rendering tests fixed

internal/generator/text_test.go

@@ -1,8 +1,8 @@
 package generator
 
 import (
-	"encoding/binary"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"golang.org/x/image/font"
@@ -32,11 +32,8 @@ func TestNewTextOverlay(t *testing.T) {
 	if o.x%6 != 0 {
 		t.Fatalf("x=%d not a multiple of 6", o.x)
 	}
-	if center := o.x + o.w/2; center < frameW/2-3 || center > frameW/2+3 {
-		t.Fatalf("box center %d not near frame center %d", center, frameW/2)
-	}
-	if o.y != 48 {
-		t.Fatalf("y=%d, want 48", o.y)
+	if o.x != 0 || o.y != 0 {
+		t.Fatalf("position = (%d,%d), want (0,0)", o.x, o.y)
 	}
 	if o.blocks == nil || len(o.blocks) != o.h*(o.w/6)*16 {
 		t.Fatalf("pre-packed tile has wrong size")
@@ -87,6 +84,78 @@ func TestNewTextOverlay(t *testing.T) {
 	}
 }
 
+func TestNewTextOverlayPositioning(t *testing.T) {
+	const frameW, frameH = 1920, 1080
+	face := testFace(t, 48)
+
+	t.Run("explicit", func(t *testing.T) {
+		o, err := NewTextOverlay("AB", frameW, frameH, 120, 48, "", face)
+		if err != nil {
+			t.Fatalf("NewTextOverlay: %v", err)
+		}
+		if o.x != 120 || o.y != 48 {
+			t.Fatalf("position = (%d,%d), want (120,48)", o.x, o.y)
+		}
+	})
+
+	for _, tc := range []struct {
+		name string
+		pos  string
+		want func(*TextOverlay) bool
+	}{
+		{name: "top center", pos: "tc", want: func(o *TextOverlay) bool {
+			return o.x%6 == 0 && absInt((o.x+o.w/2)-frameW/2) <= 3 && o.y == 0
+		}},
+		{name: "center", pos: "cc", want: func(o *TextOverlay) bool {
+			return o.x%6 == 0 && absInt((o.x+o.w/2)-frameW/2) <= 3 && o.y == (frameH-o.h)/2
+		}},
+		{name: "bottom right", pos: "br", want: func(o *TextOverlay) bool {
+			return o.x+o.w == frameW && o.y+o.h == frameH
+		}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			o, err := NewTextOverlay("AB", frameW, frameH, 0, 0, tc.pos, face)
+			if err != nil {
+				t.Fatalf("NewTextOverlay: %v", err)
+			}
+			if !tc.want(o) {
+				t.Fatalf("unexpected %s position: box=(%d,%d %dx%d)", tc.pos, o.x, o.y, o.w, o.h)
+			}
+		})
+	}
+}
+
+func TestNewTextOverlayRejectsInvalidPosition(t *testing.T) {
+	const frameW, frameH = 1920, 1080
+	face := testFace(t, 48)
+
+	tests := []struct {
+		name       string
+		x, y       int
+		wantErrSub string
+	}{
+		{name: "unaligned x", x: 7, y: 0, wantErrSub: "divisible by 6"},
+		{name: "negative x", x: -6, y: 0, wantErrSub: "must not be negative"},
+		{name: "right overflow", x: 1902, y: 0, wantErrSub: "does not fit"},
+		{name: "bottom overflow", x: 0, y: 1070, wantErrSub: "does not fit"},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := NewTextOverlay("AB", frameW, frameH, tc.x, tc.y, "", face)
+			if err == nil || !strings.Contains(err.Error(), tc.wantErrSub) {
+				t.Fatalf("error = %v, want substring %q", err, tc.wantErrSub)
+			}
+		})
+	}
+}
+
+func absInt(v int) int {
+	if v < 0 {
+		return -v
+	}
+	return v
+}
+
 func TestTextOverlayApplyV210(t *testing.T) {
 	const frameW, frameH = 1920, 1080
 	o, err := NewTextOverlay("MXL", frameW, frameH, 0, 0, "", testFace(t, 48))
@@ -102,34 +171,11 @@ func TestTextOverlayApplyV210(t *testing.T) {
 		t.Fatalf("ApplyV210: %v", err)
 	}
 
-	sample := func(x, y int) (yc, cb, cr uint32) {
-		p := y*frameW + x
-		off := (p / 6) * 16
-		w0 := binary.LittleEndian.Uint32(frame[off:])
-		w1 := binary.LittleEndian.Uint32(frame[off+4:])
-		w2 := binary.LittleEndian.Uint32(frame[off+8:])
-		w3 := binary.LittleEndian.Uint32(frame[off+12:])
-		switch p % 6 {
-		case 0:
-			return (w0 >> 10) & 0x3FF, w0 & 0x3FF, (w0 >> 20) & 0x3FF
-		case 1:
-			return w1 & 0x3FF, w0 & 0x3FF, (w0 >> 20) & 0x3FF
-		case 2:
-			return (w1 >> 20) & 0x3FF, (w1 >> 10) & 0x3FF, w2 & 0x3FF
-		case 3:
-			return (w2 >> 10) & 0x3FF, (w1 >> 10) & 0x3FF, w2 & 0x3FF
-		case 4:
-			return w3 & 0x3FF, (w2 >> 20) & 0x3FF, (w3 >> 10) & 0x3FF
-		default:
-			return (w3 >> 20) & 0x3FF, (w2 >> 20) & 0x3FF, (w3 >> 10) & 0x3FF
-		}
-	}
-
 	// Every box pixel: Y from coverage, neutral chroma at even columns.
 	for row := 0; row < o.h; row++ {
 		for col := 0; col < o.w; col++ {
 			wantY := uint32(64 + (int(o.cov[row*o.w+col])*876+127)/255)
-			yc, cb, cr := sample(o.x+col, o.y+row)
+			yc, cb, cr := sampleV210(frame, frameW, o.x+col, o.y+row)
 			if yc != wantY {
 				t.Fatalf("box pixel (%d,%d): Y=%d, want %d", o.x+col, o.y+row, yc, wantY)
 			}