port clipLines from -js

src/mbgl/renderer/symbol_bucket.cpp

@@ -18,6 +18,7 @@
 #include <mbgl/util/token.hpp>
 #include <mbgl/util/math.hpp>
 #include <mbgl/util/merge_lines.hpp>
+#include <mbgl/util/clip_lines.hpp>
 #include <mbgl/util/std.hpp>
 
 namespace mbgl {
@@ -269,9 +270,11 @@ void SymbolBucket::addFeature(const std::vector<std::vector<Coordinate>> &lines,
         layout.icon.rotation_alignment == RotationAlignmentType::Map &&
         layout.placement == PlacementType::Line;
 
-    // TODO clip lines here
+    auto& clippedLines = layout.placement == PlacementType::Line ?
+        util::clipLines(lines, 0, 0, 4096, 4096) :
+        lines;
 
-    for (const std::vector<Coordinate> &line : lines) {
+    for (const std::vector<Coordinate> &line : clippedLines) {
         if (!line.size()) continue;
 
         // Calculate the anchor points around which you want to place labels

src/mbgl/util/clip_lines.cpp

@@ -0,0 +1,66 @@
+#include "clip_lines.hpp"
+
+namespace mbgl {
+namespace util {
+
+std::vector<std::vector<Coordinate>> clipLines(const std::vector<std::vector<Coordinate>> &lines,
+        const int16_t x1, const int16_t y1, const int16_t x2, const int16_t y2) {
+
+    std::vector<std::vector<Coordinate>> clippedLines;
+
+    for (auto& line : lines) {
+
+        if (!line.size())
+            continue;
+
+        auto end = line.end() - 1;
+        for (auto it = line.begin(); it != end; it++) {
+            Coordinate p0 = *(it);
+            Coordinate p1 = *(it + 1);
+
+            if (p0.x < x1 && p1.x < x1) {
+                continue;
+            } else if (p0.x < x1) {
+                p0 = { x1, static_cast<int16_t>(p0.y + static_cast<float>(p1.y - p0.y) * ((x1 - p0.x) / (p1.x - p0.x))) };
+            } else if (p1.x < x1) {
+                p1 = { x1, static_cast<int16_t>(p0.y + static_cast<float>(p1.y - p0.y) * ((x1 - p0.x) / (p1.x - p0.x))) };
+            }
+
+            if (p0.y < y1 && p1.y < y1) {
+                continue;
+            } else if (p0.y < y1) {
+                p0 = { static_cast<int16_t>(p0.x + static_cast<float>(p1.x - p0.x) * ((y1 - p0.y) / (p1.y - p0.y))), y1 };
+            } else if (p1.y < y1) {
+                p1 = { static_cast<int16_t>(p0.x + static_cast<float>(p1.x - p0.x) * ((y1 - p0.y) / (p1.y - p0.y))), y1 };
+            }
+
+            if (p0.x >= x2 && p1.x >= x2) {
+                continue;
+            } else if (p0.x >= x2) {
+                p0 = { x2, static_cast<int16_t>(p0.y + static_cast<float>(p1.y - p0.y) * ((x2 - p0.x) / (p1.x - p0.x))) };
+            } else if (p1.x >= x2) {
+                p1 = { x2, static_cast<int16_t>(p0.y + static_cast<float>(p1.y - p0.y) * ((x2 - p0.x) / (p1.x - p0.x))) };
+            }
+
+            if (p0.y >= y2 && p1.y >= y2) {
+                continue;
+            } else if (p0.y >= y2) {
+                p0 = { static_cast<int16_t>(p0.x + static_cast<float>(p1.x - p0.x) * ((y2 - p0.y) / (p1.y - p0.y))), y2 };
+            } else if (p1.y >= y2) {
+                p1 = { static_cast<int16_t>(p0.x + static_cast<float>(p1.x - p0.x) * ((y2 - p0.y) / (p1.y - p0.y))), y2 };
+            }
+
+            if (!clippedLines.size() || (clippedLines.back().size() && !(p0 == clippedLines.back().back()))) {
+                clippedLines.emplace_back();
+                clippedLines.back().push_back(p0);
+            }
+
+            clippedLines.back().push_back(p1);
+        }
+    }
+
+    return clippedLines;
+}
+
+} // end namespace util
+} // end namespace mbgl

src/mbgl/util/clip_lines.hpp

@@ -0,0 +1,19 @@
+#ifndef MBGL_UTIL_CLIP_LINES
+#define MBGL_UTIL_CLIP_LINES
+
+#include <map>
+#include <string>
+#include <vector>
+#include <mbgl/renderer/symbol_bucket.hpp>
+
+namespace mbgl {
+namespace util {
+
+
+std::vector<std::vector<Coordinate>> clipLines(const std::vector<std::vector<Coordinate>> &lines,
+        const int16_t x1, const int16_t y1, const int16_t x2, const int16_t y2);
+
+} // end namespace util
+} // end namespace mbgl
+
+#endif