refactor: 抽象背景选择对话框为独立的BgSelectorDialog类

- 新增BgSelectorDialog对话框类，继承Dialog
- 新增dialog_bg_selector.xml布局文件定义对话框视图
- 重构ImageViewerActivity.switchBg()使用新的BgSelectorDialog
- 重构CropActivity.showBgDialog()使用新的BgSelectorDialog
- 统一两个Activity的背景选择交互方式

gallery/build.properties

@@ -1,8 +1,8 @@
 #Created by .winboll/winboll_app_build.gradle
-#Fri May 01 09:21:07 HKT 2026
+#Fri May 01 10:20:57 CST 2026
 stageCount=14
 libraryProject=
 baseVersion=15.0
 publishVersion=15.0.13
-buildCount=0
+buildCount=3
 baseBetaVersion=15.0.14

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

@@ -0,0 +1,64 @@
+package cc.winboll.studio.gallery;
+
+import android.app.Dialog;
+import android.content.Context;
+import android.view.View;
+import android.widget.RadioButton;
+import android.widget.RadioGroup;
+
+public class BgSelectorDialog extends Dialog {
+
+    public interface OnBgSelectedListener {
+        void onBgSelected(int bgType);
+    }
+
+    private int currentBgType;
+    private OnBgSelectedListener listener;
+
+    public BgSelectorDialog(Context context, int currentBgType) {
+        super(context);
+        this.currentBgType = currentBgType;
+        setContentView(R.layout.dialog_bg_selector);
+        initViews();
+    }
+
+    private void initViews() {
+        RadioGroup radioGroup = findViewById(R.id.radio_group_bg);
+        RadioButton radioCheckerboard = findViewById(R.id.radio_checkerboard);
+        RadioButton radioWhite = findViewById(R.id.radio_white);
+        RadioButton radioBlack = findViewById(R.id.radio_black);
+
+        switch (currentBgType) {
+            case 0:
+                radioCheckerboard.setChecked(true);
+                break;
+            case 1:
+                radioWhite.setChecked(true);
+                break;
+            case 2:
+                radioBlack.setChecked(true);
+                break;
+        }
+
+        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(RadioGroup group, int checkedId) {
+                int which = 0;
+                if (checkedId == R.id.radio_white) {
+                    which = 1;
+                } else if (checkedId == R.id.radio_black) {
+                    which = 2;
+                }
+
+                if (listener != null) {
+                    listener.onBgSelected(which);
+                }
+                dismiss();
+            }
+        });
+    }
+
+    public void setOnBgSelectedListener(OnBgSelectedListener listener) {
+        this.listener = listener;
+    }
+}

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

@@ -147,25 +147,20 @@ public class CropActivity extends AppCompatActivity {
     }
     
     private void showBgDialog() {
-        final String[] bgNames = {"灰白相间", "全白", "全黑"};
-        final int[] bgDrawables = {R.drawable.bg_checkerboard, R.drawable.bg_white, R.drawable.bg_black};
         final View colorView = findViewById(R.id.color_view);
         final GradientDrawable colorDrawable = (GradientDrawable) colorView.getBackground();
         final int currentBgType = cropCanvasView.getBackgroundType();
         
-        new AlertDialog.Builder(this)
-            .setTitle("选择背景")
-            .setSingleChoiceItems(bgNames, currentBgType, new android.content.DialogInterface.OnClickListener() {
-                @Override
-                public void onClick(android.content.DialogInterface dialog, int which) {
-                    cropCanvasView.setBackgroundType(which);
-                    prefs.setBgType(which);
-                    updateColorView(colorDrawable, which);
-                    dialog.dismiss();
-                }
-            })
-            .setNegativeButton("取消", null)
-            .show();
+        BgSelectorDialog dialog = new BgSelectorDialog(this, currentBgType);
+        dialog.setOnBgSelectedListener(new BgSelectorDialog.OnBgSelectedListener() {
+            @Override
+            public void onBgSelected(int which) {
+                cropCanvasView.setBackgroundType(which);
+                prefs.setBgType(which);
+                updateColorView(colorDrawable, which);
+            }
+        });
+        dialog.show();
     }
     
     private void loadImage() {

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

@@ -169,28 +169,24 @@ public class ImageViewerActivity extends Activity implements ViewPager.OnPageCha
     }
     
     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();
+        BgSelectorDialog dialog = new BgSelectorDialog(this, bgType);
+        dialog.setOnBgSelectedListener(new BgSelectorDialog.OnBgSelectedListener() {
+            @Override
+            public void onBgSelected(int which) {
+                bgType = which;
+                prefs.setBgType(which);
+                int currentItem = viewPager.getCurrentItem();
+                View container = findViewById(R.id.container);
+                if (container != null) {
+                    container.setBackgroundResource(bgResources[which]);
                 }
-            })
-            .setNegativeButton("取消", null)
-            .show();
+                viewPager.setAdapter(new ImagePagerAdapter(imageUrls, bgType));
+                viewPager.setCurrentItem(currentItem);
+            }
+        });
+        dialog.show();
     }
     
     private void showDeleteDialog() {

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

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical"
+    android:padding="16dp">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="选择背景"
+        android:textSize="20sp"
+        android:textStyle="bold"
+        android:gravity="center"
+        android:paddingBottom="16dp" />
+
+    <RadioGroup
+        android:id="@+id/radio_group_bg"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content">
+
+        <RadioButton
+            android:id="@+id/radio_checkerboard"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:text="灰白相间"
+            android:padding="12dp" />
+
+        <RadioButton
+            android:id="@+id/radio_white"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:text="全白"
+            android:padding="12dp" />
+
+        <RadioButton
+            android:id="@+id/radio_black"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:text="全黑"
+            android:padding="12dp" />
+
+    </RadioGroup>
+
+</LinearLayout>