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Add BC block copy support to CopyRectangle #752

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Add BC block copy support to CopyRectangle #752

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27f3c09
Add BC block copy support to CopyRectangle
nv3ifu Oct 9, 2026
a898119
Apply clang-format to CopyRectangle BC copy code
nv3ifu Oct 10, 2026
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60 changes: 58 additions & 2 deletions DirectXTex/DirectXTexMisc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -260,8 +260,64 @@ _Use_decl_annotations_ HRESULT DirectX::CopyRectangle(const Image& srcImage,
if (!srcImage.pixels || !dstImage.pixels)
return E_POINTER;

if (IsCompressed(srcImage.format) || IsCompressed(dstImage.format) || IsPlanar(srcImage.format) || IsPlanar(dstImage.format)
|| IsPalettized(srcImage.format) || IsPalettized(dstImage.format))
if (IsCompressed(srcImage.format) || IsCompressed(dstImage.format))
{
if (srcImage.format != dstImage.format)
return HRESULT_E_NOT_SUPPORTED;

const size_t bytesPerBlock = BytesPerBlock(srcImage.format);
if (!bytesPerBlock)
return HRESULT_E_NOT_SUPPORTED;

if (!srcRect.w || !srcRect.h || srcRect.x >= srcImage.width || srcRect.y >= srcImage.height
|| srcRect.w > srcImage.width - srcRect.x || srcRect.h > srcImage.height - srcRect.y || xOffset >= dstImage.width
|| yOffset >= dstImage.height || srcRect.w > dstImage.width - xOffset || srcRect.h > dstImage.height - yOffset)
return E_INVALIDARG;

// Copy whole 4x4 blocks covering srcRect, including pixels outside it.
// Round the destination origin down to a block boundary.
const size_t srcX = srcRect.x / 4;
const size_t srcY = srcRect.y / 4;
const size_t dstX = xOffset / 4;
const size_t dstY = yOffset / 4;

const size_t blockWidth = (srcRect.x + srcRect.w - 1) / 4 + 1 - srcX;
const size_t blockHeight = (srcRect.y + srcRect.h - 1) / 4 + 1 - srcY;
const size_t dstWidth = (dstImage.width - 1) / 4 + 1;
const size_t dstHeight = (dstImage.height - 1) / 4 + 1;
if (blockWidth > dstWidth - dstX || blockHeight > dstHeight - dstY)
return E_INVALIDARG;

const auto validStorage = [bytesPerBlock](const Image& image, size_t x, size_t y, size_t width, size_t height) noexcept
{
const size_t imageBlocks = (image.width - 1) / 4 + 1;
if (!image.rowPitch || imageBlocks > image.rowPitch / bytesPerBlock)
return false;

const size_t rowEnd = (x + width) * bytesPerBlock;
return rowEnd <= image.slicePitch && y + height - 1 <= (image.slicePitch - rowEnd) / image.rowPitch;
};

if (!validStorage(srcImage, srcX, srcY, blockWidth, blockHeight) || !validStorage(dstImage, dstX, dstY, blockWidth, blockHeight))
return E_FAIL;

const size_t copyBytes = blockWidth * bytesPerBlock;
const uint8_t* pSrc = srcImage.pixels + srcY * srcImage.rowPitch + srcX * bytesPerBlock;
uint8_t* pDest = dstImage.pixels + dstY * dstImage.rowPitch + dstX * bytesPerBlock;
for (size_t row = 0; row < blockHeight; ++row)
{
memcpy(pDest, pSrc, copyBytes);
if (row + 1 < blockHeight)
{
pSrc += srcImage.rowPitch;
pDest += dstImage.rowPitch;
}
}

return S_OK;
}

if (IsPlanar(srcImage.format) || IsPlanar(dstImage.format) || IsPalettized(srcImage.format) || IsPalettized(dstImage.format))
return HRESULT_E_NOT_SUPPORTED;

// Validate rectangle/offset
Expand Down