Draw line annotation endings (arrow, circle, ...)

Line endings are already parsed from /LE array and are gettable and
settable as enum value in current APIs.

With this commit we implement the drawing operations so that line
endings become actually visible when document is rendered.

poppler/Annot.cc

@@ -79,6 +79,10 @@
 #include <string.h>
 #include <algorithm>
 
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
 #define fieldFlagReadOnly           0x00000001
 #define fieldFlagRequired           0x00000002
 #define fieldFlagNoExport           0x00000004
@@ -1652,6 +1656,89 @@ void AnnotAppearanceBuilder::drawCircleBottomRight(double cx, double cy, double
   appearBuf->append("S\n");
 }
 
+void AnnotAppearanceBuilder::drawLineEndSquare(double x, double y, double size, bool fill, const Matrix& m) {
+  const double x1[3] {x - size/2., x - size/2., x + size/2.};
+  const double y1[3] {y + size/2., y - size/2., y - size/2.};
+  double tx, ty;
+
+  m.transform (x + size/2., y + size/2., &tx, &ty);
+  appendf ("{0:.2f} {1:.2f} m\n", tx, ty);
+  for (int i = 0; i<3; i++) {
+    m.transform (x1[i], y1[i], &tx, &ty);
+    appendf ("{0:.2f} {1:.2f} l\n", tx, ty);
+  }
+  appearBuf->append(fill ? "b\n" : "s\n");
+}
+
+void AnnotAppearanceBuilder::drawLineEndCircle(double x, double y, double size, bool fill, const Matrix& m) {
+  const double r = size/2.;
+  const double x1[4] {x + r, x - bezierCircle * r, x - r, x + bezierCircle * r};
+  const double x2[4] {x + bezierCircle*r, x - r, x - bezierCircle*r, x + r};
+  const double x3[4] {x, x - r, x, x + r};
+  const double y1[4] {y + bezierCircle * r, y + r, y - bezierCircle * r, y - r};
+  const double y2[4] {y + r, y + bezierCircle * r, y - r, y - bezierCircle * r};
+  const double y3[4] {y + r, y, y - r, y};
+  double tx[3];
+  double ty[3];
+
+  m.transform(x + r, y, &tx[0], &ty[0]);
+  appearBuf->appendf("{0:.2f} {1:.2f} m\n", tx[0], ty[0]);
+  for (int i=0; i<4; i++) {
+    m.transform(x1[i], y1[i], &tx[0], &ty[0]);
+    m.transform(x2[i], y2[i], &tx[1], &ty[1]);
+    m.transform(x3[i], y3[i], &tx[2], &ty[2]);
+    appearBuf->appendf("{0:.2f} {1:.2f} {2:.2f} {3:.2f} {4:.2f} {5:.2f} c\n",
+        tx[0], ty[0], tx[1], ty[1], tx[2], ty[2]);
+  }
+  appearBuf->append(fill ? "b\n" : "s\n");
+}
+
+void AnnotAppearanceBuilder::drawLineEndDiamond(double x, double y, double size, bool fill, const Matrix& m) {
+  const double x1[3] {x, x - size/2., x};
+  const double y1[3] {y + size/2., y, y - size/2.};
+  double tx, ty;
+
+  m.transform (x + size/2., y, &tx, &ty);
+  appendf ("{0:.2f} {1:.2f} m\n", tx, ty);
+  for (int i = 0; i<3; i++) {
+    m.transform (x1[i], y1[i], &tx, &ty);
+    appendf ("{0:.2f} {1:.2f} l\n", tx, ty);
+  }
+  appearBuf->append(fill ? "b\n" : "s\n");
+}
+
+void AnnotAppearanceBuilder::drawLineEndArrow(double x, double y, double size, int orientation, bool isOpen, bool fill, const Matrix& m) {
+  const double alpha {M_PI/6.};
+  const double xOffs { orientation*size/2.};
+  const double yOffs { tan(alpha)*size };
+  double tx, ty;
+
+  m.transform (x - xOffs, y+yOffs, &tx, &ty);
+  appendf ("{0:.2f} {1:.2f} m\n", tx, ty);
+  m.transform (x + xOffs, y, &tx, &ty);
+  appendf ("{0:.2f} {1:.2f} l\n", tx, ty);
+  m.transform (x - xOffs, y-yOffs, &tx, &ty);
+  appendf ("{0:.2f} {1:.2f} l\n", tx, ty);
+
+  if (isOpen) {
+    appearBuf->append("S\n");
+  } else {
+    appearBuf->append(fill ? "b\n" : "s\n");
+  }
+}
+
+void AnnotAppearanceBuilder::drawLineEndSlash(double x, double y, double size, const Matrix& m) {
+  const double alpha {M_PI/3.};
+  const double xOffs { cos(alpha)*size };
+  double tx, ty;
+
+  m.transform (x + size/2. - xOffs, y - size/2., &tx, &ty);
+  appendf ("{0:.2f} {1:.2f} m\n", tx, ty);
+  m.transform (x + size/2., y + size/2., &tx, &ty);
+  appendf ("{0:.2f} {1:.2f} l\n", tx, ty);
+  appearBuf->append("S\n");
+}
+
 Object Annot::createForm(const GooString *appearBuf, double *bbox, bool transparencyGroup, Dict *resDict) {
   return createForm(appearBuf, bbox, transparencyGroup, resDict ? Object(resDict) : Object());
 }
@@ -3070,9 +3157,70 @@ void AnnotLine::setIntent(AnnotLineIntent new_intent) {
   update ("IT", Object(objName, intentName));
 }
 
+double AnnotLine::shortenMainSegmentForEnding(AnnotLineEndingStyle endingStyle, double x, double size) {
+  switch(endingStyle) {
+  case annotLineEndingSquare:
+  case annotLineEndingCircle:
+  case annotLineEndingDiamond:
+  case annotLineEndingOpenArrow:
+  case annotLineEndingButt:
+    return x;
+  case annotLineEndingClosedArrow:
+  case annotLineEndingRClosedArrow:
+  case annotLineEndingROpenArrow:
+    return x - size;
+  case annotLineEndingSlash:
+    return x - cos(M_PI/3.)*size/2.;
+  default:
+    break;
+  }
+  return x;
+}
+
+void AnnotLine::drawLineEnding(AnnotLineEndingStyle endingStyle, AnnotAppearanceBuilder& appearBuilder, double x, double y, double size, bool fill, const Matrix& m) {
+  switch(endingStyle) {
+  case annotLineEndingSquare:
+    appearBuilder.drawLineEndSquare(x, y, size, fill, m);
+    break;
+  case annotLineEndingCircle:
+    appearBuilder.drawLineEndCircle(x, y, size, fill, m);
+    break;
+  case annotLineEndingDiamond:
+    appearBuilder.drawLineEndDiamond(x, y, size, fill, m);
+    break;
+  case annotLineEndingOpenArrow:
+    appearBuilder.drawLineEndArrow(x, y, size, 1, true, fill, m);
+    break;
+  case annotLineEndingClosedArrow:
+    appearBuilder.drawLineEndArrow(x, y, size, 1, false, fill, m);
+    break;
+  case annotLineEndingButt:
+    {
+      double tx, ty;
+      m.transform (x + size/2., y + size/2., &tx, &ty);
+      appearBuilder.appendf ("{0:.2f} {1:.2f} m\n", tx, ty);
+      m.transform (x + size/2., y - size/2., &tx, &ty);
+      appearBuilder.appendf ("{0:.2f} {1:.2f} l S\n", tx, ty);
+    }
+    break;
+  case annotLineEndingROpenArrow:
+    appearBuilder.drawLineEndArrow(x, y, size, -1, true, fill, m);
+    break;
+  case annotLineEndingRClosedArrow:
+    appearBuilder.drawLineEndArrow(x, y, size, -1, false, fill, m);
+    break;
+  case annotLineEndingSlash:
+    appearBuilder.drawLineEndSlash(x, y, size, m);
+    break;
+  default:
+    break;
+  }
+}
+
 void AnnotLine::generateLineAppearance()
 {
   double borderWidth, ca = opacity;
+  bool fill = false;
 
   appearBBox = std::make_unique<AnnotAppearanceBBox>(rect.get());
   AnnotAppearanceBuilder appearBuilder;
@@ -3080,7 +3228,10 @@ void AnnotLine::generateLineAppearance()
   if (color) {
     appearBuilder.setDrawColor(color.get(), false);
   }
-
+  if (interiorColor) {
+    appearBuilder.setDrawColor(interiorColor.get(), true);
+    fill = true;
+  }
   appearBuilder.setLineStyleForBorder(border.get());
   borderWidth = border->getWidth();
   appearBBox->setBorderWidth(std::max(1., borderWidth));
@@ -3107,6 +3258,7 @@ void AnnotLine::generateLineAppearance()
   const double fontsize = 9;
   const double captionhmargin = 2; // Left and right margin (inline caption only)
   const double captionmaxwidth = main_len - 2 * captionhmargin;
+  const double lineendingSize = std::min(6. * borderWidth, main_len/2);
 
   Dict *fontResDict;
   GfxFont *font;
@@ -3138,7 +3290,7 @@ void AnnotLine::generateLineAppearance()
   }
 
   // Draw main segment
-  matr.transform (0, leaderLineLength, &tx, &ty);
+  matr.transform (shortenMainSegmentForEnding(startStyle, 0, -lineendingSize), leaderLineLength, &tx, &ty);
   appearBuilder.appendf ("{0:.2f} {1:.2f} m\n", tx, ty);
   appearBBox->extendTo (tx, ty);
 
@@ -3150,11 +3302,25 @@ void AnnotLine::generateLineAppearance()
     appearBuilder.appendf ("{0:.2f} {1:.2f} m\n", tx, ty);
   }
 
-  matr.transform (main_len, leaderLineLength, &tx, &ty);
+  matr.transform (shortenMainSegmentForEnding(endStyle, main_len, lineendingSize), leaderLineLength, &tx, &ty);
   appearBuilder.appendf ("{0:.2f} {1:.2f} l S\n", tx, ty);
   appearBBox->extendTo (tx, ty);
 
-  // TODO: Line endings
+  if (startStyle != annotLineEndingNone) {
+    drawLineEnding(startStyle, appearBuilder, 0 + lineendingSize/2., leaderLineLength, -lineendingSize, fill, matr);
+    matr.transform (0, leaderLineLength+lineendingSize/2., &tx, &ty);
+    appearBBox->extendTo (tx, ty);
+    matr.transform (0, leaderLineLength-lineendingSize/2., &tx, &ty);
+    appearBBox->extendTo (tx, ty);
+  }
+
+  if (endStyle != annotLineEndingNone) {
+    drawLineEnding(endStyle, appearBuilder, main_len - lineendingSize/2., leaderLineLength, lineendingSize, fill, matr);
+    matr.transform (main_len, leaderLineLength+lineendingSize/2., &tx, &ty);
+    appearBBox->extendTo (tx, ty);
+    matr.transform (main_len, leaderLineLength-lineendingSize/2., &tx, &ty);
+    appearBBox->extendTo (tx, ty);
+  }
 
   // Draw caption text
   if (caption) {

poppler/Annot.h

@@ -532,7 +532,7 @@ private:
 //------------------------------------------------------------------------
 // AnnotAppearanceBuilder
 //------------------------------------------------------------------------
-
+class Matrix;
 class AnnotAppearanceBuilder {
 public:
   AnnotAppearanceBuilder();
@@ -547,6 +547,11 @@ public:
   void drawCircle(double cx, double cy, double r, bool fill);
   void drawCircleTopLeft(double cx, double cy, double r);
   void drawCircleBottomRight(double cx, double cy, double r);
+  void drawLineEndSquare(double x, double y, double size, bool fill, const Matrix& m);
+  void drawLineEndCircle(double x, double y, double size, bool fill, const Matrix& m);
+  void drawLineEndDiamond(double x, double y, double size, bool fill, const Matrix& m);
+  void drawLineEndArrow(double x, double y, double size, int orientation, bool isOpen, bool fill, const Matrix& m);
+  void drawLineEndSlash(double x, double y, double size, const Matrix& m);
   void drawFieldBorder(const FormField *field, const AnnotBorder *border, const AnnotAppearanceCharacs *appearCharacs, const PDFRectangle *rect);
   bool drawFormField(const FormField *field, const Form *form, const GfxResources *resources, const GooString *da, const AnnotBorder *border, const AnnotAppearanceCharacs *appearCharacs, const PDFRectangle *rect, const GooString *appearState, XRef *xref, bool *addedDingbatsResource);
 
@@ -569,6 +574,7 @@ private:
 		bool txField, bool forceZapfDingbats,
 		XRef *xref, bool *addedDingbatsResource, // xref and addedDingbatsResource both must not be null if forceZapfDingbats is passed
 		bool password);
+  void drawArrowPath(double x, double y, const Matrix& m, int orientation=1);
 
   GooString *appearBuf;
 };
@@ -1098,6 +1104,8 @@ protected:
 
   void initialize(PDFDoc *docA, Dict *dict);
   void generateLineAppearance();
+  static double shortenMainSegmentForEnding(AnnotLineEndingStyle endingStyle, double x, double size);
+  static void drawLineEnding(AnnotLineEndingStyle endingStyle, AnnotAppearanceBuilder& appearBuilder, double x, double y, double size, bool fill, const Matrix& m);
 
   // required
   std::unique_ptr<AnnotCoord> coord1;