Resolves #140

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "pdfium-render"
-version = "0.8.18"
+version = "0.8.19"
 edition = "2018"
 publish = true
 description = "A high-level idiomatic Rust wrapper around Pdfium, the C++ PDF library used by the Google Chromium project."

README.md

@@ -83,10 +83,14 @@ available at <https://github.com/ajrcarey/pdfium-render/tree/master/examples>. T
 _Note: upcoming release 0.9.0 will remove all deprecated items. For a complete list of deprecated
 items, see <https://github.com/ajrcarey/pdfium-render/issues/36>._
 
-Release 0.8.19 adds support for creating new annotations, positioning those annotations,
+Release 0.8.20 adds support for creating new annotations, positioning those annotations,
 associating them with page objects, and retrieving and setting more annotation properties for each
 annotation type. A new `examples/create_annotations.rs` example demonstrates the extended functionality.
 
+Release 0.8.19 fixes a bug in `PdfPage::flatten()` that prevented the effect of the flatten operation
+from taking effect until the page was dropped and reloaded. The effect of the flatten operation
+is now immediately available.
+
 Releases 0.8.17 and 0.8.18 adjust the WASM implementation of `pdfium-render` to account for some small packaging
 changes in the upstream releases of Pdfium published at <https://github.com/paulocoutinhox/pdfium-lib/releases>;
 release 0.8.17 also fixes a potential segmentation fault that could occur when dropping a `PdfDocument`
@@ -345,7 +349,7 @@ functions specific to interactive scripting, user interaction, and printing.
 * Releases numbered 0.8.x aim to progressively add support for all remaining Pdfium editing functions to `pdfium-render`.
 * Releases numbered 0.9.x aim to fill any remaining gaps in the high-level interface prior to 1.0.
 
-There are 368 `FPDF_*` functions in the Pdfium API. As of version 0.8.18, 325 (88%) have
+There are 368 `FPDF_*` functions in the Pdfium API. As of version 0.8.19, 325 (88%) have
 bindings available in `PdfiumLibraryBindings`, with the functionality of the majority of these
 available via the `pdfium-render` high-level interface.
 
@@ -358,7 +362,7 @@ at <https://github.com/ajrcarey/pdfium-render/issues>.
 
 ## Version history
 
-* 0.8.19: adds `PdfPageAnnotationAttachmentPoints` struct and matching iterator; adds new annotation functions
+* 0.8.20: adds `PdfPageAnnotationAttachmentPoints` struct and matching iterator; adds new annotation functions
   to `PdfPageAnnotationCommon` along with their matching implementations in `PdfPageAnnotationPrivate`,
   including `PdfPageAnnotationCommon::set_bounds()`, `PdfPageAnnotationCommon::set_position()`,
   `PdfPageAnnotationCommon::set_width()`, `PdfPageAnnotationCommon::set_height()`,
@@ -369,7 +373,11 @@ at <https://github.com/ajrcarey/pdfium-render/issues>.
   `chrono::DateTime` types to PDF date strings in `utils::dates`; adds mutability and annotation
   creation functions to `PdfPageAnnotations` collection; adds new `create_annotations.rs` example;
   adds `PdfPageTextSegment::chars()` convenience function.
-* 0.8.18: Adjusts `PdfiumRenderWasmState::bind_to_pdfium()` to fall back to
+* 0.8.19: adjusts the behaviour of `PdfPage::flatten()` so that the page is reloaded after the
+  call to `FPDFPage_Flatten()`. This ensures that the effect of the flatten operation is immediately
+  visible to the caller; previously, it was necessary for the caller to drop and reload the page
+  themselves. For more details, see <https://github.com/ajrcarey/pdfium-render/issues/140>.
+* 0.8.18: adjusts `PdfiumRenderWasmState::bind_to_pdfium()` to fall back to
   `Module["wasmExports"]["__indirect_function_table"]` if `Window.wasmTable` global variable is
   not available, in response to upstream packaging changes at
   <https://github.com/paulocoutinhox/pdfium-lib/releases>. For more details, see

src/page.rs

@@ -849,22 +849,7 @@ impl<'a> PdfPage<'a> {
             // transformation to take effect. For more information, see:
             // https://github.com/ajrcarey/pdfium-render/issues/93
 
-            if let Some(page_index) =
-                PdfPageIndexCache::get_index_for_page(self.document_handle, self.page_handle)
-            {
-                self.drop_impl();
-
-                self.page_handle = self
-                    .bindings
-                    .FPDF_LoadPage(self.document_handle, page_index as c_int);
-
-                PdfPageIndexCache::set_index_for_page(
-                    self.document_handle,
-                    self.page_handle,
-                    page_index,
-                );
-            }
-
+            self.reload_in_place();
             Ok(())
         } else {
             Err(PdfiumError::PdfiumLibraryInternalError(
@@ -915,9 +900,16 @@ impl<'a> PdfPage<'a> {
             .FPDFPage_Flatten(self.page_handle, flag as c_int) as u32
         {
             FLATTEN_SUCCESS => {
-                self.is_content_regeneration_required = true;
+                self.regenerate_content()?;
 
-                self.regenerate_content()
+                // As noted at https://bugs.chromium.org/p/pdfium/issues/detail?id=2055,
+                // FPDFPage_Flatten() updates the underlying dictionaries and content streams for
+                // the page, but does not update the FPDF_Page structure. We must reload the
+                // page for the effects of the flatten operation to be visible. For more information, see:
+                // https://github.com/ajrcarey/pdfium-render/issues/140
+
+                self.reload_in_place();
+                Ok(())
             }
             FLATTEN_NOTHINGTODO => Ok(()),
             FLATTEN_FAIL => Err(PdfiumError::PageFlattenFailure),
@@ -1025,6 +1017,28 @@ impl<'a> PdfPage<'a> {
         }
     }
 
+    /// Reloads the page transparently to any caller, forcing a refresh of all page data structures.
+    /// This will replace this page's `FPDF_PAGE` handle. The page index cache will be updated.
+    fn reload_in_place(&mut self) {
+        if let Some(page_index) =
+            PdfPageIndexCache::get_index_for_page(self.document_handle, self.page_handle)
+        {
+            self.drop_impl();
+
+            self.page_handle = self
+                .bindings
+                .FPDF_LoadPage(self.document_handle, page_index as c_int);
+
+            PdfPageIndexCache::set_index_for_page(
+                self.document_handle,
+                self.page_handle,
+                page_index,
+            );
+        }
+    }
+
+    /// Drops the page by calling `FPDF_ClosePage()`, freeing held memory. This will invalidate
+    /// this page's `FPDF_PAGE` handle. The page index cache will be updated.
     fn drop_impl(&mut self) {
         if self.regeneration_strategy != PdfPageContentRegenerationStrategy::Manual
             && self.is_content_regeneration_required