Compositor: Support backdrop offset for the Viewer node

This is only part of the experimental "Full Frame" mode (disabled
by default). See T88150.

Currently the viewer node uses buffer paddings to display image offset
in the backdrop as a temporal solution implemented for {D12466}.
This solution is inefficient memory and performance-wise. Another
issue is that the paddings are part the image when saved.

This patch instead sets the offset in the Viewer node image
as variables and makes the backdrop take it into account
when drawing the image or any related gizmo.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D12750

2 files changed, 14 insertions, 35 deletions

diff --git a/source/blender/compositor/operations/COM_ViewerOperation.cc b/source/blender/compositor/operations/COM_ViewerOperation.cc
index bc7e08ee98a..7f0eaecfff7 100644
--- a/source/blender/compositor/operations/COM_ViewerOperation.cc
+++ b/source/blender/compositor/operations/COM_ViewerOperation.cc
@@ -10,9 +10,9 @@
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
 
-namespace blender::compositor {
+#include "DNA_node_types.h"
 
-static int MAX_VIEWER_TRANSLATION_PADDING = 12000;
+namespace blender::compositor {
 
 ViewerOperation::ViewerOperation()
 {
@@ -137,23 +137,12 @@ void ViewerOperation::init_image()
     return;
   }
 
-  int padding_x = abs(canvas_.xmin) * 2;
-  int padding_y = abs(canvas_.ymin) * 2;
-  if (padding_x > MAX_VIEWER_TRANSLATION_PADDING) {
-    padding_x = MAX_VIEWER_TRANSLATION_PADDING;
-  }
-  if (padding_y > MAX_VIEWER_TRANSLATION_PADDING) {
-    padding_y = MAX_VIEWER_TRANSLATION_PADDING;
-  }
-
-  display_width_ = get_width() + padding_x;
-  display_height_ = get_height() + padding_y;
-  if (ibuf->x != display_width_ || ibuf->y != display_height_) {
+  if (ibuf->x != get_width() || ibuf->y != get_height()) {
     imb_freerectImBuf(ibuf);
     imb_freerectfloatImBuf(ibuf);
     IMB_freezbuffloatImBuf(ibuf);
-    ibuf->x = display_width_;
-    ibuf->y = display_height_;
+    ibuf->x = get_width();
+    ibuf->y = get_height();
     /* zero size can happen if no image buffers exist to define a sensible resolution */
     if (ibuf->x > 0 && ibuf->y > 0) {
       imb_addrectfloatImBuf(ibuf);
@@ -187,11 +176,13 @@ void ViewerOperation::update_image(const rcti *rect)
     return;
   }
 
+  image_->display_offset_x = canvas_.xmin;
+  image_->display_offset_y = canvas_.ymin;
   float *buffer = output_buffer_;
   IMB_partial_display_buffer_update(ibuf_,
                                     buffer,
                                     nullptr,
-                                    display_width_,
+                                    get_width(),
                                     0,
                                     0,
                                     view_settings_,
@@ -224,32 +215,23 @@ void ViewerOperation::update_memory_buffer_partial(MemoryBuffer *UNUSED(output),
     return;
   }
 
-  const int offset_x = area.xmin + (canvas_.xmin > 0 ? canvas_.xmin * 2 : 0);
-  const int offset_y = area.ymin + (canvas_.ymin > 0 ? canvas_.ymin * 2 : 0);
   MemoryBuffer output_buffer(
-      output_buffer_, COM_DATA_TYPE_COLOR_CHANNELS, display_width_, display_height_);
+      output_buffer_, COM_DATA_TYPE_COLOR_CHANNELS, get_width(), get_height());
   const MemoryBuffer *input_image = inputs[0];
-  output_buffer.copy_from(input_image, area, offset_x, offset_y);
+  output_buffer.copy_from(input_image, area);
   if (use_alpha_input_) {
     const MemoryBuffer *input_alpha = inputs[1];
-    output_buffer.copy_from(
-        input_alpha, area, 0, COM_DATA_TYPE_VALUE_CHANNELS, offset_x, offset_y, 3);
+    output_buffer.copy_from(input_alpha, area, 0, COM_DATA_TYPE_VALUE_CHANNELS, 3);
   }
 
   if (depth_buffer_) {
     MemoryBuffer depth_buffer(
-        depth_buffer_, COM_DATA_TYPE_VALUE_CHANNELS, display_width_, display_height_);
+        depth_buffer_, COM_DATA_TYPE_VALUE_CHANNELS, get_width(), get_height());
     const MemoryBuffer *input_depth = inputs[2];
-    depth_buffer.copy_from(input_depth, area, offset_x, offset_y);
+    depth_buffer.copy_from(input_depth, area);
   }
 
-  rcti display_area;
-  BLI_rcti_init(&display_area,
-                offset_x,
-                offset_x + BLI_rcti_size_x(&area),
-                offset_y,
-                offset_y + BLI_rcti_size_y(&area));
-  update_image(&display_area);
+  update_image(&area);
 }
 
 void ViewerOperation::clear_display_buffer()
diff --git a/source/blender/compositor/operations/COM_ViewerOperation.h b/source/blender/compositor/operations/COM_ViewerOperation.h
index 1ad6cc51269..ed9e5871eae 100644
--- a/source/blender/compositor/operations/COM_ViewerOperation.h
+++ b/source/blender/compositor/operations/COM_ViewerOperation.h
@@ -35,9 +35,6 @@ class ViewerOperation : public MultiThreadedOperation {
   SocketReader *alpha_input_;
   SocketReader *depth_input_;
 
-  int display_width_;
-  int display_height_;
-
  public:
   ViewerOperation();
   void init_execution() override;