Add background_image

kitty/bgimage_fragment.glsl

@@ -0,0 +1,26 @@
+#version GLSL_VERSION
+#define LAYOUT_TYPE
+
+uniform sampler2D image;
+uniform float bgimage_opacity;
+#ifdef TILED
+uniform float bgimage_scale;
+
+// These are of the window, not the screen.
+uniform float width;
+uniform float height;
+#endif
+in vec2 texcoord;
+out vec4 color;
+
+void main() {
+#ifdef TILED
+    vec2 txsz = vec2(width,height) / textureSize(image,0);
+    txsz /= bgimage_scale;
+    color = texture(image, texcoord * txsz);
+#endif
+#ifdef SIMPLE
+    color = texture(image, texcoord);
+#endif
+    color = vec4(color.rgb, color.a * bgimage_opacity);
+}

kitty/bgimage_vertex.glsl

@@ -0,0 +1,9 @@
+#version GLSL_VERSION
+
+layout(location=0) in vec4 src;
+out vec2 texcoord;
+
+void main() {
+    texcoord = clamp(vec2(src[0], src[1]*-1), 0, 1);
+    gl_Position = src;
+}

kitty/borders.py

@@ -60,9 +60,11 @@ class Borders:
         active_window,
         current_layout,
         extra_blank_rects,
-        draw_window_borders=True
+        draw_window_borders=True,
+        draw_blank_rects=False
     ):
         add_borders_rect(self.os_window_id, self.tab_id, 0, 0, 0, 0, BorderColor.default_bg)
+        if draw_blank_rects:
             for br in chain(current_layout.blank_rects, extra_blank_rects):
                 add_borders_rect(self.os_window_id, self.tab_id, *br, BorderColor.default_bg)
         bw, pw = self.border_width, self.padding_width

kitty/child-monitor.c

@@ -657,6 +657,7 @@ render(monotonic_t now, bool input_read) {
 
     for (size_t i = 0; i < global_state.num_os_windows; i++) {
         OSWindow *w = global_state.os_windows + i;
+        w->render_calls++;
         if (!w->num_tabs) continue;
         if (!should_os_window_be_rendered(w)) {
             update_os_window_title(w);
@@ -688,6 +689,7 @@ render(monotonic_t now, bool input_read) {
         if (!w->fonts_data) { log_error("No fonts data found for window id: %llu", w->id); continue; }
         if (prepare_to_render_os_window(w, now, &active_window_id, &active_window_bg, &num_visible_windows, &all_windows_have_same_bg)) needs_render = true;
         if (w->last_active_window_id != active_window_id || w->last_active_tab != w->active_tab || w->focused_at_last_render != w->is_focused) needs_render = true;
+        if (w->render_calls < 3 && w->bgimage != NULL) needs_render = true;
         if (needs_render) render_os_window(w, now, active_window_id, active_window_bg, num_visible_windows, all_windows_have_same_bg);
     }
     last_render_at = now;

kitty/config_data.py

@@ -846,6 +846,37 @@ of windows set :opt:`dynamic_background_opacity` to :code:`yes` (this is off by
 default as it has a performance cost)
 '''))
 
+
+def startup_session(x):
+    if x.lower() == 'none':
+        return
+    x = os.path.expanduser(x)
+    x = os.path.expandvars(x)
+    if not os.path.isabs(x):
+        x = os.path.join(config_dir, x)
+    return x
+
+
+o('background_image', 'none', option_type=startup_session, long_text=_('''
+Path to a background image. Must be PNG.'''))
+
+o('background_image_layout', 'tiling', option_type=choices('tiling', 'scaled', 'mirror_tiled'), long_text=_('''
+Whether to tile or scale the background image.'''))
+
+o('background_image_linear', False, long_text=_('''
+When background image is scaled, whether linear interpolation should be used.'''))
+
+o('background_image_opacity', 0.5, option_type=positive_float, long_text=_('''
+Background image opacity, between 0.0 and 1.0 inclusive. This
+can only ever decrease a background's opacity, if the image is already
+semi-transparent, "1" is interpreted as the image's current transparency.'''))
+
+o('background_image_scale', 1.0, option_type=positive_float, long_text=_('''
+Only has an effect if :opt:`background_image_layout` is tiling, should be positive.'''))
+
+o('background_image_scale', 1.0, option_type=positive_float, long_text=_('''
+Only has an effect if :opt:`background_image_layout` is tiling, should be positive.'''))
+
 o('dynamic_background_opacity', False, long_text=_('''
 Allow changing of the :opt:`background_opacity` dynamically, using either keyboard
 shortcuts (:sc:`increase_background_opacity` and :sc:`decrease_background_opacity`)
@@ -966,16 +997,6 @@ The default is to check every 24 hrs, set to zero to disable.
 '''))
 
 
-def startup_session(x):
-    if x.lower() == 'none':
-        return
-    x = os.path.expanduser(x)
-    x = os.path.expandvars(x)
-    if not os.path.isabs(x):
-        x = os.path.join(config_dir, x)
-    return x
-
-
 o('startup_session', 'none', option_type=startup_session, long_text=_('''
 Path to a session file to use for all kitty instances. Can be overridden
 by using the :option:`kitty --session` command line option for individual

kitty/data-types.h

@@ -55,6 +55,7 @@ typedef enum MouseTrackingModes { NO_TRACKING, BUTTON_MODE, MOTION_MODE, ANY_MOD
 typedef enum MouseTrackingProtocols { NORMAL_PROTOCOL, UTF8_PROTOCOL, SGR_PROTOCOL, URXVT_PROTOCOL} MouseTrackingProtocol;
 typedef enum MouseShapes { BEAM, HAND, ARROW } MouseShape;
 typedef enum { NONE, MENUBAR, WINDOW, ALL } WindowTitleIn;
+typedef enum { TILING, SCALED, MIRRORED } BackgroundImageLayout;
 
 #define MAX_CHILDREN 512
 #define BLANK_CHAR 0

kitty/glfw.c

@@ -377,7 +377,7 @@ make_os_window_context_current(OSWindow *w) {
 }
 
 
-static inline void
+void
 get_window_content_scale(GLFWwindow *w, float *xscale, float *yscale, double *xdpi, double *ydpi) {
     if (w) glfwGetWindowContentScale(w, xscale, yscale);
     else {

kitty/graphics.c

@@ -5,6 +5,7 @@
  * Distributed under terms of the GPL3 license.
  */
 
+#include "gl.h"
 #include "graphics.h"
 #include "state.h"
 
@@ -29,9 +30,8 @@ static bool send_to_gpu = true;
 GraphicsManager*
 grman_alloc() {
     GraphicsManager *self = (GraphicsManager *)GraphicsManager_Type.tp_alloc(&GraphicsManager_Type, 0);
-    self->images_capacity = 64;
+    self->images_capacity = self->capacity = 64;
     self->images = calloc(self->images_capacity, sizeof(Image));
-    self->capacity = 64;
     self->render_data = calloc(self->capacity, sizeof(ImageRenderData));
     if (self->images == NULL || self->render_data == NULL) {
         PyErr_NoMemory();
@@ -248,6 +248,38 @@ add_trim_predicate(Image *img) {
     return !img->data_loaded || (!img->client_id && !img->refcnt);
 }
 
+bool png_path_to_bitmap(uint8_t** data, unsigned int* width, unsigned int* height, size_t* sz) {
+    const char* path = OPT(background_image);
+    if (access(path, R_OK) != 0) {
+        log_error("File %s, (requested background image,) does not exist (%d)", path, errno);
+        return false;
+    }
+    FILE* fp = fopen(path, "r");
+    if (fp == NULL) {
+        log_error("File %s, (requested background image,) could not be opened", path);
+        return false;
+    }
+    fseek(fp, 0L, SEEK_END);
+    size_t filesize = ftell(fp);
+    *data = calloc(filesize, sizeof(char));
+    fseek(fp, 0L, SEEK_SET); // rewind() deprecated on some platforms
+    fread(*data, sizeof(char), filesize, fp);
+    fclose(fp);
+    png_read_data d;
+    memset(&d, 0, sizeof(png_read_data));
+    inflate_png_inner(&d, *data, filesize);
+    if (!d.ok) {
+        log_error("File %s, (requested background image,) not readable by libpng", path);
+        return false;
+    }
+    free(*data);
+    *data = d.decompressed;
+    *sz = d.sz;
+    *height = d.height; *width = d.width;
+    return true;
+}
+
+
 static inline Image*
 find_or_create_image(GraphicsManager *self, uint32_t id, bool *existing) {
     if (id) {
@@ -421,7 +453,7 @@ handle_add_command(GraphicsManager *self, const GraphicsCommand *g, const uint8_
     size_t required_sz = (img->load_data.is_opaque ? 3 : 4) * img->width * img->height;
     if (img->load_data.data_sz != required_sz) ABRT(EINVAL, "Image dimensions: %ux%u do not match data size: %zu, expected size: %zu", img->width, img->height, img->load_data.data_sz, required_sz);
     if (LIKELY(img->data_loaded && send_to_gpu)) {
-        send_image_to_gpu(&img->texture_id, img->load_data.data, img->width, img->height, img->load_data.is_opaque, img->load_data.is_4byte_aligned);
+        send_image_to_gpu(&img->texture_id, img->load_data.data, img->width, img->height, img->load_data.is_opaque, img->load_data.is_4byte_aligned, false, REPEAT_CLAMP);
         free_load_data(&img->load_data);
         self->used_storage += required_sz;
         img->used_storage = required_sz;

kitty/graphics.h

@@ -55,6 +55,12 @@ typedef struct {
     size_t used_storage;
 } Image;
 
+typedef struct {
+    uint32_t texture_id;
+    unsigned int height, width;
+    uint8_t* bitmap;
+} BackgroundImage;
+
 typedef struct {
     float vertices[16];
     uint32_t texture_id, group_count;
@@ -71,6 +77,8 @@ typedef struct {
     Image *images;
     size_t count, capacity;
     ImageRenderData *render_data;
+    Image bgimage;
+    ImageRenderData bgimage_rd;
     bool layers_dirty;
     // The number of images below MIN_ZINDEX / 2, then the number of refs between MIN_ZINDEX / 2 and -1 inclusive, then the number of refs above 0 inclusive.
     size_t num_of_below_refs, num_of_negative_refs, num_of_positive_refs;
@@ -93,3 +101,4 @@ void grman_scroll_images(GraphicsManager *self, const ScrollData*, CellPixelSize
 void grman_resize(GraphicsManager*, index_type, index_type, index_type, index_type);
 void grman_rescale(GraphicsManager *self, CellPixelSize fg);
 void gpu_data_for_centered_image(ImageRenderData *ans, unsigned int screen_width_px, unsigned int screen_height_px, unsigned int width, unsigned int height);
+bool png_path_to_bitmap(uint8_t** data, unsigned int* width, unsigned int* height, size_t* sz);

kitty/screen.c

@@ -111,6 +111,7 @@ new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
         self->historybuf = alloc_historybuf(MAX(scrollback, lines), columns, OPT(scrollback_pager_history_size));
         self->main_grman = grman_alloc();
         self->alt_grman = grman_alloc();
+
         self->grman = self->main_grman;
         self->pending_mode.wait_time = 2.0;
         self->disable_ligatures = OPT(disable_ligatures);

kitty/shaders.c

@@ -7,10 +7,12 @@
 
 #include "fonts.h"
 #include "gl.h"
+#include "png-reader.h"
+#include <png.h>
 #include <stddef.h>
 
-enum { CELL_PROGRAM, CELL_BG_PROGRAM, CELL_SPECIAL_PROGRAM, CELL_FG_PROGRAM, BORDERS_PROGRAM, GRAPHICS_PROGRAM, GRAPHICS_PREMULT_PROGRAM, GRAPHICS_ALPHA_MASK_PROGRAM, BLIT_PROGRAM, NUM_PROGRAMS };
+enum { CELL_PROGRAM, CELL_BG_PROGRAM, CELL_SPECIAL_PROGRAM, CELL_FG_PROGRAM, BORDERS_PROGRAM, GRAPHICS_PROGRAM, GRAPHICS_PREMULT_PROGRAM, GRAPHICS_ALPHA_MASK_PROGRAM, BLIT_PROGRAM, BGIMAGE_PROGRAM, BGIMAGE_TILED_PROGRAM, NUM_PROGRAMS };
-enum { SPRITE_MAP_UNIT, GRAPHICS_UNIT, BLIT_UNIT };
+enum { SPRITE_MAP_UNIT, GRAPHICS_UNIT, BLIT_UNIT, BGIMAGE_UNIT };
 
 // Sprites {{{
 typedef struct {
@@ -22,6 +24,7 @@ typedef struct {
 
 static const SpriteMap NEW_SPRITE_MAP = { .xnum = 1, .ynum = 1, .last_num_of_layers = 1, .last_ynum = -1 };
 static GLint max_texture_size = 0, max_array_texture_layers = 0;
+//static uint8_t *bg_image = NULL;
 
 SPRITE_MAP_HANDLE
 alloc_sprite_map(unsigned int cell_width, unsigned int cell_height) {
@@ -132,14 +135,23 @@ send_sprite_to_gpu(FONTS_DATA_HANDLE fg, unsigned int x, unsigned int y, unsigne
 }
 
 void
-send_image_to_gpu(GLuint *tex_id, const void* data, GLsizei width, GLsizei height, bool is_opaque, bool is_4byte_aligned) {
+send_image_to_gpu(GLuint *tex_id, const void* data, GLsizei width, GLsizei height, bool is_opaque, bool is_4byte_aligned, bool linear, RepeatStrategy repeat) {
     if (!(*tex_id)) { glGenTextures(1, tex_id);  }
     glBindTexture(GL_TEXTURE_2D, *tex_id);
     glPixelStorei(GL_UNPACK_ALIGNMENT, is_4byte_aligned ? 4 : 1);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, linear ? GL_LINEAR : GL_NEAREST);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, linear ? GL_LINEAR : GL_NEAREST);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    RepeatStrategy r;
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    switch (repeat) {
+        case REPEAT_MIRROR:
+            r = GL_MIRRORED_REPEAT; break;
+        case REPEAT_CLAMP:
+            r = GL_CLAMP_TO_EDGE; break;
+        default:
+            r = GL_REPEAT;
+    }
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, r);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, r);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, is_opaque ? GL_RGB : GL_RGBA, GL_UNSIGNED_BYTE, data);
 }
 
@@ -323,6 +335,47 @@ cell_prepare_to_render(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen, GLfloa
     return changed;
 }
 
+void
+draw_bg(int program, OSWindow *w) {
+    if (w->bvao_idx == 0) {
+        const GLfloat screenrect[4][2] = {
+            { -1.0,  1.0  },
+            { -1.0, -1.0  },
+            {  1.0, -1.0  },
+            {  1.0, 1.0  },
+        };
+        w->bvao_idx = create_vao();
+        bind_vertex_array(w->bvao_idx);
+        glGenBuffers(1, &w->vbo_idx);
+        glBindBuffer(GL_ARRAY_BUFFER, w->vbo_idx);
+        glBufferData(GL_ARRAY_BUFFER, 4*2*sizeof(float), screenrect, GL_STATIC_DRAW);
+    }
+    bind_vertex_array(w->bvao_idx);
+    glBindBuffer(GL_ARRAY_BUFFER, w->vbo_idx);
+
+    glClear(GL_COLOR_BUFFER_BIT);
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0);
+    glEnableVertexAttribArray(0);
+
+    bind_program(program);
+    static bool bgimage_constants_set;
+    if (!bgimage_constants_set) {
+        glUniform1i(glGetUniformLocation(program_id(program), "image"), BGIMAGE_UNIT);
+        glUniform1f(glGetUniformLocation(program_id(program), "bgimage_scale"), OPT(background_image_scale));
+        glUniform1f(glGetUniformLocation(program_id(program), "bgimage_opacity"), OPT(background_image_opacity));
+        bgimage_constants_set = true;
+    }
+    glUniform1f(glGetUniformLocation(program_id(program), "height"), (float)(w->window_height));
+    glUniform1f(glGetUniformLocation(program_id(program), "width"), (float)(w->window_width));
+    glActiveTexture(GL_TEXTURE0 + BGIMAGE_UNIT);
+
+    glBindTexture(GL_TEXTURE_2D, w->bgimage->texture_id);
+    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+
+    unbind_vertex_array();
+    unbind_program();
+}
+
 static void
 draw_graphics(int program, ssize_t vao_idx, ssize_t gvao_idx, ImageRenderData *data, GLuint start, GLuint count) {
     bind_program(program);
@@ -389,16 +442,18 @@ draw_cells_simple(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen) {
 }
 
 static void
-draw_cells_interleaved(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen) {
+draw_cells_interleaved(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen, OSWindow *w) {
     glEnable(GL_BLEND);
     BLEND_ONTO_OPAQUE;
 
     bind_program(CELL_BG_PROGRAM);
     // draw background for all cells
     glUniform1ui(cell_program_layouts[CELL_BG_PROGRAM].draw_bg_bitfield_location, 3);
+    // This gives users a way to still use background images without a compositor.
+    if (OPT(background_opacity) != 0.0)
     glDrawArraysInstanced(GL_TRIANGLE_FAN, 0, 4, screen->lines * screen->columns);
 
-    if (screen->grman->num_of_below_refs) {
+    if (screen->grman->num_of_below_refs || w->bgimage != NULL) {
         draw_graphics(GRAPHICS_PROGRAM, vao_idx, gvao_idx, screen->grman->render_data, 0, screen->grman->num_of_below_refs);
         bind_program(CELL_BG_PROGRAM);
         // draw background for non-default bg cells
@@ -435,12 +490,13 @@ draw_cells_interleaved_premult(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen
     glBindFramebuffer(GL_DRAW_FRAMEBUFFER, os_window->offscreen_framebuffer);
     glFramebufferTexture(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, os_window->offscreen_texture_id, 0);
     /* if (glCheckFramebufferStatus(GL_DRAW_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) fatal("Offscreen framebuffer not complete"); */
+    glEnable(GL_BLEND);
+    BLEND_PREMULT;
+    glClear(GL_COLOR_BUFFER_BIT);
     bind_program(CELL_BG_PROGRAM);
     // draw background for all cells
     glUniform1ui(cell_program_layouts[CELL_BG_PROGRAM].draw_bg_bitfield_location, 3);
     glDrawArraysInstanced(GL_TRIANGLE_FAN, 0, 4, screen->lines * screen->columns);
-    glEnable(GL_BLEND);
-    BLEND_PREMULT;
 
     if (screen->grman->num_of_below_refs) {
         draw_graphics(GRAPHICS_PREMULT_PROGRAM, vao_idx, gvao_idx, screen->grman->render_data, 0, screen->grman->num_of_below_refs);
@@ -469,11 +525,10 @@ draw_cells_interleaved_premult(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen
 
     if (screen->grman->num_of_positive_refs) draw_graphics(GRAPHICS_PREMULT_PROGRAM, vao_idx, gvao_idx, screen->grman->render_data, screen->grman->num_of_negative_refs + screen->grman->num_of_below_refs, screen->grman->num_of_positive_refs);
 
-    glDisable(GL_BLEND);
     glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+    glEnable(GL_SCISSOR_TEST);
 
     // Now render the framebuffer to the screen
-    glEnable(GL_SCISSOR_TEST);
     bind_program(BLIT_PROGRAM); bind_vertex_array(blit_vertex_array);
     static bool blit_constants_set = false;
     if (!blit_constants_set) {
@@ -484,6 +539,7 @@ draw_cells_interleaved_premult(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen
     glBindTexture(GL_TEXTURE_2D, os_window->offscreen_texture_id);
     glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
     glDisable(GL_SCISSOR_TEST);
+    glDisable(GL_BLEND);
 }
 
 static inline void
@@ -496,6 +552,7 @@ set_cell_uniforms(float current_inactive_text_alpha, bool force) {
         cell_uniform_data.amask_premult_loc = glGetUniformLocation(program_id(GRAPHICS_ALPHA_MASK_PROGRAM), "alpha_mask_premult");
 #define S(prog, name, val, type) { bind_program(prog); glUniform##type(glGetUniformLocation(program_id(prog), #name), val); }
         S(GRAPHICS_PROGRAM, image, GRAPHICS_UNIT, 1i);
+        S(GRAPHICS_PROGRAM, image, BGIMAGE_UNIT, 1i);
         S(GRAPHICS_PREMULT_PROGRAM, image, GRAPHICS_UNIT, 1i);
         S(CELL_PROGRAM, sprites, SPRITE_MAP_UNIT, 1i); S(CELL_FG_PROGRAM, sprites, SPRITE_MAP_UNIT, 1i);
         S(CELL_PROGRAM, dim_opacity, OPT(dim_opacity), 1f); S(CELL_FG_PROGRAM, dim_opacity, OPT(dim_opacity), 1f);
@@ -558,10 +615,10 @@ draw_cells(ssize_t vao_idx, ssize_t gvao_idx, GLfloat xstart, GLfloat ystart, GL
     );
 #undef SCALE
     if (os_window->is_semi_transparent) {
-        if (screen->grman->count) draw_cells_interleaved_premult(vao_idx, gvao_idx, screen, os_window);
+        if (screen->grman->count || os_window->bgimage != NULL) draw_cells_interleaved_premult(vao_idx, gvao_idx, screen, os_window);
         else draw_cells_simple(vao_idx, gvao_idx, screen);
     } else {
-        if (screen->grman->num_of_negative_refs || screen->grman->num_of_below_refs) draw_cells_interleaved(vao_idx, gvao_idx, screen);
+        if (screen->grman->num_of_negative_refs || screen->grman->num_of_below_refs || os_window->bgimage != NULL) draw_cells_interleaved(vao_idx, gvao_idx, screen, os_window);
         else draw_cells_simple(vao_idx, gvao_idx, screen);
     }
 }
@@ -604,16 +661,28 @@ create_border_vao(void) {
 
 void
 draw_borders(ssize_t vao_idx, unsigned int num_border_rects, BorderRect *rect_buf, bool rect_data_is_dirty, uint32_t viewport_width, uint32_t viewport_height, color_type active_window_bg, unsigned int num_visible_windows, bool all_windows_have_same_bg, OSWindow *w) {
+    glEnable(GL_BLEND);
+    BLEND_ONTO_OPAQUE;
+
+    if (w->bgimage != NULL) {
+        int program;
+        if (OPT(background_image_layout) == TILING || OPT(background_image_layout) == MIRRORED) program = BGIMAGE_TILED_PROGRAM;
+        else program = BGIMAGE_PROGRAM;
+
+        draw_bg(program, w);
+    }
+
     if (num_border_rects) {
+    bind_vertex_array(vao_idx);
+        bind_program(BORDERS_PROGRAM);
         if (rect_data_is_dirty) {
             size_t sz = sizeof(GLuint) * 5 * num_border_rects;
             void *borders_buf_address = alloc_and_map_vao_buffer(vao_idx, sz, 0, GL_STATIC_DRAW, GL_WRITE_ONLY);
             if (borders_buf_address) memcpy(borders_buf_address, rect_buf, sz);
             unmap_vao_buffer(vao_idx, 0);
         }
-        bind_program(BORDERS_PROGRAM);
 #define CV3(x) (((float)((x >> 16) & 0xff))/255.f), (((float)((x >> 8) & 0xff))/255.f), (((float)(x & 0xff))/255.f)
-        glUniform1f(border_uniform_locations[BORDER_background_opacity], w->is_semi_transparent ? w->background_opacity : 1.0f);
+        glUniform1f(border_uniform_locations[BORDER_background_opacity], w->is_semi_transparent ? MAX(w->background_opacity, OPT(background_image_opacity)) : 1.0f);
         glUniform3f(border_uniform_locations[BORDER_active_border_color], CV3(OPT(active_border_color)));
         glUniform3f(border_uniform_locations[BORDER_inactive_border_color], CV3(OPT(inactive_border_color)));
         glUniform3f(border_uniform_locations[BORDER_bell_border_color], CV3(OPT(bell_border_color)));
@@ -621,11 +690,11 @@ draw_borders(ssize_t vao_idx, unsigned int num_border_rects, BorderRect *rect_bu
         color_type default_bg = (num_visible_windows > 1 && !all_windows_have_same_bg) ? OPT(background) : active_window_bg;
         glUniform3f(border_uniform_locations[BORDER_default_bg], CV3(default_bg));
 #undef CV3
-        bind_vertex_array(vao_idx);
         glDrawArraysInstanced(GL_TRIANGLE_FAN, 0, 4, num_border_rects);
     unbind_vertex_array();
         unbind_program();
     }
+    glDisable(GL_BLEND);
 }
 
 // }}}
@@ -722,7 +791,7 @@ static PyMethodDef module_methods[] = {
 bool
 init_shaders(PyObject *module) {
 #define C(x) if (PyModule_AddIntConstant(module, #x, x) != 0) { PyErr_NoMemory(); return false; }
-    C(CELL_PROGRAM); C(CELL_BG_PROGRAM); C(CELL_SPECIAL_PROGRAM); C(CELL_FG_PROGRAM); C(BORDERS_PROGRAM); C(GRAPHICS_PROGRAM); C(GRAPHICS_PREMULT_PROGRAM); C(GRAPHICS_ALPHA_MASK_PROGRAM); C(BLIT_PROGRAM);
+    C(CELL_PROGRAM); C(CELL_BG_PROGRAM); C(CELL_SPECIAL_PROGRAM); C(CELL_FG_PROGRAM); C(BORDERS_PROGRAM); C(GRAPHICS_PROGRAM); C(GRAPHICS_PREMULT_PROGRAM); C(GRAPHICS_ALPHA_MASK_PROGRAM); C(BLIT_PROGRAM); C(BGIMAGE_PROGRAM); C(BGIMAGE_TILED_PROGRAM);
     C(GLSL_VERSION);
     C(GL_VERSION);
     C(GL_VENDOR);

kitty/state.c

@@ -81,6 +81,39 @@ add_os_window() {
     ans->tab_bar_render_data.vao_idx = create_cell_vao();
     ans->gvao_idx = create_graphics_vao();
     ans->background_opacity = OPT(background_opacity);
+
+    bool wants_bg = OPT(background_image) != NULL;
+    if (wants_bg) {
+        bool has_bg;
+        has_bg = global_state.bgimage != NULL;
+
+        if (!has_bg) {
+            BackgroundImage* bgimage = calloc(1, sizeof(BackgroundImage));
+            size_t size;
+
+            has_bg = png_path_to_bitmap(&bgimage->bitmap, &bgimage->width, &bgimage->height, &size);
+            if (has_bg) {
+                bgimage->texture_id = 0;
+                RepeatStrategy r;
+                switch (OPT(background_image_layout)) {
+                    case TILING:
+                        r = REPEAT_DEFAULT; break;
+                    case SCALED:
+                        r = REPEAT_CLAMP; break;
+                    case MIRRORED:
+                        r = REPEAT_MIRROR;
+                }
+                send_image_to_gpu(&bgimage->texture_id, bgimage->bitmap, bgimage->width,
+                        bgimage->height, false, true, false, r);
+                ans->bgimage = bgimage;
+                global_state.bgimage = bgimage;
+            }
+        } else {
+            // Reusing already loaded bgimage
+            ans->bgimage = global_state.bgimage;
+        }
+    }
+
     ans->font_sz_in_pts = global_state.font_sz_in_pts;
     END_WITH_OS_WINDOW_REFS
     return ans;
@@ -416,6 +449,17 @@ window_title_in(PyObject *title_in) {
     return ALL;
 }
 
+static BackgroundImageLayout bglayout(PyObject *layout_name) {
+    const char *name = PyUnicode_AsUTF8(layout_name);
+    switch(name[0]) {
+        case 't': return TILING;
+        case 'm': return MIRRORED;
+        case 's': return SCALED;
+        default: break;
+    }
+    return TILING;
+}
+
 static MouseShape
 pointer_shape(PyObject *shape_name) {
     const char *name = PyUnicode_AsUTF8(shape_name);
@@ -484,6 +528,10 @@ PYWRAP1(set_options) {
     S(cursor_blink_interval, parse_s_double_to_monotonic_t);
     S(cursor_stop_blinking_after, parse_s_double_to_monotonic_t);
     S(background_opacity, PyFloat_AsFloat);
+    S(background_image_opacity, PyFloat_AsFloat);
+    S(background_image_scale, PyFloat_AsFloat);
+    S(background_image_layout, bglayout);
+    S(background_image, (char*)PyUnicode_AsUTF8);
     S(dim_opacity, PyFloat_AsFloat);
     S(dynamic_background_opacity, PyObject_IsTrue);
     S(inactive_text_alpha, PyFloat_AsFloat);

kitty/state.h

@@ -13,6 +13,7 @@
 
 typedef enum { LEFT_EDGE, TOP_EDGE, RIGHT_EDGE, BOTTOM_EDGE } Edge;
 typedef enum { RESIZE_DRAW_STATIC, RESIZE_DRAW_SCALED, RESIZE_DRAW_BLANK, RESIZE_DRAW_SIZE } ResizeDrawStrategy;
+typedef enum { REPEAT_MIRROR, REPEAT_CLAMP, REPEAT_DEFAULT } RepeatStrategy;
 
 typedef struct {
     monotonic_t visual_bell_duration, cursor_blink_interval, cursor_stop_blinking_after, mouse_hide_wait, click_interval;
@@ -37,6 +38,12 @@ typedef struct {
     int adjust_line_height_px, adjust_column_width_px;
     float adjust_line_height_frac, adjust_column_width_frac;
     float background_opacity, dim_opacity;
+
+    char* background_image;
+    BackgroundImageLayout background_image_layout;
+    float background_image_opacity;
+    float background_image_scale;
+
     bool dynamic_background_opacity;
     float inactive_text_alpha;
     float window_padding_width;
@@ -136,6 +143,7 @@ typedef struct {
     int viewport_width, viewport_height, window_width, window_height;
     double viewport_x_ratio, viewport_y_ratio;
     Tab *tabs;
+    BackgroundImage *bgimage;
     unsigned int active_tab, num_tabs, capacity, last_active_tab, last_num_tabs, last_active_window_id;
     bool focused_at_last_render, needs_render;
     ScreenRenderData tab_bar_render_data;
@@ -158,8 +166,10 @@ typedef struct {
     id_type temp_font_group_id;
     enum RENDER_STATE render_state;
     monotonic_t last_render_frame_received_at;
+    uint64_t render_calls;
     id_type last_focused_counter;
-    ssize_t gvao_idx;
+    ssize_t gvao_idx, bvao_idx;
+    unsigned int vbo_idx;
 } OSWindow;
 
 
@@ -168,6 +178,7 @@ typedef struct {
 
     id_type os_window_id_counter, tab_id_counter, window_id_counter;
     PyObject *boss;
+    BackgroundImage *bgimage;
     OSWindow *os_windows;
     size_t num_os_windows, capacity;
     OSWindow *callback_os_window;
@@ -223,11 +234,12 @@ void draw_centered_alpha_mask(OSWindow *w, size_t screen_width, size_t screen_he
 void update_surface_size(int, int, uint32_t);
 void free_texture(uint32_t*);
 void free_framebuffer(uint32_t*);
-void send_image_to_gpu(uint32_t*, const void*, int32_t, int32_t, bool, bool);
+void send_image_to_gpu(uint32_t*, const void*, int32_t, int32_t, bool, bool, bool, RepeatStrategy);
 void send_sprite_to_gpu(FONTS_DATA_HANDLE fg, unsigned int, unsigned int, unsigned int, pixel*);
 void blank_canvas(float, color_type);
 void blank_os_window(OSWindow *);
 void set_titlebar_color(OSWindow *w, color_type color);
+void get_window_content_scale(GLFWwindow *w, float *xscale, float *yscale, double *xdpi, double *ydpi);
 FONTS_DATA_HANDLE load_fonts_data(double, double, double);
 void send_prerendered_sprites_for_window(OSWindow *w);
 #ifdef __APPLE__

kitty/window.py

@@ -15,14 +15,14 @@ from .constants import (
     ScreenGeometry, WindowGeometry, appname, get_boss, wakeup
 )
 from .fast_data_types import (
-    BLIT_PROGRAM, CELL_BG_PROGRAM, CELL_FG_PROGRAM, CELL_PROGRAM,
+    BLIT_PROGRAM, BGIMAGE_PROGRAM, BGIMAGE_TILED_PROGRAM, CELL_BG_PROGRAM,
-    CELL_SPECIAL_PROGRAM, CSI, DCS, DECORATION, DIM,
+    CELL_FG_PROGRAM, CELL_PROGRAM, CELL_SPECIAL_PROGRAM, CSI, DCS, DECORATION,
-    GRAPHICS_ALPHA_MASK_PROGRAM, GRAPHICS_PREMULT_PROGRAM, GRAPHICS_PROGRAM,
+    DIM, GRAPHICS_ALPHA_MASK_PROGRAM, GRAPHICS_PREMULT_PROGRAM,
-    MARK, MARK_MASK, OSC, REVERSE, SCROLL_FULL, SCROLL_LINE, SCROLL_PAGE,
+    GRAPHICS_PROGRAM, MARK, MARK_MASK, OSC, REVERSE, SCROLL_FULL, SCROLL_LINE,
-    STRIKETHROUGH, Screen, add_window, cell_size_for_window, compile_program,
+    SCROLL_PAGE, STRIKETHROUGH, Screen, add_window, cell_size_for_window,
-    get_clipboard_string, init_cell_program, set_clipboard_string,
+    compile_program, get_clipboard_string, init_cell_program,
-    set_titlebar_color, set_window_render_data, update_window_title,
+    set_clipboard_string, set_titlebar_color, set_window_render_data,
-    update_window_visibility, viewport_for_window
+    update_window_title, update_window_visibility, viewport_for_window
 )
 from .keys import defines, extended_key_event, keyboard_mode_name
 from .rgb import to_color
@@ -83,6 +83,7 @@ def load_shader_programs(semi_transparent=False):
             vv = vv.replace('#define USE_SELECTION_FG', '#define DONT_USE_SELECTION_FG')
             ff = ff.replace('#define USE_SELECTION_FG', '#define DONT_USE_SELECTION_FG')
         compile_program(p, vv, ff)
+
     v, f = load_shaders('graphics')
     for which, p in {
             'SIMPLE': GRAPHICS_PROGRAM,
@@ -91,6 +92,15 @@ def load_shader_programs(semi_transparent=False):
     }.items():
         ff = f.replace('ALPHA_TYPE', which)
         compile_program(p, v, ff)
+
+    v, f = load_shaders('bgimage')
+    for which, p in {
+            'SIMPLE': BGIMAGE_PROGRAM,
+            'TILED': BGIMAGE_TILED_PROGRAM,
+    }.items():
+        ff = f.replace('LAYOUT_TYPE', which)
+        compile_program(p, v, ff)
+
     init_cell_program()