xxhdpi屏幕上使用的最低dpi可绘制

Question

I have two imagebuttons, with dimensions 256x256 dp and scaleType="centerCrop" . When I see the preview in AS or when I launch the application on my nexus 5 the images are blurry. The images are of the right dimensions for the respective folders, up to xxxhdpi(192x192).

<LinearLayout
    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:orientation="vertical"
    android:background="@android:color/black">

    <ImageButton
        android:layout_marginTop="48dp"
        android:layout_width="256dp"
        android:layout_height="256dp"
        android:id="@+id/button"
        android:layout_gravity="center_horizontal"
        android:src="@mipmap/button_off"
        android:background="@android:color/black"
        android:scaleType="centerInside"
        />
    <ImageButton
        android:layout_width="256dp"
        android:layout_height="256dp"
        android:id="@+id/second_button"
        android:layout_gravity="center_horizontal"
        android:src="@mipmap/second_off"
        android:background="@android:color/black"
        android:scaleType="centerInside"
        />

</LinearLayout>

Answer 1

Please see this documentation first

https://developer.android.com/guide/topics/resources/providing-resources.html

then check your project structure. It's quite unlikely you got this part wrong and there're low-res resources matching first.

Answer 2

If I understood it right - in your XML layout file you set an ImageButton with width=256dp and height=256dp , and src=drawable/your_drawable. The xxxhdpi drawable has width and height 192px (I assume than mdpi - 48, hdpi - 72, xhdpi - 96, xxhdpi - 144, xxxhdpi - 192).

If so, than of course the images are blurred, because you set the ImageButtons width/height in mdpi (in xml to 256dp), but you used 144x144 (nexus 5 is xxhdpi) Drawable stretched (because of the scaleType= centerCrop ).

If you don't want to have stretched images, here are some options for you (maybe not all):

1. you need to change the scaleType to centerInside (or without scaleType) - you will get smaller buttons - the images are scaleDowned only if needed
2. you need to make the ImageButton smaller - 48x48
3. you need to add bigger drawable resources - your mdpi drawable should be as big as your ImageButton in xml (mdpi - 256x 256, hdpi - 384x384, xhdpi - 512x512, xxhdpi - 768x768, xxxhdpi - 1024x1024)
4. you post some layout code (XML) in your question with detailed drawable resources resolution which you used and maybe we can make further investigation in your problem