Transformation matrix

libqpdf/QPDFMatrix.cc

@@ -0,0 +1,90 @@
+#include <qpdf/QPDFMatrix.hh>
+#include <qpdf/QUtil.hh>
+
+QPDFMatrix::QPDFMatrix() :
+    a(1.0),
+    b(0.0),
+    c(0.0),
+    d(1.0),
+    e(0.0),
+    f(0.0)
+{
+}
+
+QPDFMatrix::QPDFMatrix(double a, double b, double c,
+                       double d, double e, double f) :
+    a(a),
+    b(b),
+    c(c),
+    d(d),
+    e(e),
+    f(f)
+{
+}
+
+std::string
+QPDFMatrix::unparse() const
+{
+    return (QUtil::double_to_string(a, 5) + " " +
+            QUtil::double_to_string(b, 5) + " " +
+            QUtil::double_to_string(c, 5) + " " +
+            QUtil::double_to_string(d, 5) + " " +
+            QUtil::double_to_string(e, 5) + " " +
+            QUtil::double_to_string(f, 5));
+}
+
+void
+QPDFMatrix::concat(QPDFMatrix const& other)
+{
+    double ap = (this->a * other.a) + (this->c * other.b);
+    double bp = (this->b * other.a) + (this->d * other.b);
+    double cp = (this->a * other.c) + (this->c * other.d);
+    double dp = (this->b * other.c) + (this->d * other.d);
+    double ep = (this->a * other.e) + (this->c * other.f) + this->e;
+    double fp = (this->b * other.e) + (this->d * other.f) + this->f;
+    this-> a = ap;
+    this-> b = bp;
+    this-> c = cp;
+    this-> d = dp;
+    this-> e = ep;
+    this-> f = fp;
+}
+
+void
+QPDFMatrix::scale(double sx, double sy)
+{
+    concat(QPDFMatrix(sx, 0, 0, sy, 0, 0));
+}
+
+void
+QPDFMatrix::translate(double tx, double ty)
+{
+    concat(QPDFMatrix(1, 0, 0, 1, tx, ty));
+}
+
+void
+QPDFMatrix::rotatex90(int angle)
+{
+    switch (angle)
+    {
+      case 90:
+        concat(QPDFMatrix(0, 1, -1, 0, 0, 0));
+        break;
+      case 180:
+        concat(QPDFMatrix(-1, 0, 0, -1, 0, 0));
+        break;
+      case 270:
+        concat(QPDFMatrix(0, -1, 1, 0, 0, 0));
+        break;
+      default:
+        // ignore
+        break;
+    }
+}
+
+void
+QPDFMatrix::transform(double x, double y, double& xp, double& yp)
+{
+    xp = (this->a * x) + (this->c * y) + this->e;
+    yp = (this->b * x) + (this->d * y) + this->f;
+}

libqpdf/build.mk

@@ -41,6 +41,7 @@ SRCS_libqpdf = \
 	libqpdf/QPDFAnnotationObjectHelper.cc \
 	libqpdf/QPDFExc.cc \
 	libqpdf/QPDFFormFieldObjectHelper.cc \
+	libqpdf/QPDFMatrix.cc \
 	libqpdf/QPDFNameTreeObjectHelper.cc \
 	libqpdf/QPDFNumberTreeObjectHelper.cc \
 	libqpdf/QPDFObjGen.cc \

libqpdf/qpdf/QPDFMatrix.hh

@@ -0,0 +1,43 @@
+#ifndef QPDFMATRIX_HH
+#define QPDFMATRIX_HH
+
+#include <qpdf/DLL.h>
+#include <string>
+
+class QPDFMatrix
+{
+  public:
+    QPDF_DLL
+    QPDFMatrix();
+    QPDF_DLL
+    QPDFMatrix(double a, double b, double c,
+               double d, double e, double f);
+
+    QPDF_DLL
+    std::string unparse() const;
+
+    // This is not part of the public API. Just provide the methods we
+    // need as we need them.
+    QPDF_DLL
+    void concat(QPDFMatrix const& other);
+    QPDF_DLL
+    void scale(double sx, double sy);
+    QPDF_DLL
+    void translate(double tx, double ty);
+    // Any value other than 90, 180, or 270 is ignored
+    QPDF_DLL
+    void rotatex90(int angle);
+
+    QPDF_DLL
+    void transform(double x, double y, double& xp, double& yp);
+
+  private:
+    double a;
+    double b;
+    double c;
+    double d;
+    double e;
+    double f;
+};
+
+#endif // QPDFMATRIX_HH

libtests/build.mk

@@ -12,6 +12,7 @@ BINS_libtests = \
 	input_source \
 	json \
 	lzw \
+	matrix \
 	md5 \
 	numrange \
 	pointer_holder \

libtests/matrix.cc

@@ -0,0 +1,55 @@
+#include <qpdf/QPDFMatrix.hh>
+#include <qpdf/QUtil.hh>
+#include <assert.h>
+#include <iostream>
+
+static void check(QPDFMatrix const& m, std::string const& exp)
+{
+    std::string u = m.unparse();
+    if (u != exp)
+    {
+        std::cout << "got " << u << ", wanted " << exp << std::endl;
+    }
+}
+
+static void check_xy(double x, double y, std::string const& exp)
+{
+    std::string u = (QUtil::double_to_string(x, 2) + " " +
+                     QUtil::double_to_string(y, 2));
+    if (u != exp)
+    {
+        std::cout << "got " << u << ", wanted " << exp << std::endl;
+    }
+}
+
+int main()
+{
+    QPDFMatrix m;
+    check(m, "1.00000 0.00000 0.00000 1.00000 0.00000 0.00000");
+    m.translate(10, 20);
+    check(m, "1.00000 0.00000 0.00000 1.00000 10.00000 20.00000");
+    m.scale(1.5, 2);
+    check(m, "1.50000 0.00000 0.00000 2.00000 10.00000 20.00000");
+    m.translate(30, 40);
+    check(m, "1.50000 0.00000 0.00000 2.00000 55.00000 100.00000");
+    m.concat(QPDFMatrix(1, 2, 3, 4, 5, 6));
+    check(m, "1.50000 4.00000 4.50000 8.00000 62.50000 112.00000");
+    m.rotatex90(90);
+    check(m, "4.50000 8.00000 -1.50000 -4.00000 62.50000 112.00000");
+    m.rotatex90(180);
+    check(m, "-4.50000 -8.00000 1.50000 4.00000 62.50000 112.00000");
+    m.rotatex90(270);
+    check(m, "-1.50000 -4.00000 -4.50000 -8.00000 62.50000 112.00000");
+    m.rotatex90(180);
+    check(m, "1.50000 4.00000 4.50000 8.00000 62.50000 112.00000");
+    m.rotatex90(12345);
+    check(m, "1.50000 4.00000 4.50000 8.00000 62.50000 112.00000");
+
+    double xp = 0;
+    double yp = 0;
+    m.transform(240, 480, xp, yp);
+    check_xy(xp, yp, "2582.50 4912.00");
+
+    std::cout << "matrix tests done" << std::endl;
+    return 0;
+}