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

12 files changed, 93 insertions, 68 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;
diff --git a/source/blender/draw/engines/image/image_drawing_mode.hh b/source/blender/draw/engines/image/image_drawing_mode.hh
index 46482ab6668..af3ec24d085 100644
--- a/source/blender/draw/engines/image/image_drawing_mode.hh
+++ b/source/blender/draw/engines/image/image_drawing_mode.hh
@@ -129,7 +129,6 @@ template<typename TextureMethod> class ScreenSpaceDrawingMode : public AbstractD
   {
     GPUShader *shader = IMAGE_shader_depth_get();
     DRWShadingGroup *shgrp = DRW_shgroup_create(shader, instance_data.passes.depth_pass);
-
     float image_mat[4][4];
     unit_m4(image_mat);
 
diff --git a/source/blender/draw/engines/image/image_engine.cc b/source/blender/draw/engines/image/image_engine.cc
index e972d21cda4..09efaea3e71 100644
--- a/source/blender/draw/engines/image/image_engine.cc
+++ b/source/blender/draw/engines/image/image_engine.cc
@@ -99,8 +99,11 @@ class ImageEngine {
     /* Setup the matrix to go from screen UV coordinates to UV texture space coordinates. */
     float image_resolution[2] = {image_buffer ? image_buffer->x : 1024.0f,
                                  image_buffer ? image_buffer->y : 1024.0f};
-    space->init_ss_to_texture_matrix(
-        draw_ctx->region, image_resolution, instance_data->ss_to_texture);
+    float image_display_offset[2] = {(float)instance_data->image->display_offset_x,
+                                     (float)instance_data->image->display_offset_y};
+    space->init_ss_to_texture_matrix(draw_ctx->region,
+                                     image_display_offset,
+                                     image_resolution, instance_data->ss_to_texture);
 
     const Scene *scene = DRW_context_state_get()->scene;
     instance_data->sh_params.update(space.get(), scene, instance_data->image, image_buffer);
diff --git a/source/blender/draw/engines/image/image_instance_data.hh b/source/blender/draw/engines/image/image_instance_data.hh
index 682b93a80b3..02ca86312c6 100644
--- a/source/blender/draw/engines/image/image_instance_data.hh
+++ b/source/blender/draw/engines/image/image_instance_data.hh
@@ -21,7 +21,7 @@
 /**
  * \brief max allowed textures to use by the ScreenSpaceDrawingMode.
  *
- * 4 textures are used to reduce uploading screen space textures when translating the image.
+ * 1 texture is used to reduce uploading screen space textures when translating the image.
  */
 constexpr int SCREEN_SPACE_DRAWING_MODE_TEXTURE_LEN = 1;
 
diff --git a/source/blender/draw/engines/image/image_space.hh b/source/blender/draw/engines/image/image_space.hh
index 7a11d14b567..a2f923a7118 100644
--- a/source/blender/draw/engines/image/image_space.hh
+++ b/source/blender/draw/engines/image/image_space.hh
@@ -77,6 +77,7 @@ class AbstractSpaceAccessor {
    * (0..1) to texture space UV coordinates.
    */
   virtual void init_ss_to_texture_matrix(const ARegion *region,
+                                         const float image_display_offset[2],
                                          const float image_resolution[2],
                                          float r_uv_to_texture[4][4]) const = 0;
 
diff --git a/source/blender/draw/engines/image/image_space_image.hh b/source/blender/draw/engines/image/image_space_image.hh
index 40aa117514c..7c15d780d07 100644
--- a/source/blender/draw/engines/image/image_space_image.hh
+++ b/source/blender/draw/engines/image/image_space_image.hh
@@ -148,20 +148,29 @@ class SpaceImageAccessor : public AbstractSpaceAccessor {
   }
 
   void init_ss_to_texture_matrix(const ARegion *region,
-                                 const float UNUSED(image_resolution[2]),
+                                 const float image_display_offset[2],
+                                 const float image_resolution[2],
                                  float r_uv_to_texture[4][4]) const override
   {
-    unit_m4(r_uv_to_texture);
-    float scale_x = 1.0 / BLI_rctf_size_x(&region->v2d.cur);
-    float scale_y = 1.0 / BLI_rctf_size_y(&region->v2d.cur);
-    float translate_x = scale_x * -region->v2d.cur.xmin;
-    float translate_y = scale_y * -region->v2d.cur.ymin;
-
-    r_uv_to_texture[0][0] = scale_x;
-    r_uv_to_texture[1][1] = scale_y;
-    r_uv_to_texture[3][0] = translate_x;
-    r_uv_to_texture[3][1] = translate_y;
-  }
+     float zoom_x = image_resolution[0] * sima->zoom;
+     float zoom_y = image_resolution[1] * sima ->zoom;
+     float image_offset_x = (region->winx - zoom_x) / 2 + sima->xof + image_display_offset[0];
+     float image_offset_y = (region->winy - zoom_y) / 2 + sima->yof + image_display_offset[1];
+
+     unit_m4(r_uv_to_texture);
+     float scale_x = 1.0 / BLI_rctf_size_x(&region->v2d.cur);
+     float scale_y = 1.0 / BLI_rctf_size_y(&region->v2d.cur);
+     float offset_x = 1.0 / image_resolution[0] * image_offset_x;
+     float offset_y = 1.0 / image_resolution[1] * image_offset_y;
+
+     float translate_x = scale_x * (-region->v2d.cur.xmin + offset_x);
+     float translate_y = scale_y * (-region->v2d.cur.ymin + offset_y);
+
+     r_uv_to_texture[0][0] = scale_x;
+     r_uv_to_texture[1][1] = scale_y;
+     r_uv_to_texture[3][0] = translate_x;
+     r_uv_to_texture[3][1] = translate_y;
+   }
 };
 
 }  // namespace blender::draw::image_engine
diff --git a/source/blender/draw/engines/image/image_space_node.hh b/source/blender/draw/engines/image/image_space_node.hh
index 6f38dcb86aa..4057f7b78cf 100644
--- a/source/blender/draw/engines/image/image_space_node.hh
+++ b/source/blender/draw/engines/image/image_space_node.hh
@@ -99,6 +99,7 @@ class SpaceNodeAccessor : public AbstractSpaceAccessor {
    * screen.
    */
   void init_ss_to_texture_matrix(const ARegion *region,
+                                 const float image_display_offset[2],
                                  const float image_resolution[2],
                                  float r_uv_to_texture[4][4]) const override
   {
@@ -107,10 +108,10 @@ class SpaceNodeAccessor : public AbstractSpaceAccessor {
     mul_v2_v2fl(display_resolution, image_resolution, snode->zoom);
     const float scale_x = display_resolution[0] / region->winx;
     const float scale_y = display_resolution[1] / region->winy;
-    const float translate_x = ((region->winx - display_resolution[0]) * 0.5f + snode->xof) /
-                              region->winx;
-    const float translate_y = ((region->winy - display_resolution[1]) * 0.5f + snode->yof) /
-                              region->winy;
+    const float translate_x = ((region->winx - display_resolution[0]) * 0.5f + snode->xof + image_display_offset[0]) /
+                          region->winx ;
+    const float translate_y = ((region->winy - display_resolution[1]) * 0.5f + snode->yof + image_display_offset[1]) /
+                          region->winy;
 
     r_uv_to_texture[0][0] = scale_x;
     r_uv_to_texture[1][1] = scale_y;
diff --git a/source/blender/editors/space_node/drawnode.cc b/source/blender/editors/space_node/drawnode.cc
index 365a17c0a04..ad647cf019d 100644
--- a/source/blender/editors/space_node/drawnode.cc
+++ b/source/blender/editors/space_node/drawnode.cc
@@ -1499,8 +1499,10 @@ void draw_nodespace_back_pix(const bContext &C,
   if (ibuf) {
     /* somehow the offset has to be calculated inverse */
     wmOrtho2_region_pixelspace(&region);
-    const float x = (region.winx - snode.zoom * ibuf->x) / 2 + snode.xof;
-    const float y = (region.winy - snode.zoom * ibuf->y) / 2 + snode.yof;
+    const float offset_x = snode.xof + ima->display_offset_x;
+    const float offset_y = snode.yof + ima->display_offset_y;
+    const float x = (region.winx - snode.zoom * ibuf->x) / 2 + offset_x;
+    const float y = (region.winy - snode.zoom * ibuf->y) / 2 + offset_y;
 
     /** \note draw selected info on backdrop */
     if (snode.edittree) {
diff --git a/source/blender/editors/space_node/node_gizmo.cc b/source/blender/editors/space_node/node_gizmo.cc
index 4f27f9baabc..832ec36ab34 100644
--- a/source/blender/editors/space_node/node_gizmo.cc
+++ b/source/blender/editors/space_node/node_gizmo.cc
@@ -38,25 +38,39 @@ namespace blender::ed::space_node {
 
 static void node_gizmo_calc_matrix_space(const SpaceNode *snode,
                                          const ARegion *region,
+                                         const float image_offset[2],
                                          float matrix_space[4][4])
 {
   unit_m4(matrix_space);
   mul_v3_fl(matrix_space[0], snode->zoom);
   mul_v3_fl(matrix_space[1], snode->zoom);
-  matrix_space[3][0] = (region->winx / 2) + snode->xof;
-  matrix_space[3][1] = (region->winy / 2) + snode->yof;
+  const float offset_x = snode->xof + image_offset[0];
+  const float offset_y = snode->yof + image_offset[1];
+  matrix_space[3][0] = (region->winx / 2) + offset_x;
+  matrix_space[3][1] = (region->winy / 2) + offset_y;
 }
 
 static void node_gizmo_calc_matrix_space_with_image_dims(const SpaceNode *snode,
                                                          const ARegion *region,
+                                                         const float image_offset[2],
                                                          const float image_dims[2],
                                                          float matrix_space[4][4])
 {
   unit_m4(matrix_space);
   mul_v3_fl(matrix_space[0], snode->zoom * image_dims[0]);
   mul_v3_fl(matrix_space[1], snode->zoom * image_dims[1]);
-  matrix_space[3][0] = ((region->winx / 2) + snode->xof) - ((image_dims[0] / 2.0f) * snode->zoom);
-  matrix_space[3][1] = ((region->winy / 2) + snode->yof) - ((image_dims[1] / 2.0f) * snode->zoom);
+  const float offset_x = snode->xof + image_offset[0];
+  const float offset_y = snode->yof + image_offset[1];
+  matrix_space[3][0] = ((region->winx / 2) + offset_x) - ((image_dims[0] / 2.0f) * snode->zoom);
+  matrix_space[3][1] = ((region->winy / 2) + offset_y) - ((image_dims[1] / 2.0f) * snode->zoom);
+}
+
+static void get_viewer_image_offset(const bContext *C, float r_offset[2])
+{
+  Main *bmain = CTX_data_main(C);
+  const Image *image = BKE_image_ensure_viewer(bmain, IMA_TYPE_COMPOSITE, "Viewer Node");
+  r_offset[0] = image->display_offset_x;
+  r_offset[1] = image->display_offset_y;
 }
 
 /** \} */
@@ -127,11 +141,13 @@ static void WIDGETGROUP_node_transform_refresh(const bContext *C, wmGizmoGroup *
   Main *bmain = CTX_data_main(C);
   wmGizmo *cage = ((wmGizmoWrapper *)gzgroup->customdata)->gizmo;
   const ARegion *region = CTX_wm_region(C);
-  /* center is always at the origin */
-  const float origin[3] = {float(region->winx / 2), float(region->winy / 2), 0.0f};
 
-  void *lock;
   Image *ima = BKE_image_ensure_viewer(bmain, IMA_TYPE_COMPOSITE, "Viewer Node");
+  /* Center is always at the origin. */
+  const float origin[3] ={ (region->winx / 2) + (float)ima->display_offset_x,
+                           (region->winy / 2) + (float)ima->display_offset_y};
+
+  void *lock;
   ImBuf *ibuf = BKE_image_acquire_ibuf(ima, nullptr, &lock);
 
   if (ibuf) {
@@ -340,7 +356,9 @@ static void WIDGETGROUP_node_crop_draw_prepare(const bContext *C, wmGizmoGroup *
 
   SpaceNode *snode = CTX_wm_space_node(C);
 
-  node_gizmo_calc_matrix_space(snode, region, gz->matrix_space);
+  float image_offset[2];
+  get_viewer_image_offset(C, image_offset);
+  node_gizmo_calc_matrix_space(snode, region, image_offset, gz->matrix_space);
 }
 
 static void WIDGETGROUP_node_crop_refresh(const bContext *C, wmGizmoGroup *gzgroup)
@@ -453,8 +471,10 @@ static void WIDGETGROUP_node_sbeam_draw_prepare(const bContext *C, wmGizmoGroup
 
   SpaceNode *snode = CTX_wm_space_node(C);
 
+  float image_offset[2];
+  get_viewer_image_offset(C, image_offset);
   node_gizmo_calc_matrix_space_with_image_dims(
-      snode, region, sbeam_group->state.dims, gz->matrix_space);
+      snode, region, image_offset, sbeam_group->state.dims, gz->matrix_space);
 }
 
 static void WIDGETGROUP_node_sbeam_refresh(const bContext *C, wmGizmoGroup *gzgroup)
@@ -560,9 +580,12 @@ static void WIDGETGROUP_node_corner_pin_draw_prepare(const bContext *C, wmGizmoG
 
   SpaceNode *snode = CTX_wm_space_node(C);
 
+  float image_offset[2];
+  get_viewer_image_offset(C, image_offset);
+
   float matrix_space[4][4];
   node_gizmo_calc_matrix_space_with_image_dims(
-      snode, region, cpin_group->state.dims, matrix_space);
+      snode, region, image_offset, cpin_group->state.dims, matrix_space);
 
   for (int i = 0; i < 4; i++) {
     wmGizmo *gz = cpin_group->gizmos[i];
diff --git a/source/blender/editors/space_node/space_node.cc b/source/blender/editors/space_node/space_node.cc
index 82b850653be..af93c4d823c 100644
--- a/source/blender/editors/space_node/space_node.cc
+++ b/source/blender/editors/space_node/space_node.cc
@@ -352,9 +352,14 @@ static void node_area_listener(const wmSpaceTypeListenerParams *params)
         case ND_FRAME:
           ED_area_tag_refresh(area);
           break;
-        case ND_COMPO_RESULT:
+        case ND_COMPO_RESULT: {
           ED_area_tag_redraw(area);
+          /* Backdrop image offset is calculated during compositing so gizmos need to be updated
+           * afterwards. */
+          const ARegion *region = BKE_area_find_region_type(area, RGN_TYPE_WINDOW);
+          WM_gizmomap_tag_refresh(region->gizmo_map);
           break;
+        }
         case ND_TRANSFORM_DONE:
           if (ED_node_is_compositor(snode)) {
             if (snode->flag & SNODE_AUTO_RENDER) {
diff --git a/source/blender/makesdna/DNA_image_types.h b/source/blender/makesdna/DNA_image_types.h
index 06b589d4f76..8f327d12735 100644
--- a/source/blender/makesdna/DNA_image_types.h
+++ b/source/blender/makesdna/DNA_image_types.h
@@ -199,6 +199,9 @@ typedef struct Image {
   char eye;
   char views_format;
 
+  /** Displayed offset in backdrop for viewer nodes in pixel space. */
+  int display_offset_x, display_offset_y;
+
   /* ImageTile list for UDIMs. */
   int active_tile_index;
   ListBase tiles;