From 0609cdb4cd27b543f6926e53a0baac86c34945fa Mon Sep 17 00:00:00 2001
From: Meizar Rimadana <meizar.rimadana@formulatrix.com>
Date: Sun, 27 Jul 2025 16:09:11 +0700
Subject: [PATCH] cropping feature

---
 WebApp/ImageGenerator.cs | 63 +++++++++++++++++++++++++++++++++-------
 WebApp/RequestBody.cs    |  4 +++
 2 files changed, 57 insertions(+), 10 deletions(-)

diff --git a/WebApp/ImageGenerator.cs b/WebApp/ImageGenerator.cs
index 44955f9..3d29be6 100644
--- a/WebApp/ImageGenerator.cs
+++ b/WebApp/ImageGenerator.cs
@@ -54,7 +54,7 @@ public class ImageGenerator
         double scale = requestBody.OutputScale;
 
         (var matrix, int rowCount, int colCount) = GenerateMatrix(coord0, coord1);
-        Mat temp = GenerateTempMat(a1Mat, rowCount, colCount);
+        Mat temp = GenerateMatCanvas(a1Mat, rowCount, colCount, new Rect());
 
         Parallel.ForEach(matrix, item =>
         {
@@ -94,20 +94,42 @@ public class ImageGenerator
         Coordinate coord1 = new Coordinate(inputs[1]);
 
         (var matrix, int rowCount, int colCount) = GenerateMatrix(coord0, coord1);
-        Mat temp = GenerateTempMat(a1Mat, rowCount, colCount);
+        
+        Rect canvasRect = GenerateInitialRectCanvas(a1Mat, rowCount, colCount);
+        
+        //Determine cropping region
+        var globalRoI = GenerateGlobalRoI(requestBody.CropOffset, requestBody.CropSize, canvasRect.Width,
+            canvasRect.Height);
+        
+        Mat canvas = new Mat(globalRoI.Width, globalRoI.Height, a1Mat.Type());
 
         Parallel.ForEach(matrix, item =>
         {
-            Mat mat = new Mat(item.Path);
-            if (scale < 1)
+            try
             {
-                mat = mat.Resize(new Size(width, height));
+                Mat mat = new Mat(item.Path);
+                if (scale < 1)
+                {
+                    mat = mat.Resize(new Size(width, height));
+                }
+
+                Rect origin = new Rect((item.Col - 1) * a1Mat.Cols, (item.Row - 1) * a1Mat.Rows, a1Mat.Cols, a1Mat.Rows);
+                var offset = origin.Location;
+                var roi = origin.Intersect(globalRoI);
+                if (roi.Width == 0 || roi.Height == 0) return;
+                
+                Rect placement = roi.Subtract(globalRoI.Location);
+                var localRoi = roi.Subtract(offset);
+                var subMat = mat.SubMat(localRoi);
+                subMat.CopyTo(canvas[placement]);
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine( $"Error {item}, {e.Message}" );
             }
-            Rect rect = new Rect((item.Col - 1) * a1Mat.Cols, (item.Row - 1) * a1Mat.Rows, a1Mat.Cols, a1Mat.Rows);
-            mat.CopyTo(temp[rect]);
         });
 
-        var result = temp.ImEncode();
+        var result = canvas.ImEncode();
         var end = DateTime.Now;
         var elapsed = end - start;
         Console.WriteLine($"Elapsed: {elapsed.TotalMilliseconds} ms");
@@ -163,8 +185,29 @@ public class ImageGenerator
         return (results, rowCount, colCount);
     }
 
-    internal Mat GenerateTempMat(Mat reference, int rowCount, int colCount)
+    internal Mat GenerateMatCanvas(Mat reference, int rowCount, int colCount, Rect canvas)
     {
-        return new Mat(reference.Rows * rowCount, reference.Cols * colCount, reference.Type());
+        return new Mat(canvas.Width, canvas.Height, reference.Type());
+        // return new Mat(reference.Rows * rowCount - offset.X, reference.Cols * colCount - offset.Y, reference.Type());
+    }
+
+    private Rect GenerateInitialRectCanvas(Mat reference, int rowCount, int colCount)
+    {
+        int width = reference.Rows * rowCount;
+        int height = reference.Cols * colCount;
+        return new Rect(0, 0, width, height);
+    }
+
+    internal Rect GenerateGlobalRoI(double[] cropOffset, double[] cropSize, int width, int height)
+    {
+        int x = (int)(cropOffset[0] * width);
+        int y = (int)(cropOffset[1] * height);
+        width = (int)(cropSize[0] * width);
+        height = (int)(cropSize[1] * height);
+        
+        Point location = new Point(x, y);
+        Size size = new Size(width, height);
+        Rect cropRegion = new Rect( location, size);
+        return cropRegion;
     }
 }
\ No newline at end of file
diff --git a/WebApp/RequestBody.cs b/WebApp/RequestBody.cs
index 7421f68..9a821fa 100644
--- a/WebApp/RequestBody.cs
+++ b/WebApp/RequestBody.cs
@@ -5,5 +5,9 @@ namespace WebApp;
 public record struct RequestBody(
     [property: JsonPropertyName("canvas_rect")]
     string CanvasRect,
+    [property: JsonPropertyName("crop_offset")]
+    double[] CropOffset,
+    [property: JsonPropertyName("crop_size")]
+    double[] CropSize,
     [property: JsonPropertyName("output_scale")]
     double OutputScale );
\ No newline at end of file