Specify scale type for glide thumbnails.

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerManagementAdapter.java

@@ -273,6 +273,7 @@ final class StickerManagementAdapter extends SectionedRecyclerViewAdapter<String
 
       glideRequests.load(new DecryptableUri(stickerPack.getCover().getUri()))
                    .transition(DrawableTransitionOptions.withCrossFade())
+                   .fitCenter()
                    .set(ApngOptions.ANIMATE, allowApngAnimation)
                    .into(cover);
 

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerPackPreviewActivity.java

@@ -206,6 +206,7 @@ public final class StickerPackPreviewActivity extends PassphraseRequiredActivity
                                                 : new StickerRemoteUri(cover.getPackId(), cover.getPackKey(), cover.getId());
       GlideApp.with(this).load(model)
               .transition(DrawableTransitionOptions.withCrossFade())
+              .fitCenter()
               .set(ApngOptions.ANIMATE, DeviceProperties.shouldAllowApngStickerAnimation(this))
               .into(coverImage);
     } else {

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerPackPreviewAdapter.java

@@ -82,6 +82,7 @@ public final class StickerPackPreviewAdapter extends RecyclerView.Adapter<Sticke
       glideRequests.load(currentGlideModel)
                    .transition(DrawableTransitionOptions.withCrossFade())
                    .set(ApngOptions.ANIMATE, allowApngAnimation)
+                   .centerInside()
                    .into(image);
 
       image.setOnLongClickListener(v -> {

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerPreviewPopup.java

@@ -40,6 +40,7 @@ final class StickerPreviewPopup extends PopupWindow {
     emojiText.setText(emoji);
     glideRequests.load(stickerGlideModel)
                  .diskCacheStrategy(DiskCacheStrategy.NONE)
+                 .fitCenter()
                  .into(image);
   }
 }