Add SIXEL cache.

regress/image-sixel-cache.sh

@@ -0,0 +1,78 @@
+#!/bin/sh
+
+# Check that cached colours and dithering survive clipping and client changes,
+# and that a visible crop is drawn when the whole scaled image is too large.
+
+PATH=/bin:/usr/bin
+TERM=screen
+export TERM
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+python3 -B - "$TEST_TMUX" <<'PY'
+import sys
+from image_test import image_test, sixel, check_image
+
+levels = [0, 14, 29, 43, 57, 71, 86, 100]
+palette = [(r, g, b) for r in levels for g in levels for b in levels]
+wire = sixel(32, 16, palette, list(range(512)))
+
+with image_test(sys.argv[1]) as test:
+    first = test.attach()
+    test.emit(wire)
+    original = first.images()
+    assert len(original) == 1 and original[0][:2] == (32, 16)
+
+    # Clients with the same cell size draw identical indexed pixels.
+    second = test.attach()
+    test.redraw()
+    assert first.images() == second.images() == original
+
+    # A different cell size must not replace the first clients' result.
+    small = test.attach(cw=4, ch=8)
+    test.redraw()
+    scaled = small.images()
+    assert len(scaled) == 1 and scaled[0][:2] == (16, 8)
+    assert first.images() == second.images() == original
+
+    # Overwrite the first cell. The remaining pixels retain the full palette
+    # and dithering, rather than converting the smaller rectangle again.
+    test.emit(b'\033[HX')
+    expected = [original[0][2][y * 32 + x]
+        for y in range(16) for x in range(8, 32)]
+    for client in (first, second):
+        images = client.images()
+        assert len(images) == 1
+        check_image(images[0], 24, 16, expected)
+    small_expected = [scaled[0][2][y * 16 + x]
+        for y in range(8) for x in range(4, 16)]
+    images = small.images()
+    assert len(images) == 1
+    check_image(images[0], 12, 8, small_expected)
+
+    # Changing back to an earlier cell size reuses the same indexed pixels.
+    test.resize(small, 40, 16)
+    test.redraw()
+    for client in (first, second, small):
+        images = client.images()
+        assert len(images) == 1
+        check_image(images[0], 24, 16, expected)
+
+    # Replacing the source must not draw pixels from the deleted image.
+    test.emit(b'\033[2J\033[H' +
+        sixel(8, 16, [(100, 0, 0)], [0] * (8 * 16)))
+    for client in (first, second, small):
+        images = client.images()
+        assert len(images) == 1
+        check_image(images[0], 8, 16, [(255, 0, 0)] * (8 * 16))
+
+with image_test(sys.argv[1], sx=1) as test:
+    client = test.attach()
+    test.emit(sixel(16, 16, [(100, 0, 0)], [0] * (16 * 16)))
+    # The whole image would be 12000 pixels wide, beyond the SIXEL limit.
+    # Its visible first cell is still valid and must be converted directly.
+    test.resize(client, 1, 16, cw=6000, ch=16)
+    test.redraw()
+    images = client.images()
+    assert len(images) == 1
+    check_image(images[0], 6000, 16, [(255, 0, 0)] * (6000 * 16))
+PY