android - 安卓的背景图选用的图片像素应该用多少？

问题描述

问 题

就是一个APP，引导页写了三个layout,分别放了三张图片

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >


    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
        android:src="@drawable/guideimg1"
        />



</RelativeLayout>

第一次启动的时候显示引导页，然后在进入登录的页面，登录的界面也设置了一张背景图

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" 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"
    android:weightSum="1"
    android:background="@drawable/login_background">

    <Button
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="微信登录"
        android:textColor="#fff"
        android:textSize="23dp"
        android:id="@+id/login_btn"
        android:drawableLeft="@mipmap/ic_wechat"
        android:drawablePadding="-95dp"
        android:paddingLeft="95dp"
        android:background="@drawable/button_style_login"
        android:layout_gravity="center_horizontal"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="15dp"
        android:elevation="21dp" />
</RelativeLayout>

但如果背景图的像素设成750*1344，然后到登录界面程序就崩了，内存溢出的错

java.lang.OutOfMemoryError
    android.graphics.BitmapFactory.nativeDecodeAsset(Native Method)
    android.graphics.BitmapFactory.decodeStream(BitmapFactory.java)
    android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java)
    android.graphics.drawable.Drawable.createFromResourceStream(Drawable.java)
    android.content.res.Resources.loadDrawable(Resources.java)
    android.content.res.Resources.getDrawable(Resources.java)
    android.support.v4.content.ContextCompat.getDrawable(ContextCompat.java:346)
    android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:197)
    android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:185)
    android.support.v7.content.res.AppCompatResources.getDrawable(AppCompatResources.java:100)
    android.support.v7.view.menu.MenuItemImpl.getIcon(MenuItemImpl.java:421)
    android.support.design.internal.NavigationMenuItemView.initialize(NavigationMenuItemView.java:113)
    android.support.design.internal.NavigationMenuPresenter$NavigationMenuAdapter.onBindViewHolder(NavigationMenuPresenter.java:415)
    android.support.design.internal.NavigationMenuPresenter$NavigationMenuAdapter.onBindViewHolder(NavigationMenuPresenter.java:338)
    android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:5825)
    android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:5858)
    android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5094)
    android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4970)
    android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2029)
    android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1414)
    android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1377)
    android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:578)
    android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3315)
    android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3124)
    android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3568)
    android.view.View.layout(View.java)
    android.view.ViewGroup.layout(ViewGroup.java)
    android.widget.FrameLayout.layoutChildren(FrameLayout.java)
    android.widget.FrameLayout.onLayout(FrameLayout.java)
    android.view.View.layout(View.java)
    android.view.ViewGroup.layout(ViewGroup.java)
    android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1221)
    android.view.View.layout(View.java)
    android.view.ViewGroup.layout(ViewGroup.java)
    android.widget.FrameLayout.layoutChildren(FrameLayout.java)
    android.widget.FrameLayout.onLayout(FrameLayout.java)
    android.view.View.layout(View.java)
    android.view.ViewGroup.layout(ViewGroup.java)
    android.widget.LinearLayout.setChildFrame(LinearLayout.java)
    android.widget.LinearLayout.layoutVertical(LinearLayout.java)
    android.widget.LinearLayout.onLayout(LinearLayout.java)
    android.view.View.layout(View.java)
    android.view.ViewGroup.layout(ViewGroup.java)
    android.widget.FrameLayout.layoutChildren(FrameLayout.java)
    android.widget.FrameLayout.onLayout(FrameLayout.java)
    android.view.View.layout(View.java)
    android.view.ViewGroup.layout(ViewGroup.java)
    android.widget.LinearLayout.setChildFrame(LinearLayout.java)
    android.widget.LinearLayout.layoutVertical(LinearLayout.java)
    android.widget.LinearLayout.onLayout(LinearLayout.java)

将登录界面的像素调小写就不报错了

我想问一下这种问题应该怎么处理，图片的像素设成多少比较合适？

解决方案

典型的drawable文件夹带来的问题，建议是UI只出一套高清无码大图放在xxh-dpi文件夹中，当在分辨率低的手机上运行时，会自动按照比例加载图片，不会出现OOM的问题。直接放在drawable下，默认是适配低分辨率，手机为高分辨率时，会按比例放大，OOM没得商量的。

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