extmod/modframebuf: Fix FrameBuffer size check for stride corner-cases.

This is a fix for issue #15944, and handles corner cases in the FrameBuffer
code when using stride values where the last line's stride may extend past
the end of the underlying buffer.  This commit includes extra tests for
these corner cases.

For example a GS8 format FrameBuffer with a width of 8, height of 2 and
stride of 10 should be able to fit into a buffer of size 18 (10 bytes for
the first horizontal line, and 8 bytes for the second -- the full 10 bytes
are not needed).

Similarly a 1 by 9 FrameBuffer in MONO_VLSB format with a stride of 10
should be able to fit into a buffer of length 11 (10 bytes for the first
8 lines, and then one byte for the 9th line.

Being able to do this is particularly important when cropping the corner of
an existing FrameBuffer, either to copy a sprite or to clip drawing.

Signed-off-by: Corran Webster <cwebster@unital.dev>

2 files changed, 60 insertions, 0 deletions

diff --git a/tests/extmod/framebuf_bounds.py b/tests/extmod/framebuf_bounds.py
index 3035b365b..2a7647cfb 100644
--- a/tests/extmod/framebuf_bounds.py
+++ b/tests/extmod/framebuf_bounds.py
@@ -21,11 +21,25 @@ test_constructor(bytearray(20), 10, 10, framebuf.MONO_HLSB, 11)
 test_constructor(bytearray(20), 10, 10, framebuf.MONO_HLSB, 10)
 test_constructor(bytearray(20), 10, 10, framebuf.MONO_HLSB, 9)
 test_constructor(bytearray(20), 10, 10, framebuf.MONO_HLSB, -1)
+test_constructor(bytearray(20), 10, 10, framebuf.MONO_HLSB, 16)
+test_constructor(bytearray(20), 10, 10, framebuf.MONO_HLSB, 17)
+test_constructor(bytearray(19), 8, 10, framebuf.MONO_HLSB, 16)
+test_constructor(bytearray(18), 8, 10, framebuf.MONO_HLSB, 9)
+test_constructor(bytearray(19), 8, 10, framebuf.MONO_HLSB, 16)
 
 print(framebuf.MONO_VLSB)
 test_constructor(bytearray(8), 8, 1, framebuf.MONO_VLSB)
 test_constructor(bytearray(7), 8, 1, framebuf.MONO_VLSB)
 test_constructor(bytearray(8), 8, 8, framebuf.MONO_VLSB)
+test_constructor(bytearray(1), 1, 8, framebuf.MONO_VLSB)
+test_constructor(bytearray(1), 1, 9, framebuf.MONO_VLSB)
+test_constructor(bytearray(2), 1, 9, framebuf.MONO_VLSB)
+test_constructor(bytearray(1), 1, 8, framebuf.MONO_VLSB, 10)
+test_constructor(bytearray(8), 8, 8, framebuf.MONO_VLSB, 10)
+test_constructor(bytearray(8), 8, 8, framebuf.MONO_VLSB, 7)
+test_constructor(bytearray(11), 1, 9, framebuf.MONO_VLSB, 10)
+test_constructor(bytearray(10), 1, 9, framebuf.MONO_VLSB, 10)
+test_constructor(bytearray(11), 1, 16, framebuf.MONO_VLSB, 10)
 
 for f in (framebuf.MONO_HLSB, framebuf.MONO_HMSB):
     print(f)
@@ -40,21 +54,37 @@ test_constructor(bytearray(8), 4, 8, framebuf.GS2_HMSB)
 test_constructor(bytearray(15), 5, 8, framebuf.GS2_HMSB)
 test_constructor(bytearray(16), 5, 8, framebuf.GS2_HMSB)
 test_constructor(bytearray(9), 4, 9, framebuf.GS2_HMSB)
+test_constructor(bytearray(2), 7, 1, framebuf.GS2_HMSB, 9)
+test_constructor(bytearray(4), 7, 2, framebuf.GS2_HMSB, 9)
+test_constructor(bytearray(5), 7, 2, framebuf.GS2_HMSB, 9)
 
 print(framebuf.GS4_HMSB)
 test_constructor(bytearray(8), 2, 8, framebuf.GS4_HMSB)
 test_constructor(bytearray(15), 3, 8, framebuf.GS4_HMSB)
 test_constructor(bytearray(16), 3, 8, framebuf.GS4_HMSB)
 test_constructor(bytearray(9), 2, 9, framebuf.GS4_HMSB)
+test_constructor(bytearray(4), 7, 1, framebuf.GS4_HMSB, 9)
+test_constructor(bytearray(8), 7, 2, framebuf.GS4_HMSB, 9)
+test_constructor(bytearray(9), 7, 2, framebuf.GS4_HMSB, 9)
 
 print(framebuf.GS8)
 test_constructor(bytearray(63), 8, 8, framebuf.GS8)
 test_constructor(bytearray(64), 8, 8, framebuf.GS8)
 test_constructor(bytearray(64), 9, 8, framebuf.GS8)
 test_constructor(bytearray(64), 8, 9, framebuf.GS8)
+test_constructor(bytearray(64), 4, 8, framebuf.GS8, 8)
+test_constructor(bytearray(64), 4, 8, framebuf.GS8, 9)
+test_constructor(bytearray(8), 8, 1, framebuf.GS8, 10)
+test_constructor(bytearray(17), 8, 2, framebuf.GS8, 10)
+test_constructor(bytearray(18), 8, 2, framebuf.GS8, 10)
 
 print(framebuf.RGB565)
 test_constructor(bytearray(127), 8, 8, framebuf.RGB565)
 test_constructor(bytearray(128), 8, 8, framebuf.RGB565)
 test_constructor(bytearray(128), 9, 8, framebuf.RGB565)
 test_constructor(bytearray(128), 8, 9, framebuf.RGB565)
+test_constructor(bytearray(128), 4, 8, framebuf.RGB565, 8)
+test_constructor(bytearray(128), 4, 8, framebuf.RGB565, 9)
+test_constructor(bytearray(16), 8, 1, framebuf.RGB565, 10)
+test_constructor(bytearray(34), 8, 2, framebuf.RGB565, 10)
+test_constructor(bytearray(36), 8, 2, framebuf.RGB565, 10)
diff --git a/tests/extmod/framebuf_bounds.py.exp b/tests/extmod/framebuf_bounds.py.exp
index 3125013bc..b9c221b42 100644
--- a/tests/extmod/framebuf_bounds.py.exp
+++ b/tests/extmod/framebuf_bounds.py.exp
@@ -6,10 +6,24 @@ Valid
 Valid
 ValueError
 ValueError
+Valid
+ValueError
+Valid
+ValueError
+Valid
 0
 Valid
 ValueError
 Valid
+Valid
+ValueError
+Valid
+Valid
+Valid
+ValueError
+Valid
+ValueError
+Valid
 3
 Valid
 ValueError
@@ -27,18 +41,34 @@ Valid
 ValueError
 Valid
 Valid
+Valid
+ValueError
+Valid
 2
 Valid
 ValueError
 Valid
 Valid
+Valid
+ValueError
+Valid
 6
 ValueError
 Valid
 ValueError
 ValueError
+Valid
+ValueError
+Valid
+ValueError
+Valid
 1
 ValueError
 Valid
 ValueError
 ValueError
+Valid
+ValueError
+Valid
+ValueError
+Valid