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Fix vline height with custom clip window #168

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Merged
tuupola merged 2 commits into from
Mar 8, 2026
Merged

Fix vline height with custom clip window #168

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52a34d7
Add failing test for vline height with custom clip window
tuupola Mar 8, 2026
09cdb81
Fix vline height with custom clip window
tuupola Mar 8, 2026
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2 changes: 1 addition & 1 deletion src/hagl_vline.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ void hagl_draw_vline_xyh(

/* y0 is top of clip window, ignore start part. */
if (y0 < surface->clip.y0) {
height = height + y0;
height = height - (surface->clip.y0 - y0);
y0 = surface->clip.y0;
}

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27 changes: 27 additions & 0 deletions tests/test_vline.c
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Original file line number Diff line number Diff line change
Expand Up @@ -328,6 +328,32 @@ TEST test_draw_vline_xyh_custom_clip_regression(void) {
PASS();
}

/*
* Line clipped by top edge of custom clip window only:
* Only y=50..59 visible.
*/
TEST test_draw_vline_xyh_custom_clip_top(void) {
hagl_set_clip(&bitmap, 50, 50, 200, 200);
hagl_draw_vline_xyh(&bitmap, 75, 40, 20, 0xFFFF);

/* On line: top edge of clip window */
ASSERT_EQ(0xFFFF, hagl_get_pixel(&bitmap, 75, 50));

/* On line: bottom endpoint of original line */
ASSERT_EQ(0xFFFF, hagl_get_pixel(&bitmap, 75, 59));

/* Outside: just above clip window */
ASSERT_EQ(0x0000, hagl_get_pixel(&bitmap, 75, 49));

/* Outside: just below original line end */
ASSERT_EQ(0x0000, hagl_get_pixel(&bitmap, 75, 60));

/* Total: 10 pixels */
ASSERT_EQ(10, count_pixels(&bitmap, 0xFFFF));

PASS();
}

SUITE(vline_suite) {
SET_SETUP(setup_callback, NULL);
SET_TEARDOWN(teardown_callback, NULL);
Expand All @@ -345,6 +371,7 @@ SUITE(vline_suite) {
RUN_TEST(test_draw_vline_xyh_outside);
RUN_TEST(test_draw_vline_xyh_custom_clip);
RUN_TEST(test_draw_vline_xyh_custom_clip_regression);
RUN_TEST(test_draw_vline_xyh_custom_clip_top);
}

GREATEST_MAIN_DEFS();
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