render: implement coordinate-based anchor positioning

Not to be confused with Minecraft coordinates.

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Ifdb90fc92a1565ba1d30b85c91d6e1ab6a6a6964

include/chroma.h

@@ -104,6 +104,8 @@ typedef struct {
   chroma_scale_mode_t scale_mode;
   chroma_filter_quality_t filter_quality;
   chroma_anchor_t anchor;
+  float anchor_x; // custom X offset (0-100, 50=center)
+  float anchor_y; // custom Y offset (0-100, 50=center)
   bool config_loaded;
 
   // OpenGL resource cache
@@ -123,6 +125,8 @@ typedef struct {
   chroma_scale_mode_t scale_mode;
   chroma_filter_quality_t filter_quality;
   chroma_anchor_t anchor;
+  float anchor_x; // custom X offset (0-100, 50=center, 0=left, 100=right)
+  float anchor_y; // custom Y offset (0-100, 50=center, 0=top, 100=bottom)
 } chroma_config_mapping_t;
 
 // Application configuration
@@ -136,6 +140,8 @@ typedef struct {
   chroma_scale_mode_t default_scale_mode;
   chroma_filter_quality_t default_filter_quality;
   chroma_anchor_t default_anchor;
+  float default_anchor_x; // custom anchor X offset (0-100, 50=center)
+  float default_anchor_y; // custom anchor Y offset (0-100, 50=center)
 
   // Image downsampling settings
   bool enable_downsampling; // enable automatic downsampling
@@ -248,7 +254,7 @@ const char *chroma_config_get_image_for_output(chroma_config_t *config,
 int chroma_config_get_mapping_for_output(
     chroma_config_t *config, const char *output_name,
     chroma_scale_mode_t *scale_mode, chroma_filter_quality_t *filter_quality,
-    chroma_anchor_t *anchor);
+    chroma_anchor_t *anchor, float *anchor_x, float *anchor_y);
 
 void chroma_config_print(const chroma_config_t *config);
 

src/config.c

@@ -184,7 +184,8 @@ static int add_output_mapping(chroma_config_t *config, const char *output_name,
                               const char *image_path,
                               chroma_scale_mode_t scale_mode,
                               chroma_filter_quality_t filter_quality,
-                              chroma_anchor_t anchor) {
+                              chroma_anchor_t anchor, float anchor_x,
+                              float anchor_y) {
   if (!config || !output_name || !image_path) {
     return CHROMA_ERROR_INIT;
   }
@@ -218,13 +219,17 @@ static int add_output_mapping(chroma_config_t *config, const char *output_name,
   mapping->scale_mode = scale_mode;
   mapping->filter_quality = filter_quality;
   mapping->anchor = anchor;
+  mapping->anchor_x = anchor_x;
+  mapping->anchor_y = anchor_y;
 
   config->mapping_count++;
 
   chroma_log(
-      "DEBUG", "Added mapping: %s -> %s (scale: %s, filter: %s, anchor: %s)",
+      "DEBUG",
+      "Added mapping: %s -> %s (scale: %s, filter: %s, anchor: %s @ %.1f,%.1f)",
       output_name, image_path, scale_mode_to_string(scale_mode),
-      filter_quality_to_string(filter_quality), anchor_to_string(anchor));
+      filter_quality_to_string(filter_quality), anchor_to_string(anchor),
+      anchor_x, anchor_y);
   chroma_log("TRACE", "Output mapping %d: '%s' -> '%s' (path length: %zu)",
              config->mapping_count, output_name, image_path, path_len);
   return CHROMA_OK;
@@ -244,6 +249,8 @@ static void init_default_config(chroma_config_t *config) {
   config->default_scale_mode = CHROMA_SCALE_FILL;
   config->default_filter_quality = CHROMA_FILTER_LINEAR;
   config->default_anchor = CHROMA_ANCHOR_CENTER;
+  config->default_anchor_x = 50.0f; // center
+  config->default_anchor_y = 50.0f; // center
 
   // Set default downsampling settings
   config->enable_downsampling = true; // enable by default, performance etc.
@@ -351,6 +358,34 @@ static int parse_config_line(chroma_config_t *config, char *line,
     config->default_anchor = parse_anchor(value);
     chroma_log("DEBUG", "Set default anchor: %s",
                anchor_to_string(config->default_anchor));
+  } else if (strcasecmp(key, "anchor_x") == 0) {
+    char *endptr = NULL;
+    float ax = strtof(value, &endptr);
+    if (endptr == value || *endptr != '\0') {
+      chroma_log("WARN", "Invalid anchor_x: %s (not a number, using 50)",
+                 value);
+      config->default_anchor_x = 50.0f;
+    } else if (ax < 0.0f || ax > 100.0f) {
+      chroma_log("WARN", "Invalid anchor_x: %s (range 0-100, using 50)", value);
+      config->default_anchor_x = 50.0f;
+    } else {
+      config->default_anchor_x = ax;
+      chroma_log("DEBUG", "Set default anchor_x: %.1f", ax);
+    }
+  } else if (strcasecmp(key, "anchor_y") == 0) {
+    char *endptr = NULL;
+    float ay = strtof(value, &endptr);
+    if (endptr == value || *endptr != '\0') {
+      chroma_log("WARN", "Invalid anchor_y: %s (not a number, using 50)",
+                 value);
+      config->default_anchor_y = 50.0f;
+    } else if (ay < 0.0f || ay > 100.0f) {
+      chroma_log("WARN", "Invalid anchor_y: %s (range 0-100, using 50)", value);
+      config->default_anchor_y = 50.0f;
+    } else {
+      config->default_anchor_y = ay;
+      chroma_log("DEBUG", "Set default anchor_y: %.1f", ay);
+    }
   } else if (strcasecmp(key, "max_output_width") == 0) {
     int width = atoi(value);
     if (width > 0 && width <= 16384) { // Reasonable limits
@@ -418,8 +453,70 @@ static int parse_config_line(chroma_config_t *config, char *line,
                    filter_quality_to_string(mapping->filter_quality));
       } else if (strcasecmp(property, "anchor") == 0) {
         mapping->anchor = parse_anchor(value);
-        chroma_log("DEBUG", "Set anchor for output %s: %s", output_name,
+        // Set anchor_x/anchor_y based on named anchor
-                   anchor_to_string(mapping->anchor));
+        switch (mapping->anchor) {
+        case CHROMA_ANCHOR_TOP:
+          mapping->anchor_x = 50.0f;
+          mapping->anchor_y = 0.0f;
+          break;
+        case CHROMA_ANCHOR_BOTTOM:
+          mapping->anchor_x = 50.0f;
+          mapping->anchor_y = 100.0f;
+          break;
+        case CHROMA_ANCHOR_LEFT:
+          mapping->anchor_x = 0.0f;
+          mapping->anchor_y = 50.0f;
+          break;
+        case CHROMA_ANCHOR_RIGHT:
+          mapping->anchor_x = 100.0f;
+          mapping->anchor_y = 50.0f;
+          break;
+        case CHROMA_ANCHOR_TOP_LEFT:
+          mapping->anchor_x = 0.0f;
+          mapping->anchor_y = 0.0f;
+          break;
+        case CHROMA_ANCHOR_TOP_RIGHT:
+          mapping->anchor_x = 100.0f;
+          mapping->anchor_y = 0.0f;
+          break;
+        case CHROMA_ANCHOR_BOTTOM_LEFT:
+          mapping->anchor_x = 0.0f;
+          mapping->anchor_y = 100.0f;
+          break;
+        case CHROMA_ANCHOR_BOTTOM_RIGHT:
+          mapping->anchor_x = 100.0f;
+          mapping->anchor_y = 100.0f;
+          break;
+        default:
+          mapping->anchor_x = 50.0f;
+          mapping->anchor_y = 50.0f;
+          break;
+        }
+        chroma_log("DEBUG", "Set anchor for output %s: %s (x=%.1f, y=%.1f)",
+                   output_name, anchor_to_string(mapping->anchor),
+                   mapping->anchor_x, mapping->anchor_y);
+      } else if (strcasecmp(property, "anchor_x") == 0) {
+        float ax = atof(value);
+        if (ax >= 0.0f && ax <= 100.0f) {
+          mapping->anchor_x = ax;
+          chroma_log("DEBUG", "Set anchor_x for output %s: %.1f", output_name,
+                     ax);
+        } else {
+          mapping->anchor_x = 50.0f;
+          chroma_log("WARN", "Invalid anchor_x: %s (range 0-100, using 50)",
+                     value);
+        }
+      } else if (strcasecmp(property, "anchor_y") == 0) {
+        float ay = atof(value);
+        if (ay >= 0.0f && ay <= 100.0f) {
+          mapping->anchor_y = ay;
+          chroma_log("DEBUG", "Set anchor_y for output %s: %.1f", output_name,
+                     ay);
+        } else {
+          mapping->anchor_y = 50.0f;
+          chroma_log("WARN", "Invalid anchor_y: %s (range 0-100, using 50)",
+                     value);
+        }
       } else {
         chroma_log("WARN", "Unknown output property: %s (line %d)", property,
                    line_number);
@@ -442,10 +539,10 @@ static int parse_config_line(chroma_config_t *config, char *line,
       return CHROMA_OK;
     }
 
-    if (add_output_mapping(config, output_name, path_to_validate,
+    if (add_output_mapping(
-                           config->default_scale_mode,
+            config, output_name, path_to_validate, config->default_scale_mode,
-                           config->default_filter_quality,
+            config->default_filter_quality, config->default_anchor,
-                           config->default_anchor) != CHROMA_OK) {
+            config->default_anchor_x, config->default_anchor_y) != CHROMA_OK) {
       chroma_log("ERROR", "Failed to add output mapping: %s -> %s", output_name,
                  path_to_validate);
       if (expanded_path) {
@@ -589,12 +686,13 @@ const char *chroma_config_get_image_for_output(chroma_config_t *config,
 }
 
 // Get configuration mapping for output, including scale mode, filter
-// quality, and anchor
+// quality, anchor, and custom anchor coordinates
 int chroma_config_get_mapping_for_output(
     chroma_config_t *config, const char *output_name,
     chroma_scale_mode_t *scale_mode, chroma_filter_quality_t *filter_quality,
-    chroma_anchor_t *anchor) {
+    chroma_anchor_t *anchor, float *anchor_x, float *anchor_y) {
-  if (!config || !output_name || !scale_mode || !filter_quality || !anchor) {
+  if (!config || !output_name || !scale_mode || !filter_quality || !anchor ||
+      !anchor_x || !anchor_y) {
     return CHROMA_ERROR_INIT;
   }
 
@@ -604,12 +702,14 @@ int chroma_config_get_mapping_for_output(
       *scale_mode = config->mappings[i].scale_mode;
       *filter_quality = config->mappings[i].filter_quality;
       *anchor = config->mappings[i].anchor;
+      *anchor_x = config->mappings[i].anchor_x;
+      *anchor_y = config->mappings[i].anchor_y;
       chroma_log("DEBUG",
                  "Found specific mapping for output %s: scale=%s, filter=%s, "
-                 "anchor=%s",
+                 "anchor=%s @ %.1f,%.1f",
                  output_name, scale_mode_to_string(*scale_mode),
                  filter_quality_to_string(*filter_quality),
-                 anchor_to_string(*anchor));
+                 anchor_to_string(*anchor), *anchor_x, *anchor_y);
       return CHROMA_OK;
     }
   }
@@ -618,10 +718,14 @@ int chroma_config_get_mapping_for_output(
   *scale_mode = config->default_scale_mode;
   *filter_quality = config->default_filter_quality;
   *anchor = config->default_anchor;
-  chroma_log(
+  *anchor_x = config->default_anchor_x;
-      "DEBUG", "Using defaults for output %s: scale=%s, filter=%s, anchor=%s",
+  *anchor_y = config->default_anchor_y;
+  chroma_log("DEBUG",
+             "Using defaults for output %s: scale=%s, filter=%s, anchor=%s @ "
+             "%.1f,%.1f",
              output_name, scale_mode_to_string(*scale_mode),
-      filter_quality_to_string(*filter_quality), anchor_to_string(*anchor));
+             filter_quality_to_string(*filter_quality),
+             anchor_to_string(*anchor), *anchor_x, *anchor_y);
   return CHROMA_OK;
 }
 

src/core.c

@@ -113,20 +113,29 @@ static int assign_wallpaper_to_output(chroma_state_t *state,
   chroma_scale_mode_t old_scale_mode = output->scale_mode;
   chroma_filter_quality_t old_filter_quality = output->filter_quality;
   chroma_anchor_t old_anchor = output->anchor;
+  float old_anchor_x = output->anchor_x;
+  float old_anchor_y = output->anchor_y;
   bool had_config = output->config_loaded;
 
-  // Load configuration for this output (scale mode, filter quality, anchor)
+  // Load configuration for this output (scale mode, filter quality, anchor,
+  // anchor coords)
   if (chroma_config_get_mapping_for_output(
           &state->config, output->name ? output->name : "unknown",
-          &output->scale_mode, &output->filter_quality, &output->anchor) == CHROMA_OK) {
+          &output->scale_mode, &output->filter_quality, &output->anchor,
+          &output->anchor_x, &output->anchor_y) == CHROMA_OK) {
     output->config_loaded = true;
-    chroma_log("DEBUG", "Loaded config for output %u: scale=%d, filter=%d, anchor=%d",
+    chroma_log("DEBUG",
-               output->id, output->scale_mode, output->filter_quality, output->anchor);
+               "Loaded config for output %u: scale=%d, filter=%d, anchor=%d @ "
+               "%.1f,%.1f",
+               output->id, output->scale_mode, output->filter_quality,
+               output->anchor, output->anchor_x, output->anchor_y);
 
     // Check if configuration changed and invalidate texture if needed
-    if (had_config && (old_scale_mode != output->scale_mode ||
+    if (had_config &&
+        (old_scale_mode != output->scale_mode ||
          old_filter_quality != output->filter_quality ||
-                       old_anchor != output->anchor)) {
+         old_anchor != output->anchor || old_anchor_x != output->anchor_x ||
+         old_anchor_y != output->anchor_y)) {
       chroma_output_invalidate_texture(output);
       output->vbo_dirty = true; // VBO needs update for new scale mode
       chroma_log("DEBUG",
@@ -380,14 +389,16 @@ void chroma_log(const char *level, const char *format, ...) {
   gettimeofday(&tv, NULL);
   tm_info = localtime(&tv.tv_sec);
 
-  truncation_check = snprintf(timestamp, sizeof(timestamp), "%04d-%02d-%02d %02d:%02d:%02d.%03d",
+  truncation_check =
-           tm_info->tm_year + 1900, tm_info->tm_mon + 1, tm_info->tm_mday,
+      snprintf(timestamp, sizeof(timestamp),
-           tm_info->tm_hour, tm_info->tm_min, tm_info->tm_sec,
+               "%04d-%02d-%02d %02d:%02d:%02d.%03d", tm_info->tm_year + 1900,
-           (int)(tv.tv_usec / 1000));
+               tm_info->tm_mon + 1, tm_info->tm_mday, tm_info->tm_hour,
+               tm_info->tm_min, tm_info->tm_sec, (int)(tv.tv_usec / 1000));
 
   if (truncation_check > 32 || truncation_check < 0) {
-    // Something went seriously wrong with the snprintf, this is a fairly serious error as
+    // Something went seriously wrong with the snprintf, this is a fairly
-    // the timestamp may be incomplete or corrupted, so print a warning
+    // serious error as the timestamp may be incomplete or corrupted, so print a
+    // warning
     printf("Following timestamp may be incomplete, truncated or corrupted!\n");
   }
   printf("[%s] %s: ", timestamp, level);

src/render.c

@@ -43,7 +43,7 @@ static void get_gl_filter_params(chroma_filter_quality_t quality,
 
 // Calculate texture coordinates based on scaling mode and anchor position
 static void calculate_texture_coords(chroma_scale_mode_t scale_mode,
-                                     chroma_anchor_t anchor,
+                                     float anchor_x, float anchor_y,
                                      int image_width, int image_height,
                                      int output_width, int output_height,
                                      float tex_coords[8]) {
@@ -143,53 +143,13 @@ static void calculate_texture_coords(chroma_scale_mode_t scale_mode,
     break;
   }
 
-  // Apply anchor-based offset by shifting the visible crop region
+  // Apply anchor-based offset using anchor_x and anchor_y (0-100, 50=center)
-  // For fill: shift which part of image is shown
+  // anchor_x: 0=left edge, 50=center, 100=right edge
-  // For fit/center: shift where the image is positioned
+  // anchor_y: 0=top edge, 50=center, 100=bottom edge
-  // 
+  // u_shift: negative moves view left (shows more right side of image)
-  // Positive shift reveals left/bottom portion
+  // v_shift: negative moves view up (shows more top of image)
-  // Negative shift reveals right/top portion
+  float u_shift = (anchor_x - 50.0f) / 50.0f; // -1 to 1
-  float u_shift = 0.0f;
+  float v_shift = (50.0f - anchor_y) / 50.0f; // -1 to 1 (inverted for top-down)
-  float v_shift = 0.0f;
-
-  switch (anchor) {
-  case CHROMA_ANCHOR_CENTER:
-    u_shift = 0.0f;
-    v_shift = 0.0f;
-    break;
-  case CHROMA_ANCHOR_TOP:
-    u_shift = 0.0f;
-    v_shift = -0.5f; // shift up to show top of image
-    break;
-  case CHROMA_ANCHOR_BOTTOM:
-    u_shift = 0.0f;
-    v_shift = 0.5f; // shift down to show bottom of image
-    break;
-  case CHROMA_ANCHOR_LEFT:
-    u_shift = -0.5f; // shift left to show left of image
-    v_shift = 0.0f;
-    break;
-  case CHROMA_ANCHOR_RIGHT:
-    u_shift = 0.5f; // shift right to show right of image
-    v_shift = 0.0f;
-    break;
-  case CHROMA_ANCHOR_TOP_LEFT:
-    u_shift = -0.5f;
-    v_shift = -0.5f;
-    break;
-  case CHROMA_ANCHOR_TOP_RIGHT:
-    u_shift = 0.5f;
-    v_shift = -0.5f;
-    break;
-  case CHROMA_ANCHOR_BOTTOM_LEFT:
-    u_shift = -0.5f;
-    v_shift = 0.5f;
-    break;
-  case CHROMA_ANCHOR_BOTTOM_RIGHT:
-    u_shift = 0.5f;
-    v_shift = 0.5f;
-    break;
-  }
 
   // Calculate the shift amount based on crop/border space available
   float u_crop = 1.0f - (u2 - u1);
@@ -755,11 +715,13 @@ int chroma_render_wallpaper(chroma_state_t *state, chroma_output_t *output) {
   // Update VBO only if needed. E.g, image changed, scale mode changed, or first
   // render
   if (output->vbo_dirty) {
-    // Calculate texture coordinates based on scaling mode and anchor
+    // Calculate texture coordinates based on scaling mode, anchor, and anchor
+    // coords
     float tex_coords[8];
-    calculate_texture_coords(output->scale_mode, output->anchor,
+    calculate_texture_coords(output->scale_mode, output->anchor_x,
-                             output->image->width, output->image->height,
+                             output->anchor_y, output->image->width,
-                             output->width, output->height, tex_coords);
+                             output->image->height, output->width,
+                             output->height, tex_coords);
 
     // Create dynamic vertex data with calculated texture coordinates
     float dynamic_vertices[] = {