diff --git a/CMakeLists.txt b/CMakeLists.txt
index bb47b10..8d75405 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -163,6 +163,8 @@ set(PDF2HTMLEX_SRC ${PDF2HTMLEX_SRC}
     src/Color.cc
     src/CoveredTextHandler.h
     src/CoveredTextHandler.cc
+    src/DrawingTracer.h
+    src/DrawingTracer.cc
     src/HTMLState.h
     src/HTMLTextLine.h
     src/HTMLTextLine.cc
diff --git a/src/DrawingTracer.cc b/src/DrawingTracer.cc
new file mode 100644
index 0000000..15b9f20
--- /dev/null
+++ b/src/DrawingTracer.cc
@@ -0,0 +1,218 @@
+/*
+ * DrawingTracer.cc
+ *
+ *  Created on: 2014-6-15
+ *      Author: duanyao
+ */
+
+#include "GfxFont.h"
+
+#include "util/math.h"
+#include "DrawingTracer.h"
+
+namespace pdf2htmlEX
+{
+
+DrawingTracer::DrawingTracer(const Param & param):param(param)
+{
+}
+
+DrawingTracer::~DrawingTracer()
+{
+    finish();
+}
+
+void DrawingTracer::reset(GfxState *state)
+{
+    if (!param.process_covered_text)
+        return;
+    finish();
+    cairo_rectangle_t page_box {0, 0, width:state->getPageWidth(), height:state->getPageHeight()};
+    cairo_surface_t * surface = cairo_recording_surface_create(CAIRO_CONTENT_COLOR_ALPHA, &page_box);
+    cairo = cairo_create(surface);
+}
+
+void DrawingTracer::finish()
+{
+    if (cairo)
+    {
+        cairo_destroy(cairo);
+        cairo = nullptr;
+    }
+}
+
+void DrawingTracer::set_ctm(GfxState *state)
+{
+    if (!param.process_covered_text)
+        return;
+    double * ctm = state->getCTM();
+    cairo_matrix_t matrix;
+    matrix.xx = ctm[0];
+    matrix.yx = ctm[1];
+    matrix.xy = ctm[2];
+    matrix.yy = ctm[3];
+    matrix.x0 = ctm[4];
+    matrix.y0 = ctm[5];
+    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);
+    cairo_clip (cairo);
+}
+
+void DrawingTracer::clip_to_stroke_path(GfxState * state)
+{
+    if (!param.process_covered_text)
+        return;
+    // TODO cairo_stroke_to_path() ?
+}
+
+void DrawingTracer::save()
+{
+    if (!param.process_covered_text)
+        return;
+    cairo_save(cairo);
+}
+void DrawingTracer::restore()
+{
+    if (!param.process_covered_text)
+        return;
+    cairo_restore(cairo);
+}
+
+void DrawingTracer::do_path(GfxState * state, GfxPath * path)
+{
+    //copy from CairoOutputDev::doPath
+    GfxSubpath *subpath;
+    int i, j;
+    double x, y;
+    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);
+            j = 1;
+            while (j < subpath->getNumPoints()) {
+                if (subpath->getCurve(j)) {
+                    x = subpath->getX(j+2);
+                    y = subpath->getY(j+2);
+                    cairo_curve_to(cairo,
+                        subpath->getX(j), subpath->getY(j),
+                        subpath->getX(j+1), subpath->getY(j+1),
+                        x, y);
+                    j += 3;
+                } else {
+                    x = subpath->getX(j);
+                    y = subpath->getY(j);
+                    cairo_line_to (cairo, x, y);
+                    ++j;
+                }
+            }
+            if (subpath->isClosed()) {
+                cairo_close_path (cairo);
+            }
+        }
+    }
+}
+
+void DrawingTracer::stroke(GfxState * state)
+{
+    if (!param.process_covered_text)
+        return;
+    // TODO
+    // 1. if stroke extents is large, break the path into pieces and handle each of them;
+    // 2. if the line width is small, could just ignore the path?
+    do_path(state, state->getPath());
+    cairo_set_line_width(cairo, state->getLineWidth());
+    double sbox[4];
+    cairo_stroke_extents(cairo, sbox, sbox + 1, sbox + 2, sbox + 3);
+    draw_non_char_bbox(state, sbox);
+}
+
+void DrawingTracer::fill(GfxState * state, bool even_odd)
+{
+    if (!param.process_covered_text)
+        return;
+    do_path(state, state->getPath());
+    //cairo_fill_extents don't take fill rule into account.
+    //cairo_set_fill_rule (cairo, even_odd? CAIRO_FILL_RULE_EVEN_ODD : CAIRO_FILL_RULE_WINDING);
+    double fbox[4];
+    cairo_fill_extents(cairo, fbox, fbox + 1, fbox + 2, fbox + 3);
+    draw_non_char_bbox(state, fbox);
+}
+
+void DrawingTracer::draw_non_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_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);
+}
+
+void DrawingTracer::draw_image(GfxState *state)
+{
+    if (!param.process_covered_text)
+        return;
+    double bbox[4] {0, 0, 1, 1};
+    draw_non_char_bbox(state, bbox);
+}
+
+void DrawingTracer::draw_char(GfxState *state, double x, double y, double ax, double ay)
+{
+    if (!param.process_covered_text)
+        return;
+
+    Matrix tm, itm;
+    //memcpy(tm_ctm.m, this->cur_text_tm, sizeof(tm_ctm.m));
+    memcpy(tm.m, state->getTextMat(), sizeof(tm.m));
+    double fs = state->getFontSize();
+
+    double cx = state->getCurX(), cy = state->getCurY(),
+            ry = state->getRise(), h = state->getHorizScaling();
+
+    //cx and cy has been transformed by text matrix, we need to reverse them.
+    tm.invertTo(&itm);
+    double char_cx, char_cy;
+    itm.transform(cx, cy, &char_cx, &char_cy);
+
+    //TODO Vertical? Currently vertical/type3 chars are treated as non-chars.
+    double tchar[6] {fs * h, 0, 0, fs, char_cx + x, char_cy + y + ry};
+
+    double tfinal[6];
+    tm_multiply(tfinal, tm.m, tchar);
+
+    auto font = state->getFont();
+    double bbox[4] {0, 0, ax, ay};
+    double desc = font->getDescent(), asc = font->getAscent();
+    if (font->getWMode() == 0)
+    {
+        bbox[1] += desc;
+        bbox[3] += asc;
+    }
+    else
+    {//TODO Vertical?
+    }
+    tm_transform_bbox(tfinal, bbox);
+    draw_char_bbox(state, bbox);
+}
+
+} /* namespace pdf2htmlEX */
diff --git a/src/DrawingTracer.h b/src/DrawingTracer.h
new file mode 100644
index 0000000..81fd4b0
--- /dev/null
+++ b/src/DrawingTracer.h
@@ -0,0 +1,66 @@
+/*
+ * DrawingTracer.h
+ *
+ *  Created on: 2014-6-15
+ *      Author: duanyao
+ */
+
+#ifndef DRAWINGTRACER_H__
+#define DRAWINGTRACER_H__
+
+#include <functional>
+
+#include <GfxState.h>
+#include <cairo.h>
+
+#include "Param.h"
+
+namespace pdf2htmlEX
+{
+
+class DrawingTracer
+{
+public:
+    /*
+     * The callback to receive drawn event.
+     * bbox in device space.
+     */
+    std::function<void(double * bbox)> on_non_char_drawn;
+    std::function<void(double * bbox)> on_char_drawn;
+    std::function<void(double * bbox)> on_char_clipped;
+
+    DrawingTracer(const Param & param);
+    virtual ~DrawingTracer();
+    void reset(GfxState * state);
+
+    /*
+     * A character is drawing
+     * x, y: glyph-drawing position, in PDF text object space.
+     * ax, ay: glyph advance, in glyph space.
+     */
+    void draw_char(GfxState * state, double x, double y, double ax, double ay);
+    /*
+     * An image is drawing
+     */
+    void draw_image(GfxState * state);
+    void set_ctm(GfxState * state);
+    void clip(GfxState * state, bool even_odd = false);
+    void clip_to_stroke_path(GfxState * state);
+    void fill(GfxState * state, bool even_odd = false);
+    void stroke(GfxState * state);
+    void save();
+    void restore();
+
+private:
+    void finish();
+    // Following methods operate in user space (just before CTM is applied)
+    void do_path(GfxState * state, GfxPath * path);
+    void draw_non_char_bbox(GfxState * state, double * bbox);
+    void draw_char_bbox(GfxState * state, double * bbox);
+
+    const Param & param;
+    cairo_t * cairo = nullptr;
+};
+
+} /* namespace pdf2htmlEX */
+#endif /* DRAWINGTRACER_H__ */
diff --git a/src/HTMLRenderer/HTMLRenderer.h b/src/HTMLRenderer/HTMLRenderer.h
index 75293f8..8aa0a0f 100644
--- a/src/HTMLRenderer/HTMLRenderer.h
+++ b/src/HTMLRenderer/HTMLRenderer.h
@@ -20,6 +20,8 @@
 #include <GfxFont.h>
 #include <Annot.h>
 
+#include <cairo.h>
+
 #include "pdf2htmlEX-config.h"
 
 #include "Param.h"
@@ -32,10 +34,12 @@
 
 #include "BackgroundRenderer/BackgroundRenderer.h"
 #include "CoveredTextHandler.h"
+#include "DrawingTracer.h"
 
 #include "util/const.h"
 #include "util/misc.h"
 
+
 namespace pdf2htmlEX {
 
 class HTMLRenderer : public OutputDev
@@ -90,7 +94,9 @@ public:
      * We just mark as changed, and recheck if they have been changed when we are about to output a new string
      */
 
-    virtual void restoreState(GfxState * state) { updateAll(state); }
+    virtual void restoreState(GfxState * state);
+
+    virtual void saveState(GfxState *state);
 
     virtual void updateAll(GfxState * state);
 
@@ -135,15 +141,16 @@ public:
                        GfxImageColorMap *maskColorMap,
                        GBool maskInterpolate);
 
-    virtual void stroke(GfxState *state) { css_do_path(state, false); }
-    virtual void fill(GfxState *state) { css_do_path(state, true); }
+    virtual void stroke(GfxState *state); ////{ css_do_path(state, false); }
+    virtual void fill(GfxState *state); ////{ css_do_path(state, true); }
+    virtual void eoFill(GfxState *state);
     virtual GBool axialShadedFill(GfxState *state, GfxAxialShading *shading, double tMin, double tMax);
 
     virtual void processLink(AnnotLink * al);
 
     /* capacity test */
-    bool can_stroke(GfxState *state) { return css_do_path(state, false, true); }
-    bool can_fill(GfxState *state) { return css_do_path(state, true, true); }
+    bool can_stroke(GfxState *state) { return false; } ////{ return css_do_path(state, false, true); }
+    bool can_fill(GfxState *state) { return false; } ////{ return css_do_path(state, true, true); }
 
     const std::vector<bool> & get_chars_covered() { return covered_text_handler.get_chars_covered(); }
 
@@ -207,6 +214,7 @@ protected:
     // make sure the current HTML style consistent with PDF
     void prepare_text_line(GfxState * state);
 
+#if 0 //disable CSS drawing
     ////////////////////////////////////////////////////
     // CSS drawing
     ////////////////////////////////////////////////////
@@ -226,20 +234,8 @@ protected:
             double * line_width_array, int line_width_count,
             const GfxRGB * line_color, const GfxRGB * fill_color, 
             void (*style_function)(void *, std::ostream &) = nullptr, void * style_function_data = nullptr );
+#endif //disable CSS drawing
 
-    ////////////////////////////////////////////////////
-    // Covered text handling
-    ////////////////////////////////////////////////////
-    /*
-     * Cue CoveredTextHandler that a character is drawn
-     * x, y: glyph-drawing position, in PDF text object space.
-     * ax, ay: glyph advance, in glyph space.
-     */
-    void add_char_bbox(GfxState *state, double x, double y, double ax, double ay);
-    /*
-     * Cue CoveredTextHandler that an image is drawn
-     */
-    void add_image_bbox(GfxState *state);
 
     ////////////////////////////////////////////////////
     // PDF stuffs
@@ -365,6 +361,7 @@ protected:
     static const std::string MANIFEST_FILENAME;
 
     CoveredTextHandler covered_text_handler;
+    DrawingTracer tracer;
 };
 
 } //namespace pdf2htmlEX
diff --git a/src/HTMLRenderer/draw.cc b/src/HTMLRenderer/draw.cc
index 7a84b1a..b87c897 100644
--- a/src/HTMLRenderer/draw.cc
+++ b/src/HTMLRenderer/draw.cc
@@ -30,6 +30,38 @@ using std::sqrt;
 using std::vector;
 using std::ostream;
 
+void HTMLRenderer::restoreState(GfxState * state)
+{
+    updateAll(state); tracer.restore();
+}
+
+void HTMLRenderer::saveState(GfxState *state)
+{
+    tracer.save();
+}
+
+void HTMLRenderer::stroke(GfxState * state)
+{
+    tracer.stroke(state);
+}
+
+void HTMLRenderer::fill(GfxState * state)
+{
+    tracer.fill(state);
+}
+
+void HTMLRenderer::eoFill(GfxState * state)
+{
+    tracer.fill(state, true);
+}
+
+GBool HTMLRenderer::axialShadedFill(GfxState *state, GfxAxialShading *shading, double tMin, double tMax)
+{
+    tracer.fill(state); //TODO correct?
+    return true;
+}
+
+#if 0 //disable css drawing
 static bool is_horizontal_line(GfxSubpath * path)
 {
     return ((path->getNumPoints() == 2)
@@ -415,6 +447,7 @@ void HTMLRenderer::css_draw_rectangle(double x, double y, double w, double h, co
 
     (*f_curpage) << "\"></div>";
 }
+#endif //disable css drawing
 
 
 } // namespace pdf2htmlEX
diff --git a/src/HTMLRenderer/general.cc b/src/HTMLRenderer/general.cc
index 3d43ede..d784f3b 100644
--- a/src/HTMLRenderer/general.cc
+++ b/src/HTMLRenderer/general.cc
@@ -11,6 +11,7 @@
 #include <cmath>
 #include <algorithm>
 #include <vector>
+#include <functional>
 
 #include <GlobalParams.h>
 
@@ -46,6 +47,7 @@ HTMLRenderer::HTMLRenderer(const Param & param)
     ,html_text_page(param, all_manager)
     ,preprocessor(param)
     ,tmp_files(param)
+    ,tracer(param)
 {
     if(!(param.debug))
     {
@@ -76,6 +78,13 @@ HTMLRenderer::HTMLRenderer(const Param & param)
     all_manager.height      .set_eps(EPS);
     all_manager.width       .set_eps(EPS);
     all_manager.bottom      .set_eps(EPS);
+
+    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
+    tracer.on_non_char_drawn =
+            [this](double * box) { covered_text_handler.add_non_char_bbox(box); };
 }
 
 HTMLRenderer::~HTMLRenderer()
@@ -136,7 +145,6 @@ void HTMLRenderer::process(PDFDoc *doc)
         // We handle covered texts during doc->displayPage(this...),
         // and bg_renderer->render_page() depends on the result, so it must be called after
         // doc->displayPage(this...).
-        covered_text_handler.reset();
         doc->displayPage(this, i,
                 text_zoom_factor() * DEFAULT_DPI, text_zoom_factor() * DEFAULT_DPI,
                 0,
@@ -194,6 +202,9 @@ void HTMLRenderer::startPage(int pageNum, GfxState *state)
 void HTMLRenderer::startPage(int pageNum, GfxState *state, XRef * xref)
 #endif
 {
+    covered_text_handler.reset();
+    tracer.reset(state);
+
     this->pageNum = pageNum;
 
     double pageWidth = state->getPageWidth();
diff --git a/src/HTMLRenderer/image.cc b/src/HTMLRenderer/image.cc
index 3e4f8d0..91ca767 100644
--- a/src/HTMLRenderer/image.cc
+++ b/src/HTMLRenderer/image.cc
@@ -14,7 +14,7 @@ namespace pdf2htmlEX {
 
 void HTMLRenderer::drawImage(GfxState * state, Object * ref, Stream * str, int width, int height, GfxImageColorMap * colorMap, GBool interpolate, int *maskColors, GBool inlineImg)
 {
-    add_image_bbox(state);
+    tracer.draw_image(state);
 
     return OutputDev::drawImage(state,ref,str,width,height,colorMap,interpolate,maskColors,inlineImg);
 
@@ -73,21 +73,11 @@ void HTMLRenderer::drawSoftMaskedImage(GfxState *state, Object *ref, Stream *str
                    GfxImageColorMap *maskColorMap,
                    GBool maskInterpolate)
 {
-    add_image_bbox(state);
+    tracer.draw_image(state);
 
-    return OutputDev::drawSoftMaskedImage(state,ref,str,
+    return OutputDev::drawSoftMaskedImage(state,ref,str, // TODO really required?
             width,height,colorMap,interpolate,
             maskStr, maskWidth, maskHeight, maskColorMap, maskInterpolate);
 }
 
-void HTMLRenderer::add_image_bbox(GfxState *state)
-{
-    if (!param.process_covered_text)
-        return;
-    auto ctm = state->getCTM();
-    double bbox[4] {0, 0, 1, 1};
-    tm_transform_bbox(ctm, bbox);
-    covered_text_handler.add_non_char_bbox(bbox);
-}
-
 } // namespace pdf2htmlEX
diff --git a/src/HTMLRenderer/state.cc b/src/HTMLRenderer/state.cc
index 8df9700..498655a 100644
--- a/src/HTMLRenderer/state.cc
+++ b/src/HTMLRenderer/state.cc
@@ -46,6 +46,7 @@ void HTMLRenderer::updateFont(GfxState * state)
 void HTMLRenderer::updateCTM(GfxState * state, double m11, double m12, double m21, double m22, double m31, double m32) 
 {
     ctm_changed = true; 
+    tracer.set_ctm(state);
 }
 void HTMLRenderer::updateTextMat(GfxState * state) 
 {
@@ -89,14 +90,17 @@ void HTMLRenderer::updateStrokeColor(GfxState * state)
 void HTMLRenderer::clip(GfxState * state)
 {
     clip_changed = true;
+    tracer.clip(state);
 }
 void HTMLRenderer::eoClip(GfxState * state)
 {
     clip_changed = true;
+    tracer.clip(state, true);
 }
 void HTMLRenderer::clipToStrokePath(GfxState * state)
 {
     clip_changed = true;
+    tracer.clip_to_stroke_path(state);
 }
 void HTMLRenderer::reset_state()
 {
diff --git a/src/HTMLRenderer/text.cc b/src/HTMLRenderer/text.cc
index 0122356..13f2065 100644
--- a/src/HTMLRenderer/text.cc
+++ b/src/HTMLRenderer/text.cc
@@ -72,7 +72,7 @@ void HTMLRenderer::drawString(GfxState * state, GooString * s)
             cerr << "TODO: non-zero origins" << endl;
         }
 
-        add_char_bbox(state, dx, dy, dx1, dy1);
+        tracer.draw_char(state, dx, dy, dx1, dy1); //TODO dx dy seems not correct?
 
         bool is_space = false;
         if (n == 1 && *p == ' ') 
@@ -145,43 +145,4 @@ void HTMLRenderer::drawString(GfxState * state, GooString * s)
     draw_ty += dy;
 }
 
-void HTMLRenderer::add_char_bbox(GfxState *state, double x, double y, double ax, double ay)
-{
-    if (!param.process_covered_text)
-        return;
-
-    Matrix tm_ctm, tm, itm;
-    memcpy(tm_ctm.m, this->cur_text_tm, sizeof(tm_ctm.m));
-    memcpy(tm.m, state->getTextMat(), sizeof(tm.m));
-    double fs = state->getFontSize();
-
-    double cx = state->getCurX(), cy = state->getCurY(),
-            ry = state->getRise(), h = state->getHorizScaling();
-
-    //cx and cy has been transformed by text matrix, we need to reverse them.
-    tm.invertTo(&itm);
-    double char_cx, char_cy;
-    itm.transform(cx, cy, &char_cx, &char_cy);
-
-    //TODO Vertical? Currently vertical/type3 chars are treated as non-chars.
-    double tchar[6] {fs * h, 0, 0, fs, char_cx + x, char_cy + y + ry};
-
-    double tfinal[6];
-    tm_multiply(tfinal, tm_ctm.m, tchar);
-
-    auto font = state->getFont();
-    double bbox[4] {0, 0, ax, ay};
-    double desc = font->getDescent(), asc = font->getAscent();
-    if (font->getWMode() == 0)
-    {
-        bbox[1] += desc;
-        bbox[3] += asc;
-    }
-    else
-    {//TODO Vertical?
-    }
-    tm_transform_bbox(tfinal, bbox);
-    covered_text_handler.add_char_bbox(bbox);
-}
-
 } // namespace pdf2htmlEX