✨ Ability to disable preview of assets using SpecialPickerType.noPreview (#102)

Author: yanivshaked

example/lib/pages/multi_assets_page.dart

@@ -191,6 +191,23 @@ class _MultiAssetsPageState extends State<MultiAssetsPage> {
             );
           },
         ),
+        PickMethodModel(
+          icon: '🚀',
+          name: 'No preview',
+          description: 'Pick assets like the WhatsApp/MegaTok pattern.',
+          method: (
+            BuildContext context,
+            List<AssetEntity> assets,
+          ) async {
+            return await AssetPicker.pickAssets(
+              context,
+              maxAssets: maxAssetsCount,
+              selectedAssets: assets,
+              requestType: RequestType.common,
+              specialPickerType: SpecialPickerType.noPreview,
+            );
+          },
+        ),
         PickMethodModel(
           icon: '🎚',
           name: 'Custom image preview thumb size',

example/lib/pages/single_assets_page.dart

@@ -186,6 +186,23 @@ class _SingleAssetPageState extends State<SingleAssetPage> {
             );
           },
         ),
+        PickMethodModel(
+          icon: '🚀',
+          name: 'No preview',
+          description: 'Pick assets like the WhatsApp/MegaTok pattern.',
+          method: (
+            BuildContext context,
+            List<AssetEntity> assets,
+          ) async {
+            return await AssetPicker.pickAssets(
+              context,
+              maxAssets: maxAssetsCount,
+              selectedAssets: assets,
+              requestType: RequestType.common,
+              specialPickerType: SpecialPickerType.noPreview,
+            );
+          },
+        ),
       ];
 
   Future<void> selectAssets(PickMethodModel model) async {

lib/src/constants/enums.dart

@@ -6,7 +6,27 @@
 /// Provide some special picker types to integrate
 /// un-common pick pattern.
 /// 提供一些特殊的选择器类型以整合非常规的选择行为。
-enum SpecialPickerType { wechatMoment }
+enum SpecialPickerType { 
+  /// WeChat Moments mode.
+  /// 微信朋友圈模式
+  ///
+  /// The user can only select *one video* or *multiple images* at the same time,
+  /// and those two asset types cannot be selected at the same time.
+  /// 用户只可以选择 **一个视频** 或 **多个图片**，并且两种类型互斥。
+  wechatMoment,
+
+  /// Disable preview of assets.
+  /// 禁用资源预览
+  ///
+  /// There is no preview mode when clicking grid items.
+  /// In multiple select mode, any click (either on the select indicator or on
+  /// the asset itself) will select the asset.
+  /// In single select mode, any click directly selects the asset and returns.
+  /// 用户在点击网格的 item 时无法进入预览。
+  /// 在多选模式下无论点击选择指示还是 item 都将触发选择，
+  /// 而在单选模式下将直接返回点击的资源。
+  noPreview,
+}
 
 /// Provide an item slot for custom widget insertion.
 /// 提供一个自定义位置供特殊item放入资源列表中。

lib/src/delegates/asset_picker_builder_delegate.dart

@@ -455,12 +455,15 @@ class DefaultAssetPickerBuilderDelegate
   /// The current special picker type for the picker.
   /// 当前特殊选择类型
   ///
-  /// There're several types which are special:
+  /// Several types which are special:
   /// * [SpecialPickerType.wechatMoment] When user selected video, no more images
   /// can be selected.
+  /// * [SpecialPickerType.noPreview] Disable preview of asset; Clicking on an
+  /// asset selects it.
   ///
   /// 这里包含一些特殊选择类型：
   /// * [SpecialPickerType.wechatMoment] 微信朋友圈模式。当用户选择了视频，将不能选择图片。
+  /// * [SpecialPickerType.noPreview] 禁用资源预览。多选时单击资产将直接选中，单选时选中并返回。
   final SpecialPickerType? specialPickerType;
 
   /// [Duration] when triggering path switching.
@@ -471,6 +474,10 @@ class DefaultAssetPickerBuilderDelegate
   /// 切换路径时的动画曲线
   Curve get switchingPathCurve => Curves.easeInOut;
 
+  /// Whether the preview of assets is enabled.
+  /// 资源的预览是否启用
+  bool get isPreviewEnabled => specialPickerType != SpecialPickerType.noPreview;
+
   @override
   Widget androidLayout(BuildContext context) {
     return FixedAppBarWrapper(
@@ -491,7 +498,8 @@ class DefaultAssetPickerBuilderDelegate
                         child: Column(
                           children: <Widget>[
                             Expanded(child: assetsGridBuilder(context)),
-                            if (!isSingleAssetMode) bottomActionBar(context),
+                            if (!isSingleAssetMode && isPreviewEnabled)
+                              bottomActionBar(context),
                           ],
                         ),
                       ),
@@ -513,7 +521,9 @@ class DefaultAssetPickerBuilderDelegate
       centerTitle: isAppleOS,
       title: pathEntitySelector(context),
       leading: backButton(context),
-      actions: !isAppleOS ? <Widget>[confirmButton(context)] : null,
+      actions: !isAppleOS && (isPreviewEnabled || !isSingleAssetMode)
+          ? <Widget>[confirmButton(context)]
+          : null,
       actionsPadding: const EdgeInsets.only(right: 14.0),
       blurRadius: isAppleOS ? appleOSBlurRadius : 0.0,
     );
@@ -537,7 +547,8 @@ class DefaultAssetPickerBuilderDelegate
                               Positioned.fill(
                                 child: assetsGridBuilder(context),
                               ),
-                              if (!isSingleAssetMode || isAppleOS)
+                              if ((!isSingleAssetMode || isAppleOS) &&
+                                  isPreviewEnabled)
                                 PositionedDirectional(
                                   bottom: 0.0,
                                   child: bottomActionBar(context),
@@ -1148,63 +1159,67 @@ class DefaultAssetPickerBuilderDelegate
         );
         final bool selected = selectedAssets.contains(asset);
         final double indicatorSize = Screens.width / gridCount / 3;
-        return Positioned(
-          top: 0.0,
-          right: 0.0,
-          child: GestureDetector(
-            behavior: HitTestBehavior.opaque,
-            onTap: () {
-              if (selected) {
-                provider.unSelectAsset(asset);
-              } else {
-                if (isSingleAssetMode) {
-                  provider.selectedAssets.clear();
-                }
-                provider.selectAsset(asset);
+        final Widget innerSelector = AnimatedContainer(
+          duration: switchingPathDuration,
+          width: indicatorSize / (isAppleOS ? 1.25 : 1.5),
+          height: indicatorSize / (isAppleOS ? 1.25 : 1.5),
+          decoration: BoxDecoration(
+            border:
+                !selected ? Border.all(color: Colors.white, width: 2.0) : null,
+            color: selected ? themeColor : null,
+            shape: BoxShape.circle,
+          ),
+          child: AnimatedSwitcher(
+            duration: switchingPathDuration,
+            reverseDuration: switchingPathDuration,
+            child: selected
+                ? isSingleAssetMode
+                    ? const Icon(Icons.check, size: 18.0)
+                    : Text(
+                        '${selectedAssets.indexOf(asset) + 1}',
+                        style: TextStyle(
+                          color: selected
+                              ? theme.textTheme.bodyText1?.color
+                              : null,
+                          fontSize: isAppleOS ? 16.0 : 14.0,
+                          fontWeight:
+                              isAppleOS ? FontWeight.w600 : FontWeight.bold,
+                        ),
+                      )
+                : const SizedBox.shrink(),
+          ),
+        );
+        final GestureDetector selectorWidget = GestureDetector(
+          behavior: HitTestBehavior.opaque,
+          onTap: () {
+            if (selected) {
+              provider.unSelectAsset(asset);
+            } else {
+              if (isSingleAssetMode) {
+                provider.selectedAssets.clear();
               }
-            },
-            child: Container(
-              margin: EdgeInsets.all(
-                Screens.width / gridCount / (isAppleOS ? 12.0 : 15.0),
-              ),
-              width: indicatorSize,
-              height: indicatorSize,
-              alignment: AlignmentDirectional.topEnd,
-              child: AnimatedContainer(
-                duration: switchingPathDuration,
-                width: indicatorSize / (isAppleOS ? 1.25 : 1.5),
-                height: indicatorSize / (isAppleOS ? 1.25 : 1.5),
-                decoration: BoxDecoration(
-                  border: !selected
-                      ? Border.all(color: Colors.white, width: 2.0)
-                      : null,
-                  color: selected ? themeColor : null,
-                  shape: BoxShape.circle,
-                ),
-                child: AnimatedSwitcher(
-                  duration: switchingPathDuration,
-                  reverseDuration: switchingPathDuration,
-                  child: selected
-                      ? isSingleAssetMode
-                          ? const Icon(Icons.check, size: 18.0)
-                          : Text(
-                              '${selectedAssets.indexOf(asset) + 1}',
-                              style: TextStyle(
-                                color: selected
-                                    ? theme.textTheme.bodyText1?.color
-                                    : null,
-                                fontSize: isAppleOS ? 16.0 : 14.0,
-                                fontWeight: isAppleOS
-                                    ? FontWeight.w600
-                                    : FontWeight.bold,
-                              ),
-                            )
-                      : const SizedBox.shrink(),
-                ),
-              ),
+              provider.selectAsset(asset);
+              if (isSingleAssetMode && !isPreviewEnabled) {
+                Navigator.of(context).pop(provider.selectedAssets);
+              }
+            }
+          },
+          child: Container(
+            margin: EdgeInsets.all(
+              Screens.width / gridCount / (isAppleOS ? 12.0 : 15.0),
             ),
+            width: isPreviewEnabled ? indicatorSize : null,
+            height: isPreviewEnabled ? indicatorSize : null,
+            alignment: AlignmentDirectional.topEnd,
+            child: (!isPreviewEnabled && isSingleAssetMode && !selected)
+                ? const SizedBox.shrink()
+                : innerSelector,
           ),
         );
+        if (isPreviewEnabled) {
+          return Positioned(top: 0.0, right: 0.0, child: selectorWidget);
+        }
+        return selectorWidget;
       },
     );
   }
@@ -1214,9 +1229,9 @@ class DefaultAssetPickerBuilderDelegate
     return Positioned.fill(
       child: GestureDetector(
         onTap: () async {
-          // While the special type is WeChat moment, picture and video cannot
+          // When the special type is WeChat Moment, pictures and videos cannot
           // be selected at the same time. Video select should be banned if any
-          // picture is selected.
+          // pictures are selected.
           if (specialPickerType == SpecialPickerType.wechatMoment &&
               asset.type == AssetType.video &&
               provider.selectedAssets.isNotEmpty) {

lib/src/widget/asset_picker.dart

@@ -56,14 +56,13 @@ class AssetPicker<A, P> extends StatelessWidget {
         'Theme and theme color cannot be set at the same time.',
       );
     }
-    if (specialPickerType != null && requestType != RequestType.image) {
-      throw ArgumentError(
-        'specialPickerType and requestType cannot be set at the same time.',
-      );
-    } else {
-      if (specialPickerType == SpecialPickerType.wechatMoment) {
-        requestType = RequestType.common;
+    if (specialPickerType == SpecialPickerType.wechatMoment) {
+      if (requestType != RequestType.image) {
+        throw ArgumentError(
+          'SpecialPickerType.wechatMoment and requestType cannot be set at the same time.',
+        );
       }
+      requestType = RequestType.common;
     }
     if ((specialItemBuilder == null &&
             specialItemPosition != SpecialItemPosition.none) ||