Android 利用ViewDragHelper打造側滑關閉控制元件
阿新 • • 發佈:2019-01-27
效果:
核心思想:
- 自定義ViewGroup控制元件,利用ViewDragHelper讓此控制元件擁有滑動功能。
- 將此控制元件附加到每一個Activity。
程式碼很簡單就不一一解釋了,程式碼備註很詳細,所以直接貼程式碼了:
import android.app.Activity;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v4.widget.ViewDragHelper;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import view.peakchao.view.R;
/**
* 基於ViewDragHelper的側滑關閉View
* Created by Chao on 2018-09-09.
*/
public class SwipeBackLayout extends FrameLayout {
private ViewDragHelper mHelper;
private Activity mActivity;
private View mView;
public SwipeBackLayout(@NonNull Context context) {
super(context);
initViewDragHelper();
}
/**
* 繫結 Activity
*
* @param activity 容器 Activity
*/
public void attachActivity(Activity activity) {
mActivity = activity;
ViewGroup decor = (ViewGroup) activity.getWindow().getDecorView();
View content = decor.getChildAt(0 );
decor.removeView(content);
mView = content;
addView(content);
decor.addView(this);
}
/**
* 初始化方法
*/
private void initViewDragHelper() {
mHelper = ViewDragHelper.create(this, 1.0f, new ViewDragHelper.Callback() {
@Override
public boolean tryCaptureView(View child, int pointerId) {
// 預設不撲獲 View
return false;
}
@Override
public int clampViewPositionHorizontal(View child, int left, int dx) {
// 拖動限制(大於左邊界)
return Math.max(0, left);
}
@Override
public int clampViewPositionVertical(View child, int top, int dy) {
//左右側滑時,限制不能上下拖動。
return 0;
}
@Override
public void onViewReleased(View releasedChild, float xvel, float yvel) {
// 拖動距離大於螢幕的一半右移,拖動距離小於螢幕的一半左移
int left = releasedChild.getLeft();
if (left > getWidth() / 2) {
if (mActivity != null) {
mActivity.finish();
mActivity.overridePendingTransition(0, R.anim.right_out);
}
} else {
mHelper.settleCapturedViewAt(0, 0);
}
invalidate();
}
@Override
public void onEdgeDragStarted(int edgeFlags, int pointerId) {
// 移動子 View
mHelper.captureChildView(mView, pointerId);
}
});
// 跟蹤左邊界拖動
mHelper.setEdgeTrackingEnabled(ViewDragHelper.EDGE_LEFT);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
// 攔截代理
return mHelper.shouldInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// Touch Event 代理
mHelper.processTouchEvent(event);
return true;
}
@Override
public void computeScroll() {
// 子 View 需要更新狀態
if (mHelper.continueSettling(true)) {
invalidate();
}
}
}
編寫公共父類,或者將此類下面程式碼新增到需要側滑關閉的Activity即可:
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import view.peakchao.view.R;
import view.peakchao.view.view.SwipeBackLayout;
/**
* Created by Chao on 2018-09-09.
*/
public class SwipeActivity extends AppCompatActivity {
private SwipeBackLayout mSwipeBackLayout;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_swipe);//如果此類作為基類,這裡layout需要從子類獲取
mSwipeBackLayout = new SwipeBackLayout(this);
}
@Override
protected void onPostCreate(@Nullable Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
mSwipeBackLayout.attachActivity(this);
}
public void start(View view) {
startActivity(new Intent(this, SwipeActivity.class));
}
}