PR pending https://gitlab.gnome.org/GNOME/dia/-/merge_requests/149
see also https://bugs.gentoo.org/983078
Fix crash when importing pdf
From 72fad360a06c46214b81081ec7778c8e3a0313c7 Mon Sep 17 00:00:00 2001
From: Ted Rodgers <ted.d.rodgers@gmail.com>
Date: Tue, 29 Sep 2026 09:51:23 -0400
Subject: [PATCH] apply this first:
 https://gitlab.gnome.org/GNOME/dia/-/merge_requests/146

pdf:
- Modern Poppler matrix handling and coordinate scaling
- Update updateCTM to use const auto& to match modern Poppler APIs
- Fix undefined behavior in restoreState by checking for an empty matrix stack before poppin
- Remove redundant scaling factors from subpath points and text positioning
- Correct coordinate scaling in doPath for starting points and Bezier curves
--- a/plug-ins/pdf/pdf-import.cpp
+++ b/plug-ins/pdf/pdf-import.cpp
@@ -144,17 +144,13 @@ public :
 		 double m21, double m22,
 		 double m31, double m32)
   {
-    DiaMatrix mat;
-
-    mat.xx = m11;
-    mat.yx = m12;
-    mat.xy = m21;
-    mat.yy = m22;
-    mat.x0 = m31 * scale;
-    mat.y0 = m32 * scale;
-
-    //this->matrix = mat;
-    dia_matrix_multiply (&this->matrix, &mat, &this->matrix);
+    const auto& ctm = state->getCTM();
+    this->matrix.xx = ctm[0];
+    this->matrix.yx = ctm[1];
+    this->matrix.xy = ctm[2];
+    this->matrix.yy = ctm[3];
+    this->matrix.x0 = ctm[4] * scale;
+    this->matrix.y0 = ctm[5] * scale;
 
     updateLineDash(state);
     updateLineJoin(state);
@@ -437,9 +433,12 @@ public :
   //! Change back to the old state
   void restoreState(GfxState *state)
   {
-    // just restore the matrix for now
-    this->matrices.pop_back();
-    this->matrix = this->matrices.back();
+    if (!this->matrices.empty()) {
+      this->matrix = this->matrices.back();
+      this->matrices.pop_back();
+    } else {
+      g_warning("PDF import: restoreState called with an empty matrix stack");
+    }
     // should contain all of our update*() methods?
     updateLineWidth(state);
     updateLineDash(state);
@@ -467,6 +466,7 @@ public :
   startPage (int pageNum, GfxState *state G_GNUC_UNUSED)
   {
     this->pageNum = pageNum;
+    this->matrices.clear();
   }
 
 
@@ -474,7 +474,8 @@ public :
   void endPage()
   {
     DiaObject *group;
-    g_return_if_fail (objects != NULL);
+    if (this->objects == NULL)
+      return;
 
     /* approx 4:3 page distribution */
     int m = (int)sqrt (num_pages / 0.75);
@@ -839,13 +840,9 @@ DiaOutputDev::drawString(GfxState *state, GooString *s)
     text_color.alpha = 0.0;
 
   // not sure how state->getLineX() is related, it's 0 in my test cases
-  double tx = state->getCurX();
-  double ty = state->getCurY();
-  int rot = state->getRotate();
-  if (rot == 0)
-    obj = create_standard_text (tx * scale, page_height - ty * scale);
-  else /* XXX: at least for rot==90 */
-    obj = create_standard_text (ty * scale, tx * scale);
+  Point p = { state->getCurX(), state->getCurY() };
+  transform_point(&p, &this->matrix);
+  obj = create_standard_text (p.x, p.y);
   //not applyStyle (obj, TEXT);
   GPtrArray *plist = g_ptr_array_new ();
   // the "text" property is special, it must be initialized with text