Added background color support and missing tile test

README.md

@@ -1,3 +1,8 @@
+[![GoDoc](https://godoc.org/github.com/brendan-ward/tilemerge?status.svg)](https://godoc.org/github.com/brendan-ward/tilemerge)
+[![Build Status](https://travis-ci.org/brendan-ward/tilemerge.svg?branch=master)](https://travis-ci.org/brendan-ward/tilemerge)
+[![Coverage Status](https://coveralls.io/repos/github/brendan-ward/tilemerge/badge.svg?branch=master)](https://coveralls.io/github/brendan-ward/tilemerge?branch=master)
+[![Go Report Card](https://goreportcard.com/badge/github.com/brendan-ward/tilemerge)](https://goreportcard.com/report/github.com/brendan-ward/tilemerge)
+
 # tilemerge
 Merge 2D map tiles into a single image.
 

tilemerge.go

@@ -6,8 +6,8 @@ import (
 	"image/color"
 	"image/draw"
 
-	_ "image/jpeg"
-	_ "image/png"
+	_ "image/jpeg" // load jpeg decoder
+	_ "image/png"  // load png decoder
 )
 
 // TILE_SIZE uses default size of map tiles for now
@@ -34,11 +34,15 @@ type Tiles struct {
 // Any tile that
 func Merge(tiles Tiles, xOff, yOff, width, height int, bg color.Color) (image.Image, error) {
 
-	// TODO: fill with background color.  Is this needed for transparency?
 	img := image.NewRGBA(image.Rect(0, 0,
 		(tiles.X1-tiles.X0+1)*TILE_SIZE,
 		(tiles.Y1-tiles.Y0+1)*TILE_SIZE))
 
+	if bg != nil {
+		// Fill background color
+		draw.Draw(img, img.Bounds(), &image.Uniform{bg}, image.ZP, draw.Src)
+	}
+
 	// tile transform is x = (tile.X - x0) * TILE_SIZE, y = (tile.Y - y) * TILE_SIZE
 	for _, tile := range tiles.Tiles {
 		if tile.Data == nil {

tilemerge_test.go

@@ -5,6 +5,7 @@ import (
 	"flag"
 	"fmt"
 	"image"
+	"image/color"
 	"image/jpeg"
 	"io/ioutil"
 	"os"
@@ -249,3 +250,37 @@ func Test_Merge_crop(t *testing.T) {
 	verifyDimensions(t, img, width, height)
 	verifyJPG(t, img, "test_data/output/test_crop.jpg")
 }
+
+func Test_Merge_Missing_Tile(t *testing.T) {
+	tiles := jpgTiles()
+	// remove a tile's data
+	tiles.Tiles[0].Data = nil
+	img, err := Merge(tiles, 0, 0, 2*TILE_SIZE, 2*TILE_SIZE, nil)
+	if err != nil {
+		panic(err)
+	}
+
+	if *update {
+		exportJPG(img, "test_data/output/test_missing.jpg")
+	}
+
+	verifyDimensions(t, img, 2*TILE_SIZE, 2*TILE_SIZE)
+	verifyJPG(t, img, "test_data/output/test_missing.jpg")
+}
+
+func Test_Merge_Background(t *testing.T) {
+	tiles := jpgTiles()
+	// remove a tile's data
+	tiles.Tiles[0].Data = nil
+	img, err := Merge(tiles, 0, 0, 2*TILE_SIZE, 2*TILE_SIZE, color.RGBA{uint8(255), uint8(0), uint8(0), uint8(255)})
+	if err != nil {
+		panic(err)
+	}
+
+	if *update {
+		exportJPG(img, "test_data/output/test_background.jpg")
+	}
+
+	verifyDimensions(t, img, 2*TILE_SIZE, 2*TILE_SIZE)
+	verifyJPG(t, img, "test_data/output/test_background.jpg")
+}