java - ImageButton 设置LayoutParams 后图像模糊

Question

我四处看了看这里和其他地方，但我似乎找不到解决这个问题的方法。我对 Java 并不陌生，尽管这是我的第一个 android 应用程序。

我正在显示 3 个 ImageButton(一个在另一个右边)，需要调整它们的大小以适应任何屏幕(即 7-10 英寸的平板电脑到 4 英寸的手机)。我已经弄清楚了这个逻辑，但我遇到的问题是 7 英寸以上设备上的图像质量很糟糕。这是我的 xml 的代码:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" 
android:id="@+id/mainLayout" >

<ImageButton
    android:id="@+id/btn_god"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:background="@null"
    android:src="@drawable/godtext" />

<ImageButton
    android:id="@+id/btn_growth"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerVertical="true"
    android:layout_centerHorizontal="true"
    android:background="@null"
    android:src="@drawable/growthtext" />

<ImageButton
    android:id="@+id/btn_service"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_alignParentBottom="true"
    android:background="@null"
    android:src="@drawable/servicetext" /> 

</RelativeLayout>

这是我 Activity 的相关部分:

    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    int version = VERSION.SDK_INT;
    int height = 0;
    int width = 0;
    if (version < 13){
        DisplayMetrics displaymetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
        height = displaymetrics.heightPixels;
        width = displaymetrics.widthPixels;
    } else {
        Display display = getWindowManager().getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        width = size.x;
        height = size.y;
    }

    /**
     * Creating all buttons instances
     * */
    // Dashboard God button
    ImageButton btn_god = (ImageButton) findViewById(R.id.btn_god);
    btn_god.setAdjustViewBounds(true);
    ViewGroup.LayoutParams params = btn_god.getLayoutParams();
    params.height = height/4;
    params.width = params.height;
    btn_god.setLayoutParams(params);

    // Dashboard Growth button
    ImageButton btn_growth = (ImageButton) findViewById(R.id.btn_growth);
    btn_growth.setAdjustViewBounds(true);
    params = btn_growth.getLayoutParams();
    params.height = height/4;
    params.width = params.height;
    btn_growth.setLayoutParams(params);
    btn_growth.setImageResource(R.drawable.growthtext);

    // Dashboard Service button
    ImageButton btn_service = (ImageButton) findViewById(R.id.btn_service);
    btn_service.setAdjustViewBounds(true);
    params = btn_service.getLayoutParams();
    params.height = height/4;
    params.width = params.height;
    btn_service.setLayoutParams(params);

我想做的是拍摄高分辨率图像，然后缩小它以适应较小的屏幕。但是，它似乎正在拍摄低分辨率图像并将其放大以用于更大的屏幕。有没有人遇到过类似的问题？你是怎么解决的？感谢您的回复!

Answer 1

xlarge screens are at least 960dp x 720dp
large screens are at least 640dp x 480dp
normal screens are at least 470dp x 320dp
small screens are at least 426dp x 320dp
Generalised Dpi values for screens:

ldpi Resources for low-density (ldpi) screens (~120dpi)
mdpi Resources for medium-density (mdpi) screens (~160dpi). (This is the baseline    density.)
hdpi Resources for high-density (hdpi) screens (~240dpi).
xhdpi Resources for extra high-density (xhdpi) screens (~320dpi).

Therefore generalised size of your resources (assuming they are full screen):

ldpi
Vertical = 426 * 120 / 160 = 319.5px
Horizontal = 320 * 120 / 160 = 240px
mdpi
Vertical = 470 * 160 / 160 = 470px
Horizontal = 320 * 160 / 160 = 320px
hdpi
Vertical = 640 * 240 / 160 = 960px
Horizontal = 480 * 240 / 160 = 720px
xhdpi
Vertical = 960 * 320 / 160 = 1920px
Horizontal = 720 * 320 / 160 = 1440px

px = dp*dpi/160

这是我从这个网站上得到的，也许它会有所帮助