Quick/dirty fix: apply rotation after text-offset

src/symbol/quads.js

@@ -153,8 +153,10 @@ function getIconQuads(anchor, shapedIcon, boxScale, line, layer, alongLine, shap
  */
 function getGlyphQuads(anchor, shaping, boxScale, line, layer, alongLine, globalProperties, featureProperties) {
 
+    const oneEm = 24;
     const textRotate = layer.getLayoutValue('text-rotate', globalProperties, featureProperties) * Math.PI / 180;
     const keepUpright = layer.layout['text-keep-upright'];
+    const textOffset = layer.getLayoutValue('text-offset', globalProperties, featureProperties).map((t)=> t * oneEm);
 
     const positionedGlyphs = shaping.positionedGlyphs;
     const quads = [];
@@ -189,32 +191,19 @@ function getGlyphQuads(anchor, shaping, boxScale, line, layer, alongLine, global
             }];
         }
 
-        const x1 = positionedGlyph.x + glyph.left;
-        const y1 = positionedGlyph.y - glyph.top;
-        const x2 = x1 + rect.w;
-        const y2 = y1 + rect.h;
-
-        const center = new Point(positionedGlyph.x, glyph.advance / 2);
-
-        const otl = new Point(x1, y1);
-        const otr = new Point(x2, y1);
-        const obl = new Point(x1, y2);
-        const obr = new Point(x2, y2);
-
-        if (positionedGlyph.angle !== 0) {
-            otl._sub(center)._rotate(positionedGlyph.angle)._add(center);
-            otr._sub(center)._rotate(positionedGlyph.angle)._add(center);
-            obl._sub(center)._rotate(positionedGlyph.angle)._add(center);
-            obr._sub(center)._rotate(positionedGlyph.angle)._add(center);
-        }
+        const baseQuad = {
+            upright: calculateBaseQuad(positionedGlyph, glyph, rect, textOffset),
+            upsideDown: calculateBaseQuad(positionedGlyph, glyph, rect, [textOffset[0], -textOffset[1]])
+        };
 
         for (let i = 0; i < glyphInstances.length; i++) {
 
             const instance = glyphInstances[i];
-            let tl = otl,
-                tr = otr,
-                bl = obl,
-                br = obr;
+            const base = baseQuad[instance.upsideDown ? 'upsideDown' : 'upright'];
+            let tl = base.tl,
+                tr = base.tr,
+                bl = base.bl,
+                br = base.br;
 
             if (textRotate) {
                 const sin = Math.sin(textRotate),
@@ -240,6 +229,30 @@ function getGlyphQuads(anchor, shaping, boxScale, line, layer, alongLine, global
     return quads;
 }
 
+function calculateBaseQuad(positionedGlyph, glyph, rect, offset) {
+    const x1 = positionedGlyph.x + glyph.left + offset[0];
+    const y1 = positionedGlyph.y - glyph.top + offset[1];
+    const x2 = x1 + rect.w;
+    const y2 = y1 + rect.h;
+
+    const center = new Point(positionedGlyph.x, glyph.advance / 2);
+
+    const tl = new Point(x1, y1);
+    const tr = new Point(x2, y1);
+    const bl = new Point(x1, y2);
+    const br = new Point(x2, y2);
+
+    if (positionedGlyph.angle !== 0) {
+        tl._sub(center)._rotate(positionedGlyph.angle)._add(center);
+        tr._sub(center)._rotate(positionedGlyph.angle)._add(center);
+        bl._sub(center)._rotate(positionedGlyph.angle)._add(center);
+        br._sub(center)._rotate(positionedGlyph.angle)._add(center);
+    }
+
+    return { tl, tr, bl, br };
+}
+
+
 /**
  * We can only render glyph quads that slide along a straight line. To draw
  * curved lines we need an instance of a glyph for each segment it appears on.

src/symbol/shaping.js

@@ -300,8 +300,9 @@ function justifyLine(positionedGlyphs, glyphs, start, end, justify) {
 }
 
 function align(positionedGlyphs, justify, horizontalAlign, verticalAlign, maxLineLength, lineHeight, lineCount, translate) {
-    const shiftX = (justify - horizontalAlign) * maxLineLength + translate[0];
-    const shiftY = (-verticalAlign * lineCount + 0.5) * lineHeight + translate[1];
+    // TODO: moving translate part to quads.js
+    const shiftX = (justify - horizontalAlign) * maxLineLength;// + translate[0];
+    const shiftY = (-verticalAlign * lineCount + 0.5) * lineHeight;// + translate[1];
 
     for (let j = 0; j < positionedGlyphs.length; j++) {
         positionedGlyphs[j].x += shiftX;

test/integration/render-tests/text-keep-upright/line-placement-true-offset/style.json

@@ -0,0 +1,58 @@
+{
+  "version": 8,
+  "metadata": {
+    "test": {
+      "height": 64,
+      "operations": [
+          [ "setBearing", 20 ],
+          [ "wait" ]
+        ]
+    }
+  },
+  "center": [ 0, 0 ],
+  "zoom": 0,
+  "sources": {
+    "geojson": {
+      "type": "geojson",
+      "data": {
+        "type": "Feature",
+        "properties": {},
+        "geometry": {
+          "type": "LineString",
+          "coordinates": [
+            [-20, -20],
+            [20, -20],
+            [20, 20],
+            [-20, 20]
+          ]
+        }
+      }
+    }
+  },
+  "glyphs": "local://glyphs/{fontstack}/{range}.pbf",
+  "layers": [
+    {
+      "id": "guid",
+      "type": "line",
+      "source": "geojson"
+    },
+    {
+      "id": "text",
+      "type": "symbol",
+      "source": "geojson",
+      "layout": {
+        "symbol-placement": "line",
+        "symbol-spacing": 3,
+        "text-allow-overlap": true,
+        "text-ignore-placement": true,
+        "text-field": "A",
+        "text-font": [
+          "Open Sans Semibold",
+          "Arial Unicode MS Bold"
+        ],
+        "text-keep-upright": true,
+        "text-offset": [0, -1]
+      }
+    }
+  ]
+}