Android特效開發
本次我要向大家介紹一個Android特效，這個特效也是我在某款軟件中看到的，至于軟件叫什么，
好了，我來上一張動態效果圖 在下面，屏幕小的請往下拉。
我不知道原軟件是怎么個實現法，在這里我只是說說我的實現方法，代碼可能不太好，這只是本人的一個idea 原理很簡單！
改變按鈕的寬度，每次當你點擊按鈕時，只有兩個按鈕改變寬度，一個變長，一個變短，只是這個變化是慢慢
進行，不是秒變的，你懂的，這就是動畫效果。你點擊短的按鈕后會漸漸地變長，長的按鈕會隨著被壓縮，其他按鈕寬度不變。
我寫這篇文章想起到一個拋磚引玉的效果，希望讀者看了這篇文章后繼續寫個更好的文章。當然你不要忘記我啊，
記得要與我和大家分享啊。
下面是特效Demo運行后的效果圖：
可以看到view被擠壓的效果，點擊短的view會慢慢長大。在短的view慢慢長大的同時，最長的view會慢慢縮小，而且每次動畫結束后都
有一個最長的view 。我這里所說的view在本次Demo中是按鈕，當然你也可以換成其他的控件，或者是ViewGroup的子類也行。
[java] view plaincopyprint?
public class PinchActivity extends Activity implements View.OnClickListener {
private final static String TAG = "MainActivity";
// 屏幕寬度
private int screentWidth = 0;
// View可伸展最長的寬度
private int maxWidth;
// View可伸展最小寬度
private int minWidth;
// 當前點擊的View
private View currentView;
// 顯示最長的那個View
private View preView;
// 主布局ViewGroup
private LinearLayout mainContain;
// 標識符 動畫是否結束
private boolean animationIsEnd = true;
// 變大操作
private static final int OPE_BIG = 1;
// 變小操作
private static final int OPE_SMALL = 2;
// 當前操作 -1表示無效操作
private int currentOpe = -1;
// 前進的步伐距離
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; // 屏幕寬度（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);
}
// 初始化寬度 測量max min 長度
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);
}
}
// 這里用handler更新界面
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
if (msg.what == 1) {
setCurrentViewParams();
}
}
};
// 停止動畫
private void stopAnimation() {
currentOpe = -1;
currentView = null;
}
private void startAnimation() {
if (currentView == null || currentOpe == -1) {
Log.d(TAG, "無效動畫");
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);
}
}
}
大家學了過后，有沒有幫助啊。學android特效上IT藍豹。
