Android上的交叉淡化图片视图未重置 - 点击相同的图片

Question

我正在尝试编写一个应用程序，以便在两个图像之间交叉淡入淡出，然后在单击时返回。 初始方法fade可以正常工作并淡化到新图像，但是当单击第二个图像时，没有任何效果。 我认为问题是第一个图像仍然覆盖在第二个图像上，所以我只是一遍又一遍地点击第一个图像。 但是我添加了打印图像变量的hashcode()以检查执行情况，并且它似乎每次仅从方法fadeBack返回相同的变量。 我在日志（// n click on image n）中注释了每次点击时出现的条目，但是当应该调用fadeBack时，似乎调用相同的方法fade。

需要更多信息，请告知我们。

日志：

12-29 19:02:22.273 15746-15746/? I/art: Not late-enabling -Xcheck:jni (already on)
12-29 19:02:22.566 15746-15746/com.example.richardcurteis.layoutdemo W/System: ClassLoader referenced unknown path: /data/app/com.example.richardcurteis.layoutdemo-2/lib/x86
12-29 19:02:22.842 15746-15757/com.example.richardcurteis.layoutdemo I/art: Background sticky concurrent mark sweep GC freed 22155(972KB) AllocSpace objects, 0(0B) LOS objects, 0% free, 16MB/16MB, paused 14.211ms total 68.404ms
12-29 19:02:22.871 15746-15757/com.example.richardcurteis.layoutdemo W/art: Suspending all threads took: 29.427ms
12-29 19:02:22.905 15746-15757/com.example.richardcurteis.layoutdemo W/art: Suspending all threads took: 13.161ms
12-29 19:02:22.980 15746-15757/com.example.richardcurteis.layoutdemo I/art: Background partial concurrent mark sweep GC freed 130(10KB) AllocSpace objects, 0(0B) LOS objects, 19% free, 16MB/20MB, paused 16.186ms total 106.877ms
12-29 19:02:23.014 15746-15757/com.example.richardcurteis.layoutdemo W/art: Suspending all threads took: 33.481ms
12-29 19:02:23.018 15746-15767/com.example.richardcurteis.layoutdemo D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
12-29 19:02:23.138 15746-15767/com.example.richardcurteis.layoutdemo I/OpenGLRenderer: Initialized EGL, version 1.4
12-29 19:02:23.192 15746-15767/com.example.richardcurteis.layoutdemo W/EGL_emulation: eglSurfaceAttrib not implemented
12-29 19:02:23.192 15746-15767/com.example.richardcurteis.layoutdemo W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xad7a0a80, error=EGL_SUCCESS
12-29 19:02:27.146 15746-15746/com.example.richardcurteis.layoutdemo I/System.out: Hashcode in fadeBack - will: 176777760 //First click on image 1
12-29 19:02:27.146 15746-15746/com.example.richardcurteis.layoutdemo I/System.out: Hashcode in fadeBack - obama: 261627865 //First click on image 1
12-29 19:02:30.197 15746-15746/com.example.richardcurteis.layoutdemo I/System.out: Hashcode in fadeBack - will: 176777760 //Second click on image 2
12-29 19:02:30.197 15746-15746/com.example.richardcurteis.layoutdemo I/System.out: Hashcode in fadeBack - obama: 261627865 // //Second click on image 2

代码：

package com.example.richardcurteis.layoutdemo;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {

    ImageView obama;
    ImageView will;

    public void fade(View view) {
        System.out.println("Hashcode in fade - will: " + will.hashCode());
        System.out.println("Hashcode in fade - obama: " + obama.hashCode());
        obama.animate().alpha(0f).setDuration(2000);
        will.animate().alpha(1f).setDuration(2000);

    }

    public void fadeBack(View view) {
        System.out.println("Hashcode in fadeBack - will: " + will.hashCode());
        System.out.println("Hashcode in fadeBack - obama: " + obama.hashCode());
        will.animate().alpha(1f).setDuration(2000);
        obama.animate().alpha(0f).setDuration(2000);

    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        obama = (ImageView) findViewById(R.id.obama);
        will = (ImageView) findViewById(R.id.will);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

活动主要xml文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.richardcurteis.layoutdemo.MainActivity"
    tools:showIn="@layout/activity_main"
    android:clickable="false">

     <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/obama"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true"
         android:src="@drawable/obama"
         android:onClick="fade" />

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/will"
        android:layout_alignTop="@+id/obama"
        android:layout_alignParentStart="true"
        android:src="@drawable/will"
        android:alpha="0"
        android:onClick="fadeBack" />
</RelativeLayout>

Answer 1

好的想通了。 作为drawable，will位于设计中的obama之上，fadeBack方法始终被调用。 更改了代码，以便交叉淡入淡出和返回包含在一个方法中，并带有一个计数器来控制它的运行方式。

MainActivity.java

package com.example.richardcurteis.layoutdemo;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {

    ImageView obama;
    ImageView will;
    int count;

    public void fade(View view) {

        if (count == 0) {
            obama.animate().alpha(0f).setDuration(2000);
            will.animate().alpha(1f).setDuration(2000);
            count++;
        } else {
            will.animate().alpha(0f).setDuration(2000);
            obama.animate().alpha(1f).setDuration(2000);
            count = 0;
        }

    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        obama = (ImageView) findViewById(R.id.obama);
        will = (ImageView) findViewById(R.id.will);
        count = 0;

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

content_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.richardcurteis.layoutdemo.MainActivity"
    tools:showIn="@layout/activity_main"
    android:clickable="false">

     <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/obama"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true"
         android:src="@drawable/obama"
         android:layout_alignParentLeft="true" />

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/will"
        android:layout_alignTop="@+id/obama"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:src="@drawable/will"
        android:onClick="fade"
        android:alpha="0" />
</RelativeLayout>