Added icetClearImageTrueBackground.

Use it to correct some background correction problems with blank tiles.

Changes.txt

@@ -112,5 +112,6 @@ not done automatically.  icetSingleImageCollect does it for you, though.
 Added internal state variables ICET_NEED_BACKGROUND_CORRECTION,
 ICET_TRUE_BACKGROUND_COLOR, and ICET_TRUE_BACKGROUND_COLOR_WORD.
 
-icetImageCorrectBackground, icetDecompressImageCorrectBackground, and
+icetImageCorrectBackground, icetClearImageTrueBackground,
+icetDecompressImageCorrectBackground, and
 icetDecompressSubImageCorrectBackground functions.

src/ice-t/image.c

@@ -2275,6 +2275,28 @@ void icetImageCorrectBackground(IceTImage image)
     icetTimingBlendEnd();
 }
 
+void icetClearImageTrueBackground(IceTImage image)
+{
+    IceTFloat true_background[4];
+    IceTInt true_background_word;
+    IceTFloat original_background[4];
+    IceTInt original_background_word;
+
+    icetGetFloatv(ICET_TRUE_BACKGROUND_COLOR, true_background);
+    icetGetIntegerv(ICET_TRUE_BACKGROUND_COLOR_WORD, &true_background_word);
+
+    icetGetFloatv(ICET_BACKGROUND_COLOR, original_background);
+    icetGetIntegerv(ICET_BACKGROUND_COLOR_WORD, &original_background_word);
+
+    icetStateSetFloatv(ICET_BACKGROUND_COLOR, 4, true_background);
+    icetStateSetInteger(ICET_BACKGROUND_COLOR_WORD, true_background_word);
+
+    icetClearImage(image);
+
+    icetStateSetFloatv(ICET_BACKGROUND_COLOR, 4, original_background);
+    icetStateSetInteger(ICET_BACKGROUND_COLOR_WORD, original_background_word);
+}
+
 static IceTImage renderTile(int tile,
                             IceTInt *screen_viewport,
                             IceTInt *target_viewport,

src/include/IceTDevImage.h

@@ -181,6 +181,7 @@ ICET_EXPORT void icetCompressedCompressedComposite(
                                              IceTSparseImage dest_buffer);
 
 ICET_EXPORT void icetImageCorrectBackground(IceTImage image);
+ICET_EXPORT void icetClearImageTrueBackground(IceTImage image);
 
 #define ICET_BLEND_UBYTE(front, back, dest)                             \
 {                                                                       \

src/strategies/direct.c

@@ -71,21 +71,24 @@ IceTImage icetDirectCompose(void)
                                  outSparseImage,
                                  tile_image_dest);
 
-    if ((display_tile >= 0) && (num_contributors < 1)) {
-      /* Must be displaying a blank tile. */
-        const IceTInt *tile_viewports
-            = icetUnsafeStateGetInteger(ICET_TILE_VIEWPORTS);
-        const IceTInt *display_tile_viewport = tile_viewports + 4*display_tile;
-        IceTInt display_tile_width = display_tile_viewport[2];
-        IceTInt display_tile_height = display_tile_viewport[3];
-
-        icetRaiseDebug("Returning blank tile.");
-        icetImageSetDimensions(image, display_tile_width, display_tile_height);
-        icetClearImage(image);
-    }
-
     if (display_tile >= 0) {
-        icetImageCorrectBackground(image);
+        if (num_contributors > 0) {
+            icetImageCorrectBackground(image);
+        } else {
+            /* Must be displaying a blank tile. */
+            const IceTInt *tile_viewports
+                = icetUnsafeStateGetInteger(ICET_TILE_VIEWPORTS);
+            const IceTInt *display_tile_viewport
+                = tile_viewports + 4*display_tile;
+            IceTInt display_tile_width = display_tile_viewport[2];
+            IceTInt display_tile_height = display_tile_viewport[3];
+
+            icetRaiseDebug("Returning blank tile.");
+            icetImageSetDimensions(image,
+                                   display_tile_width,
+                                   display_tile_height);
+            icetClearImageTrueBackground(image);
+        }
     }
 
     return image;

src/strategies/reduce.c

@@ -515,7 +515,7 @@ IceTImage reduceCollect(const IceTSparseImage composited_image,
     if ((tile_displayed >= 0) && (tile_displayed != compose_tile)) {
         /* Return empty image if nothing in this tile. */
         icetRaiseDebug("Clearing pixels");
-        icetClearImage(result_image);
+        icetClearImageTrueBackground(result_image);
     }
 
     return result_image;

src/strategies/split.c

@@ -124,7 +124,7 @@ static void icetCollectImage(IceTImage imageFragment,
                 }
             }
         } else {
-            icetClearImage(fullImage);
+            icetClearImageTrueBackground(fullImage);
         }
     }
 
@@ -202,7 +202,7 @@ IceTImage icetSplitCompose(void)
             my_height = tile_viewports[4*tile_displayed + 3];
             fullImage = icetGetStateBufferImage(SPLIT_FULL_IMAGE_BUFFER,
                                                 my_width, my_height);
-            icetClearImage(fullImage);
+            icetClearImageTrueBackground(fullImage);
         }
         return fullImage;
     }

src/strategies/vtree.c

@@ -226,13 +226,35 @@ IceTImage icetVtreeCompose(void)
   /* Hacks for when "this" tile was not rendered. */
     if ((tile_displayed >= 0) && (tile_displayed != tile_held)) {
         if (all_contained_tmasks[rank*num_tiles + tile_displayed]) {
-          /* Only "this" node draws "this" tile.  Because the image never */
-          /* needed to be transferred, it was never rendered above.  Just */
-          /* render it now.                                               */
+          /* Only "this" node draws "this" tile.  Because the image never needed
+              to be transferred, it was never rendered above.  Just render it
+              now.  We might save some time by rendering with the true
+              background color rather than correcting it later. */
+            IceTFloat true_background[4];
+            IceTInt true_background_word;
+            IceTFloat original_background[4];
+            IceTInt original_background_word;
+
+            icetGetFloatv(ICET_TRUE_BACKGROUND_COLOR, true_background);
+            icetGetIntegerv(ICET_TRUE_BACKGROUND_COLOR_WORD,
+                            &true_background_word);
+
+            icetGetFloatv(ICET_BACKGROUND_COLOR, original_background);
+            icetGetIntegerv(ICET_BACKGROUND_COLOR_WORD,
+                            &original_background_word);
+
+            icetStateSetFloatv(ICET_BACKGROUND_COLOR, 4, true_background);
+            icetStateSetInteger(ICET_BACKGROUND_COLOR_WORD,
+                                true_background_word);
+
             icetRaiseDebug("Rendering tile to display.");
           /* This may uncessarily read a buffer if not outputing an input
              buffer */
             icetGetTileImage(tile_displayed, image);
+
+            icetStateSetFloatv(ICET_BACKGROUND_COLOR, 4, original_background);
+            icetStateSetInteger(ICET_BACKGROUND_COLOR_WORD,
+                                original_background_word);
         } else {
           /* "This" tile is blank. */
             const IceTInt *display_tile_viewport
@@ -243,11 +265,9 @@ IceTImage icetVtreeCompose(void)
             icetRaiseDebug("Returning blank image.");
             icetImageSetDimensions(
                                 image, display_tile_width, display_tile_height);
-            icetClearImage(image);
+            icetClearImageTrueBackground(image);
         }
-    }
-
-    if (tile_displayed >= 0) {
+    } else if (tile_displayed >= 0) {
         icetImageCorrectBackground(image);
     }