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colorcrop.go

@@ -0,0 +1,67 @@
+// Go library for cropping images by removing borders with specified color.
+package colorcrop
+
+import (
+	"image"
+	"image/color"
+)
+
+// Crop returns cropped image with default comparator.
+func Crop(img image.Image, color color.Color, thresold float64) image.Image {
+	return CropWithComparator(img, color, thresold, CmpRGBComponentsDiff)
+}
+
+// Crop returns cropped image with specified comparator.
+func CropWithComparator(img image.Image, color color.Color, thresold float64, comparator comparator) image.Image {
+	return img.(interface {
+		SubImage(r image.Rectangle) image.Image
+	}).SubImage(cropRectanle(img, color, thresold, comparator))
+}
+
+// cropRectanle returns rectangle of image without borders.
+func cropRectanle(img image.Image, color color.Color, thresold float64, comparator comparator) image.Rectangle {
+	rectangle := img.Bounds()
+
+TopLoop:
+	for y := rectangle.Min.Y; y < rectangle.Max.Y; y++ {
+		rectangle.Min.Y = y
+		for x := rectangle.Min.X; x < rectangle.Max.X; x++ {
+			if comparator(img.At(x, y), color) > thresold {
+				break TopLoop
+			}
+		}
+	}
+
+BottomLoop:
+	for y := rectangle.Max.Y - 1; y >= rectangle.Min.Y; y-- {
+		rectangle.Max.Y = y + 1
+		for x := rectangle.Min.X; x < rectangle.Max.X; x++ {
+			if comparator(img.At(x, y), color) > thresold {
+				break BottomLoop
+			}
+		}
+	}
+
+LeftLoop:
+	for x := rectangle.Min.X; x < rectangle.Max.X; x++ {
+		rectangle.Min.X = x
+		for y := rectangle.Min.Y; y < rectangle.Max.Y; y++ {
+			if comparator(img.At(x, y), color) > thresold {
+				break LeftLoop
+			}
+		}
+
+	}
+
+RightLoop:
+	for x := rectangle.Max.X - 1; x >= rectangle.Min.X; x-- {
+		rectangle.Max.X = x + 1
+		for y := rectangle.Min.Y; y < rectangle.Max.Y; y++ {
+			if comparator(img.At(x, y), color) > thresold {
+				break RightLoop
+			}
+		}
+	}
+
+	return rectangle
+}