fix(sdk+launcher): 图标不渲染真根因(agent-219) — meow_ui_img.c scale_buf cover 采样把乘写成除(÷缩放比→采到源图左上角透明区,全丢); 改乘+居中裁剪偏移修正; 宿主旧测试用纯色图掩盖了该bug。+ main_menu App退出/结构变化重绘时 fb_pan_buf0_force 无条件pan回buffer0(防App翻页留buffer1致菜单残帧)

meow_ui.a→3e0ee8f7 launcher→9d0efc2f hello→9609ea6e files→90f5cf07 ncm→be8be221(均已上卡); 真机截图证据 .tmp/meowbug/fix1.png+fix_b2_after.png

patch_v2/sdk/meow_ui_vol.c

@@ -50,3 +50,72 @@ int meow_ui_vol_read(const char *path, const char *key, int def)
     while (*found == ' ' || *found == '\t') found++;   /* value 左去空白；atoi 天然停于非数字 */
     return atoi(found);
 }
+
+/* 改 settings.conf 一个 int 键：流式拷贝原文件到 <path>.tmp，命中键行改写为
+ * "key = value"（launcher 落盘格式，带空格），键缺失则末尾追加；rename 原子替换。
+ * 保留其余行（注释/其它设置）——绝不 O_TRUNC 整文件。 */
+int meow_ui_vol_set(const char *path, const char *key, int val)
+{
+    if (!path || !path[0] || !key || !key[0]) return -1;
+    FILE *in = fopen(path, "r");
+    char tmp[512];
+    int kl = (int)strlen(key);
+    snprintf(tmp, sizeof tmp, "%s.tmp", path);
+    FILE *out = fopen(tmp, "w");
+    if (!out) { if (in) fclose(in); return -1; }
+
+    int found = 0;
+    char line[256];
+    while (in && fgets(line, sizeof line, in)) {
+        char *eq = strchr(line, '=');
+        char *k = line;
+        while (*k == ' ' || *k == '\t') k++;
+        int n = eq ? (int)(eq - k) : 0;
+        while (n > 0 && (k[n-1] == ' ' || k[n-1] == '\t')) n--;
+        if (eq && n == kl && strncmp(k, key, (size_t)kl) == 0) {
+            fprintf(out, "%s = %d\n", key, val);   /* 命中：改写为规范格式 */
+            found = 1;
+        } else {
+            fputs(line, out);                       /* 其它行原样保留 */
+        }
+    }
+    if (in) fclose(in);
+    if (!found) fprintf(out, "%s = %d\n", key, val);
+    fclose(out);
+
+    if (rename(tmp, path) != 0) { remove(tmp); return -1; }
+    return 0;
+}
+
+/* 音量步进（系统语义，与 launcher 设置页/watchdog 同源：volume_step/volume_max 约束）。
+ * 只做 settings 逻辑 + 持久化；DAC 写入由调用方（meow_ui_vol_dac_write）负责。 */
+int meow_ui_vol_step(const char *path, int dir)
+{
+    int vol    = meow_ui_vol_read(path, "audio.volume",      MEOW_UI_VOL_DEFAULT);
+    int vol_max= meow_ui_vol_read(path, "audio.volume_max",  MEOW_UI_VOL_MAX_DEF);
+    int step   = meow_ui_vol_read(path, "audio.volume_step", 1);
+    if (step < 1) step = 1;
+    if (step > 5) step = 5;           /* 与 watchdog 读取口径一致（1..5） */
+    if (dir < 0) dir = -1;
+    else if (dir > 0) dir = 1;
+    else return vol;
+
+    int v = meow_ui_vol_clamp(vol + dir * step, vol_max);
+    if (v == vol) return vol;         /* 已在上下限：无进展，不写 */
+    meow_ui_vol_set(path, "audio.volume", v);
+    return v;
+}
+
+/* 真实 DAC 音量（CS43198, numid 1/2, 0-255），pct→255 映射直写两声道。
+ * 与 launcher meow_dac_vol_write / watchdog wd_vol_write 完全同路径（语义同源）。 */
+void meow_ui_vol_dac_write(int pct)
+{
+    int dac = pct * 255 / 100;
+    if (dac < 0) dac = 0;
+    if (dac > 255) dac = 255;
+    char cmd[160];
+    snprintf(cmd, sizeof cmd,
+             "amixer -c 0 cset numid=1 %d >/dev/null 2>&1; amixer -c 0 cset numid=2 %d >/dev/null 2>&1",
+             dac, dac);
+    system(cmd);
+}