉。
我不知道原软件是怎么个实现法，在这里我只是说说我的实现方法，代码可能不太好，这只是本人的一个idea 原理很简单！
改变按钮的宽度，每次当你点击按钮时，只有两个按钮改变宽度，一个变长，一个变短，只是这个变化是慢慢
进行，不是秒变的，你懂的，这就是动画效果。你点击短的按钮后会渐渐地变长，长的按钮会随着被压缩，其他按钮宽度不变。
我写这篇文章想起到一个抛砖引玉的效果，希望读者看了这篇文章后继续写个更好的文章。当然你不要忘记我啊，
记得要与我和大家分享啊。
下面是特效Demo运行后的效果图：
可以看到view被挤压的效果，点击短的view会慢慢长大。在短的view慢慢长大的同时，最长的view会慢慢缩小，而且每次动画结束后都
有一个最长的view 。我这里所说的view在本次Demo中是按钮，当然你也可以换成其他的控件，或者是ViewGroup的子类也行。
[java] view plaincopyprint?
public class PinchActivity extends Activity implements View.OnClickListener {
private final static String TAG = "MainActivity";
// 屏幕宽度
private int screentWidth = 0;
// View可伸展最长的宽度
private int maxWidth;
// View可伸展最小宽度
private int minWidth;
// 当前点击的View
private View currentView;
// 显示最长的那个View
private View preView;
// 主布局ViewGroup
private LinearLayout mainContain;
// 标识符 动画是否结束
private boolean animationIsEnd = true;
// 变大操作
private static final int OPE_BIG = 1;
// 变小操作
private static final int OPE_SMALL = 2;
// 当前操作 -1表示无效操作
private int currentOpe = -1;
// 前进的步伐距离
private static final int STEP = 10;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initCommonData();
initViewData();
measureWidth(screentWidth);
}
private void initViewData() {
mainContain = (LinearLayout) this.findViewById(R.id.main_contain);
View child;
int childCount = mainContain.getChildCount();
for (int i = 0; i < childCount; i++) {
child = mainContain.getChildAt(i);
child.setOnClickListener(this);
}
}
private void initCommonData()
{
DisplayMetrics metric = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metric);
screentWidth = metric.widthPixels; // 屏幕宽度（像素）
}
private void setCurrentViewParams() {
if (currentView == null) {
return;
}
LayoutParams params = currentView.getLayoutParams();
if (params == null) {
return;
}
int realWidth = params.width;
int nextWidth = 0;
if (currentOpe == OPE_BIG) {
nextWidth = realWidth + STEP;
} else if (currentOpe == OPE_SMALL) {
nextWidth = realWidth - STEP;
}
if (nextWidth > maxWidth) {
nextWidth = maxWidth;
} else if (nextWidth < minWidth) {
nextWidth = minWidth;
}
params.width = nextWidth;
currentView.setLayoutParams(params);
if (nextWidth == maxWidth || nextWidth == minWidth) {
animationIsEnd = true;
onOffClickable();
stopAnimation();
return;
}
mHandler.sendEmptyMessageDelayed(1, 20);
}
// 初始化宽度 测量max min 长度
private void measureWidth(int screenWidth) {
int halfWidth = screenWidth / 2;
maxWidth = halfWidth - 50;
minWidth = (screenWidth - maxWidth) / (mainContain.getChildCount() - 1);
View child;
int childCount = mainContain.getChildCount();
for (int i = 0; i < childCount; i++) {
child = mainContain.getChildAt(i);
LayoutParams params = child.getLayoutParams();
if (i == 0) {
preView = child;
params.width = maxWidth;
} else {
params.width = minWidth;
}
child.setLayoutParams(params);
}
}
// 这里用handler更新界面
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
if (msg.what == 1) {
setCurrentViewParams();
}
}
};
// 停止动画
private void stopAnimation() {
currentOpe = -1;
currentView = null;
}
private void startAnimation() {
if (currentView == null || currentOpe == -1) {
Log.d(TAG, "无效动画");
return;
}
animationIsEnd = false;
onOffClickable();
mHandler.sendEmptyMessage(1);
}
@Override
public void onClick(View v) {
int id = v.getId();
switch (id) {
case R.id.btnOne:
currentView = mainContain.getChildAt(0);
break;
case R.id.btnTwo:
currentView = mainContain.getChildAt(1);
break;
case R.id.btnThree:
currentView = mainContain.getChildAt(2);
break;
case R.id.btnFour:
currentView = mainContain.getChildAt(3);
break;
}
Log.i(TAG, ((Button) currentView).getText().toString() + " click");
if (currentView != null && animationIsEnd) {
int currentViewWidth = currentView.getWidth();
if (currentViewWidth == maxWidth) {
currentOpe = OPE_SMALL;
} else {
currentOpe = OPE_BIG;
}
clickEvent(currentView);
startAnimation();
}
}
private void clickEvent(View view) {
View child;
int childCount = mainContain.getChildCount();
for (int i = 0; i < childCount; i++) {
child = mainContain.getChildAt(i);
if (preView == child) {
LinearLayout.LayoutParams params = (android.widget.LinearLayout.LayoutParams) child
.getLayoutParams();
params.weight = 1.0f;
child.setLayoutParams(params);
} else {
LinearLayout.LayoutParams params = (android.widget.LinearLayout.LayoutParams) child
.getLayoutParams();
params.weight = 0.0f;
params.width = minWidth;
child.setLayoutParams(params);
}
}
preView = view;
printWeight();
}
private void printWeight() {
View child;
int childCount = mainContain.getChildCount();
for (int i = 0; i < childCount; i++) {
child = mainContain.getChildAt(i);
LinearLayout.LayoutParams params = (android.widget.LinearLayout.LayoutParams) child
.getLayoutParams();
Log.i("mm1", ((Button) child).getText() + ": " + params.weight);
}
}
//
private void onOffClickable()
{
View child;
boolean clickable = animationIsEnd;
int childCount = mainContain.getChildCount();
for (int i = 0; i < childCount; i++) {
child = mainContain.getChildAt(i);
child.setClickable(clickable);
}
}
}
大家学了过后，有没有帮助啊。学android特效上IT蓝豹。
