Merge pull request #11200 from rouault/GDALRasterComputeMinMaxLocation

Add GDALRasterComputeMinMaxLocation / GDALRasterBand::ComputeMinMaxLocation, and map it to SWIG

autotest/cpp/test_gdal.cpp

@@ -4777,4 +4777,143 @@ TEST_F(test_gdal, ReadRaster)
     }
 }
 
+// Test GDALComputeRasterMinMaxLocation
+TEST_F(test_gdal, GDALComputeRasterMinMaxLocation)
+{
+    GDALDatasetH hDS = GDALOpen(GCORE_DATA_DIR "byte.tif", GA_ReadOnly);
+    ASSERT_NE(hDS, nullptr);
+    GDALRasterBandH hBand = GDALGetRasterBand(hDS, 1);
+    {
+        double dfMin = 0;
+        double dfMax = 0;
+        int nMinX = -1;
+        int nMinY = -1;
+        int nMaxX = -1;
+        int nMaxY = -1;
+        EXPECT_EQ(GDALComputeRasterMinMaxLocation(hBand, &dfMin, &dfMax, &nMinX,
+                                                  &nMinY, &nMaxX, &nMaxY),
+                  CE_None);
+        EXPECT_EQ(dfMin, 74.0);
+        EXPECT_EQ(dfMax, 255.0);
+        EXPECT_EQ(nMinX, 9);
+        EXPECT_EQ(nMinY, 17);
+        EXPECT_EQ(nMaxX, 2);
+        EXPECT_EQ(nMaxY, 18);
+        GByte val = 0;
+        EXPECT_EQ(GDALRasterIO(hBand, GF_Read, nMinX, nMinY, 1, 1, &val, 1, 1,
+                               GDT_Byte, 0, 0),
+                  CE_None);
+        EXPECT_EQ(val, 74);
+        EXPECT_EQ(GDALRasterIO(hBand, GF_Read, nMaxX, nMaxY, 1, 1, &val, 1, 1,
+                               GDT_Byte, 0, 0),
+                  CE_None);
+        EXPECT_EQ(val, 255);
+    }
+    {
+        int nMinX = -1;
+        int nMinY = -1;
+        EXPECT_EQ(GDALComputeRasterMinMaxLocation(hBand, nullptr, nullptr,
+                                                  &nMinX, &nMinY, nullptr,
+                                                  nullptr),
+                  CE_None);
+        EXPECT_EQ(nMinX, 9);
+        EXPECT_EQ(nMinY, 17);
+    }
+    {
+        int nMaxX = -1;
+        int nMaxY = -1;
+        EXPECT_EQ(GDALComputeRasterMinMaxLocation(hBand, nullptr, nullptr,
+                                                  nullptr, nullptr, &nMaxX,
+                                                  &nMaxY),
+                  CE_None);
+        EXPECT_EQ(nMaxX, 2);
+        EXPECT_EQ(nMaxY, 18);
+    }
+    {
+        EXPECT_EQ(GDALComputeRasterMinMaxLocation(hBand, nullptr, nullptr,
+                                                  nullptr, nullptr, nullptr,
+                                                  nullptr),
+                  CE_None);
+    }
+    GDALClose(hDS);
+}
+
+// Test GDALComputeRasterMinMaxLocation
+TEST_F(test_gdal, GDALComputeRasterMinMaxLocation_byte_min_max_optim)
+{
+    GDALDatasetUniquePtr poDS(GDALDriver::FromHandle(GDALGetDriverByName("MEM"))
+                                  ->Create("", 1, 4, 1, GDT_Byte, nullptr));
+    std::array<uint8_t, 4> buffer = {
+        1,    //////////////////////////////////////////////////////////
+        0,    //////////////////////////////////////////////////////////
+        255,  //////////////////////////////////////////////////////////
+        1,    //////////////////////////////////////////////////////////
+    };
+    GDALRasterIOExtraArg sExtraArg;
+    INIT_RASTERIO_EXTRA_ARG(sExtraArg);
+    EXPECT_EQ(poDS->GetRasterBand(1)->RasterIO(
+                  GF_Write, 0, 0, 1, 4, buffer.data(), 1, 4, GDT_Byte,
+                  sizeof(uint8_t), 1 * sizeof(uint8_t), &sExtraArg),
+              CE_None);
+
+    double dfMin = 0;
+    double dfMax = 0;
+    int nMinX = -1;
+    int nMinY = -1;
+    int nMaxX = -1;
+    int nMaxY = -1;
+    EXPECT_EQ(poDS->GetRasterBand(1)->ComputeRasterMinMaxLocation(
+                  &dfMin, &dfMax, &nMinX, &nMinY, &nMaxX, &nMaxY),
+              CE_None);
+    EXPECT_EQ(dfMin, 0);
+    EXPECT_EQ(dfMax, 255);
+    EXPECT_EQ(nMinX, 0);
+    EXPECT_EQ(nMinY, 1);
+    EXPECT_EQ(nMaxX, 0);
+    EXPECT_EQ(nMaxY, 2);
+}
+
+// Test GDALComputeRasterMinMaxLocation
+TEST_F(test_gdal, GDALComputeRasterMinMaxLocation_with_mask)
+{
+    GDALDatasetUniquePtr poDS(GDALDriver::FromHandle(GDALGetDriverByName("MEM"))
+                                  ->Create("", 2, 2, 1, GDT_Byte, nullptr));
+    std::array<uint8_t, 6> buffer = {
+        2, 10,  //////////////////////////////////////////////////////////
+        4, 20,  //////////////////////////////////////////////////////////
+    };
+    GDALRasterIOExtraArg sExtraArg;
+    INIT_RASTERIO_EXTRA_ARG(sExtraArg);
+    EXPECT_EQ(poDS->GetRasterBand(1)->RasterIO(
+                  GF_Write, 0, 0, 2, 2, buffer.data(), 2, 2, GDT_Byte,
+                  sizeof(uint8_t), 2 * sizeof(uint8_t), &sExtraArg),
+              CE_None);
+
+    poDS->GetRasterBand(1)->CreateMaskBand(0);
+    std::array<uint8_t, 6> buffer_mask = {
+        0, 255,  //////////////////////////////////////////////////////////
+        255, 0,  //////////////////////////////////////////////////////////
+    };
+    EXPECT_EQ(poDS->GetRasterBand(1)->GetMaskBand()->RasterIO(
+                  GF_Write, 0, 0, 2, 2, buffer_mask.data(), 2, 2, GDT_Byte,
+                  sizeof(uint8_t), 2 * sizeof(uint8_t), &sExtraArg),
+              CE_None);
+
+    double dfMin = 0;
+    double dfMax = 0;
+    int nMinX = -1;
+    int nMinY = -1;
+    int nMaxX = -1;
+    int nMaxY = -1;
+    EXPECT_EQ(poDS->GetRasterBand(1)->ComputeRasterMinMaxLocation(
+                  &dfMin, &dfMax, &nMinX, &nMinY, &nMaxX, &nMaxY),
+              CE_None);
+    EXPECT_EQ(dfMin, 4);
+    EXPECT_EQ(dfMax, 10);
+    EXPECT_EQ(nMinX, 0);
+    EXPECT_EQ(nMinY, 1);
+    EXPECT_EQ(nMaxX, 1);
+    EXPECT_EQ(nMaxY, 0);
+}
+
 }  // namespace

autotest/gcore/basic_test.py

@@ -987,3 +987,22 @@ def test_colorinterp():
         assert name not in d
         d[name] = c
         assert gdal.GetColorInterpretationByName(name) == c
+
+
+def test_ComputeMinMaxLocation():
+
+    ds = gdal.Open("data/byte.tif")
+    ret = ds.GetRasterBand(1).ComputeMinMaxLocation()
+    assert (
+        ret.min == 74
+        and ret.max == 255
+        and ret.minX == 9
+        and ret.minY == 17
+        and ret.maxX == 2
+        and ret.maxY == 18
+    )
+
+    ds = gdal.GetDriverByName("MEM").Create("", 1, 1, 1, gdal.GDT_Float64)
+    ds.GetRasterBand(1).Fill(float("nan"))
+    ret = ds.GetRasterBand(1).ComputeMinMaxLocation()
+    assert ret is None

doc/source/api/python_samples.rst

@@ -47,6 +47,7 @@ Python Raster Sample scripts
     - hsv_merge: Merge greyscale image into RGB image as intensity in HSV space.
     - gdal_ls: Display the list of files in a virtual directory, like /vsicurl or /vsizip
     - gdal_cp: Copy a virtual file
+    - gdal_minmax_location: returns the location where min/max values of a raster are hit.
 
 Python Vector Sample scripts
 ------------------------------

gcore/gdal.h

@@ -1670,6 +1670,10 @@ CPLErr CPL_DLL CPL_STDCALL GDALSetRasterScale(GDALRasterBandH hBand,
 CPLErr CPL_DLL CPL_STDCALL GDALComputeRasterMinMax(GDALRasterBandH hBand,
                                                    int bApproxOK,
                                                    double adfMinMax[2]);
+CPLErr CPL_DLL GDALComputeRasterMinMaxLocation(GDALRasterBandH hBand,
+                                               double *pdfMin, double *pdfMax,
+                                               int *pnMinX, int *pnMinY,
+                                               int *pnMaxX, int *pnMaxY);
 CPLErr CPL_DLL CPL_STDCALL GDALFlushRasterCache(GDALRasterBandH hBand);
 CPLErr CPL_DLL CPL_STDCALL GDALDropRasterCache(GDALRasterBandH hBand);
 CPLErr CPL_DLL CPL_STDCALL GDALGetRasterHistogram(

gcore/gdal_priv.h

@@ -1810,6 +1810,9 @@ class CPL_DLL GDALRasterBand : public GDALMajorObject
     virtual CPLErr SetStatistics(double dfMin, double dfMax, double dfMean,
                                  double dfStdDev);
     virtual CPLErr ComputeRasterMinMax(int bApproxOK, double *adfMinMax);
+    virtual CPLErr ComputeRasterMinMaxLocation(double *pdfMin, double *pdfMax,
+                                               int *pnMinX, int *pnMinY,
+                                               int *pnMaxX, int *pnMaxY);
 
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 #ifdef DOXYGEN_SKIP