From 2aa01c58a1dbb520ee59ec2d9da41ba7e3a30420 Mon Sep 17 00:00:00 2001
From: itepechi <72330683+itepechi@users.noreply.github.com>
Date: Mon, 25 Oct 2021 06:34:52 +0900
Subject: [PATCH] Add option `background_image_anchor` to configure bgimage
 position

---
 kitty/bgimage_vertex.glsl        |  3 ++-
 kitty/boss.py                    |  7 ++-----
 kitty/data-types.h               |  1 +
 kitty/fast_data_types.pyi        |  3 ++-
 kitty/graphics.h                 |  1 +
 kitty/options/definition.py      |  5 +++++
 kitty/options/parse.py           |  8 ++++++++
 kitty/options/to-c-generated.h   | 15 +++++++++++++++
 kitty/options/to-c.h             | 30 ++++++++++++++++++++++++++++++
 kitty/options/types.py           |  4 ++++
 kitty/rc/set_background_image.py | 11 ++++++++++-
 kitty/shaders.c                  | 17 ++++++++++++++++-
 kitty/state.c                    |  9 +++++++--
 kitty/state.h                    |  1 +
 14 files changed, 104 insertions(+), 11 deletions(-)

diff --git a/kitty/bgimage_vertex.glsl b/kitty/bgimage_vertex.glsl
index 0b2a41cd0..b66a656db 100644
--- a/kitty/bgimage_vertex.glsl
+++ b/kitty/bgimage_vertex.glsl
@@ -9,6 +9,7 @@
 #define tex_bottom 1
 
 uniform float tiled;
+uniform vec2 translate; // [ left, top ]
 uniform vec4 sizes;  // [ window_width, window_height, image_width, image_height ]
 
 out vec2 texcoord;
@@ -37,6 +38,6 @@ float tiling_factor(int i) {
 
 void main() {
     vec2 tex_coords = tex_map[gl_VertexID];
-    texcoord = vec2(tex_coords[0] * tiling_factor(0), tex_coords[1] * tiling_factor(1));
+    texcoord = vec2(tex_coords[0] * tiling_factor(0) - translate[0], tex_coords[1] * tiling_factor(1) - translate[1]);
     gl_Position = vec4(pos_map[gl_VertexID], 0, 1);
 }
diff --git a/kitty/boss.py b/kitty/boss.py
index e1121cfbb..0a481fb6a 100755
--- a/kitty/boss.py
+++ b/kitty/boss.py
@@ -1975,11 +1975,8 @@ class Boss:
 
         self.choose_entry('Choose an OS window to move the tab to', items, chosen)
 
-    def set_background_image(self, path: Optional[str], os_windows: Tuple[int, ...], configured: bool, layout: Optional[str]) -> None:
-        if layout:
-            set_background_image(path, os_windows, configured, layout)
-        else:
-            set_background_image(path, os_windows, configured)
+    def set_background_image(self, path: Optional[str], os_windows: Tuple[int, ...], configured: bool, layout: Optional[str], anchor: Optional[str]) -> None:
+        set_background_image(path, os_windows, configured, layout, anchor)
         for os_window_id in os_windows:
             self.default_bg_changed_for(os_window_id)
 
diff --git a/kitty/data-types.h b/kitty/data-types.h
index 91cf1f504..a9c558447 100644
--- a/kitty/data-types.h
+++ b/kitty/data-types.h
@@ -65,6 +65,7 @@ typedef enum MouseTrackingProtocols { NORMAL_PROTOCOL, UTF8_PROTOCOL, SGR_PROTOC
 typedef enum MouseShapes { BEAM, HAND, ARROW } MouseShape;
 typedef enum { NONE, MENUBAR, WINDOW, ALL } WindowTitleIn;
 typedef enum { TILING, SCALED, MIRRORED } BackgroundImageLayout;
+typedef enum { NORTHWEST, NORTH, NORTHEAST, EAST, SOUTHEAST, SOUTH, SOUTHWEST, WEST, CENTER } BackgroundImageAnchor;
 
 #define MAX_CHILDREN 512
 #define BLANK_CHAR 0
diff --git a/kitty/fast_data_types.pyi b/kitty/fast_data_types.pyi
index e58f1549d..c9468d27c 100644
--- a/kitty/fast_data_types.pyi
+++ b/kitty/fast_data_types.pyi
@@ -598,7 +598,8 @@ def set_background_image(
     path: Optional[str],
     os_window_ids: Tuple[int, ...],
     configured: bool = True,
-    layout_name: Optional[str] = None
+    layout_name: Optional[str] = None,
+    anchor_name: Optional[str] = None
 ) -> None:
     pass
 
diff --git a/kitty/graphics.h b/kitty/graphics.h
index 55015e88a..4a25fb739 100644
--- a/kitty/graphics.h
+++ b/kitty/graphics.h
@@ -66,6 +66,7 @@ typedef struct {
     unsigned int height, width;
     uint8_t* bitmap;
     uint32_t refcnt;
+    BackgroundImageAnchor anchor;
 } BackgroundImage;
 
 typedef struct {
diff --git a/kitty/options/definition.py b/kitty/options/definition.py
index ab2c5ba5a..ff95b3127 100644
--- a/kitty/options/definition.py
+++ b/kitty/options/definition.py
@@ -1110,6 +1110,11 @@ opt('background_image_layout', 'tiled',
     long_text='Whether to tile or scale the background image.'
     )
 
+opt('background_image_anchor', 'northwest',
+    choices=('northwest', 'north', 'northeast', 'east', 'southeast', 'south', 'southwest', 'west', 'center'), ctype='bganchor',
+    long_text='Where to position the background image in the window.'
+    )
+
 opt('background_image_linear', 'no',
     option_type='to_bool', ctype='bool',
     long_text='When background image is scaled, whether linear interpolation should be used.'
diff --git a/kitty/options/parse.py b/kitty/options/parse.py
index bd1b7f9a8..97b542609 100644
--- a/kitty/options/parse.py
+++ b/kitty/options/parse.py
@@ -57,6 +57,14 @@ class Parser:
     def background_image(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['background_image'] = config_or_absolute_path(val)
 
+    def background_image_anchor(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
+        val = val.lower()
+        if val not in self.choices_for_background_image_anchor:
+            raise ValueError(f"The value {val} is not a valid choice for background_image_anchor")
+        ans["background_image_anchor"] = val
+
+    choices_for_background_image_anchor = frozenset(('northwest', 'north', 'northeast', 'east', 'southeast', 'south', 'southwest', 'west', 'center'))
+
     def background_image_layout(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         val = val.lower()
         if val not in self.choices_for_background_image_layout:
diff --git a/kitty/options/to-c-generated.h b/kitty/options/to-c-generated.h
index 6e26952f7..348e1a257 100644
--- a/kitty/options/to-c-generated.h
+++ b/kitty/options/to-c-generated.h
@@ -694,6 +694,19 @@ convert_from_opts_background_image_layout(PyObject *py_opts, Options *opts) {
     Py_DECREF(ret);
 }
 
+static void
+convert_from_python_background_image_anchor(PyObject *val, Options *opts) {
+    opts->background_image_anchor = bganchor(val);
+}
+
+static void
+convert_from_opts_background_image_anchor(PyObject *py_opts, Options *opts) {
+    PyObject *ret = PyObject_GetAttrString(py_opts, "background_image_anchor");
+    if (ret == NULL) return;
+    convert_from_python_background_image_anchor(ret, opts);
+    Py_DECREF(ret);
+}
+
 static void
 convert_from_python_background_image_linear(PyObject *val, Options *opts) {
     opts->background_image_linear = PyObject_IsTrue(val);
@@ -1049,6 +1062,8 @@ convert_opts_from_python_opts(PyObject *py_opts, Options *opts) {
     if (PyErr_Occurred()) return false;
     convert_from_opts_background_image_layout(py_opts, opts);
     if (PyErr_Occurred()) return false;
+    convert_from_opts_background_image_anchor(py_opts, opts);
+    if (PyErr_Occurred()) return false;
     convert_from_opts_background_image_linear(py_opts, opts);
     if (PyErr_Occurred()) return false;
     convert_from_opts_dynamic_background_opacity(py_opts, opts);
diff --git a/kitty/options/to-c.h b/kitty/options/to-c.h
index cbbd84334..5e9e41ff3 100644
--- a/kitty/options/to-c.h
+++ b/kitty/options/to-c.h
@@ -77,6 +77,36 @@ bglayout(PyObject *layout_name) {
     return TILING;
 }
 
+static BackgroundImageAnchor
+bganchor(PyObject *anchor_name) {
+    const char *name = PyUnicode_AsUTF8(anchor_name);
+    if (strcmp(name, "north") == 0) {
+        return NORTH;
+    }
+    else if (strcmp(name, "northeast") == 0) {
+        return NORTHEAST;
+    }
+    else if (strcmp(name, "east") == 0) {
+        return EAST;
+    }
+    else if (strcmp(name, "southeast") == 0) {
+        return SOUTHEAST;
+    }
+    else if (strcmp(name, "south") == 0) {
+        return SOUTH;
+    }
+    else if (strcmp(name, "southwest") == 0) {
+        return SOUTHWEST;
+    }
+    else if (strcmp(name, "west") == 0) {
+        return WEST;
+    }
+    else if (strcmp(name, "center") == 0) {
+        return CENTER;
+    }
+    return NORTHWEST;
+}
+
 #define STR_SETTER(name) { \
     free(opts->name); opts->name = NULL; \
     if (src == Py_None || !PyUnicode_Check(src)) return; \
diff --git a/kitty/options/types.py b/kitty/options/types.py
index a0b832312..595468e2e 100644
--- a/kitty/options/types.py
+++ b/kitty/options/types.py
@@ -14,6 +14,7 @@ from kitty.types import FloatEdges, SingleKey
 import kitty.types
 
 if typing.TYPE_CHECKING:
+    choices_for_background_image_anchor = typing.Literal['northwest', 'north', 'northeast', 'east', 'southeast', 'south', 'southwest', 'west', 'center']
     choices_for_background_image_layout = typing.Literal['mirror-tiled', 'scaled', 'tiled']
     choices_for_default_pointer_shape = typing.Literal['arrow', 'beam', 'hand']
     choices_for_linux_display_server = typing.Literal['auto', 'wayland', 'x11']
@@ -27,6 +28,7 @@ if typing.TYPE_CHECKING:
     choices_for_tab_powerline_style = typing.Literal['angled', 'round', 'slanted']
     choices_for_tab_switch_strategy = typing.Literal['last', 'left', 'previous', 'right']
 else:
+    choices_for_background_image_anchor = str
     choices_for_background_image_layout = str
     choices_for_default_pointer_shape = str
     choices_for_linux_display_server = str
@@ -53,6 +55,7 @@ option_names = (  # {{{
  'allow_remote_control',
  'background',
  'background_image',
+ 'background_image_anchor',
  'background_image_layout',
  'background_image_linear',
  'background_opacity',
@@ -453,6 +456,7 @@ class Options:
     allow_remote_control: str = 'n'
     background: Color = Color(0, 0, 0)
     background_image: typing.Optional[str] = None
+    background_image_anchor: choices_for_background_image_anchor = 'northwest'
     background_image_layout: choices_for_background_image_layout = 'tiled'
     background_image_linear: bool = False
     background_opacity: float = 1.0
diff --git a/kitty/rc/set_background_image.py b/kitty/rc/set_background_image.py
index 9d7c4dfe4..7eb41961b 100644
--- a/kitty/rc/set_background_image.py
+++ b/kitty/rc/set_background_image.py
@@ -24,6 +24,7 @@ class SetBackgroundImage(RemoteCommand):
     img_id+: Unique uuid (as string) used for chunking
     match: Window to change opacity in
     layout: The image layout
+    anchor: The image anchor
     all: Boolean indicating operate on all windows
     configured: Boolean indicating if the configured value should be changed
     '''
@@ -52,6 +53,12 @@ choices=tiled,scaled,mirror-tiled,configured
 How the image should be displayed. The value of configured will use the configured value.
 
 
+--anchor
+type=choices
+choices=northwest,north,northeast,east,southeast,south,southwest,west,northwest,north,center,configured
+Where the image should be positioned. The value of configured will use the configured value.
+
+
 --no-response
 type=bool-set
 default=false
@@ -74,6 +81,7 @@ failed, the command will exit with a success code.
             'match': opts.match,
             'configured': opts.configured,
             'layout': opts.layout,
+            'anchor': opts.anchor,
             'all': opts.all,
             'img_id': str(uuid4())
         }
@@ -110,6 +118,7 @@ failed, the command will exit with a success code.
         windows = self.windows_for_payload(boss, window, payload_get)
         os_windows = tuple({w.os_window_id for w in windows})
         layout = payload_get('layout')
+        anchor = payload_get('anchor')
         if data == '-':
             path = None
         else:
@@ -120,7 +129,7 @@ failed, the command will exit with a success code.
             f.flush()
 
         try:
-            boss.set_background_image(path, os_windows, payload_get('configured'), layout)
+            boss.set_background_image(path, os_windows, payload_get('configured'), layout, anchor)
         except ValueError as err:
             err.hide_traceback = True  # type: ignore
             raise
diff --git a/kitty/shaders.c b/kitty/shaders.c
index 598ed91fc..78f0219e0 100644
--- a/kitty/shaders.c
+++ b/kitty/shaders.c
@@ -166,7 +166,7 @@ typedef struct {
 static CellProgramLayout cell_program_layouts[NUM_PROGRAMS];
 static ssize_t blit_vertex_array;
 typedef struct {
-    GLint image_location, tiled_location, sizes_location, opacity_location, premult_location;
+    GLint image_location, tiled_location, translate_location, sizes_location, opacity_location, premult_location;
 } BGImageProgramLayout;
 static BGImageProgramLayout bgimage_program_layout = {0};
 typedef struct {
@@ -199,6 +199,7 @@ init_cell_program(void) {
     bgimage_program_layout.opacity_location = get_uniform_location(BGIMAGE_PROGRAM, "opacity");
     bgimage_program_layout.sizes_location = get_uniform_location(BGIMAGE_PROGRAM, "sizes");
     bgimage_program_layout.tiled_location = get_uniform_location(BGIMAGE_PROGRAM, "tiled");
+    bgimage_program_layout.translate_location = get_uniform_location(BGIMAGE_PROGRAM, "translate");
     bgimage_program_layout.premult_location = get_uniform_location(BGIMAGE_PROGRAM, "premult");
     tint_program_layout.tint_color_location = get_uniform_location(TINT_PROGRAM, "tint_color");
     tint_program_layout.edges_location = get_uniform_location(TINT_PROGRAM, "edges");
@@ -415,6 +416,20 @@ draw_bg(OSWindow *w) {
         glUniform1f(bgimage_program_layout.tiled_location, tiled);
         bgimage_constants_set = true;
     }
+    float translate_left = 0.0f, translate_top = 0.0f;
+    if (OPT(background_image_layout) != SCALED) {
+        if (w->bgimage->anchor == NORTH || w->bgimage->anchor == CENTER || w->bgimage->anchor == SOUTH) {
+            translate_left = ((float)w->window_width / 2.0f - (float)w->bgimage->width / 2.0f) / (float)w->bgimage->width;
+        } else if (w->bgimage->anchor == NORTHEAST || w->bgimage->anchor == EAST || w->bgimage->anchor == SOUTHEAST) {
+            translate_left = ((float)w->window_width - (float)w->bgimage->width) / (float)w->bgimage->width;
+        }
+        if (w->bgimage->anchor == WEST || w->bgimage->anchor == CENTER || w->bgimage->anchor == EAST) {
+            translate_top = ((float)w->window_height / 2.0f - (float)w->bgimage->height / 2.0f) / (float)w->bgimage->height;
+        } else if (w->bgimage->anchor == SOUTHWEST || w->bgimage->anchor == SOUTH || w->bgimage->anchor == SOUTHEAST) {
+            translate_top = ((float)w->window_height - (float)w->bgimage->height) / (float)w->bgimage->height;
+        }
+    }
+    glUniform2f(bgimage_program_layout.translate_location, (GLfloat)translate_left, (GLfloat)translate_top);
     glUniform4f(bgimage_program_layout.sizes_location,
         (GLfloat)w->window_width, (GLfloat)w->window_height, (GLfloat)w->bgimage->width, (GLfloat)w->bgimage->height);
     glUniform1f(bgimage_program_layout.premult_location, w->is_semi_transparent ? 1.f : 0.f);
diff --git a/kitty/state.c b/kitty/state.c
index 49264d291..9de2462ec 100644
--- a/kitty/state.c
+++ b/kitty/state.c
@@ -180,6 +180,7 @@ add_os_window() {
             global_state.bgimage = calloc(1, sizeof(BackgroundImage));
             if (!global_state.bgimage) fatal("Out of memory allocating the global bg image object");
             global_state.bgimage->refcnt++;
+            global_state.bgimage->anchor = OPT(background_image_anchor);
             size_t size;
             if (png_path_to_bitmap(OPT(background_image), &global_state.bgimage->bitmap, &global_state.bgimage->width, &global_state.bgimage->height, &size)) {
                 send_bgimage_to_gpu(OPT(background_image_layout), global_state.bgimage);
@@ -961,11 +962,13 @@ static PyObject*
 pyset_background_image(PyObject *self UNUSED, PyObject *args) {
     const char *path;
     PyObject *layout_name = NULL;
+    PyObject *anchor_name = NULL;
     PyObject *os_window_ids;
     int configured = 0;
-    PA("zO!|pU", &path, &PyTuple_Type, &os_window_ids, &configured, &layout_name);
+    PA("zO!|pOO", &path, &PyTuple_Type, &os_window_ids, &configured, &layout_name, &anchor_name);
     size_t size;
-    BackgroundImageLayout layout = layout_name ? bglayout(layout_name) : OPT(background_image_layout);
+    BackgroundImageLayout layout = PyUnicode_Check(layout_name) ? bglayout(layout_name) : OPT(background_image_layout);
+    BackgroundImageAnchor anchor = PyUnicode_Check(anchor_name) ? bganchor(anchor_name) : OPT(background_image_anchor);
     BackgroundImage *bgimage = NULL;
     if (path) {
         bgimage = calloc(1, sizeof(BackgroundImage));
@@ -983,6 +986,7 @@ pyset_background_image(PyObject *self UNUSED, PyObject *args) {
         global_state.bgimage = bgimage;
         if (bgimage) bgimage->refcnt++;
         OPT(background_image_layout) = layout;
+        OPT(background_image_anchor) = anchor;
     }
     for (Py_ssize_t i = 0; i < PyTuple_GET_SIZE(os_window_ids); i++) {
         id_type os_window_id = PyLong_AsUnsignedLongLong(PyTuple_GET_ITEM(os_window_ids, i));
@@ -990,6 +994,7 @@ pyset_background_image(PyObject *self UNUSED, PyObject *args) {
             make_os_window_context_current(os_window);
             free_bgimage(&os_window->bgimage, true);
             os_window->bgimage = bgimage;
+            os_window->bgimage->anchor = anchor;
             os_window->render_calls = 0;
             if (bgimage) bgimage->refcnt++;
         END_WITH_OS_WINDOW
diff --git a/kitty/state.h b/kitty/state.h
index 0f05ff719..9780bb214 100644
--- a/kitty/state.h
+++ b/kitty/state.h
@@ -47,6 +47,7 @@ typedef struct {
 
     char* background_image;
     BackgroundImageLayout background_image_layout;
+    BackgroundImageAnchor background_image_anchor;
     bool background_image_linear;
     float background_tint;