Trying to get the canvas looking okay. It doesn't

imaging/circles.go

@@ -1,43 +1,49 @@
 package imaging
 
 import (
+	"fmt"
 	"image"
+	"math"
 
 	"git.fjla.uk/fred.boniface/map-dots/data"
 	"git.fjla.uk/fred.boniface/map-dots/log"
 	"github.com/fogleman/gg"
 )
 
-func mapCirclesToCanvas(img *image.RGBA, circles []data.LocationData) {
-	log.Msg.Debug("Mapping circles to canvas")
+func mapCirclesToCanvas(img *image.RGBA, locations []data.LocationData) {
+	log.Msg.Debug("Mapping locations to canvas")
 	dc := gg.NewContextForRGBA(img)
 	dc.SetRGB(1, 1, 1) // Set canvas background color (white in this case)
 
-	circleRadius := 10 // Replace with your desired fixed radius
+	circleRadius := 4 // Replace with your desired fixed radius
 
 	bounds := img.Bounds()
 	canvasWidth := bounds.Max.X - bounds.Min.X
 	canvasHeight := bounds.Max.Y - bounds.Min.Y
 
 	var minLat, maxLat, minLon, maxLon float64
-	for _, circle := range circles {
-		if circle.Latitude < minLat {
-			minLat = circle.Latitude
+	for _, loc := range locations {
+		if loc.Latitude < minLat {
+			minLat = loc.Latitude
 		}
-		if circle.Latitude > maxLat {
-			maxLat = circle.Latitude
+		if loc.Latitude > maxLat {
+			maxLat = loc.Latitude
 		}
-		if circle.Longitude < minLon {
-			minLon = circle.Longitude
+		if loc.Longitude < minLon {
+			minLon = loc.Longitude
 		}
-		if circle.Longitude > maxLon {
-			maxLon = circle.Longitude
+		if loc.Longitude > maxLon {
+			maxLon = loc.Longitude
 		}
 	}
 
-	for _, circle := range circles {
-		// Convert latitude and longitude to pixel position on the canvas
-		pixelX, pixelY := convertCoordinatesToPixels(circle.Latitude, circle.Longitude, minLat, maxLat, minLon, maxLon, canvasWidth, canvasHeight)
+	centerLat := (maxLat + minLat) / 2.0
+	centerLon := (maxLon + minLon) / 2.0
+	latRange := maxLat - minLat
+	lonRange := maxLon - minLon
+
+	for _, loc := range locations {
+		pixelX, pixelY := convertCoordinatesToPixels(loc.Latitude, loc.Longitude, centerLat, centerLon, latRange, lonRange, canvasWidth, canvasHeight)
 
 		// Draw the circle on the canvas using gg
 		dc.DrawCircle(float64(pixelX), float64(pixelY), float64(circleRadius))
@@ -50,29 +56,27 @@ func mapCirclesToCanvas(img *image.RGBA, circles []data.LocationData) {
 	// Optional: Save the canvas as an image file
 	err := dc.SavePNG("output.png")
 	if err != nil {
-		// Handle error
+		log.Msg.Error("Error saving file")
+	} else {
+		fmt.Println("Canvas saves to file")
 	}
 }
 
-func convertCoordinatesToPixels(latitude, longitude float64, minLat, maxLat, minLon, maxLon float64, canvasWidth, canvasHeight int) (int, int) {
-	// Calculate margins as a percentage of canvas dimensions
-	marginPercentage := 0.1 // 10% margin
-	marginWidth := int(float64(canvasWidth) * marginPercentage)
-	marginHeight := int(float64(canvasHeight) * marginPercentage)
+func convertCoordinatesToPixels(latitude, longitude float64, centerLat, centerLon, latRange, lonRange float64, canvasWidth, canvasHeight int) (int, int) {
+	// Calculate normalized latitude and longitude distances from the center
+	latDist := (latitude - centerLat) / (latRange * 0.5)
+	lonDist := (longitude - centerLon) / (lonRange * 0.5)
 
-	// Adjust the bounding box with margins
-	minLat -= (maxLat - minLat) * marginPercentage
-	maxLat += (maxLat - minLat) * marginPercentage
-	minLon -= (maxLon - minLon) * marginPercentage
-	maxLon += (maxLon - minLon) * marginPercentage
+	// Calculate the maximum distance from the center as a proportion of canvas size
+	maxDistance := math.Max(math.Abs(latDist), math.Abs(lonDist))
 
-	// Calculate the position within the adjusted bounding box
-	latPercentage := (latitude - minLat) / (maxLat - minLat)
-	lonPercentage := (longitude - minLon) / (maxLon - minLon)
+	// Adjust the normalized distances to match the canvas size with margins
+	adjustedLatDist := latDist / maxDistance * 0.45
+	adjustedLonDist := lonDist / maxDistance * 0.45
 
-	// Calculate the pixel positions on the canvas
-	pixelX := int(lonPercentage*float64(canvasWidth-marginWidth*2)) + marginWidth
-	pixelY := canvasHeight - (int(latPercentage*float64(canvasHeight-marginHeight*2)) + marginHeight)
+	// Calculate pixel positions
+	pixelX := int((adjustedLonDist + 0.5) * float64(canvasWidth))
+	pixelY := int((0.5 - adjustedLatDist) * float64(canvasHeight))
 
 	return pixelX, pixelY
 }

run/server.go

@@ -60,6 +60,10 @@ func handleTraccarRequest(w http.ResponseWriter, r *http.Request) {
 		)
 	} else {
 		log.Msg.Debug("Position data fetched")
+		for _, loc := range locations {
+			fmt.Printf("Latitude: %.7f, Longitude: %.7f, Speed: %d, Altitude: %.4f\n",
+				loc.Latitude, loc.Longitude, loc.Speed, loc.Altitude)
+		}
 	}
 
 	var _ = imaging.Generate(height, width, style, format, locations)