From b298cb019d019dbaf8aa3a3489a5d851798b26af Mon Sep 17 00:00:00 2001
From: Balakrishnan Balasubramanian <git.user@balki.me>
Date: Fri, 11 Aug 2023 23:20:53 -0400
Subject: [PATCH] add Make collage

---
 collage/collage.go      | 52 +++++++++++++++++++++++++++++++++--------
 collage/collage_test.go | 50 +++++++++++++++++++++++++++++++++++----
 2 files changed, 87 insertions(+), 15 deletions(-)

diff --git a/collage/collage.go b/collage/collage.go
index 61db586..832e17b 100644
--- a/collage/collage.go
+++ b/collage/collage.go
@@ -3,10 +3,13 @@ package collage
 
 import (
 	"errors"
-	"fmt"
 	"image"
+	"image/draw"
+	"image/jpeg"
 	"io"
 	"io/fs"
+
+	"go.oneofone.dev/resize"
 )
 
 type Dimension struct {
@@ -31,24 +34,53 @@ func (r Rectangle) ToImgRect() image.Rectangle {
 	}
 }
 
+type Photo struct {
+	ImageName string    `json:"image"`
+	Crop      Rectangle `json:"crop"`
+	Frame     Rectangle `json:"frame"`
+}
+
 type Request struct {
 	BackgroundImage string    `json:"background_image"`
 	Aspect          Dimension `json:"aspect"`
 	Dimension       Dimension `json:"dimension"`
-	Photos          []struct {
-		ImageName string    `json:"image"`
-		Crop      Rectangle `json:"crop"`
-		Frame     Rectangle `json:"frame"`
-	} `json:"photos"`
+	Photos          []Photo   `json:"photos"`
 }
 
-func Make(req Request, source fs.FS, output io.Writer) {
+func Make(req Request, source fs.FS, output io.Writer) error {
 	rec := image.Rect(0, 0, int(req.Aspect.Width), int(req.Aspect.Height))
 	canvas := image.NewRGBA64(rec)
-	for photo := range req.Photos {
-		fmt.Println(photo)
+	for _, photo := range req.Photos {
+		img, err := GetImage(source, photo.ImageName)
+		if err != nil {
+			return err
+		}
+		croppedImage, err := Crop(img, photo.Crop)
+		if err != nil {
+			return err
+		}
+
+		destRect := FrameTranslate(req.Aspect, req.Dimension, photo.Frame).ToImgRect()
+		resizedImg := resize.Resize(uint(destRect.Dx()), uint(destRect.Dy()), croppedImage, resize.Lanczos3)
+		draw.Draw(canvas, destRect, resizedImg, image.Point{0, 0}, draw.Src)
+	}
+	var opt jpeg.Options
+	opt.Quality = 100
+
+	return jpeg.Encode(output, canvas, &opt)
+}
+
+func FrameTranslate(resolution Dimension, frameSize Dimension, frame Rectangle) Rectangle {
+	newX := func(oldX uint) uint {
+		return oldX * resolution.Width / frameSize.Width
+	}
+	newY := func(oldY uint) uint {
+		return oldY * resolution.Height / frameSize.Height
+	}
+	return Rectangle{
+		Start: Point{newX(frame.Start.X), newY(frame.Start.Y)},
+		End:   Point{newX(frame.End.X), newY(frame.End.Y)},
 	}
-	fmt.Println(canvas)
 }
 
 type HasSubImage interface {
diff --git a/collage/collage_test.go b/collage/collage_test.go
index 49fa31c..5971111 100644
--- a/collage/collage_test.go
+++ b/collage/collage_test.go
@@ -26,12 +26,52 @@ func init() {
 }
 
 func TestMake(t *testing.T) {
-	t.Log("Test was run")
-	img1f, err := testDataFS.Open("img1.jpg")
-	if err != nil {
-		t.Fatalf("opening image failed %v", err)
+	req := Request{
+		BackgroundImage: "",
+		Aspect: Dimension{
+			Width:  816 * 4,
+			Height: 528 * 4 * 2,
+		},
+		Dimension: Dimension{
+			Width:  816,
+			Height: 528 * 2,
+		},
+		Photos: []Photo{
+			{
+				ImageName: "img1.jpg",
+				Crop: Rectangle{
+					Start: Point{
+						X: 431,
+						Y: 697,
+					},
+					End: Point{
+						X: 2514,
+						Y: 2047,
+					},
+				},
+				Frame: Rectangle{
+					Start: Point{
+						X: 0,
+						Y: 0,
+					},
+					End: Point{
+						X: 816,
+						Y: 528,
+					},
+				},
+			},
+		},
 	}
-	fmt.Printf("%#v\n", img1f)
+	out, err := os.Create("./test_op.jpg")
+	if err != nil {
+		t.Fatalf("failed to create ouput image file %v", err)
+	}
+
+	err = Make(req, testDataFS, out)
+	if err != nil {
+		t.Fatalf("failed to make collage %v", err)
+	}
+
 }
 
 func TestCrop(t *testing.T) {