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Diffstat (limited to 'src/mbgl/util/scaling.cpp')
| -rw-r--r-- | src/mbgl/util/scaling.cpp | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/src/mbgl/util/scaling.cpp b/src/mbgl/util/scaling.cpp new file mode 100644 index 0000000000..a554b2e137 --- /dev/null +++ b/src/mbgl/util/scaling.cpp @@ -0,0 +1,111 @@ +#include "scaling.hpp" + +namespace { + +using namespace mbgl; + +inline uint8_t bilinearInterpolate(uint8_t tl, uint8_t tr, uint8_t bl, uint8_t br, double dx, double dy) { + const double t = dx * (tr - tl) + tl; + const double b = dx * (br - bl) + bl; + return t + dy * (b - t); +} + +template <size_t i> +inline const uint8_t& b(const uint32_t& w) { + return reinterpret_cast<const uint8_t*>(&w)[i]; +} + +template <size_t i> +inline uint8_t& b(uint32_t& w) { + return reinterpret_cast<uint8_t*>(&w)[i]; +} + +vec2<double> getFactor(const Rect<uint32_t>& srcPos, const Rect<uint32_t>& dstPos) { + return { + double(srcPos.w) / dstPos.w, + double(srcPos.h) / dstPos.h + }; +} + +vec2<uint32_t> getBounds(const vec2<uint32_t>& srcSize, const Rect<uint32_t>& srcPos, + const vec2<uint32_t>& dstSize, const Rect<uint32_t>& dstPos, + const vec2<double>& factor) { + if (srcPos.x > srcSize.x || srcPos.y > srcSize.y || + dstPos.x > dstSize.x || dstPos.y > dstSize.y) { + // Source or destination position is out of range. + return { 0, 0 }; + } + + // Make sure we don't read/write values out of range. + return { std::min(uint32_t(double(srcSize.x - srcPos.x) / factor.x), + std::min(dstSize.x - dstPos.x, dstPos.w)), + std::min(uint32_t(double(srcSize.y - srcPos.y) / factor.y), + std::min(dstSize.y - dstPos.y, dstPos.h)) }; +} +} + +namespace mbgl { +namespace util { + +void bilinearScale(const uint32_t* srcData, const vec2<uint32_t>& srcSize, + const Rect<uint32_t>& srcPos, uint32_t* dstData, const vec2<uint32_t>& dstSize, + const Rect<uint32_t>& dstPos) { + const auto factor = getFactor(srcPos, dstPos); + const auto bounds = getBounds(srcSize, srcPos, dstSize, dstPos, factor); + + double fractSrcY = srcPos.y; + double fractSrcX; + uint32_t x, y; + size_t i = dstSize.x * dstPos.y + dstPos.x; + for (y = 0; y < bounds.y; y++) { + fractSrcX = srcPos.x; + const uint32_t srcY0 = fractSrcY; + const uint32_t srcY1 = std::min(srcY0 + 1, srcSize.y - 1); + for (x = 0; x < bounds.x; x++) { + const uint32_t srcX0 = fractSrcX; + const uint32_t srcX1 = std::min(srcX0 + 1, srcSize.x - 1); + + const uint32_t tl = srcData[srcSize.x * srcY0 + srcX0]; + const uint32_t tr = srcData[srcSize.x * srcY0 + srcX1]; + const uint32_t bl = srcData[srcSize.x * srcY1 + srcX0]; + const uint32_t br = srcData[srcSize.x * srcY1 + srcX1]; + + const double dx = fractSrcX - srcX0; + const double dy = fractSrcY - srcY0; + uint32_t& dst = dstData[i + x]; + b<0>(dst) = bilinearInterpolate(b<0>(tl), b<0>(tr), b<0>(bl), b<0>(br), dx, dy); + b<1>(dst) = bilinearInterpolate(b<1>(tl), b<1>(tr), b<1>(bl), b<1>(br), dx, dy); + b<2>(dst) = bilinearInterpolate(b<2>(tl), b<2>(tr), b<2>(bl), b<2>(br), dx, dy); + b<3>(dst) = bilinearInterpolate(b<3>(tl), b<3>(tr), b<3>(bl), b<3>(br), dx, dy); + fractSrcX += factor.x; + } + i += dstSize.x; + fractSrcY += factor.y; + } +} + +void nearestNeighborScale(const uint32_t* srcData, const vec2<uint32_t>& srcSize, + const Rect<uint32_t>& srcPos, uint32_t* dstData, + const vec2<uint32_t>& dstSize, const Rect<uint32_t>& dstPos) { + const auto factor = getFactor(srcPos, dstPos); + const auto bounds = getBounds(srcSize, srcPos, dstSize, dstPos, factor); + + double fractSrcY = srcPos.y; + double fractSrcX; + size_t i = dstSize.x * dstPos.y + dstPos.x; + uint32_t srcY; + uint32_t x, y; + for (y = 0; y < bounds.y; y++) { + fractSrcX = srcPos.x; + srcY = srcSize.x * uint32_t(fractSrcY); + for (x = 0; x < bounds.x; x++) { + dstData[i + x] = srcData[srcY + uint32_t(fractSrcX)]; + fractSrcX += factor.x; + } + i += dstSize.x; + fractSrcY += factor.y; + } +} + +} +}
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