Handle out-of-range coordinates from an XYZ named destination.

The in-page coordinates from an XYZ named destination sometimes can be
out of the range of the PDF's page width and height.

This CL preprocesses such out-of-range x and y coordinates before
converting them from in-page coordinates to in-screen coordinates.

Bug: 1157061
Change-Id: I3279890459188e3856c75478caebefa6bafaa655
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2633191
Commit-Queue: Hui Yingst <nigi@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846253}

pdf/pdfium/pdfium_engine.cc

@@ -392,6 +392,10 @@ std::string GetXYZParamsString(FPDF_DEST dest, PDFiumPage* page) {
     return "";
   }
 
+  // Handle out-of-range page coordinates.
+  x = has_x_coord ? page->PreProcessInPageCoordX(x) : 0;
+  y = has_y_coord ? page->PreProcessInPageCoordY(y) : 0;
+
   // Convert in-page coordinates to in-screen coordinates.
   gfx::PointF xy(x, y);
   gfx::PointF screen_coords = page->TransformPageToScreenXY(xy);

pdf/pdfium/pdfium_page.cc

@@ -852,10 +852,15 @@ PDFiumPage::Area PDFiumPage::GetDestinationTarget(FPDF_DEST destination,
   base::Optional<float> x;
   base::Optional<float> y;
   GetPageDestinationTarget(destination, &x, &y, &target->zoom);
-  if (x)
-    target->x_in_pixels = TransformPageToScreenX(x.value());
-  if (y)
-    target->y_in_pixels = TransformPageToScreenY(y.value());
+
+  if (x) {
+    target->x_in_pixels =
+        TransformPageToScreenX(PreProcessInPageCoordX(x.value()));
+  }
+  if (y) {
+    target->y_in_pixels =
+        TransformPageToScreenY(PreProcessInPageCoordY(y.value()));
+  }
 
   return DOCLINK_AREA;
 }
@@ -890,6 +895,18 @@ void PDFiumPage::GetPageDestinationTarget(FPDF_DEST destination,
     *zoom_value = zoom;
 }
 
+float PDFiumPage::PreProcessInPageCoordX(float x) {
+  // If `x` < 0, scroll to the left side of the page.
+  // If `x` > width, scroll to the right side of the page.
+  return std::max<float>(std::min<float>(x, FPDF_GetPageWidthF(GetPage())), 0);
+}
+
+float PDFiumPage::PreProcessInPageCoordY(float y) {
+  // If `y` < 0, it is a valid input, no extra handling is needed.
+  // If `y` > height, scroll to the top of the page.
+  return std::min<float>(y, FPDF_GetPageHeightF(GetPage()));
+}
+
 gfx::PointF PDFiumPage::TransformPageToScreenXY(const gfx::PointF& xy) {
   if (!available_)
     return gfx::PointF();

pdf/pdfium/pdfium_page.h

@@ -118,6 +118,11 @@ class PDFiumPage {
                                 base::Optional<float>* dest_y,
                                 base::Optional<float>* zoom_value);
 
+  // For a named destination with "XYZ" view fit type, pre-processes the in-page
+  // x/y coordinate in case it's out of the range of the page dimension.
+  float PreProcessInPageCoordX(float x);
+  float PreProcessInPageCoordY(float y);
+
   // Transforms an (x, y) position in page coordinates to screen coordinates.
   gfx::PointF TransformPageToScreenXY(const gfx::PointF& xy);