添加图片默认背景切换功能

- 工具栏添加背景切换按钮，点击弹出对话框
- 支持三种背景模式：灰白相间、全白、全黑
- 背景设置持久化保存，应用重启后保持原设置
- 切换背景时保持当前浏览的图片位置

gallery/build.properties

@@ -1,8 +1,8 @@
 #Created by .winboll/winboll_app_build.gradle
-#Sat Apr 25 19:16:31 CST 2026
+#Sat Apr 25 19:42:01 CST 2026
 stageCount=3
 libraryProject=
 baseVersion=15.0
 publishVersion=15.0.2
-buildCount=4
+buildCount=8
 baseBetaVersion=15.0.3

gallery/src/main/java/cc/winboll/studio/gallery/ImagePagerAdapter.java

@@ -16,10 +16,25 @@ import cc.winboll.studio.libappbase.LogUtils;
 public class ImagePagerAdapter extends PagerAdapter {
     public static final String TAG = "ImagePagerAdapter";
     private ArrayList<Uri> imageUrls;
+    private int bgType;
 
-    public ImagePagerAdapter(ArrayList<Uri> imageUrls) {
+    public ImagePagerAdapter(ArrayList<Uri> imageUrls, int bgType) {
         this.imageUrls = imageUrls;
-        LogUtils.d(TAG, "ImagePagerAdapter created with " + imageUrls.size() + " images");
+        this.bgType = bgType;
+        LogUtils.d(TAG, "ImagePagerAdapter created with " + imageUrls.size() + " images, bgType=" + bgType);
+    }
+    
+    private int getBgRes() {
+        switch (bgType) {
+            case 0:
+                return R.drawable.bg_checkerboard;
+            case 1:
+                return R.drawable.bg_white;
+            case 2:
+                return R.drawable.bg_black;
+            default:
+                return R.drawable.bg_checkerboard;
+        }
     }
 
     @Override
@@ -32,6 +47,7 @@ public class ImagePagerAdapter extends PagerAdapter {
     public Object instantiateItem(@NonNull ViewGroup container, int position) {
         View view = LayoutInflater.from(container.getContext())
             .inflate(R.layout.item_image_pager, container, false);
+        view.setBackgroundResource(getBgRes());
         ImageView imageView = view.findViewById(R.id.image);
         
         Glide.with(imageView.getContext())

gallery/src/main/java/cc/winboll/studio/gallery/ImageViewerActivity.java

@@ -33,8 +33,11 @@ public class ImageViewerActivity extends Activity implements ViewPager.OnPageCha
     private ImageButton btnDelete;
     private ImageButton btnShare;
     private ImageButton btnInfo;
+    private ImageButton btnBg;
+    private int bgType = 0;
     private GestureDetector gestureDetector;
     private TrashManager trashManager;
+    private Preferences prefs;
     
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -49,6 +52,8 @@ public class ImageViewerActivity extends Activity implements ViewPager.OnPageCha
         currentPosition = getIntent().getIntExtra(EXTRA_POSITION, 0);
         
         trashManager = new TrashManager(this);
+        prefs = new Preferences(this);
+        bgType = prefs.getBgType();
         
         viewPager = findViewById(R.id.view_pager);
         toolbar = findViewById(R.id.toolbar);
@@ -56,8 +61,11 @@ public class ImageViewerActivity extends Activity implements ViewPager.OnPageCha
         btnDelete = findViewById(R.id.btn_delete);
         btnShare = findViewById(R.id.btn_share);
         btnInfo = findViewById(R.id.btn_info);
+        btnBg = findViewById(R.id.btn_bg);
         
-        ImagePagerAdapter adapter = new ImagePagerAdapter(imageUrls);
+        applyBg();
+        
+        ImagePagerAdapter adapter = new ImagePagerAdapter(imageUrls, bgType);
         viewPager.setAdapter(adapter);
         viewPager.setCurrentItem(currentPosition);
         viewPager.addOnPageChangeListener(this);
@@ -104,6 +112,13 @@ public class ImageViewerActivity extends Activity implements ViewPager.OnPageCha
                 showImageInfo();
             }
         });
+        
+        btnBg.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                switchBg();
+            }
+        });
     }
     
     private void toggleToolbar() {
@@ -114,6 +129,52 @@ public class ImageViewerActivity extends Activity implements ViewPager.OnPageCha
         }
     }
     
+    private void applyBg() {
+        int bgRes;
+        switch (bgType) {
+            case 0:
+                bgRes = R.drawable.bg_checkerboard;
+                break;
+            case 1:
+                bgRes = R.drawable.bg_white;
+                break;
+            case 2:
+                bgRes = R.drawable.bg_black;
+                break;
+            default:
+                bgRes = R.drawable.bg_checkerboard;
+        }
+        View container = findViewById(R.id.container);
+        if (container != null) {
+            container.setBackgroundResource(bgRes);
+        }
+    }
+    
+    private void switchBg() {
+        final String[] bgNames = {"灰白相间", "全白", "全黑"};
+        final int[] bgResources = {R.drawable.bg_checkerboard, R.drawable.bg_white, R.drawable.bg_black};
+        
+        new AlertDialog.Builder(this)
+            .setTitle("选择背景")
+            .setSingleChoiceItems(bgNames, bgType, new android.content.DialogInterface.OnClickListener() {
+                @Override
+                public void onClick(android.content.DialogInterface dialog, int which) {
+                    bgType = which;
+                    prefs.setBgType(which);
+                    int currentItem = viewPager.getCurrentItem();
+                    View container = findViewById(R.id.container);
+                    if (container != null) {
+                        container.setBackgroundResource(bgResources[which]);
+                    }
+                    viewPager.setAdapter(new ImagePagerAdapter(imageUrls, bgType));
+                    viewPager.setCurrentItem(currentItem);
+                    dialog.dismiss();
+                }
+            })
+            .setNegativeButton("取消", null)
+            .show();
+    }
+    
     private void showDeleteDialog() {
         new AlertDialog.Builder(this)
             .setMessage("Delete to trash?")
@@ -178,7 +239,7 @@ public class ImageViewerActivity extends Activity implements ViewPager.OnPageCha
             if (currentPosition >= imageUrls.size()) {
                 currentPosition = imageUrls.size() - 1;
             }
-            viewPager.setAdapter(new ImagePagerAdapter(imageUrls));
+            viewPager.setAdapter(new ImagePagerAdapter(imageUrls, bgType));
             viewPager.setCurrentItem(currentPosition);
         }
     }

gallery/src/main/java/cc/winboll/studio/gallery/Preferences.java

@@ -8,6 +8,8 @@ public class Preferences {
     public static final String TAG = "Preferences";
     private static final String PREF_NAME = "gallery_prefs";
     private static final String KEY_FOLDER_PATH = "folder_path";
+    private static final String KEY_BG_TYPE = "bg_type";
+    private static final int DEFAULT_BG_TYPE = 0;
     private static final String DEFAULT_PATH = "/storage/emulated/0/Pictures/Gallery/owner";
     
     public static String getDefaultPath() {
@@ -30,4 +32,13 @@ public class Preferences {
         LogUtils.d(TAG, "setFolderPath: " + path);
         prefs.edit().putString(KEY_FOLDER_PATH, path).apply();
     }
+    
+    public int getBgType() {
+        return prefs.getInt(KEY_BG_TYPE, DEFAULT_BG_TYPE);
+    }
+    
+    public void setBgType(int type) {
+        LogUtils.d(TAG, "setBgType: " + type);
+        prefs.edit().putInt(KEY_BG_TYPE, type).apply();
+    }
 }

gallery/src/main/res/drawable/bg_black.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+    <solid android:color="#000000"/>
+</shape>

gallery/src/main/res/drawable/bg_white.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+    <solid android:color="#FFFFFF"/>
+</shape>

gallery/src/main/res/drawable/ic_bg.xml

@@ -0,0 +1,12 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FFFFFF"
+        android:pathData="M4,4h7v7h-7z M13,4h7v7h-7z M4,13h7v7h-7z M13,13h7v7h-7z"/>
+    <path
+        android:fillColor="#808080"
+        android:pathData="M11,4h2v7h-2z M4,11h7v2h-7z M13,11h7v2h-7z M11,13h2v7h-2z M13,4h2v7h-2z M4,13h7v2h-7z"/>
+</vector>

gallery/src/main/res/layout/activity_image_viewer.xml

@@ -52,6 +52,14 @@
             android:src="@drawable/ic_info"
             android:contentDescription="Info"/>
 
+        <ImageButton
+            android:id="@+id/btn_bg"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:background="?attr/selectableItemBackgroundBorderless"
+            android:src="@drawable/ic_bg"
+            android:contentDescription="Background"/>
+
         <ImageButton
             android:id="@+id/btn_delete"
             android:layout_width="48dp"

gallery/src/main/res/layout/item_image_pager.xml

@@ -2,8 +2,7 @@
 <FrameLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="match_parent"
+    android:layout_height="match_parent">
-    android:background="@drawable/bg_checkerboard">
 
     <ImageView
         android:id="@+id/image"