Forms: avoid the need to reload the page on every change

Add pdf_update_annot, which is called before rendering an annotation, and
checks that the annotation structure has correct information. There are
three reasons the information can be out of date.

  Attributes of a field may have been changed such that its appearance
  stream needs updating. In this case the field will have have "Dirty"
  added to its dictionary

  The mouse may have changed state over the field, and a different
  appearance stream needs selecting. The annotation structure now records
  the mouse states for which the current appearance stream is acceptable.

  The field may have changed state as recorded by its "AS" value, and a
  different appearance stream needs selecting.

1 files changed, 60 insertions, 12 deletions

diff --git a/apps/pdfapp.c b/apps/pdfapp.c
index 2e7b6ffe..aa31ab0f 100644
--- a/apps/pdfapp.c
+++ b/apps/pdfapp.c
@@ -420,6 +420,45 @@ static void pdfapp_loadpage(pdfapp_t *app)
 	app->errored = errored;
 }
 
+static void pdfapp_recreate_displaylist(pdfapp_t *app)
+{
+	fz_device *mdev = NULL;
+	int errored = 0;
+	fz_cookie cookie = { 0 };
+
+	fz_var(mdev);
+
+	if (app->page_list)
+	{
+		fz_free_display_list(app->ctx, app->page_list);
+		app->page_list = NULL;
+	}
+
+	fz_try(app->ctx)
+	{
+		/* Create display list */
+		app->page_list = fz_new_display_list(app->ctx);
+		mdev = fz_new_list_device(app->ctx, app->page_list);
+		fz_run_page(app->doc, app->page, mdev, fz_identity, &cookie);
+		if (cookie.errors)
+		{
+			pdfapp_warn(app, "Errors found on page");
+			errored = 1;
+		}
+	}
+	fz_always(app->ctx)
+	{
+		fz_free_device(mdev);
+	}
+	fz_catch(app->ctx)
+	{
+		pdfapp_warn(app, "Cannot load page");
+		errored = 1;
+	}
+
+	app->errored = errored;
+}
+
 #define MAX_TITLE 256
 
 static void pdfapp_showpage(pdfapp_t *app, int loadpage, int drawpage, int repaint)
@@ -437,20 +476,29 @@ static void pdfapp_showpage(pdfapp_t *app, int loadpage, int drawpage, int repai
 
 	if (loadpage)
 	{
-		pdfapp_loadpage(app);
+		if (loadpage == 1)
+		{
+			pdfapp_loadpage(app);
 
-		/* Zero search hit position */
-		app->hit = -1;
-		app->hitlen = 0;
+			/* Zero search hit position */
+			app->hit = -1;
+			app->hitlen = 0;
 
-		/* Extract text */
-		app->page_sheet = fz_new_text_sheet(app->ctx);
-		app->page_text = fz_new_text_page(app->ctx, app->page_bbox);
-		if (app->page_list)
+			/* Extract text */
+			app->page_sheet = fz_new_text_sheet(app->ctx);
+			app->page_text = fz_new_text_page(app->ctx, app->page_bbox);
+
+			if (app->page_list)
+			{
+				tdev = fz_new_text_device(app->ctx, app->page_sheet, app->page_text);
+				fz_run_display_list(app->page_list, tdev, fz_identity, fz_infinite_bbox, &cookie);
+				fz_free_device(tdev);
+			}
+		}
+		else
 		{
-			tdev = fz_new_text_device(app->ctx, app->page_sheet, app->page_text);
-			fz_run_display_list(app->page_list, tdev, fz_identity, fz_infinite_bbox, &cookie);
-			fz_free_device(tdev);
+			/* pdfapp_onmouse passes loadpage == 2, meaning only recreate the display list */
+			pdfapp_recreate_displaylist(app);
 		}
 	}
 
@@ -1217,7 +1265,7 @@ void pdfapp_onmouse(pdfapp_t *app, int x, int y, int btn, int modifiers, int sta
 			}
 
 			app->nowaitcursor = 1;
-			pdfapp_showpage(app, 1, 1, 1);
+			pdfapp_showpage(app, 2, 1, 1);
 			app->nowaitcursor = 0;
 			processed = 1;
 		}