Manga Border Cropper by Rieversed · Pull Request #239 · RyanYuuki/AnymeX

Rieversed · 2026-01-21T10:43:44Z

Pull Request

Title:
Manga Border Cropper

Description:
Add a new setting to toggle on/off border cropping for the manga reader. (Actual image cropping functionality mad by NITHINSPACETIME)

Summary of Changes:
Toggle for image cropping

Type of Changes:

Feature

Screen.Recording.2026-01-21.114243.mp4

Testing Notes:
Android Emulator

Linked Issue(s):
https://discord.com/channels/1303000390505336893/1436297600356843581

Additional Context:
CREDITS TO ORIGINAL COMMIT BY https://github.com/NITHINSPACETIME
aayush2622/Dartotsu#136
https://github.com/aayush2622/Dartotsu/blob/99596986956d17b1985df9c5be737f48c00a4167/lib/Functions/ImageCropper.dart

Submission Checklist:

[ ✅] I have read and followed the project's contributing guidelines
[ ✅] My code follows the code style of this project
[ ✅] I have tested the changes and ensured they do not break existing functionality
[ ✅] I have added or updated documentation as needed
[ ✅] I have linked related issues in the description above
[ ✅] I have tagged the appropriate reviewers for this pull request

Copilot

Pull request overview

This pull request adds a border cropping feature for the manga reader that allows users to automatically trim white and black borders from manga pages. The feature is implemented as a toggleable setting that users can enable or disable.

Changes:

Adds new image_cropper.dart utility with cropping logic and custom image widget
Implements UI toggle in reader settings for crop borders feature
Updates reader view to conditionally use cropped images based on user preference

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 11 comments.

File	Description
lib/utils/image_cropper.dart	New utility implementing image fetching, border detection/cropping algorithm, and custom CroppedNetworkImage widget with in-memory caching
lib/screens/manga/widgets/reader/settings_view.dart	Adds "Crop Borders" toggle switch in reader settings panel
lib/screens/manga/widgets/reader/reader_view.dart	Conditionally renders CroppedNetworkImage or ExtendedImage based on cropImages setting
lib/screens/manga/controller/reader_controller.dart	Adds cropImages state variable and persistence logic for the setting

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lib/utils/image_cropper.dart

Copilot · 2026-01-21T11:30:16Z

lib/utils/image_cropper.dart

+}
+
+class _CroppedNetworkImageState extends State<CroppedNetworkImage> {
+  static final Map<String, Uint8List> _cache = {};


The static cache map in _CroppedNetworkImageState can grow indefinitely as images are loaded, potentially causing memory issues. Each cropped image is stored in memory without any size limit or eviction policy. Consider implementing a cache size limit with an LRU (Least Recently Used) eviction strategy, or using a more sophisticated caching solution like flutter_cache_manager.

Copilot · 2026-01-21T11:30:16Z

lib/utils/image_cropper.dart

+img.Image _applyCrop(img.Image image, {required bool isWhite}) {
+  int width = image.width;
+  int height = image.height;
+  int left = 0;
+  int top = 0;
+  int right = width - 1;
+  int bottom = height - 1;
+  int threshold = 10;
+
+  bool isPixelContent(int x, int y) {
+    var pixel = image.getPixel(x, y);
+    num r = pixel.r;
+    num g = pixel.g;
+    num b = pixel.b;
+    num brightness = r + g + b;
+
+    if (isWhite) {
+      return brightness < (765 - (threshold * 3));
+    } else {
+      return brightness > (threshold * 3);
+    }
+  }
+
+  for (int x = 0; x < width; x++) {
+    bool stop = false;
+    for (int y = 0; y < height; y++) {
+      if (isPixelContent(x, y)) {
+        left = x;
+        stop = true;
+        break;
+      }
+    }
+    if (stop) break;
+  }
+
+  for (int x = width - 1; x >= left; x--) {
+    bool stop = false;
+    for (int y = 0; y < height; y++) {
+      if (isPixelContent(x, y)) {
+        right = x;
+        stop = true;
+        break;
+      }
+    }
+    if (stop) break;
+  }
+
+  for (int y = 0; y < height; y++) {
+    bool stop = false;
+    for (int x = left; x <= right; x++) {
+      if (isPixelContent(x, y)) {
+        top = y;
+        stop = true;
+        break;
+      }
+    }
+    if (stop) break;
+  }
+
+  for (int y = height - 1; y >= top; y--) {
+    bool stop = false;
+    for (int x = left; x <= right; x++) {
+      if (isPixelContent(x, y)) {
+        bottom = y;
+        stop = true;
+        break;
+      }
+    }
+    if (stop) break;
+  }
+
+  if (left > 0 || top > 0 || right < width - 1 || bottom < height - 1) {
+    int w = right - left + 1;
+    int h = bottom - top + 1;
+    if (w > 0 && h > 0) {
+      return img.copyCrop(image, x: left, y: top, width: w, height: h);
+    }
+  }
+
+  return image;


The image cropping operation is performed synchronously for every image load without timeouts. For large manga pages, the nested loops in _applyCrop can be computationally expensive (O(width * height) in worst case for each border detection), potentially blocking the UI and causing performance issues. Consider adding a timeout mechanism or optimizing the algorithm to sample pixels instead of checking every pixel.

Copilot · 2026-01-21T11:30:17Z

lib/utils/image_cropper.dart

+
+  image = _applyCrop(image, isWhite: false);
+
+  return img.encodePng(image);


The image is re-encoded to PNG format regardless of the original format (line 126). This can significantly increase file size and memory usage for images that were originally JPEG or WebP, which are common formats for manga pages. Consider preserving the original format or choosing an appropriate format based on the image content.

Suggested change

return img.encodePng(image);

// Choose an appropriate output format based on image content:

// - If the image has an alpha channel, keep PNG to preserve transparency.

// - Otherwise, use JPEG to avoid unnecessary file size inflation.

if (image.hasAlpha) {

return img.encodePng(image);

} else {

return img.encodeJpg(image, quality: 90);

}

Copilot · 2026-01-21T11:30:17Z

lib/utils/image_cropper.dart

+    return FutureBuilder<Uint8List>(
+      future: _futureBytes,
+      builder: (context, snapshot) {
+        if (snapshot.connectionState != ConnectionState.done) {
+          return widget.placeholder ?? const SizedBox.shrink();
+        }
+        if (snapshot.hasData &&
+            snapshot.data != null &&
+            snapshot.data!.isNotEmpty) {
+          return Image.memory(
+            snapshot.data!,
+            width: widget.width,
+            height: widget.height,
+            fit: widget.fit,
+            alignment: widget.alignment,
+          );
+        }
+        // Fallback: show nothing or a placeholder
+        return widget.placeholder ?? const SizedBox.shrink();
+      },


The FutureBuilder does not handle error states explicitly. If _loadBytes() throws an exception, the FutureBuilder will show hasData as false but won't distinguish between a loading state and an error state. Consider checking snapshot.hasError to provide appropriate error feedback to users.

lib/utils/image_cropper.dart

Copilot · 2026-01-21T11:30:18Z

lib/utils/image_cropper.dart

+  } catch (_) {
+    // Fall through to return empty/failed bytes


The catch block silently swallows all exceptions without logging or providing specific error information. This makes debugging network failures, parsing errors, or other issues difficult. Consider logging the error or providing more specific error handling to distinguish between different failure types (network errors, malformed URLs, image decoding failures, etc.).

Suggested change

} catch (_) {

// Fall through to return empty/failed bytes

} catch (e, stackTrace) {

// Log the error for debugging while still falling back to empty bytes.

debugPrint('fetchAndCropImageBytes failed for URL "$url": $e');

debugPrint('$stackTrace');

Copilot · 2026-01-21T11:30:18Z

lib/screens/manga/widgets/reader/reader_view.dart

+            ? CroppedNetworkImage(
+                url: page.url,
+                headers: (page.headers?.isEmpty ?? true)
+                    ? {
+                        'Referer':
+                            sourceController.activeMangaSource.value?.baseUrl ??
+                                ''
+                      }
+                    : page.headers,
+                fit: BoxFit.contain,
+                alignment: Alignment.center,
+              )


CroppedNetworkImage lacks loading and error state handling, unlike ExtendedImage.network which has comprehensive loadStateChanged callbacks. When cropping is enabled, users won't see progress indicators during loading or error messages with retry options when images fail to load. This creates an inconsistent user experience. Consider adding similar loading and error state widgets.

Copilot · 2026-01-21T11:30:18Z

lib/screens/manga/widgets/reader/reader_view.dart

+              ? CroppedNetworkImage(
+                  url: page.url,
+                  headers: (page.headers?.isEmpty ?? true)
+                      ? {
+                          'Referer': sourceController
+                                  .activeMangaSource.value?.baseUrl ??
+                              ''
+                        }
+                      : page.headers,
+                  fit: BoxFit.contain,
+                  alignment: Alignment.center,
+                )


CroppedNetworkImage lacks loading and error state handling, unlike ExtendedImage.network which has comprehensive loadStateChanged callbacks. When cropping is enabled, users won't see progress indicators during loading or error messages with retry options when images fail to load. This creates an inconsistent user experience. Consider adding similar loading and error state widgets.

@Copilot "The redundant .toString() call on line 69 has no effect since the expression is already a String. The map operation already produces a String via join(), so calling toString() on it is unnecessary. This line can be simplified to just use the result of join(';') directly or use an empty string as the null-coalescing fallback." Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

@Copilot "The HTTP request in fetchAndCropImageBytes lacks timeout configuration. Network requests without timeouts can hang indefinitely, especially on slow or unreliable connections. Consider adding a timeout parameter to the http.get call to prevent indefinite waiting and provide a better user experience." Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Rieversed added 5 commits January 21, 2026 11:21

The beggining lol

b67f39c

Refractor

8c7e7a2

Dart format

cde412b

Dart format again

4e1227f

Rename Settings

e111801

Rieversed changed the title ~~Manga Image Border Cropper~~ Manga Border Cropper Jan 21, 2026

itsmechinmoy requested review from RyanYuuki and Copilot and removed request for Copilot January 21, 2026 11:22

Copilot started reviewing on behalf of itsmechinmoy January 21, 2026 11:23 View session

Copilot AI reviewed Jan 21, 2026

View reviewed changes

Rieversed and others added 6 commits January 21, 2026 12:31

Test Update lib/utils/image_cropper.dart

06cba9f

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Useless ahh ai

cc9b468

increase time limit

54bc124

Merge branch 'main' into feature/manga-image-cropper

3c8375b

RyanYuuki merged commit f9a498f into RyanYuuki:main Jan 26, 2026
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Manga Border Cropper#239

Manga Border Cropper#239
RyanYuuki merged 11 commits intoRyanYuuki:mainfrom
Rieversed:feature/manga-image-cropper

Rieversed commented Jan 21, 2026 •

edited

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		image = _applyCrop(image, isWhite: false);

		return img.encodePng(image);

-  return img.encodePng(image);
+  // Choose an appropriate output format based on image content:
+  // - If the image has an alpha channel, keep PNG to preserve transparency.
+  // - Otherwise, use JPEG to avoid unnecessary file size inflation.
+  if (image.hasAlpha) {
+    return img.encodePng(image);
+  } else {
+    return img.encodeJpg(image, quality: 90);
+  }

-  } catch (_) {
-    // Fall through to return empty/failed bytes
+  } catch (e, stackTrace) {
+    // Log the error for debugging while still falling back to empty bytes.
+    debugPrint('fetchAndCropImageBytes failed for URL "$url": $e');
+    debugPrint('$stackTrace');

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Rieversed commented Jan 21, 2026 •

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