text overlay x & y pos as params

internal/generator/text.go

@@ -48,7 +48,7 @@ func LoadFace(path string, size float64) (font.Face, error) {
 // NewTextOverlay rasterizes text (white, anti-aliased) onto a black backing
 // box, centered horizontally. Box width and x are multiples of 6 so the box
 // covers whole v210 blocks and the per-frame copy is word-aligned.
-func NewTextOverlay(text string, frameW, frameH int, face font.Face) (*TextOverlay, error) {
+func NewTextOverlay(text string, frameW, frameH, posX, posY int, face font.Face) (*TextOverlay, error) {
 	if text == "" {
 		return nil, fmt.Errorf("text: empty string")
 	}
@@ -89,10 +89,12 @@ func NewTextOverlay(text string, frameW, frameH int, face font.Face) (*TextOverl
 		return nil, fmt.Errorf("text: box %dpx does not fit frame height %dpx", topMargin+h, frameH)
 	}
 
+	// posX = ((frameW - w) / 2 / 6) * 6
+	// posY = topMargin
 	o := &TextOverlay{
 		frameW: frameW,
-		x:      ((frameW - w) / 2 / 6) * 6,
-		y:      topMargin,
+		x:      posX,
+		y:      posY,
 		w:      w,
 		h:      h,
 		cov:    make([]byte, w*h),