Add support of negitive offset and new alignments

res/config.ini

@@ -167,6 +167,16 @@ doom_bottom_color = 0x00FFFFFF
 # Dur file path
 dur_file_path = $CONFIG_DIRECTORY/ly/example.dur
 
+# Dur file alignment (center is the default for example)
+# |-----------------|
+# |1       2       3|
+# |                 |
+# |4       0       5|
+# |                 |
+# |6       7       8|
+# |-----------------|
+dur_offset_alignment = 0
+
 # Dur offset x direction
 dur_x_offset = 0
 

src/animations/DurFile.zig

@@ -286,25 +286,41 @@ fn convert_256_to_rgb(color_256: u32) u32 {
     return rgb_color;
 }
 
+const UVec2 = @Vector(2, u16);
+const IVec2 = @Vector(2, i32);
+
+const VEC_X = 0;
+const VEC_Y = 1;
+
+const Alignment = struct {
+    pub const CENTER = 0; // Center is the default so we have it out of order
+    pub const TOP_LEFT = 1;
+    pub const TOP_CENTER = 2;
+    pub const TOP_RIGHT = 3;
+    pub const CENTER_LEFT = 4;
+    pub const CENTER_RIGHT = 5;
+    pub const BOTTOM_LEFT = 6;
+    pub const BOTTOM_CENTER = 7;
+    pub const BOTTOM_RIGHT = 8;
+};
+
+
 const DurFile = @This();
 
 allocator: Allocator,
 terminal_buffer: *TerminalBuffer,
-frames: u64,
-time_previous: i64,
-x_offset: u32,
-y_offset: u32,
-full_color: bool,
 dur_movie: DurFormat,
-frame_width: u32,
-frame_height: u32,
+frames: u64,
+frame_size: UVec2,
+start_pos: IVec2,
+full_color: bool,
 frame_time: u32,
+time_previous: i64,
 is_color_format_16: bool,
 
-pub fn init(allocator: Allocator, terminal_buffer: *TerminalBuffer, log_writer: *std.io.Writer, file_path: []const u8, x_offset: u32, y_offset: u32, full_color: bool) !DurFile {
+pub fn init(allocator: Allocator, terminal_buffer: *TerminalBuffer, log_writer: *std.io.Writer, file_path: []const u8, offset_alignment: u32, x_offset: i32, y_offset: i32, full_color: bool) !DurFile {
     var dur_movie: DurFormat = .init(allocator);
 
-    // error state is recoverable when thrown to main and results in no background with Dummy in main
     dur_movie.create_from_file(allocator, file_path) catch |err| switch (err) {
         error.FileNotFound => {
             try log_writer.print("error: dur_file was not found at: {s}\n", .{file_path});
@@ -324,19 +340,35 @@ pub fn init(allocator: Allocator, terminal_buffer: *TerminalBuffer, log_writer:
         return error.InvalidColorFormat;
     }
 
-    const buf_width: u32 = @intCast(terminal_buffer.width);
-    const buf_height: u32 = @intCast(terminal_buffer.height);
+    const buf_width: u16 = @intCast(terminal_buffer.width);
+    const buf_height: u16 = @intCast(terminal_buffer.height);
 
-    const movie_width: u32 = @intCast(dur_movie.columns.?);
-    const movie_height: u32 = @intCast(dur_movie.lines.?);
+    const movie_width: u16 = @intCast(dur_movie.columns.?);
+    const movie_height: u16 = @intCast(dur_movie.lines.?);
 
-    // Clamp to prevent user from exceeding draw window
-    const x_offset_clamped = std.math.clamp(x_offset, 0, buf_width - 1);
-    const y_offset_clamped = std.math.clamp(y_offset, 0, buf_height - 1);
+    // if the user has an even number of columns or rows, we will default to the left or higher position (e.g. 4 columns center = .x..)
+    const center = struct { 
+        fn center(v: u16) i32 { return @intCast((v / 2) + (v % 2)); }
+    }.center;
 
-    // Ensure if user offsets and frame goes offscreen, it will not overflow draw
-    const frame_width = if ((movie_width + x_offset_clamped) < buf_width) movie_width else buf_width - x_offset_clamped;
-    const frame_height = if ((movie_height + y_offset_clamped) < buf_height) movie_height else buf_height - y_offset_clamped;
+    var start_pos = switch (offset_alignment) {
+        Alignment.CENTER => IVec2{ center(buf_width) - center(movie_width), center(buf_height) - center(movie_height) },
+        Alignment.TOP_LEFT => IVec2{ 0, 0 },
+        Alignment.TOP_CENTER => IVec2{ center(buf_width) - center(movie_width), 0 },
+        Alignment.TOP_RIGHT => IVec2{ buf_width - movie_width, 0 },
+        Alignment.CENTER_LEFT => IVec2{ 0, center(buf_width) - center(movie_width) },
+        Alignment.CENTER_RIGHT => IVec2{ buf_width - movie_width, center(buf_width) - center(movie_width) },
+        Alignment.BOTTOM_LEFT => IVec2{ 0, buf_width - movie_height },
+        Alignment.BOTTOM_CENTER => IVec2{ center(buf_width) - center(movie_width), buf_width - movie_height },
+        Alignment.BOTTOM_RIGHT => IVec2{ buf_width - movie_width,  buf_height - movie_height },
+        else => return error.InvalidDurOffsetAlignment,
+    };
+    
+    start_pos += IVec2{ x_offset, y_offset };
+
+    // Draw only the needed amount if movie smaller than screen. If movie is bigger, we will just draw entire screen
+    const frame_width = if (movie_width < buf_width) movie_width else buf_width;
+    const frame_height = if (movie_height < buf_height) movie_height else buf_height;
 
     // Convert dur fps to frames per ms
     const frame_time: u32 = @intFromFloat(1000 / dur_movie.framerate.?);
@@ -346,12 +378,10 @@ pub fn init(allocator: Allocator, terminal_buffer: *TerminalBuffer, log_writer:
         .terminal_buffer = terminal_buffer,
         .frames = 0,
         .time_previous = std.time.milliTimestamp(),
-        .x_offset = x_offset_clamped,
-        .y_offset = y_offset_clamped,
+        .frame_size = UVec2{ frame_width, frame_height },
+        .start_pos = start_pos,
         .full_color = full_color,
         .dur_movie = dur_movie,
-        .frame_width = frame_width,
-        .frame_height = frame_height,
         .frame_time = frame_time,
         .is_color_format_16 = eql(u8, dur_movie.colorFormat.?, "16"),
     };
@@ -370,10 +400,25 @@ fn realloc(_: *DurFile) anyerror!void {}
 fn draw(self: *DurFile) void {
     const current_frame = self.dur_movie.frames.items[self.frames];
 
-    for (0..self.frame_height) |y| {
+    const buf_width: u16 = @intCast(self.terminal_buffer.width);
+    const buf_height: u16 = @intCast(self.terminal_buffer.height);
+
+    // y is used as an iterator in the durformat, while cell_y gives us the correct placement for the cell (same for x)
+    for (0..self.frame_size[VEC_Y]) |y| {
+        const y_offset_i: i32 = @as(i32, @intCast(y)) + self.start_pos[VEC_Y];
+        // we skip the pass if it falls outside of the draw window (ensure no int underflow)
+        const cell_y: u32 = if (y_offset_i >= 0 and y_offset_i < buf_height) @intCast(y_offset_i) else continue;
+        
         var iter = std.unicode.Utf8View.initUnchecked(current_frame.contents[y]).iterator();
 
-        for (0..self.frame_width) |x| {
+        for (0..self.frame_size[VEC_X]) |x| {
+            const x_offset_i: i32 = @as(i32, @intCast(x)) + self.start_pos[VEC_X];
+            // skip pass, same as y but also incriment the codepoint iter to fetch correct values in later passes
+            const cell_x: u32 = if (x_offset_i >= 0 and x_offset_i < buf_width) @intCast(x_offset_i) else {
+                _ = iter.nextCodepoint().?;
+                continue;
+            };
+            
             const codepoint: u21 = iter.nextCodepoint().?;
             const color_map = current_frame.colorMap[x][y];
 
@@ -390,7 +435,7 @@ fn draw(self: *DurFile) void {
 
             const cell = Cell{ .ch = @intCast(codepoint), .fg = fg_color, .bg = bg_color };
 
-            cell.put(x + self.x_offset, y + self.y_offset);
+            cell.put(cell_x, cell_y);
         }
     }
 

src/config/Config.zig

@@ -43,8 +43,9 @@ doom_top_color: u32 = 0x00FF0000,
 doom_middle_color: u32 = 0x00FFFF00,
 doom_bottom_color: u32 = 0x00FFFFFF,
 dur_file_path: []const u8 = build_options.config_directory ++ "/ly/example.dur",
-dur_x_offset: u32 = 0,
-dur_y_offset: u32 = 0,
+dur_offset_alignment: u32 = 0,
+dur_x_offset: i32 = 0,
+dur_y_offset: i32 = 0,
 edge_margin: u8 = 0,
 error_bg: u32 = 0x00000000,
 error_fg: u32 = 0x01FF0000,

src/main.zig

@@ -580,7 +580,7 @@ pub fn main() !void {
             animation = game_of_life.animation();
         },
         .dur_file => {
-            var dur = try DurFile.init(allocator, &buffer, log_writer, config.dur_file_path, config.dur_x_offset, config.dur_y_offset, config.full_color);
+            var dur = try DurFile.init(allocator, &buffer, log_writer, config.dur_file_path, config.dur_offset_alignment, config.dur_x_offset, config.dur_y_offset, config.full_color);
             animation = dur.animation();
         },
     }