Handle clips during processing of covered text.

src/CoveredTextHandler.cc

@@ -30,11 +30,18 @@ void CoveredTextHandler::reset()
 
 void CoveredTextHandler::add_char_bbox(double * bbox)
 {
-    for (int i = 0; i < 4; i++)
-        char_bboxes.push_back(bbox[i]);
+    char_bboxes.insert(char_bboxes.end(), bbox, bbox + 4);
     chars_covered.push_back(false);
 }
 
+void CoveredTextHandler::add_char_bbox_clipped(double * bbox, bool patially)
+{
+    char_bboxes.insert(char_bboxes.end(), bbox, bbox + 4);
+    chars_covered.push_back(true);
+    if (patially)
+        add_non_char_bbox(bbox, chars_covered.size() - 1);
+}
+
 void CoveredTextHandler::add_non_char_bbox(double * bbox, int index)
 {
     if (index < 0)

src/CoveredTextHandler.h

@@ -32,6 +32,8 @@ public:
      */
     void add_char_bbox(double * bbox);
 
+    void add_char_bbox_clipped(double * bbox, bool patially);
+
     /**
      * Add a drawn non-char graphics' bounding box.
      * If it intersects any previously drawn char's bbox, the char is marked as covered
@@ -51,7 +53,6 @@ public:
     const std::vector<bool> & get_chars_covered() { return chars_covered; }
 
 private:
-    //covered text test
     std::vector<bool> chars_covered;
     // x00, y00, x01, y01; x10, y10, x11, y11;...
     std::vector<double> char_bboxes;

src/DrawingTracer.cc

@@ -53,15 +53,15 @@ void DrawingTracer::set_ctm(GfxState *state)
     matrix.yy = ctm[3];
     matrix.x0 = ctm[4];
     matrix.y0 = ctm[5];
-    cairo_set_matrix (cairo, &matrix);
+    cairo_set_matrix(cairo, &matrix);
 }
 
 void DrawingTracer::clip(GfxState * state, bool even_odd)
 {
     if (!param.process_covered_text)
         return;
-    do_path (state, state->getPath());
-    cairo_set_fill_rule (cairo, even_odd? CAIRO_FILL_RULE_EVEN_ODD : CAIRO_FILL_RULE_WINDING);
+    do_path(state, state->getPath());
+    cairo_set_fill_rule(cairo, even_odd? CAIRO_FILL_RULE_EVEN_ODD : CAIRO_FILL_RULE_WINDING);
     cairo_clip (cairo);
 }
 
@@ -91,13 +91,13 @@ void DrawingTracer::do_path(GfxState * state, GfxPath * path)
     GfxSubpath *subpath;
     int i, j;
     double x, y;
-    cairo_new_path (cairo);
+    cairo_new_path(cairo);
     for (i = 0; i < path->getNumSubpaths(); ++i) {
         subpath = path->getSubpath(i);
         if (subpath->getNumPoints() > 0) {
             x = subpath->getX(0);
             y = subpath->getY(0);
-            cairo_move_to (cairo, x, y);
+            cairo_move_to(cairo, x, y);
             j = 1;
             while (j < subpath->getNumPoints()) {
                 if (subpath->getCurve(j)) {
@@ -111,7 +111,7 @@ void DrawingTracer::do_path(GfxState * state, GfxPath * path)
                 } else {
                     x = subpath->getX(j);
                     y = subpath->getY(j);
-                    cairo_line_to (cairo, x, y);
+                    cairo_line_to(cairo, x, y);
                     ++j;
                 }
             }
@@ -150,22 +150,56 @@ void DrawingTracer::fill(GfxState * state, bool even_odd)
 
 void DrawingTracer::draw_non_char_bbox(GfxState * state, double * bbox)
 {
-    double cbox[4], result[4];
+    double cbox[4];
     cairo_clip_extents(cairo, cbox, cbox + 1, cbox + 2, cbox + 3);
-    // TODO intersect
-    tm_transform_bbox(state->getCTM(), bbox);
-    if (on_non_char_drawn)
-        on_non_char_drawn(bbox);
+    if(bbox_intersect(cbox, bbox, bbox))
+    {
+        tm_transform_bbox(state->getCTM(), bbox);
+        if (on_non_char_drawn)
+            on_non_char_drawn(bbox);
+    }
 }
 
 void DrawingTracer::draw_char_bbox(GfxState * state, double * bbox)
 {
-    double cbox[4], result[4];
-    cairo_clip_extents(cairo, cbox, cbox + 1, cbox + 2, cbox + 3);
-    // TODO intersect
-    tm_transform_bbox(state->getCTM(), bbox);
-    if (on_char_drawn)
-        on_char_drawn(bbox);
+    // Note: even if 4 corner of the char are all in the clip area,
+    // it still could be partially clipped.
+    // TODO better solution?
+    int pt_in = 0;
+    if (cairo_in_clip(cairo, bbox[0], bbox[1]))
+        ++pt_in;
+    if (cairo_in_clip(cairo, bbox[2], bbox[3]))
+        ++pt_in;
+    if (cairo_in_clip(cairo, bbox[2], bbox[1]))
+        ++pt_in;
+    if (cairo_in_clip(cairo, bbox[0], bbox[3]))
+        ++pt_in;
+
+    if (pt_in == 0)
+    {
+        if(on_char_clipped)
+            on_char_clipped(bbox, false);
+    }
+    else
+    {
+        if (pt_in < 4)
+        {
+            double cbox[4];
+            cairo_clip_extents(cairo, cbox, cbox + 1, cbox + 2, cbox + 3);
+            bbox_intersect(cbox, bbox, bbox);
+        }
+        tm_transform_bbox(state->getCTM(), bbox);
+        if (pt_in < 4)
+        {
+            if(on_char_clipped)
+                on_char_clipped(bbox, true);
+        }
+        else
+        {
+            if (on_char_drawn)
+                on_char_drawn(bbox);
+        }
+    }
 }
 
 void DrawingTracer::draw_image(GfxState *state)

src/DrawingTracer.h

@@ -25,9 +25,12 @@ public:
      * The callback to receive drawn event.
      * bbox in device space.
      */
+    // a non-char graphics is drawn
     std::function<void(double * bbox)> on_non_char_drawn;
+    // a char is drawn in the clip area
     std::function<void(double * bbox)> on_char_drawn;
-    std::function<void(double * bbox)> on_char_clipped;
+    // a char is drawn out of/partially in the clip area
+    std::function<void(double * bbox, bool patially)> on_char_clipped;
 
     DrawingTracer(const Param & param);
     virtual ~DrawingTracer();

src/HTMLRenderer/draw.cc

@@ -32,7 +32,8 @@ using std::ostream;
 
 void HTMLRenderer::restoreState(GfxState * state)
 {
-    updateAll(state); tracer.restore();
+    updateAll(state);
+    tracer.restore();
 }
 
 void HTMLRenderer::saveState(GfxState *state)

src/HTMLRenderer/general.cc

@@ -82,7 +82,7 @@ HTMLRenderer::HTMLRenderer(const Param & param)
     tracer.on_char_drawn =
             [this](double * box) { covered_text_handler.add_char_bbox(box); };
     tracer.on_char_clipped =
-            [this](double * box) { covered_text_handler.add_char_bbox(box); }; //TODO
+            [this](double * box, bool partial) { covered_text_handler.add_char_bbox_clipped(box, partial); };
     tracer.on_non_char_drawn =
             [this](double * box) { covered_text_handler.add_non_char_bbox(box); };
 }

src/util/math.cc

@@ -60,12 +60,30 @@ void tm_transform_bbox(const double * tm, double * bbox)
     }
 }
 
-bool bbox_intersect(double * bbox1, double * bbox2)
+bool bbox_intersect(const double * bbox1, const double * bbox2, double * result)
 {
-    return min(bbox1[0], bbox1[2]) < max(bbox2[0], bbox2[2])
-        && max(bbox1[0], bbox1[2]) > min(bbox2[0], bbox2[2])
-        && min(bbox1[1], bbox1[3]) < max(bbox2[1], bbox2[3])
-        && max(bbox1[1], bbox1[3]) > min(bbox2[1], bbox2[3]);
+    double x0, y0, x1, y1;
+
+    x0 = max(min(bbox1[0], bbox1[2]), min(bbox2[0], bbox2[2]));
+    x1 = min(max(bbox1[0], bbox1[2]), max(bbox2[0], bbox2[2]));
+
+    if (x0 >= x1)
+        return false;
+
+    y0 = max(min(bbox1[1], bbox1[3]), min(bbox2[1], bbox2[3]));
+    y1 = min(max(bbox1[1], bbox1[3]), max(bbox2[1], bbox2[3]));
+
+    if (y0 >= y1)
+        return false;
+
+    if (result)
+    {
+        result[0] = x0;
+        result[1] = y0;
+        result[2] = x1;
+        result[3] = y1;
+    }
+    return true;
 }
 
 } //namespace pdf2htmlEX 

src/util/math.h

@@ -39,8 +39,14 @@ static inline double hypot(double x, double y) { return std::sqrt(x*x+y*y); }
 void tm_transform(const double * tm, double & x, double & y, bool is_delta = false);
 void tm_multiply(double * tm_left, const double * tm_right);
 void tm_transform_bbox(const double * tm, double * bbox);
-
-bool bbox_intersect(double * bbox1, double * bbox2);
+/**
+ * Calculate the intersection of 2 boxes.
+ * If they are intersecting, store the result to result (if not null) and return true.
+ * Otherwise return false, and result is not touched.
+ * Param result can be same as one of bbox1 and bbox2.
+ * Data in boxes are expected in the order of (x0, y0, x1, y1).
+ */
+bool bbox_intersect(const double * bbox1, const double * bbox2, double * result = nullptr);
 
 } //namespace pdf2htmlEX 
 #endif //MATH_H__