Scale wallpaper preview down

Author: suphon-t

lawnchair/src/app/lawnchair/ui/preferences/components/WallpaperPreview.kt

@@ -2,6 +2,7 @@ package app.lawnchair.ui.preferences.components
 
 import android.annotation.SuppressLint
 import android.app.WallpaperManager
+import android.graphics.drawable.BitmapDrawable
 import android.graphics.drawable.Drawable
 import androidx.compose.foundation.Image
 import androidx.compose.runtime.Composable
@@ -10,6 +11,8 @@ import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.platform.LocalContext
+import androidx.core.graphics.drawable.toBitmap
+import app.lawnchair.util.scaleDownToDisplaySize
 import com.google.accompanist.drawablepainter.rememberDrawablePainter
 import com.google.accompanist.permissions.*
 
@@ -35,7 +38,12 @@ fun wallpaperDrawable(): Drawable? {
 
     return when {
         wallpaperInfo != null -> remember { wallpaperInfo.loadThumbnail(context.packageManager) }
-        permissionState.status.isGranted -> remember { wallpaperManager.drawable }
+        permissionState.status.isGranted -> remember {
+            wallpaperManager.drawable?.let {
+                val bitmap = it.toBitmap().scaleDownToDisplaySize(context)
+                BitmapDrawable(context.resources, bitmap)
+            }
+        }
         permissionState.status.isGranted.not() -> {
             SideEffect { permissionState.launchPermissionRequest() }
             null

lawnchair/src/app/lawnchair/util/LawnchairUtils.kt

@@ -26,6 +26,8 @@ import android.content.Intent
 import android.content.pm.PackageInfo.REQUESTED_PERMISSION_GRANTED
 import android.content.pm.PackageManager
 import android.content.res.Resources
+import android.graphics.Bitmap
+import android.graphics.Matrix
 import android.net.Uri
 import android.os.Looper
 import android.provider.OpenableColumns
@@ -185,3 +187,32 @@ fun ContentResolver.getDisplayName(uri: Uri): String? {
     }
     return null
 }
+
+fun Bitmap.scaleDownToDisplaySize(context: Context, keepOriginal: Boolean = false): Bitmap {
+    val metrics = context.resources.displayMetrics
+    return scaleDownTo(kotlin.math.max(metrics.widthPixels, metrics.heightPixels), keepOriginal)
+}
+
+fun Bitmap.scaleDownTo(maxSize: Int, keepOriginal: Boolean = false): Bitmap {
+    val width = width
+    val height = height
+    val newWidth: Int
+    val newHeight: Int
+
+    when {
+        width > height && width > maxSize -> {
+            newWidth = maxSize
+            newHeight = (height * newWidth.toFloat() / width).toInt()
+        }
+        height > maxSize -> {
+            newHeight = maxSize
+            newWidth = (width * newHeight.toFloat() / height).toInt()
+        }
+        else -> return this
+    }
+    val newBitmap = Bitmap.createScaledBitmap(this, newWidth, newHeight, true)
+    if (!keepOriginal) {
+        recycle()
+    }
+    return newBitmap
+}