Add Matrix class under QPDFObjectHandle

ChangeLog

@@ -1,3 +1,9 @@
+2018-12-31  Jay Berkenbilt  <ejb@ql.org>
+
+	* Add QPDFObjectHandle::Matrix, similar to
+	QPDFObjectHandle::Rectangle, as a convenience class for
+	six-element arrays that are used as matrices.
+
 2018-12-23  Jay Berkenbilt  <ejb@ql.org>
 
 	* When specifying @arg on the command line, if the file "arg" does

include/qpdf/QPDFObjectHandle.hh

@@ -198,6 +198,38 @@ class QPDFObjectHandle
         double ury;
     };
 
+    // Convenience object for transformation matrices
+    class Matrix
+    {
+      public:
+        Matrix() :
+            a(0.0),
+            b(0.0),
+            c(0.0),
+            d(0.0),
+            e(0.0),
+            f(0.0)
+        {
+        }
+        Matrix(double a, double b, double c,
+               double d, double e, double f) :
+            a(a),
+            b(b),
+            c(c),
+            d(d),
+            e(e),
+            f(f)
+        {
+        }
+
+        double a;
+        double b;
+        double c;
+        double d;
+        double e;
+        double f;
+    };
+
     QPDF_DLL
     QPDFObjectHandle();
     QPDF_DLL
@@ -368,6 +400,8 @@ class QPDFObjectHandle
     QPDF_DLL
     static QPDFObjectHandle newArray(Rectangle const&);
     QPDF_DLL
+    static QPDFObjectHandle newArray(Matrix const&);
+    QPDF_DLL
     static QPDFObjectHandle newDictionary();
     QPDF_DLL
     static QPDFObjectHandle newDictionary(
@@ -377,6 +411,10 @@ class QPDFObjectHandle
     // form of newArray.
     QPDF_DLL
     static QPDFObjectHandle newFromRectangle(Rectangle const&);
+    // Create an array from a matrix. Equivalent to the matrix
+    // form of newArray.
+    QPDF_DLL
+    static QPDFObjectHandle newFromMatrix(Matrix const&);
 
     // Create a new stream and associate it with the given qpdf
     // object.  A subsequent call must be made to replaceStreamData()
@@ -500,6 +538,12 @@ class QPDFObjectHandle
     // rectangle. Otherwise, return the rectangle [0, 0, 0, 0]
     QPDF_DLL
     Rectangle getArrayAsRectangle();
+    QPDF_DLL
+    bool isMatrix();
+    // If the array an array of six numeric values, return as a
+    // matrix. Otherwise, return the matrix [1, 0, 0, 1, 0, 0]
+    QPDF_DLL
+    Matrix getArrayAsMatrix();
 
     // Methods for dictionary objects
     QPDF_DLL

libqpdf/QPDFMatrix.cc

@@ -22,6 +22,17 @@ QPDFMatrix::QPDFMatrix(double a, double b, double c,
 {
 }
 
+QPDFMatrix::QPDFMatrix(QPDFObjectHandle::Matrix const& m) :
+    a(m.a),
+    b(m.b),
+    c(m.c),
+    d(m.d),
+    e(m.e),
+    f(m.f)
+{
+}
+
+
 std::string
 QPDFMatrix::unparse() const
 {

libqpdf/QPDFObjectHandle.cc

@@ -575,6 +575,26 @@ QPDFObjectHandle::isRectangle()
     return true;
 }
 
+bool
+QPDFObjectHandle::isMatrix()
+{
+    if (! isArray())
+    {
+        return false;
+    }
+    if (getArrayNItems() != 6)
+    {
+        return false;
+    }
+    for (size_t i = 0; i < 6; ++i)
+    {
+        if (! getArrayItem(i).isNumber())
+        {
+            return false;
+        }
+    }
+    return true;
+}
 
 QPDFObjectHandle::Rectangle
 QPDFObjectHandle::getArrayAsRectangle()
@@ -590,6 +610,22 @@ QPDFObjectHandle::getArrayAsRectangle()
     return result;
 }
 
+QPDFObjectHandle::Matrix
+QPDFObjectHandle::getArrayAsMatrix()
+{
+    Matrix result;
+    if (isMatrix())
+    {
+        result = Matrix(getArrayItem(0).getNumericValue(),
+                        getArrayItem(1).getNumericValue(),
+                        getArrayItem(2).getNumericValue(),
+                        getArrayItem(3).getNumericValue(),
+                        getArrayItem(4).getNumericValue(),
+                        getArrayItem(5).getNumericValue());
+    }
+    return result;
+}
+
 std::vector<QPDFObjectHandle>
 QPDFObjectHandle::getArrayAsVector()
 {
@@ -1930,12 +1966,31 @@ QPDFObjectHandle::newArray(Rectangle const& rect)
     return newArray(items);
 }
 
+QPDFObjectHandle
+QPDFObjectHandle::newArray(Matrix const& matrix)
+{
+    std::vector<QPDFObjectHandle> items;
+    items.push_back(newReal(matrix.a));
+    items.push_back(newReal(matrix.b));
+    items.push_back(newReal(matrix.c));
+    items.push_back(newReal(matrix.d));
+    items.push_back(newReal(matrix.e));
+    items.push_back(newReal(matrix.f));
+    return newArray(items);
+}
+
 QPDFObjectHandle
 QPDFObjectHandle::newFromRectangle(Rectangle const& rect)
 {
     return newArray(rect);
 }
 
+QPDFObjectHandle
+QPDFObjectHandle::newFromMatrix(Matrix const& rect)
+{
+    return newArray(rect);
+}
+
 QPDFObjectHandle
 QPDFObjectHandle::newDictionary()
 {

libqpdf/qpdf/QPDFMatrix.hh

@@ -1,6 +1,7 @@
 #ifndef QPDFMATRIX_HH
 #define QPDFMATRIX_HH
 
+#include <qpdf/QPDFObjectHandle.hh>
 #include <qpdf/DLL.h>
 #include <string>
 
@@ -12,6 +13,8 @@ class QPDFMatrix
     QPDF_DLL
     QPDFMatrix(double a, double b, double c,
                double d, double e, double f);
+    QPDF_DLL
+    QPDFMatrix(QPDFObjectHandle::Matrix const&);
 
     QPDF_DLL
     std::string unparse() const;

libtests/matrix.cc

@@ -50,6 +50,11 @@ int main()
     m.transform(240, 480, xp, yp);
     check_xy(xp, yp, "2582.50 4912.00");
 
+    check(QPDFMatrix(
+              QPDFObjectHandle::parse(
+                  "[3 1 4 1 5 9.26535]").getArrayAsMatrix()),
+          "3.00000 1.00000 4.00000 1.00000 5.00000 9.26535");
+
     std::cout << "matrix tests done" << std::endl;
     return 0;
 }