fix: fall back to default DPI when GTK returns 0 on Linux (#50488)

trop[bot] · codebytere · web-flow · commit 904fbbd59801 · 2026-03-26T11:47:34.000-04:00
GetDefaultPrinterDPI() creates a blank GtkPrintSettings and reads
its resolution, which returns 0 for uninitialized settings. With
DPI=0, SetPrintableAreaIfValid() computes a zero scale factor,
producing empty page dimensions that fail PrintMsgPrintParamsIsValid().

Fall back to kDefaultPdfDpi (72) when GTK returns 0, matching the
existing Windows fallback pattern when CreateDC fails.

Co-authored-by: trop[bot] &lt;37223003+trop[bot]@users.noreply.github.com&gt;
Co-authored-by: Shelley Vohr &lt;shelley.vohr@gmail.com&gt;
diff --git a/shell/browser/printing/printing_utils.cc b/shell/browser/printing/printing_utils.cc
@@ -59,6 +59,8 @@ gfx::Size GetDefaultPrinterDPI(const std::u16string& device_name) {
   GtkPrintSettings* print_settings = gtk_print_settings_new();
   int dpi = gtk_print_settings_get_resolution(print_settings);
   g_object_unref(print_settings);
+  if (dpi <= 0)
+    dpi = printing::kDefaultPdfDpi;
   return {dpi, dpi};
 #endif
 }

Original file line number	Diff line number	Diff line change
`@@ -59,6 +59,8 @@ gfx::Size GetDefaultPrinterDPI(const std::u16string& device_name) {`
`59`	`59`	`GtkPrintSettings* print_settings = gtk_print_settings_new();`
`60`	`60`	`int dpi = gtk_print_settings_get_resolution(print_settings);`
`61`	`61`	`g_object_unref(print_settings);`
	`62`	`+ if (dpi <= 0)`
	`63`	`+ dpi = printing::kDefaultPdfDpi;`
`62`	`64`	`return {dpi, dpi};`
`63`	`65`	`#endif`
`64`	`66`	`}`