1 files changed, 53 insertions, 0 deletions
diff --git a/src/image.zig b/src/image.zig
new file mode 100644
index 00000000..a3415019
--- /dev/null
+++ b/src/image.zig
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+//! Image panes. Decoding is zstbi (C stb_image) to RGBA, downscaled; the kept
+//! pixels render as PETSCII glyph art directly into the Surface — or, when the
+//! host has kitty graphics (and Petscii isn't toggled), ride the Surface as a
+//! pixel attachment the shell transmits/places (tty: vaxis kitty; SDL: blit).
+const std = @import("std");
+const zstbi = @import("zstbi");
+const ghostty_vt = @import("ghostty-vt");
+pub const petscii = @import("petscii.zig");
+
+/// the terminal's own 16 ANSI colors — what the `terminal` palette mode
+/// scores against; cells then paint as indexed colors so the real terminal
+/// resolves the RGB
+pub fn ansiPalette() [16][3]u8 {
+    var p: [16][3]u8 = undefined;
+    for (0..16) |i| {
+        const c = ghostty_vt.color.default[i];
+        p[i] = .{ c.r, c.g, c.b };
+    }
+    return p;
+}
+
+/// cap the longest side before keeping/transmitting: a pane is at most a
+/// screenful of cells, multi-thousand-pixel photos waste decode/transmit time
+const MAX_DIM: u32 = 1280;
+
+pub const PaletteMode = enum { commodore, terminal };
+
+/// call once at startup / exit (stb_image's allocator shim)
+pub fn start(io: std.Io, gpa: std.mem.Allocator) void {
+    zstbi.init(io, gpa);
+}
+pub fn stop() void {
+    zstbi.deinit();
+}
+
+/// decode + downscale to RGBA, gpa-owned. Returns null on any failure — the
+/// pane then simply shows a blank body.
+pub fn decode(gpa: std.mem.Allocator, bytes: []const u8) ?struct { rgba: []u8, w: usize, h: usize } {
+    if (bytes.len == 0) return null;
+    var img = zstbi.Image.loadFromMemory(bytes, 4) catch return null; // 4 = RGBA
+    defer img.deinit();
+    var scaled: ?zstbi.Image = null;
+    defer if (scaled) |*s| s.deinit();
+    const longest = @max(img.width, img.height);
+    const src: *const zstbi.Image = if (longest > MAX_DIM) blk: {
+        const nw = @max(1, img.width * MAX_DIM / longest);
+        const nh = @max(1, img.height * MAX_DIM / longest);
+        scaled = img.resize(nw, nh);
+        break :blk &scaled.?;
+    } else &img;
+    const rgba = gpa.dupe(u8, src.data) catch return null;
+    return .{ .rgba = rgba, .w = src.width, .h = src.height };
+}