Adds individual image crop validation

Images with invalid crop parameters are now ignored and the crop still occurs for the other, rather than canceling all cropping.

Author: BinaryAlley

README.md

@@ -54,9 +54,10 @@ Dataset Crop was built using [Avalonia UI](https://avaloniaui.net/), so it is cr
 5. Use the preview pane to adjust crop areas on each image. They can be positioned with the mouse.
 6. Checking the **Selection mode** option and clicking on the crop area of images will toggle their "selected" state. This allows you to exclude images from the crop process. 
    Excluded images will turn their crop area preview's background to a semi-transparent red.
-7. For the **Output Path** field, browse and select a directory where the cropped images will be saved, or manually paste the path in the text box.
-8. Execute the batch crop process by clicking the **Crop** button.
-9. The cropped images should be ready to be used in the training process. The input images are not modified in any way.
+7. When defining invalid parameters (for example, when setting crop width to 100 pixels, but the image width is just 84 pixels), the preview panes will be disabled and their background set to a semi-transparent red. These images cannot be selected, and they will not be cropped.
+8. For the **Output Path** field, browse and select a directory where the cropped images will be saved, or manually paste the path in the text box.
+9. Execute the batch crop process by clicking the **Crop** button.
+10. The cropped images should be ready to be used in the training process. The input images are not modified in any way.
 
 ## Contributing
 

src/DatasetCrop/MainWindow.axaml.cs

@@ -187,7 +187,7 @@ await Task.Run(async () =>
             });
 
             var loadedImages = await Task.WhenAll(loadTasks);
-            await Dispatcher.UIThread.InvokeAsync(async () =>
+            await Dispatcher.UIThread.InvokeAsync(() =>
             {
                 foreach (var loadedImage in loadedImages)
                 {
@@ -199,15 +199,7 @@ await Dispatcher.UIThread.InvokeAsync(async () =>
                     container.HorizontalAlignment = HorizontalAlignment.Left;
                     container.VerticalAlignment = VerticalAlignment.Top;
                     container.Background = new SolidColorBrush(Avalonia.Media.Color.FromRgb(0, 0, 0), 0.1);
-                    // for each image, ensure the drag panel is not in any way bigger than the visible area of the scaled down image preview
-                    if (!ValidateCropPanelSize(loadedImage.OriginalSize.Width, loadedImage.OriginalSize.Height, cropWidth, cropHeight, previewWidth, previewHeight))
-                    {
-                        await MessageBoxManager.GetMessageBoxStandardWindow("Error!", "Specified crop size exceeds the bounds of the scaled image!" + Environment.NewLine + loadedImage.FilePath, ButtonEnum.Ok, MessageBox.Avalonia.Enums.Icon.Error).ShowDialog(this);
-                        ClearImagePreviews();
-                        return;
-                    }
                     Avalonia.Controls.Image image = new();
-                    //image.Source = bitmap;
                     image.Width = previewWidth;
                     image.Height = previewHeight;
                     image.Source = loadedImage.Image;
@@ -234,14 +226,24 @@ await Dispatcher.UIThread.InvokeAsync(async () =>
                         dragPanel.Height = cropHeight;
                         dragPanel.Margin = new Thickness(cropX, cropY, 0, 0);
                     }
+                    // for each image, ensure the drag panel is not in any way bigger than the visible area of the scaled down image preview
+                    if (!ValidateCropPanelSize(loadedImage.OriginalSize.Width, loadedImage.OriginalSize.Height, cropWidth, cropHeight, previewWidth, previewHeight))
+                    {
+                        dragPanel.Tag = false; // do not select the image, if its crop parameters are not ok 
+                        dragPanel.Background = new SolidColorBrush(Avalonia.Media.Color.FromRgb(255, 0, 0), 0.3);
+                        dragPanel.IsEnabled = false; // don't allow dragging, when the image is not valid for cropping
+                    }
+                    else
+                    {
+                        dragPanel.Background = new SolidColorBrush(Avalonia.Media.Color.FromRgb(255, 255, 255), 0.3);
+                        dragPanel.Tag = true; // true = "selected" (will be cropped), false = "deselected" (will be ignored when cropping)
+                    }
                     dragPanel.HorizontalAlignment = HorizontalAlignment.Left;
                     dragPanel.VerticalAlignment = VerticalAlignment.Top;
-                    dragPanel.Background = new SolidColorBrush(Avalonia.Media.Color.FromRgb(255, 255, 255), 0.3);
                     dragPanel.Cursor = new Cursor(StandardCursorType.SizeAll);
                     dragPanel.PointerMoved += DragPanel_PointerMoved; // subscribe the event handlers used for dragging
                     dragPanel.PointerPressed += DragPanel_PointerPressed;
                     dragPanel.PointerReleased += DragPanel_PointerReleased;
-                    dragPanel.Tag = true; // true = "selected" (will be cropped), false = "deselected" (will be ignored when cropping)
 
                     container.Children.Add(dragPanel);
                     grdImages.Children.Add(container);
@@ -391,6 +393,7 @@ private static async Task<byte[]> CropImageAsync(SixLabors.ImageSharp.Image imag
         return outputMemoryStream.ToArray();
     }
 
+    #region Validation
     /// <summary>
     /// Validates the required information for setting the input path
     /// </summary>
@@ -647,6 +650,7 @@ private async Task<bool> ValidateImageFiles()
         else
             return true;
     }
+    #endregion
 
     /// <summary>
     /// Notifies subscribers about a property's value being changed
@@ -674,14 +678,14 @@ private void DragPanel_PointerPressed(object? sender, PointerPressedEventArgs e)
     {
         if (IsSelectionMode)
         {
-            if (sender is Panel dragPanel) // when Control is pressed, toggle the "is selected" state
+            if (sender is Panel dragPanel) 
             {
                 bool isSelected = (bool)dragPanel.Tag!;
                 dragPanel.Tag = !isSelected;
                 dragPanel.Background = new SolidColorBrush(Avalonia.Media.Color.FromRgb(255, (byte)(!isSelected ? 255 : 0), (byte)(!isSelected ? 255 : 0)), 0.3); 
             }
         }
-        else // Control is not pressed, just enable dragging
+        else // not in selection mode, just enable dragging
             isDragStarted = true;
     }