1 files changed, 89 insertions, 84 deletions
diff --git a/src/mbgl/text/quads.cpp b/src/mbgl/text/quads.cpp
index 49b43c413..b2406fc4d 100644
--- a/src/mbgl/text/quads.cpp
+++ b/src/mbgl/text/quads.cpp
@@ -68,91 +68,96 @@ SymbolQuads getGlyphQuads(const Shaping& shapedText,
 
     SymbolQuads quads;
 
-    for (const PositionedGlyph &positionedGlyph: shapedText.positionedGlyphs) {
-        auto fontPositions = positions.find(positionedGlyph.font);
-        if (fontPositions == positions.end())
-            continue;
-
-        auto positionsIt = fontPositions->second.glyphPositionMap.find(positionedGlyph.glyph);
-        if (positionsIt == fontPositions->second.glyphPositionMap.end()) {
-            continue;
+    if (shapedText.lineCount == 0) return quads;
+    const float lineHeight = (std::fabs(shapedText.bottom) + std::fabs(shapedText.top)) / shapedText.lineCount;
+    for (const auto& positionedGlyphs : shapedText.positionedGlyphs) {
+        const float currentHeight = lineHeight * positionedGlyphs.first;
+        for (const PositionedGlyph& positionedGlyph : positionedGlyphs.second) {
+            auto fontPositions = positions.find(positionedGlyph.font);
+            if (fontPositions == positions.end()) continue;
+
+            auto positionsIt = fontPositions->second.glyphPositionMap.find(positionedGlyph.glyph);
+            if (positionsIt == fontPositions->second.glyphPositionMap.end()) {
+                continue;
+            }
+
+            const GlyphPosition& glyph = positionsIt->second;
+            const Rect<uint16_t>& rect = glyph.rect;
+
+            // The rects have an additional buffer that is not included in their size;
+            const float glyphPadding = 1.0f;
+            const float rectBuffer = 3.0f + glyphPadding;
+
+            const float halfAdvance = glyph.metrics.advance * positionedGlyph.scale / 2.0;
+
+            const Point<float> glyphOffset =
+                alongLine ? Point<float>{positionedGlyph.x + halfAdvance, positionedGlyph.y} : Point<float>{0.0f, 0.0f};
+
+            Point<float> builtInOffset = alongLine ? Point<float>{0.0f, 0.0f}
+                                                   : Point<float>{positionedGlyph.x + halfAdvance + textOffset[0],
+                                                                  positionedGlyph.y + textOffset[1]};
+
+            Point<float> verticalizedLabelOffset = {0.0f, 0.0f};
+            const bool rotateVerticalGlyph = (alongLine || allowVerticalPlacement) && positionedGlyph.vertical;
+            if (rotateVerticalGlyph) {
+                // Vertical POI labels, that are rotated 90deg CW and whose glyphs must preserve upright orientation
+                // need to be rotated 90deg CCW. After quad is rotated, it is translated to the original built-in
+                // offset.
+                verticalizedLabelOffset = builtInOffset;
+                builtInOffset = {0.0f, 0.0f};
+            }
+
+            const float x1 = (glyph.metrics.left - rectBuffer) * positionedGlyph.scale - halfAdvance + builtInOffset.x;
+            const float y1 = (-glyph.metrics.top - rectBuffer) * positionedGlyph.scale + builtInOffset.y;
+            const float x2 = x1 + rect.w * positionedGlyph.scale;
+            const float y2 = y1 + rect.h * positionedGlyph.scale;
+
+            Point<float> tl{x1, y1};
+            Point<float> tr{x2, y1};
+            Point<float> bl{x1, y2};
+            Point<float> br{x2, y2};
+
+            if (rotateVerticalGlyph) {
+                // Vertical-supporting glyphs are laid out in 24x24 point boxes (1 square em)
+                // In horizontal orientation, the y values for glyphs are below the midline.
+                // If the glyph's baseline is applicable, we take the relative y offset of the
+                //  glyph, which needs to erase out current line height that added to the glyphs.
+                // Otherwise, we use a "yOffset" of -17 to pull them up to the middle.
+                // By rotating counter-clockwise around the point at the center of the left
+                // edge of a 24x24 layout box centered below the midline, we align the center
+                // of the glyphs with the horizontal midline, so the yOffset is no longer
+                // necessary, but we also pull the glyph to the left along the x axis.
+                // The y coordinate includes baseline yOffset, therefore, needs to be accounted
+                // for when glyph is rotated and translated.
+                const float yShift = (shapedText.hasBaseline ? (positionedGlyph.y - currentHeight) : Shaping::yOffset);
+                const Point<float> center{-halfAdvance, halfAdvance - yShift};
+                const float verticalRotation = -M_PI_2;
+
+                // xHalfWidhtOffsetcorrection is a difference between full-width and half-width
+                // advance, should be 0 for full-width glyphs and will pull up half-width glyphs.
+                const float xHalfWidhtOffsetcorrection = util::ONE_EM / 2 - halfAdvance;
+                const Point<float> xOffsetCorrection{5.0f - yShift - xHalfWidhtOffsetcorrection, 0.0f};
+
+                tl = util::rotate(tl - center, verticalRotation) + center + xOffsetCorrection + verticalizedLabelOffset;
+                tr = util::rotate(tr - center, verticalRotation) + center + xOffsetCorrection + verticalizedLabelOffset;
+                bl = util::rotate(bl - center, verticalRotation) + center + xOffsetCorrection + verticalizedLabelOffset;
+                br = util::rotate(br - center, verticalRotation) + center + xOffsetCorrection + verticalizedLabelOffset;
+            }
+
+            if (textRotate) {
+                // Compute the transformation matrix.
+                float angle_sin = std::sin(textRotate);
+                float angle_cos = std::cos(textRotate);
+                std::array<float, 4> matrix = {{angle_cos, -angle_sin, angle_sin, angle_cos}};
+
+                tl = util::matrixMultiply(matrix, tl);
+                tr = util::matrixMultiply(matrix, tr);
+                bl = util::matrixMultiply(matrix, bl);
+                br = util::matrixMultiply(matrix, br);
+            }
+
+            quads.emplace_back(tl, tr, bl, br, rect, shapedText.writingMode, glyphOffset, positionedGlyph.sectionIndex);
         }
-
-        const GlyphPosition& glyph = positionsIt->second;
-        const Rect<uint16_t>& rect = glyph.rect;
-
-        // The rects have an additional buffer that is not included in their size;
-        const float glyphPadding = 1.0f;
-        const float rectBuffer = 3.0f + glyphPadding;
-
-        const float halfAdvance = glyph.metrics.advance * positionedGlyph.scale / 2.0;
-
-        const Point<float> glyphOffset = alongLine ?
-            Point<float>{ positionedGlyph.x + halfAdvance, positionedGlyph.y } :
-            Point<float>{ 0.0f, 0.0f };
-
-        Point<float> builtInOffset = alongLine ?
-            Point<float>{ 0.0f, 0.0f } :
-            Point<float>{ positionedGlyph.x + halfAdvance + textOffset[0], positionedGlyph.y + textOffset[1] };
-
-        Point<float> verticalizedLabelOffset = { 0.0f, 0.0f };
-        const bool rotateVerticalGlyph = (alongLine || allowVerticalPlacement) && positionedGlyph.vertical;
-        if (rotateVerticalGlyph) {
-            // Vertical POI labels, that are rotated 90deg CW and whose glyphs must preserve upright orientation
-            // need to be rotated 90deg CCW. After quad is rotated, it is translated to the original built-in offset.
-            verticalizedLabelOffset = builtInOffset;
-            builtInOffset = { 0.0f, 0.0f };
-        }
-
-        const float x1 = (glyph.metrics.left - rectBuffer) * positionedGlyph.scale - halfAdvance + builtInOffset.x;
-        const float y1 = (-glyph.metrics.top - rectBuffer) * positionedGlyph.scale + builtInOffset.y;
-        const float x2 = x1 + rect.w * positionedGlyph.scale;
-        const float y2 = y1 + rect.h * positionedGlyph.scale;
-
-        Point<float> tl{x1, y1};
-        Point<float> tr{x2, y1};
-        Point<float> bl{x1, y2};
-        Point<float> br{x2, y2};
-
-        if (rotateVerticalGlyph) {
-            // Vertical-supporting glyphs are laid out in 24x24 point boxes (1 square em)
-            // In horizontal orientation, the y values for glyphs are below the midline.
-            // If the glyph's baseline is applicable, we take the y value of the glyph.
-            // Otherwise, we use a "yOffset" of -17 to pull them up to the middle.
-            // By rotating counter-clockwise around the point at the center of the left
-            // edge of a 24x24 layout box centered below the midline, we align the center
-            // of the glyphs with the horizontal midline, so the yOffset is no longer
-            // necessary, but we also pull the glyph to the left along the x axis.
-            // The y coordinate includes baseline yOffset, therefore, needs to be accounted
-            // for when glyph is rotated and translated.
-            const float yShift = (shapedText.hasBaseline ? positionedGlyph.y : Shaping::yOffset);
-            const Point<float> center{-halfAdvance, halfAdvance - yShift};
-            const float verticalRotation = -M_PI_2;
-
-            // xHalfWidhtOffsetcorrection is a difference between full-width and half-width
-            // advance, should be 0 for full-width glyphs and will pull up half-width glyphs.
-            const float xHalfWidhtOffsetcorrection = util::ONE_EM / 2 - halfAdvance;
-            const Point<float> xOffsetCorrection{5.0f - yShift - xHalfWidhtOffsetcorrection, 0.0f};
-
-            tl = util::rotate(tl - center, verticalRotation) + center + xOffsetCorrection + verticalizedLabelOffset;
-            tr = util::rotate(tr - center, verticalRotation) + center + xOffsetCorrection + verticalizedLabelOffset;
-            bl = util::rotate(bl - center, verticalRotation) + center + xOffsetCorrection + verticalizedLabelOffset;
-            br = util::rotate(br - center, verticalRotation) + center + xOffsetCorrection + verticalizedLabelOffset;
-        }
-
-        if (textRotate) {
-            // Compute the transformation matrix.
-            float angle_sin = std::sin(textRotate);
-            float angle_cos = std::cos(textRotate);
-            std::array<float, 4> matrix = {{angle_cos, -angle_sin, angle_sin, angle_cos}};
-
-            tl = util::matrixMultiply(matrix, tl);
-            tr = util::matrixMultiply(matrix, tr);
-            bl = util::matrixMultiply(matrix, bl);
-            br = util::matrixMultiply(matrix, br);
-        }
-
-        quads.emplace_back(tl, tr, bl, br, rect, shapedText.writingMode, glyphOffset, positionedGlyph.sectionIndex);
     }
 
     return quads;